ALJOIN Final Technical Report - Transport Research & Innovation ...

CONTRACT N° : G3RD-CT-2002-00829 

PROJECT N° : GRD2-2001-50065 

ACRONYM : ALJOIN 

FINAL TECHNICAL REPORT 

TITLE : CRASHWORTHINESS OF JOINTS IN ALUMINIUM RAIL VEHICLES 

PROJECT CO-ORDINATOR: D’APPOLONIA S.P.A. 

PARTNERS : 

D’APPOLONIA S.P.A. 

ADVANCED RAILWAY RESEARCH CENTRE (ARRC) – The University of Sheffield (before 1 

March 2004) 

NEWRAIL – The University of Newcastle (from 1 March 2004 onwards) 

ALCAN 

BOMBARDIER TRANSPORTATION 

DANSTIR 

THE WELDING INSTITUTE (TWI) 

REPORTING PERIOD : FROM 1 AUGUST 2002 TO 31 JULY 2005 

PROJECT START DATE : 1 AUGUST 2002 DURATION : 36 MONTHS 

Date of issue of this report : October 2005 

Project funded by the European Community under 

the ‘Competitive and Sustainable Growth’ 

Programme (1998-2002)

Contract N° G3RD-CT-2002-00829 

Final Technical Report – draft 1 

1. TABLE OF CONTENTS 

ALJOIN 1. TABLE OF CONTENTS ...................................................................................... 2 

2. EXECUTIVE PUBLISHABLE SUMMARY .......................................................... 3 

3. OBJECTIVES ...................................................................................................... 5 

4. SCIENTIFIC AND TECHNICAL DESCRIPTION OF THE RESULTS ................. 6 

4.1 Work Package 2: Performance Criteria ........................................................ 6 

4.2 WORK PACKAGE 3: EXISTING JOINT ASSESSMENT ................................ 8 

4.3 WORK PACKAGE 4A: STATIC MODELING OF JOINTS ............................ 11 

4.4 WORK PACKAGE 4B: DYNAMIC MODELING OF COMPONENTS AND 

STRUCTURES ...................................................................................................... 17 

4.5 WORK PACKAGE 5: NEW JOINING TECHNIQUES AND JOINTS ............ 24 

4.6 WORK PACKAGE 6: EXPLOITATION PRODUCTS AND STANDARDS .... 27 

4.7 WORK PACKAGE 7: METHOD FOR ASSESSING CRASHWORTHINESS 29 

4.8 WORK PACKAGE 8: DEMONSTRATORS ................................................... 30 

4.9 WORK PACKAGE 9: VALIDATION .............................................................. 33 

5. LIST OF DELIVERABLES ................................................................................ 38 

6. COMPARISON OF INITIALLY PLANNED ACTIVITIES AND WORK ACTUALLY 

ACCOMPLISHED ..................................................................................................... 40 

7. MANAGEMENT AND CO-ORDINATION ASPECTS ........................................ 42 

7.1 Project co-ordination ................................................................................... 42 

7.2 Man Power and Progress Follow-up Table ................................................ 43 

7.3 Work Plan ...................................................................................................... 48 

7.4 Updated contact details for the consortium .............................................. 49 

8. RESULTS AND CONCLUSIONS ...................................................................... 51 

2 

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2. EXECUTIVE PUBLISHABLE SUMMARY 

ALJOIN Aluminium alloys are now in widespread use in Europe and elsewhere for rail vehicle 

construction from commuter to express trains. The main contributor to the success of 

aluminium alloys as structural materials in rail transport, is the development of closed 

cell aluminium extrusions that can easily be welded together to form lightweight rail 

vehicles with high inherent rigidity that could not be achieved with older designs. 

As rail transport is becoming more popular throughout Europe, there is an increased 

need to improve passenger safety by improving the crashworthiness of rail vehicles to 

minimise fatalities and injuries if an accident does occur. 

The strength, integrity and performance of aluminium welds in rail vehicles contribute 

greatly to the overall body shell strength and crashworthiness. In recent collisions 

involving seam welded aluminium rail coaches, some of the longitudinal seam welds 

fractured for some meters beyond the zone of severe damage, the panels themselves 

generally being intact without significant distortion. 

The experts on crashworthiness agree (in Cullen report recommendation 57) that 

consideration should be given, in the case of new vehicles constructed of aluminium, to 

the following: 

• use of alternatives to fusion welding; 

• use of improved grades of aluminium less susceptible to fusion weld 

weakening; 

• further development of analytical techniques to increase confidence in the 

crashworthiness of rail vehicle structures, particularly those constructed of 

aluminium. 

The strategy that ALJOIN used to approach the problem can be described as follows: 

• creation of performance criteria for the properties of aluminium welds in 

the new generation of rail vehicles in terms of their stress/strain 

performance; 

• assessing the existing methods of joining techniques and joints; 

• static and dynamic modelling of joints and structures; 

• formulating new joining techniques and joints; 

• definition of a method for assessing crashworthiness; 

• demonstration and validation of the innovative technologies developed 

against the performance criteria. 

Real improvements in the safety of rail vehicles, introduction of innovative techniques for 

aluminium welding and improvements in the crashworthiness of the new generation of 

rail vehicles are among the main ALJOIN outputs. 

3



ALJOIN The expected impact is a real improvement in the safety of the new generations of rail 

vehicles, contributing to the safety of European citizens as well as to the EC policies in 

safety issues and standardisation of the materials and aluminium welding methods used 

in the rail industry. 

The duration of the ALJOIN project was three years. In the first year ALJOIN was 

dedicated to the research phase where a thorough investigation of existing joint designs 

and joining techniques was carried out. This has revealed shortcomings in existing joint 

designs. 

First is the adverse effect of using partial penetration welds, which act as crack initiators 

facilitating the process of dynamic tear of welds under impact loading and second, the 

use of Al-Si filler wire (allowed by current manufacturing standards) which produces 

welds with lower strength, ductility and fracture toughness compared to welds produced 

with Al-Mg filler wires. 

The second year of the work concentrated on the understanding of the fundamental 

properties of aluminium weldments and an investigation of the performance of alternative 

joining techniques such as adhesive bonding, bolted joints, laser welding and friction stir 

welding. With the exception of adhesive bonding, which from an early stage proved 

unsuitable for rail vehicle construction, the determined joint properties were used for the 

development of analytical failure models and validated with component tests. The 

modelling efforts have produced a very close agreement between experiment and 

prediction. The modelling procedure was then used to examine solutions for improved 

joint performance. 

The final year of the project has concentrated on modelling efforts to simulate rail vehicle 

impact with and without the implementation of the recommendations for improved joint, 

as they arose from the previous work. 

Furthermore an experimental methodology for assessing the dynamic loading 

performance of joints was developed which can be used as a method of "ranking" the 

impact performance of various joint designs. The experimental results were also used to 

further validate model predictions. 

The major outputs from this work can be summarised as follows: 

• The stress levels at the weld region should be brought close to those of 

the parent plate, through thickening of the aluminium plate at the weld 

region. The precise amount of thickening would depend on alloy grade 

and welding procedure. 

• Friction stir welding (FSW) and MIG welding with Al-Mg filler wire are the 

best performing joining methods in terms of crashworthiness as long as 

the above recommendation is implemented. 

• Aluminium alloys other than the 6005 alloy in the T6 temper have not 

provided any appreciable improvement in joint strength. 

4



3. OBJECTIVES 

ALJOIN The aim of the project can be summarised to provide sufficient knowledge to design cost 

effective aluminium rail vehicle bodies that will not fail by catastrophic joint failure under 

extreme loading. To achieve such overall goal several specific objectives were 

addressed: 

• To determine the performance specifications required by critical 

aluminium joints in rail vehicle cars to ensure the structural integrity; 

• To provide physical evidence of the energy absorption capability of 

aluminium alloy welds by testing; 

• To investigate performance and failure criteria for aluminium welded and 

bolted joints; 

• To explain test results assessing the adequacy or inadequacy of current 

design and construction practices of aluminium alloy welds in the context 

of crashworthiness; 

• Implementation and validation of material failure models for welds of 

aluminium alloys; 

• Definition of the main material and structural parameters which can 

influence the mechanical behaviour of the joints; 

• Development of the material constitutive modelling for the parent material 

and the material in the welded volume; 

• Numerical modelling of simple joints subjected to axial and transversal 

forces; 

• Numerical analysis of components and structures subjected to quasistatic 

and impact (dynamic) loading conditions in order to evaluate the 

structural response in terms of mean axial crushing force, total energy 

absorption, load efficiency and uniformity, deformation mechanism. 

• To investigate alternative welding techniques and/or joint designs for 

improved joints of aluminium alloys. 

5



4. SCIENTIFIC AND TECHNICAL DESCRIPTION OF THE RESULTS 

4.1 Work Package 2: Performance Criteria 

Introduction 

ALJOIN The future of aluminium in rail vehicles will depend on the performance of aluminium 

joints. The objective of this Work Package was to determine the performance 

specifications required by critical aluminium joints in rail vehicle cars to ensure the 

structural integrity and the crashworthiness of the vehicles and to determine the 

improved future performance required of the new crashworthy aluminium rail vehicles. 

Aluminium is currently one of the preferred materials for rail vehicle manufacture. 

Aluminium railway carbodies are manufactured from longitudinal extrusions which are 

traditionally joined by automated metal inert gas (MIG) welding or bolting. The 

advantages of using aluminium extrusions in the manufacture of rail vehicles are the 

highly efficient assembly methods and the significant weight savings, whereas a 

disadvantage is the potential crashworthy performance. There have been cases where 

aluminium rail vehicles have been involved in accidents where, the energy absorption 

devices appeared to have failed to operate effectively. The failure of these devices is 

thought to be due to the breakdown of the supporting carbodies structural integrity. 

Energy absorption devices can only operate effectively if the structural integrity of the 

bodyshell is maintained. With current aluminium rail vehicles manufactured from full 

length extruded sections, the structural integrity of the bodyshell is dependant on the 

crashworthiness performance of the joints between the extrusions. There is an increased 

effort to improve the crashworthy performance of aluminium rail vehicles and the 

research is being concentrated to improve the joints and refine the analytical modelling 

of these joints in crash scenarios. 

Description of Results 

The requirements for aluminium joints are directly related to the crashworthiness 

performance of the vehicle, since they contribute to the structural integrity of the 

bodyshell. In current designs of aluminium railway vehicles, the typical longitudinal joints 

are either welded or bolted. Various techniques are available for welding and bolting 

carbody structures to form a shell. Currently the most widely used welding techniques 

are MIG, Twin Wire MIG and Friction Stir Welding (FSW). Typical bolted joints use Huck 

Bolt connections. Figure 1 shows a typical bodyside/floor Huck Bolt connection being 

assembled. 

6



ALJOIN Figure 1: Current vehicle floor structure (left) and bodyside/floor Huck Bolted 

(Bombardier) 

The European standards that target the design of rail vehicles and the welding 

procedure for metallic materials do not detail the performance criteria of the joints in 

aluminium rail vehicles. The standards and requirements of reference to be taken into 

account comprise the following: 

• BS 8118: Part 1 (1991) “Structural use of Aluminium”; 

• BS 288-4 (1992) “Welding procedures for metallic materials”; 

• Euronorm CEN 256 / BS-EN 12663 (2000) “Structural requirements of 

railway vehicle bodies” 

• TSI 96/48 – ST05 part 2 “Passive Safety Crashworthiness” 

• Railtrack Safety & Standard GM/RT 2100: part 3 (October 2000), 

“Structural requirements for railway vehicles”. 

When a new weld is first designed it has to satisfy British/EN standard 288-4. One of the 

major concerns about the current situation is that the mechanical properties and crash 

performance of the weld and heat affected zones are not understood. Improvements in 

knowledge of these properties would give numerical modellers more confidence in the 

results from analytical models. From the standards examined there is no specific 

requirement to generate detailed performance criteria for the joints in rail vehicles, but 

there is a need to understand the properties of the joints to improve the crashworthiness. 

To achieve this a comprehensive testing plan of current MIG welds is proposed which 

involves static, quasi-static and dynamic testing, all will give valuable information and will 

go towards addressing the lack of understanding of current joints. The results from 

testing should characterise the parent metal, the weld and the heat affected zones and 

this information will be used in two areas. Primarily the data will be used to establish a 

benchmark for future work, where the use of new joining techniques and different 

aluminium alloys will be investigated. Secondly the results will be used to refine the 

current analysis techniques, so the elements representing the weld region in crash 

scenarios are fully validated with experimental work. Once confidence has been 

established in relating test results to element properties, similar procedures can be used 

when changes are made to the joining process or the material. 

7



ALJOIN In an ideal situation the joint should not be the ‘weakest link’ in the bodyshell, put simply 

‘Joint performance should be equal to that of the parent metal’. 

4.2 WORK PACKAGE 3: EXISTING JOINT ASSESSMENT 

Introduction 

Carbodies of rail passenger vehicles have been manufactured using welded 6000 series 

aluminium alloy extrusions for many years in the UK and Europe. Although welded joints 

designed to conventional codes have performed satisfactorily under the normal 

operational loads, it is less certain how welded joints would behave under extreme 

loading conditions. In recent accidents involving welded aluminium rail vehicles, 

observations showed that some of the longitudinal welds had fractured for some metres 

beyond the zone of severe damage. There is a lack of knowledge in the design of 

welded joints for high rate loading situations. The objective of this work package are 

therefore: 

• To provide physical evidence of energy absorption capability, or 

incapability, of aluminium alloy welds by joint tests. 

• To establish failure criteria of aluminium welded joints. 

• To investigate performance and failure criteria of aluminium bolted joints. 

• To explain structural performance observed in joint tests. 

• To asses the adequacy on inadequacy of current design and construction 

practices of aluminium alloy welds in the context of crashworthiness. 

The MIG process is the main welding process employed by the industry today in the UK 

and Europe. Either silicon or magnesium alloyed fillers are recommended for the welding 

of 6000 series aluminium alloys, but this does not mean that the welds will perform as 

well as the parent material. There is a need to investigate the effects of the filler material 

on the structural behaviour of the welds. 

Description of results 

Materials and weld production 

The aluminium alloy used in the present work was EN AW 6005A-T6. Extrusions of this 

alloy are widely used for the construction of the carbody of rail passenger vehicles. 

Some ten meters of welds were produced with the MIG process using either aluminiumsilicon 

or aluminium-magnesium filler. These were butt welds in either 6mm thickness 

extruded plates or rail vehicle floor extrusions. 

Material characterisation testing 

Material characterisation tests were conducted to investigate material behaviour in the 

parent material, the weld metal and the HAZ of the MIG welds. These included hardness 

surveys, tensile testing, Charpy impact testing and fracture resistance testing. 

8



ALJOIN The hardness of the parent material was about 100HV5. The reduction in hardness 

values of the weld metal and the HAZ was confirmed in the hardness tests. The lowest 

hardness value in the welds made using aluminium-silicon filler was about 45HV at the 

weld centre line. The lowest hardness value in the welds made using aluminiummagnesium 

filler was about 60HV at a distance of 5 to 10mm from the weld centre line in 

the HAZ. The width of the zone of reduced hardness was about 30-40mm. 

The parent material tensile properties as tested in transverse specimens were slightly 

different from those in the longitudinal specimens, which suggested that the parent 

material extrusion was slightly anisotropic. The specimen-to-specimen variation of the 

tensile properties of the HAZ was relatively large. The lowest average 0.2% proof 

strength, ultimate strength and area reduction were from the weld metal of weld made 

using the aluminium-silicon filler. Although the weld metal 0.2% proof strength of the 

weld made using aluminium-magnesium filler was about 55% of that of the parent 

material, its ultimate strength was slightly higher than that of the parent material. The 

elongation of the HAZ at the maximum load was relatively low, only 4 to 5%, and the 

weld metals elongated a relatively small amount after the maximum load. 

Tensile testing of notched cylindrical specimens was carried out for weldments made 

using aluminium-silicon or aluminium-magnesium filler. Figure 2 shows the tensile 

testing set-up at NEWRAIL. Fracture strains as a function of stress triaxiality were 

obtained for the different zones in the welded joints. 

Figure 2: Tensile testing set-up (NEWRAIL) 

The average Charpy value of the base material was about 6 Joules. The lowest Charpy 

energy, 5Joules, was from the aluminium-silicon filler weld metal. The highest average, 

18Joules, was from the weld metal of the aluminium-magnesium filler weld. The variation 

of the Charpy energy of the HAZ was relatively large, while the Charpy energy values of 

the weld metals and the parent material varied little. 

Some seventy single edge notch bend specimens were tested under either quasi-static 

or dynamic loading. Different effects were found in the J R-curves of the three material 

zones, i.e. the parent material, the weld metal and the fusion boundary. For the parent 

material, the magnitudes of J under dynamic loading were higher than those under 

quasi-static loading for the same amount of crack extension, but the slopes of the trend 

lines of the J R-curves were quite similar. For the aluminium-silicon filler weld metal and 

the associated fusion boundary, the J values under dynamic loading were generally 

9



ALJOIN higher than those under quasi-static loading for crack extensions of less than 1.5mm. 

They tended to be lower when the crack extension was greater than 1.5mm, and the 

trend lines of the J values under the dynamic loading were flatter. For the aluminiummagnesium 

filler weld metal and the associated fusion boundary, the J values under 

dynamic loading were generally lower than those under quasi-static loading for crack 

extensions of less than 1mm. They tended to be higher, when the crack extension was 

greater than 1.5mm, and the trend lines of the J values under the dynamic loading were 

steeper. 

Joint and component testing 

Cross weld tensile specimens were extracted from welded rail vehicle floor extrusion and 

tested under quasi-static tensile loading. Plastic strain changes were monitored 

continuously during the testing and fracture locations were recorded. 

Welded joint components were extracted from the welded rail vehicle floor extrusions. 

Component behaviour was investigated under axial quasi-static crush and drop weight 

impact loading. The loading mode in these tests was predominately axial compression. 

The welds in the rail vehicle floor extrusions did not fail catastrophically by fracture, 

although severe plastic deformation occurred in the parent material. Local buckling 

developed at the attainment of the maximum load. This was followed by tearing damage 

in the local buckling area, particularly in the parent material at corners where the internal 

web met the external skin. 

Testing of bolted joints were developed with the aim of providing test data for finite 

element simulation of failure in bolted joints. Tests have comprised testing of bolted 

tubes subjected to axial impact (Figure 3 shows the example of damage joints after 

testing done at TWI) and bolted joint tearing tests (Figure 4 shows the results of testing 

and some details of the failure mode. 

Figure 3: example of damage joints after testing (TWI) 

10



Main Conclusions 

Figure 4: Result of test and detail of bolt 1 failure (NEWRAIL) 

ALJOIN Damage and final fracture will most likely be confined to the weld metal, the HAZ and /or 

the interface between the two in MIG welded joints, which are designed for normal 

operation loads, in a event of crash generating sufficient load normal to the weld, mainly 

because strength undermatch. Al-Si weld metal is shown to have poor strength and poor 

fracture toughness relative to the base material, the HAZ and the Al-Mg weld metal. The 

present results have provided some explanation for the material aspect in real life weld 

failures such as those in the Ladbroke Grove accident. 

It is clear from the test results that the mechanical properties of the MIG welds made 

with aluminium-magnesium filler metal in 6005A-T6 aluminium alloy extrusions were 

superior in terms of strength, ductility and fracture toughness to those made with 

aluminium-silicon filler metal. But there is limited scope for improvement of the 

mechanical properties of the HAZ, particularly strength, as long as a fusion welding 

process is employed. 

4.3 WORK PACKAGE 4A: STATIC MODELING OF JOINTS 

Introduction 

The failure process of aluminium alloys involves void nucleation, growth and 

coalescence. Failure mechanisms are investigated in WP3 by metallurgical and 

microstructural examinations. Potential failure criteria are studied for implementation and 

validation. The prediction of the fracture mechanism occurring in the welded regions is 

11



ALJOIN used to evaluate the progressive failure of the whole component that can occur without 

significant yielding in the base material and in some cases under elastic stresses. 

This work package aims to deliver: 

• material failure models for aluminium alloy welds; 

• constitutive model of the different welded joints; 

• numerical results of simple joints subjected to axial and transverse forces. 

Description of results 

Material Failure Models 

Dimpled rupture is a failure mode of aluminium alloys. It is strongly influenced by stress 

triaxiality and by the volume fraction of inclusions and second phase particles. 

There are two material failure models used widely for modelling of dimpled rupture, 

namely the Hancook and Johnson & Cook model and the Gurson-Tvergaard model. In 

the former, the fracture strain is expressed by the following equation: 

σ 

= D1 

+ D2EXP( 

D 

σ 

f 

ε 3 

where σm is the mean stress and σvM is the von Mises equivalent stress. σm/σvM is term 

stress triaxiality in the literature. D1, D2 and D3 are material constants. 

This model predicts the fracture strain decreases exponentially with increasing stress 

triaxiality, but the material damage before the final fracture is not modelled. The damage 

is a result of the nucleation and growth of voids at inclusions and second phase 

particles. Fracture is the final stage of this progressive damage process. 

The Gurson-Tvergaard model provides a means of modelling the progressive damage. 

The essence of the Gurson-Tvergaard model is contained in the yielding function below: 

⎛ 

F ⎜ 

σ 

= 

⎜ 

⎝ σ 

2 

⎞ 

e ⎟ 

2 

3f 

⎟ 

y 

⎠ 

m 

vM 

⎛ q2 

3 ⎞ 

m 

2 q1f 

cosh⎜ 

σ 

+ 

− ⎟ − ( 1+ 

q 

⎜ 2 ⎟ 

⎝ σy 

⎠ 

This yield function contains both the stress triaxiality and void volume fraction, which are 

the two major factors in the dimpled rupture. Details of the two models will be discussed 

in a final report for work package 4. Some of the numerical results using these two 

failure models for fracture modelling are given below. 

Numerical Simulation of Notched cylindrical specimen under tension 

Fracture characterisation was carried out using a series of notched cylindrical 

specimens. Results of load versus displacement were used to determine values of the 

parameters in the Gurson-Tvergaard model through a calibration. 

12 

) 

)



ALJOIN There were three specimens in a series. The diameter at the minimum section was 3mm 

and the three notch radii are 2, 6 and 10mm, respectively. Finite element meshes for the 

three notched cylindrical specimens are shown in Figure 5. Each of the finite element 

models with axi-symmetrical elements represents one half of the corresponding 

cylindrical specimen. The plane at the minimum diameter is a symmetrical plane, where 

displacements in the vertical direction were set zero in the finite element analyses. 

(a) (a) (a) 

Figure 5: Finite element mesh for notched cylindrical specimen with minimum neck 

radius a=1.5mm: (a) R=2mm; (b) R=6mm; and (c) R=10mm 

Values of Young’s modulus and Poisson’s ratio used in the analyses for the parent 

material 6005A-T6 were equal to 60GPa and 0.3, respectively. The true stress versus 

true plastic strain was described by the following equation: 

σ = σ + αε / ε ) 

0. 2( 

0. 

2 1 

where σ0.2=262MPa, ε0.2=σ0.2/E, α=0.15 and ß=0.135. 

Best estimate values for the parameters in Gurson-Tvergaard model for the parent 

material 6005A-T6 are summarised in Table 1. 

Table 1 Best estimate values for the parameters in Gurson-Tvergaard model 

q1 q2 q3 εN SN fN fc fN 

1.5 1.0 2.25 0.10 0.01 0.04 0.08 0.2 

The measured and computed results of load versus axial displacement in a gauge length 

of 12.5mm are compared in Figure 6. The agreement between the measured and 

computed curves is not excellent and needs to be improved. Nevertheless, the calibrated 

Gurson-Tvergaard model provides a basis for modelling fracture of the parent material 

6005A-T6. 

13 

β



Axial load, kN 

4.0 

3.0 

2.0 

1.0 

0.0 

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 

Axial displacement (12.5mm gauge length), mm 

ALJOIN a1.5R2 - Test data (M11-39) 

a1.5R6 - Test data (M11-40) 

a1.5R10 - Test data (M11-41) 

a1.5R2 FEA GT 19 

a1.5R6 FEA GT19 

a1.5R10 FEA GT 19 

Figure 6: Comparison of measured and computed load versus displacement curves for 

notch cylindrical specimen under tension 

Numerical Simulation of single edge notched specimen under bending 

Finite element analyses were carried out to predict crack propagation using the above 

calibrated Gurson-Tvergaard model in a single edge notch bend (SENB) specimen of 

the parent material 6005A-T6 under three point bending. Dimensions of the SENB 

specimen are 5mm thickness, 15mm width and 60mm span. The ratio of initial crack 

depth to specimen width is 0.35. 

A three-dimensional finite element model for the SENB specimen is shown in Figure 7. 

It is only necessary to model one quarter of the specimen geometry because of the 

double symmetry. The linear strain brick elements are used. 

Load Line 

Figure 7: Finite element mesh for a quarter of a SENB specimen (B=5mm, W=15mm, 

a/W=0.35, S=4W) 

14 

Support



ALJOIN The shape and position of the crack front are illustrated in Figure 8 for different amounts 

of load line displacement. The initial crack advanced about 0.15mm at the mid-thickness 

when the load line displacement was 0.86 ΔPmax, where ΔPmax is the load line 

displacement at the maximum load sustained in the specimen. The crack continued to 

advance as the load line displacement increased. The initially straight crack front 

became a curved line with much smaller amounts of crack extension near the outside 

surface than in the mid-thickness. 

Current crack front 

Initial crack front 

(a) (b) 

(c) 

Mid-Thickness plane 

Figure 8: Shape and position of current crack front: (a) D=0.87DPmax; (b) D=DPmax; (c) 

D=1.4DPmax 

Rail vehicle floor component under quasi-static crush 

Quasi-static testing of the rail vehicle floor extrusion component is described in detail in 

the report for work package 3. The testing was simulated using the general purpose 

finite element ABAQUS. A deformed shape of the rail vehicle floor component at the 

maximum applied load is shown in Figure 9. This is very similar to the deformed shape 

of the tested specimens. A comparison of the measured and computed load versus 

displacement curves is also given in Figure 9. 

load (kN) 

1200 

1000 

800 

600 

400 

200 

fine mesh - modes 1 to 10 imperfections 

experimental data after machine stiffness and non-linearity correction 

0 

0 1 2 3 4 5 6 7 8 9 

displacement (mm) 

Figure 9: Deformed shape of rail vehicle floor component and Comparison of measured 

and computed load versus displacement curve 

15



Rail vehicle floor component under drop weight impact 

ALJOIN Drop weight impact testing of the rail vehicle floor extrusion component was simulated 

using the general purpose finite element ABAQUS. A finite element model for the 

simulation and a comparison of the measured and computed load versus time curves is 

given in Figure 10. 

Specimen 

Drop mass 

anvil 

Ground concrete support 

Load, kN 

900 

800 

700 

600 

500 

400 

300 

200 

100 

0 

FEA 

0 2 4 6 8 

Time, ms 

Test (W05-05) 

Figure 10: Finite element model for drop weight impact testing (left) and Comparison of 

measured and computed load versus time curves 

Single bolt lap joint under tension 

Finite element analyses were carried out for a single bolt lap joint of the parent material 

6005A-T6 under tension. A finite element model is shown in Figure 11. The bolt pretension 

was simulated with a temperature field. The friction forces between the mating 

parts were modelled using contact modelling capability. Progressive damage in the joint 

as loading increases was modelled using the Gurson-Tvergaard model. The fractured 

joint is shown in Figure 11. 

Figure 11: Finite element model for single bolt lap joint and fracture simulation 

16 

10



ALJOIN 4.4 WORK PACKAGE 4B: DYNAMIC MODELING OF COMPONENTS AND 

STRUCTURES 

Introduction 

Dynamic modelling of small- and full-scale structures and analysis of correlation between 

design parameters and crashworthiness. The modelling work reflects the performance 

criteria defined in WP2. Structures to be modelled comprise thin-walled members and 

sandwich members with various types of cross sections in which the influence of the 

welding is studied. 

Objective of this work package is to design and model crashworthy structures which 

deform under a controlled force and preserve sufficient survival space around the 

occupants to limit body injury during an accident. To perform numerical analysis of 

components and structures subjected to quasi-static and impact loading conditions in 

order to evaluate the structural response in terms of mean axial crushing force, total 

energy absorption, deformation mechanism. To review of load conditions, rates of strain 

and modes of deformation of aluminium alloy welds of the rail vehicle under crash and 

derailment scenarios. 

The activities performed included: 

• Plain and Notched Tensile Tests 

• CTOA tearing tests 

• Tearing tests of bolted joints 

• Bolted Tubes subjected to axial impact 

• Cleavage tests 


Plain and Notched Tensile Tests 

Simulations of plain and notched tensile tests have been carried out to analyse mesh 

sensitivity and to verify the possibility of the Gurson model implemented in LS-DYNA to 

take into account different mesh sizes. The procedure used for the determination of the 

Gurson parameters was to start fixing most of the parameters (q1=1.5, q2=1, fN=0.01, 

En=0.3, Sn=0.1) and using the experimental results of load vs. axial displacement to 

determine the values of the remaining parameters (F0 and Fc) by best fit. An element 

size dependent function for Ff (failure void volume fraction) was defined based on finite 

element simulation of the tensile test results with 4 or 5 meshes of different sizes (see 

Figure 12). Figure 13 shows the simulation of the failure of a notched specimen (notch 

radius 2 millimetres) subjected to tensile loading. 

17



Figure 12: Meshes of 2 mm notched specimen 

ALJOIN Figure 13: Simulation of failure of notched specimen subjected to tensile loading 

CTOA tearing tests 

Numerical analyses considered the Crack Tip Opening Angle (CTOA) tearing tests 

carried out by ARRC. Testing was performed on 250 kN Mayes testing machine with a 

strain rate of 0.02mm/second. Figure 14 shows testing equipment and the detail of the 

crack growth along the weld and at the interface between the weld and the HAZ. Figure 

18



ALJOIN 15 shows the specimen geometry. Specimens were taken from the railway vehicle 

double skinned extrusions so that a crack initiator could be centred in one of the relevant 

zones: parent metal, HAZ and weld. The gauge section was machined to 2mm thick to 

remove any evidence of variation in the extrusion process and ensure flatness. Samples 

had a crack initiator machined in the centre of the gauge section to start the initial crack 

in different zones: the parent metal, the weld and the HAZ. 

Figure 14: CTOA testing set-up (left) and details of crack growth along the weld (up) and 

at the interface between HAZ and weld 

Figure 15 Crack Tip Opening Angle (CTOA) tearing tests (ARRC) 

19



ALJOIN The numerical analyses were carried out using the both the LS-DYNA explicit code and 

the FRANC2D code. Figure 16 shows the results of the analysis, in terms of distribution 

of the Von Mises equivalent stress, demonstrating the crack propagation along the 

centreline of the specimen. Figure 17 shows the results of the simulations done using 

the FRANC2D code 1 which allows to explicitly model the crack propagation in the mesh. 

As the cracks propagate, automatic remeshing algorithms delete the mesh local to the 

crack tip, extend the crack, and build a new mesh around the new tip. The constant 

critical crack tip opening angle (CTOA) fracture criterion was used in the simulations. 

The CTOD fracture criterion assumes that the crack growth will occur when the angle 

made by the upper crack surface, the crack tip, and the lower crack surface reaches a 

critical value. In a two-dimensional analysis, the displacement δ, perpendicular to the 

crack, at a fixed distance d behind the crack tip are monitored during the analytical 

loading of the model. When the displacements are such that the critical angle CTOA 

(ψC) is attained (see equation 1), the crack is advanced by releasing the crack tip nodes 

until a total distance d of crack growth is achieved. 

−1⎛ 

δ ⎞ 

ψ C = 2 tan ⎜ ⎟ 

(1) 

⎝ d ⎠ 

Then, the applied displacements are held constant while the internal forces are returned 

to equilibrium. At each load increment, the CTOA was calculated and compared to a 

critical value. When the CTOA exceeded this critical value, the crack-tip node was 

released and the crack advanced. 

t = 0.6 s 

t = 2.0 s 

Figure 16 Numerical Analysis of Crack Tip Opening (CTOA) tearing tests (Von Mises 

Equivalent Stress) 

1 Swenson D., James M., “FRANC2D/L: A Crack Propagation Simulator for Plane Layered Structures 

Version 1.4 User's Guide”, Kansas State University •Manhattan, Kansas 

20



ALJOIN Figure 17 Numerical Analysis of CTOA tearing tests showing crack running along the 

weld (left) and crack deviating towards the weld/HAZ interface 

Tearing tests of bolted joints 

The aim of these numerical analyses was to assess the existing criteria for the 

simulation of bolted joints in dynamic loading conditions and validate the approach which 

has been selected to model the bolted joints. 

The activities performed include: 

• numerical simulations of the tearing tests; 

• validation of the material model; 

• critical review and analysis of the results. 

Several simulations have been performed, considering both shell and solid elements to 

mesh the specimen. The bolts have been modelled using solid elements. The 

numerical results are in good agreement with the experimental results. In particular 

Figure 18 shows the results of the simulation in terms of global deformation and failure 

mode, which correspond to the real behaviour (see Figure 4). Figure 19 reports the 

comparison of the diagram of force versus displacements corresponding to three tests 

and the numerical prediction. The numerical model is able to predict with a good 

accuracy the peak force corresponding to the failure of the bolts. The difference in terms 

of displacements is due to the pre-load in the bolts, not considered in the model. 

21



ALJOIN Figure 18 Results of the simulation of tearing tests of bolted joints – deformed structure 

Figure 19: Tearing tests of bolted joints - comparison of measured and computed load 

versus displacement curves 

Bolted tubes subjected to axial impact 

The work performed consisted mainly in: 

• Selection of standard aluminium extrusions to be provided by ALCAN for the 

preparation of the samples; 

• Definition of small-scale sample geometry to obtain tubular bolted structures for 

dynamic impact testing (see Figure 20); 

• Design of the experiments: a fractional-factorial design of experiments using 

orthogonal arrays was selected. The factors comprise: the material and temper 

condition (AA 6005-T6 and 6008-T6), the number of bolts, and the impact 

velocity 

• Numerical analysis of the configurations selected. 

22



e 

d 

∅ = 6 mm bolt diameter 

e = 28 mm edge distance 

d = 24 mm 

e 

d 

t = 2.4 - 6 mm thickness 

thinnest outside ply 

Figure 20 Definition of small-scale bolted samples 

ALJOIN Figure 21 Numerical analysis of bolted joints subjected to axial impact – deformed 

structure (above) and comparison of measured and computed load versus time curves 

23



WP4B Overall comments 

ALJOIN • An extensive modelling work has been developed aiming at the definition 

of proper material models and simulation approaches for structures and 

joints under different loading conditions; 

• Simulations of tensile tests have been carried out to analyse mesh 

sensitivity and to verify the possibility of the Gurson model implemented in 

LS-DYNA to take into account different mesh sizes 

• Simulations of CTOA tearing tests, tearing tests of bolted samples, impact 

tests of bolted structures are in good agreement with test results. 

4.5 WORK PACKAGE 5: NEW JOINING TECHNIQUES AND JOINTS 

Introduction 

Conventional MIG welding processes and joint designs have been shown to be 

inadequate for the increasing demand of crashworthiness performance of rail vehicles. 

This has been highlighted by recent rail vehicle accidents. The need for alternative 

joining techniques and joint designs is reinforced by the findings in the work package 3 

(WP3) (existing joint assessment). The objectives of this work package (WP5) are: 

• investigate alternative welding techniques and/or joint designs for 

improved joints. 

• compare adhesive bonding and fraction stir welding with traditional 

methods. 

A review of all the emerging joining techniques was carried out and the results were 

discussed. Mechanical tests were carried out on the joints made using friction stir 

welding and adhesive bonding techniques. A new design for butt welded joints was 

proposed and is presented in the report, along with the use of finite element analyses to 

assist joint design. 


New joining techniques 

A review of MIG welding as well as laser and hybrid laser-arc processes for the 

fabrication of rail vehicle carbodies was carried out at TWI. For fusion welding 

processes it will not be possible to eliminate entirely the HAZ associated with Al alloy 

weldments. Hybrid laser-arc processes offer advantages over and above those of laser 

and arc processes individually, including: higher welding speeds leading to increased 

productivity and reduced distortion, improved weld quality (e.g. a reduced incidence of 

welding defects such as pores and cracks), increased penetration, and increased 

tolerance to fit-up, which is crucial in a production environment. For hybrid laser-arc 

processes, an appropriate selection of process parameters and filler wire is anticipated 

24



ALJOIN to lead to as-welded ultimate tensile strengths above those reported for laser welds 

(~60-80% of parent), with tensile failure occurring in the HAZ. 

Extruded plates (6mm thick) of 6005A-T6, 6008-T6 and 6008-T7 have been welded by 

friction stir welding (FSW) at DanStir (see Figure 22). The parent materials were 

supplied by ALCAN. The samples were welded in a butt-joint configuration with a 

backing bar to simulate the more common joint configuration in double-skin rail car 

structures. 

Figure 22 Welded extruded 6mm thick plate by friction stir welding at DanStir - overall 

view (left) and close-up showing backing bar 

Mechanical tests were performed to characterise material and joint mechanical 

behaviour. These included hardness survey, Charpy impact, fracture mechanics and 

cross weld tensile tests. Test results of FSW welds showed that: 

• Strength and elongation of the FSW welded joints were similar to those of 

the Al-Mg welded joints. 

• Fracture toughness of the FSW weld nugget was much better than that of 

the MIG weld metals. 

Adhesive bonded full-scale rail vehicle carbody components were manufactured. 

Preliminary tests were carried out under drop weight impact loading conditions. Peak 

loads sustained by the specimens ranged from 16 to 28kN, which were much lower than 

those sustained by the welded joints. 

New joint design 

The behaviour of partial penetration welds made by the MIG process was studied in the 

“cleavage” tests by Bombardier. These tests demonstrated that the most likely failure 

mode is weld fracture. Because of low fracture toughness of Al-Si weld metal as clearly 

shown in the small scale fracture mechanics tests, partial penetration welds made using 

Al-Si filler should not be used in safety critical components and structures. If there are no 

other options, but partial penetration weld, Al-Mg filler metal is preferred. The size of the 

weld should be such that the stresses in the weld metal should be similar to those in the 

other zones immediately adjacent to the weld metal. This can be achieved by joint 

geometry optimisation. An example of such a joint design is illustrated in Fig.11. 

Basically, the local weld zone area is “over sized”. 

25



ALJOIN Figure 23 An example of new joint design showing local thickened area circled 

Finite element analysis was employed to investigate the effect of weld over sizing on 

joint behaviour. The stress-strain data and failure models established in work package 3 

and 4 were used in the finite element analyses. It was shown that the minimum weld 

over sizing factor was 1.4, corresponding to a situation where the critical section is not in 

the joint (see Figure 24). 

No weld oversizing: failure in the HAZ 

Weld oversizing factor = 1.4: critical section not in 

the joint 

Weld oversizing factor = 1.2: failure in the HAZ 

Weld oversizing factor = 1.6: critical section not in 

the joint 

Figure 24 Finite element analysis of effect of joint geometry on fracture failure 

(D’Appolonia) 

Main Conclusions 

Many different joining/welding techniques, as an alternative to the conventional MIG 

process, were investigated for rail vehicle carbody construction. This work included 

reviews of AC-pulsed MIG, Tandem MIG, Low Stress No Distortion (LSND), Laser, and 

Hybrid laser-arc process, mechanical tests of welds made using Tandem MIG, FSW, 

26



ALJOIN Laser, and Hybrid laser-arc process, and drop weight impact tests of adhesive bonded 

joints. 

The review of various fusion welding techniques has suggested that the hybrid laser arc 

technique has potential in improving productivity and joint performance. Test results of 

FSW welds showed that: strength and elongation of the FSW welded joints were similar 

to those of the Al-Mg welded joints and that fracture toughness of the FSW weld nugget 

was much better than that of the MIG weld metals. 

For rupture due to over load transverse to the weld, localised failure will still occur in 

FSW joints, and therefore energy absorption will still be limited by the joint failure. 

Strength of the weld zone can be improved by increasing thickness in the weld zone 

area. A new joint has been designed for the MIG process. Finite element analyses 

conformed the improvement in strength of the new joints. 

4.6 WORK PACKAGE 6: EXPLOITATION PRODUCTS AND STANDARDS 

Introduction 

It is envisaged that new joining technologies and materials will be used for further 

development and, eventually, commercial exploitation in rail vehicle construction. 

Additionally exploitation will be undertaken to develop other solutions in other transport 

sectors and in different industries. 


Exploitation Products 

Current codes and standards allow an option to use Magnesium or Silicon based 

aluminium alloy welding wire based on structural performance although this has not 

been based on ‘Crashworthiness’ considerations. The comparison of partial penetration 

welds with silicon and magnesium alloy filler wire subject to dynamic loading clearly 

demonstrated the higher performance of magnesium welding in impact conditions (see . 

This result clarifies the most suitable option for Rail applications with regard to crash 

performance and also clarifies future design requirements for weld areas as being based 

on the parent material properties for the rail industry and has potential benefits for other 

transportation industries e.g. Automotive, Maritime. 

27



ALJOIN Figure 25 Silicon vs. Magnesium – partial penetration welds (Bombardier) 

Current improvements within Bombardier as a direct exploitation of the available results 

comprise: 

• change to magnesium based filler wire; 

• Friction Stir Welding of bodysides; 

• increase in material thickness around HAZ; 

• bolt together structures. 

Figure 26 reports an example of the current improvements in Bombardier, corresponding 

to new overmatched design of welded joints on the Electrostar Bodysides. 

Figure 26 New Over-matched MIG Butt weld and FSW joint on Electrostar Bodysides 

(Bombardier) 

Standards 

The two most relevant CEN standards are prEN 15085 “Railway applications – Welding 

of railway vehicles and components” and prEN 15227, the draft standard for 

Crashworthiness of Rail Vehicle Bodies. Comments have been sent for both standards 

to include (amongst other text) the following or similar statements to the effect that: 

• “Magnesium aluminium alloy (5000 series) weld fillers should be used for 

welding of 6000 series aluminium alloys.”, 

28



ALJOIN • “It is recommended that in the main structural welds along the carbody 

length, the geometry of the extrusion should ensure that weld and HAZ 

strength is matched to the parent material strength. This will generally 

require the weld and HAZ to be between 1.4 and 1.6 times thicker than 

the adjacent parent material.” 

Therefore Aljoin has produced results that will be made available for the review of the 

future revisions of the relevant standards in the field of aluminium joint crashworthiness 

and for the construction of the future aluminium railway carbodies. Moreover Aljoin 

provided a significant contribution in relation to the report to the Cullen Enquiry, related 

to the Ladbroke Grove crash (1999), that was prepared by Bombardier. 

4.7 WORK PACKAGE 7: METHOD FOR ASSESSING CRASHWORTHINESS 

Introduction 

The behaviour of aluminium joints under highly dynamic conditions was largely unknown 

before ALJOIN and also no reference testing of representative (railway) structures 

existed. In order to address such issues the work has been addressed in a direction to 

design a new method for assessing the crashworthiness of aluminium joints to be able to 

represent the real critical loading conditions. In particular the problem of weld unzipping 

needed to be studied and tested in more detail. 


A demonstrator representative of full-scale rail vehicle sub-structure was designed by 

Bombardier. The test pieces are constructed from a pair of extrusions joined using a 

number of different welding processes. The extrusions contain representative weld 

construction features and a robust ‘C’ slot for mounting in the test rig. A typical crosssection 

is shown in Figure 27. The welded pairs will be in the order of 500mm long, the 

‘C’ slot on the upper extrusion is used to support the test piece in the rig and the ‘C’ slot 

in the lower extrusion is used to load the test piece. 

Figure 27: Demonstrator Design for FSW (above) and MIG joints (Bombardier) 

29



ALJOIN The test piece is to be loaded dynamically and this has been done at Bombardier's test 

facility in Crespin, France using an Air Cannon (see Figure 28). The test rig is shown in 

Figure 29. One load cell each was installed in each of the four legs of the test rig for 

obtaining transient forces. Transient displacements at the vicinity of the impact point 

were measured with a Laser sensor. 

Figure 28: Air gun facility at Bombardier Crespin 

Figure 29: Test-Rig for the testing of demonstrators (Bombardier) 

4.8 WORK PACKAGE 8: DEMONSTRATORS 

Introduction 

30



ALJOIN The objective of this work package is the manufacturing and testing of the 

demonstrators, in agreement of the findings of WP 7 where the methodology for the 

assessment of their performance was defined. The challenge of this WP was mainly 

related to the set up of the manufacturing processes for the manufacturing of 

demonstrators characterised by constant and repetitive characteristics and the Design of 

the testing Experiments. More in detail the objectives of the WP were: 

• to apply the developed methods to the assessment of crashworthiness of 

large-scale components. 

• to demonstrate structural performance of welded joints of aluminium 

alloys made by new technique and design. 

• to perform large-scale tests of components of body shells under controlled 

laboratory loading conditions reflecting those in vehicle collision 

scenarios. 


It is worth mention that more than 150 demonstrators were manufactured and tested. 

There were two extrusion designs produced: one for MIG or hybrid Laser-MIG welds and 

the other for friction stir welds. Double skin extrusions similar to those used for rail 

vehicle floors were produced at Alcan, Switzerland, according to the sketch shown in 

Figure 27. One of the FSW demonstrators being manufactured, and one MIG 

demonstrator are shown in Figure 30. 

Figure 30: FSW demonstrator (left) (Danstir) and MIG demonstrator (TWI) 

The different configurations tested comprise a combination of the following parameters: 

• 2 material grades: 

o 6005 

o 6008 

• 2 material conditions: 

o T6 

o T7 

• 3 weld thicknesses (weld oversizing) : 

31



ALJOIN o 3mm (no oversizing of the weld – normal skin thickness used on 

the Ladbroke Grove vehicles) 

o 4.2mm (oversizing factor 1.4) 

o 4.8mm (oversizing factor 1.6) 

• 3 Welding Processes 

o MIG welded demonstrators with 5356 welding wire 

o LASER welded demonstrators 

o FSW demonstrators 

• Initiator location: 

o 1: no initiator 

o 4: initiator located in correspondence of the parent material and 

the HAZ 

For the final test programme, three specimens each with or without initiator were 

prepared for each combination of conditions. For each combination of aluminium grade 

and welding process, test would stop when all six samples (3 each with or without 

initiator) fractured in the parent material. 

Test results show that fracture occurs mostly in the weld zone of the joint without weld 

oversizing. The fracture runs through the entire length of the weld without arrest. There 

is hardly global plasticity deformation in the specimen. An example of welded 

specimens after being tested are shown in Figure 31. 

Figure 31: example of welded specimens after testing. 

The performance of the three parent materials in the impact tests is assessed in terms of 

force and energy. Comparison of the performance of the three materials in terms of 

absorbed energy in shown in Figure 32, from which it could be observed that 6005AT6 is 

considered to be stronger and more crashworthy than 6008T6 or 6008T7. 

32



ALJOIN Figure 32: comparison of performance of the three materials with respect to the 

absorbed energy. 

Some tentative conclusions from the analysis of the test results are reported below: 

• In the impact tests, 6005AT6 sustained higher fracture force and 

absorbed more energy than 6008T6. With the initially available kinetic 

energy of about 6.4kJ, 6005AT6 did not fracture completely through the 

entire length of the specimen, while 6008T6 did. 6005AT6 was, therefore, 

a more crashworthy material than 6008T6 under the loading conditions 

similar to those prevailing in the tests. 

• the weld zone stress levels can be reduced enough for fracture to occur in 

the parent material by the increase of the weld zone thickness. The 

minimum ratio of the thickness of the weld zone to that of the parent 

material has been found to be between 1.4 to 1.6 for 3mm extrusion 

skins. The precise ratio would depend on welding process and aluminium 

grade. Increases in thickness above the optimum although they increase 

the static failure load they have an adverse effect on the dynamic 

response. 

• from a crashworthiness viewpoint, fracture in the parent material appears 

to be the best option. With this in mind, all the welding processes 

considered in the present work can be used to produce good quality butt 

welded joints, which should lead to fracture in the parent material when 

the thickness of the weld zone is increased to the above mentioned 

values. 

4.9 WORK PACKAGE 9: VALIDATION 

Introduction 

The objectives of WP9 are to validate project results by testing and by modelling. 

Validation by testing has comprised the detailed analysis of the tests results of the 

demonstrators with the aim of understanding the effects of the main parameters (parent 

33



ALJOIN material, filler material, welding technology, joint design) on the performance of the joints 

in terms of crashworthiness (adsorbed energy, and resistance to crack growth) and then 

to transfer such findings to the design of the new joints of the full vehicle. Validation by 

modelling has comprised the simulation of the testing of the demonstrators with the aim 

of setting up the material models and the related parameters. Finally the validated 

models have been used to the prediction of the performance of the joints of a full vehicle 

under various collision scenarios. 


Simulation of the demonstrator tests has been carried out with the aim of validating the 

material models. Two materials models have been considered at this purpose: the 

Gurson model and a model based on the maximum strain at failure. The two models are 

able to simulate the crack initiation and growth in the material, as demonstrated in Figure 

33. Figure on the left of Figure 33 shows a case (material 6005 T6, weld thickness 4.2 

millimetres, magnesium filler wire, no crack initiator) in which failure was located in the 

parent material and the material failure model was based on the maximum plastic strain. 

Figure on the right of Figure 33 shows a case (material 6005 T6, weld thickness 3.0 

millimetres, magnesium filler wire, no crack initiator) in which failure was located at the 

interface between the HAZ and the weld, and the material model was the Gurson model. 

The results shows the ability of the code and of the material model to represent the crack 

growth in the structure. Different mesh densities have been considered in order to 

assess the mesh sensitivity. 

Figure 33: Results of the simulation of the demonstrators in case of failure located in the 

parent material (left) and in the joint area 

Simulations have been extended to the analysis of a full vehicle. Bombardier Vehicle 

Class 165 was selected, being the type of vehicle involved in the Ladbroke Grove 

disaster which originated ALJOIN. The computer model of the vehicle is shown in Figure 

34. The goal was to demonstrate the progress made within ALJOIN with respect to the 

state of the art concerning the ability to design crashworthy joints in aluminium rail 

structures and to model their behaviour under impact conditions. The benchmark for 

such analysis is represented by the vehicle which was involved in the Ladbroke Grove 

34



ALJOIN accident, shown in Figure 35. The pictures clearly show the catastrophic failure of the 

longitudinal joints (partial penetration welds) without any plastic deformation. 

Various impact scenarios have been investigated (different obstacle shapes) with the 

aim of study the effect on the joints and their failure. Figure 36 shows the result of the 

simulations considering an impact at 20 kilometres per hour against a flat obstacle and 

with standard welded joints. The weld lines are highlighted in red. In the figure it is 

clearly visible the simulation is able to predict the catastrophic failure of the longitudinal 

joints ahead of the area of impact, a mechanism which is analogue to what occurred in 

the Ladbroke Grove impact. The way forward to the current situation is represented by 

the results of the simulations shown in Figure 37 and Figure 38. Figure 37 shows the 

results of the simulations using the validated material model and considering a joint 

oversising factor of 1.4. In this case we do not observe a dramatic failure of the joints 

ahead of the area of impact and the entire section of the vehicle remain connected, 

providing an improved protection to the passengers. 

The analyses have been further extended to consider different shapes of the obstacles 

with the aim of putting the joints in different loading conditions. Figure 38 shows the 

results of the simulations obtained considering the Gurson material model, and 

oversizing factor of 1.4 for the joints, and an obstacle of cylindrical and prismatic shape. 

Also in this case the joints do not fail catastrophically, and the structure can exploit a 

certain plastic deformation as a mechanism to increase impact energy absorption. 

Figure 34: FEM model of Bombardier Vehicle Class 165 (Bombadier) 

35



ALJOIN Figure 35: vehicle involved in the Ladbroke Grove accident (Bombadier) 

Figure 36: Simulation of full-vehicle impact at speed of 20 km/h with standard welded 

joints 

Figure 37: Simulation of full-vehicle impact with improved joint design 

36



ALJOIN Figure 38: Simulation of full-vehicle impact with improved joint design and different 

obstacle shape 

37



ALJOIN 5. LIST OF DELIVERABLES 

The list of deliverables, according to the Work Programme, is presented in the table 

below. 

Table 2 Deliverables produced in the first 18 Month period 

TASK DELIVERABLE Date Partner TYPE & CONTENT 

WP 2 

WP 3 

WP 3 

WP 3 

WP 3 

WP 3 

WP3 

Performance Criteria 

Report 

Progress Report on 

ALJOIN WP3 – material 

and structural behaviour 

of MIG butt welds in 

6005A-T6 aluminium 

alloy extrusions under 

quasi-static and impact 

loading 

WP3 Testing 

Material and structural 

behaviour of MIG butt 

welds in 6005A-T6 

aluminium alloy 

extrusions under quasistatic 

and impact loading 

Plain and notched tensile 

tests and analysis on 

welded 6005A-T6 

specimens for ALJOIN 

WP 3 

Laser and hybrid laserarc 

welding of aluminium 

alloys – Principles and 

potential for application to 

rail vehicle body 

structures 

Mechanical and Material 

Analysis of Welded 

Aluminium 6005A-T6 

Specimens for ALJOIN 

Work Package 3 

WP3 Bolted Tearing Tests 

WP3 

Adhesive and Silicon 

Welded Tensile test 

February 2003 

ARRC, 

Bombardier 

October 2003 TWI 

September 

2003 

ARRC 

February 2004 TWI 

January 2002 ARRC 

January 2004 TWI 

May 2004 NEWRAIL 

November 

2004 

November 

2004 

NEWRAIL 

NEWRAIL 

WP 4A Static Modelling of Joints March 2004 TWI 

38 

Report 

Formulation of performance criteria 

Future requirements for crashworthy 

aluminium rail vehicles. 

Report containing the findings on 

testing of 6005A-T6 aluminium alloy 

extrusions under different test 

conditions 

Report containing ARRC results on 

hardness tests, notched tensile, and 

Crack Tip Opening Angle (CTOA) 

tearing tests. FEA of tests was also 

performed. 

Report containing the findings on 

testing of 6005A-T6 aluminium alloy 

extrusions under different test 

conditions 

Report containing results of a set of 

plain and notched tensile tests for the 

evaluation of the tri-axiality and true 

strain values required by the selected 

failure model. 

Report containing a review of current 

application of laser and hybrid laserarc 

welding of aluminium alloys in 

transportation and feasibility for 

application to rail vehicle body 

structures 

Report detailing the development and 

the results of uniaxial tests, TOA tests, 

hardness tests developed by 

NEWRAIL. Also microscopy images 

of the materials are reported and 

commented. 

Description of results of bolted tearing 

tests performed by NEWRAIL 

Report describing tensile tests on 

adhesive and silicon welded joints 

performed by NEWRAIL 

Report delivering: material failure 

models for aluminium alloy welds, 

constitutive model of the different 

welded joints, and numerical results of



ALJOIN TASK DELIVERABLE Date Partner TYPE & CONTENT 

WP4B 

WP5 

WP6 

WP7 

WP8 

WP8 

WP9 

WP4B-Dynamic 

Modelling of Components 

and Structures 

WP5 Report - New 

Joining Techniques and 

Joints 

Technological 

Implementation Plan 

Design of Cleavage test 

and test specifications 

Analysis of large scale 

impact tests of welded rail 

vehicle components of 

aluminium alloys 

Demonstrator Test 

Results 

Validation of the 

modelling activities and 

new joints design 

performance evaluation 

March 2004 D’Appolonia 

March 2004 TWI 

March 2004 

Bombardier + 

all 

May 2004 Bombardier 

July 2005 TWI 

July 2005 Bombardier 

September 

2005 

D’Appolonia 

simple joints subjected to axial and 

transverse forces 

Report detailing the results of the 

simulations of CTOA tearing tests, 

tearing tests of bolted joints, bolted 

Tubes subjected to axial impact, and 

cleavage tests 

Report providing the results of WP5 

concerning new joining techniques 

and joints 

Draft of TIP for the mid term of project 

containing the plans for the 

exploitation of the project results by all 

partners 

Drawings of the MIG and FSW 

demonstrators to be tested 

dynamically and test specifications 

Report describing the methodology 

used for the testing of the ALJOIN 

demonstrators and the analysis of the 

results 

Test results of demonstrators, 

containing the values of the forces 

and impact energy 

measured/calculated from the tests 

and the pictures of the tested samples 

Presentation of the validation activities 

at the Final ALJOIN Workshop held in 

York 

The list of milestones, according to the Work Programme, is presented in the table 

below. 

Table 3 Overview of Milestones 

O V E R V I E W O F M I L E S T O N E S 

Milestone Due Brief description of Decision criteria for 

No. date M milestone objectives 

assessment 

M1.1 6 Consortium agreement. 

Approved and signed by all the 

partners. 

M2.1 6 

Completion of WP2 

Performance Criteria report 

Criteria assessed, future 

performance investigated 

M3.1 12 Completion of WP3 report 

Method of assessing Joints in 

Aluminum created. 

M1.2 18 MID-TERM REVIEW 

Successful evaluation of the 

innovative solutions 

39



ALJOIN 6. COMPARISON OF INITIALLY PLANNED ACTIVITIES AND WORK ACTUALLY 

ACCOMPLISHED 

The work has been carried out according to the original Work Programme. 

The table below summarises the status of each project task with respect to the 

planned progress. 

Table 1: Status of Project Tasks 

WORK PACKAGE ACTUAL vs. PLANNED PROGRESS STATUS 

WP 2 – 

Performance 

Criteria 

WP 3 – Existing 

Joint Assessment 

WP 4A – Static 

Modelling of Joints 

WP 4B - Dynamic 

Modeling of 

Components and 

Structures 

WP 5: New 

Joining 

Techniques and 

Joints 

WP 6: Exploitation 

Products and 

Standards 

WP 7: Method for 

Assessing 

Crashworthiness 

WP 8: 

Demonstrators 

Performance criteria for critical aluminium joints in 

railway vehicles have been defined. 

No deviation from the planning. 

An extensive testing activity has been carried out on 

different materials. 

An extension of this WP was required to perform tests 

originally not planned. 

Material failure models suitable for the simulation of the 

aluminium extrusions and the ALJOIN materials have 

been analysed. 

Numerical results on simple joints have been carried 

out using such material models. 


Numerical analysis of bolted structures, Crack Tip 

Opening Angle (CTOA) tearing tests, numerical 

analysis of “cleavage” test, tearing tests of bolted joints. 


New Joining techniques and Joints have been 

analysed, comprising Hybrid laser-arc process, 

adhesive bonded joints, and friction stir joints. 


The innovations produced within ALJOIN, in particular 

concerning the new joining techniques, have been 

already used by Bombardier in their production. 

Comments to the main standards relevant to ALJOIN 

have been issued. 


Test planning completed for the tests to be developed 

on small specimens and full-scale components. 


A prototype dynamic cleavage demonstrator 

component test methodology has been developed and 

40 

Completed 

Completed 

Completed 

Completed 

Completed 

Completed 

Completed 

Completed



ALJOIN WORK PACKAGE ACTUAL vs. PLANNED PROGRESS STATUS 

WP 9: Validation 

prototype demonstrators have been tested. The test 

has the potential to become a new standard for the 

evaluation of resistance to crack growth of welded 

structures. 


Validation by modelling of rail vehicle in crash 

scenarios and of full-scale cleavage tests 

41 

Completed



7. MANAGEMENT AND CO-ORDINATION ASPECTS 

ALJOIN 7.1 Project co-ordination 

A number of technical meetings were held during the project development to address the 

main technical aspects of the work. The list of the main project meetings is shown in the 

following Table. 

Description 

Table 4 List of Main Meetings 

Location 

Date 

ALJOIN kick-off meeting D’appolonia 

Genova 

06-09-02 

A general Kick-off meeting, with introduction presentations and discussions 

about the ALJOIN project 

WP2 Meeting Bombardier Transport, Derby 17-10-02 

Discussed design standards. Different joining techniques. Alternative materials 

and WP3 kick-off meeting 

FSW workshop TWI – Cambridge 06-11-02 

A Friction Stir Welding workshop, Chaired by Torben Lorentzen (DANSTIR) 

presentations on technical benefits, current and potential applications and 

demonstrations 

WP2 Review Meeting TWI – Cambridge 13-11-02 

Discuss the work needed to complete WP2 

WP2 Review Meeting ARRC – University of 

Sheffield 

20-11-02 

ARRC and D’Appolonia discussed the work needed to complete WP2 

WP3 Kick off meeting ARRC – University of 

Sheffield 

28-11-02 

WP3 kick-off meeting, presentations from all represented parties, development 

of a matrix for the testing to be carried out in WP3 

WP2 Report Preparation 

Discussion Meeting 

Bombardier Transport, Derby 14-01-03 

To discuss the performance criteria report for WP2 and further work necessary 

for WP2 deliverables 

WP2 Report Preparation ARRC – University of 05-02-03 


Sheffield 

ARRC and D’Appolonia to discuss the current version of the report for WP2 

6 Month Management 

Meeting 

D’Appolonia S.p.A., Genova 24-02-03 

Six Month Meeting to discuss the accomplished activities 

12 Month Management 

Meeting 

TWI The Welding Institute 30-07-03 

12 Month Meeting to discuss the accomplished activities 

WP5 Kick Off Meeting TWI The Welding Institute 27-08-03 

To discuss the work needed on WP5 

WP3 Tear Test 

ARRC – University of September 03 


Sheffield 

Discussed results from WP3 testing 

42



Description 

43 

Location 

ALJOIN Date 

Pre-18 Month Review 

Meeting 

Bombardier Transport, Derby January 04 

Review of project development in preparation to the Mid Term Review and 

discussion on RSSB participation and demonstrator testing 

18 Month Review Meeting NEWRAIL, Newcastle 

University, UK 

March 04 

21 Month Meeting 

Mid Term Assessment Meeting 

TWI, Cambridge April 04 

Technical Meeting to review the progress of work and discuss the testing 

activities 

24 Month Review Meeting D’Appolonia S.p.A., Genova August 04 


24 Month Review Meeting 

Bombardier Transport, 

Bruxelles 


February 05 

Demonstrator Testing Bombardier Transport, 

Crespin (France) 

April 05 

Attendance to the demonstrator testing 

Technical Meeting Newrail, Newcastle (UK) June 05 

Discussion on overall project development in preparation to the Final Review 

Final Meeting D’Appolonia S.p.A., Rome 

Final Review Meeting 

July 05 

7.2 Man Power and Progress Follow-up Table 

The Man Power and Progress Follow-up Table is reported in the next pages. 

The effort globally spent by the partners in the project shows no major deviation from 

what planned.

44 

Task/Subtask 

(N°/title) 

WP1 Project 

Management and 

Dissemination 

WP2 Performance 

Criteria 

WP3 Existing Joint 

Assessment 

Partner 

(Name/ 

abbrev.) 

Planned efforts - at start of period 

(MM) 

Month 1- 

18 

Month 

18-24 

Table 5 Man Power and Progress Follow-up Table 

Actual 

Devia- 

Planned 

Assessed* Devia-tion 

effort 

tion 

(%) 

(%) 

(%) 

(MM) 

Comments on major 

(MM) 

Contract 

deviations and/or 

Month 1- Month 



Year 3 Total Totals Year 3 Year 3 Month 36 

modifications of planned 

18 18-24 

18 18-24 

18 18-24 

efforts. 

(a1+b1+c1 

(a+b+c) 

(a1+b1)/ 

a1/d1 

) (d1-d)/d 

/d 

d1 

/d1 

Number G3RD-CT-2002-00829 

Year 3 Total 

a b c d a1 b1 c1 d1 d1-d a/d (a+b)/d 

DAPP 6 2 3 11 7,1 3,75 2,4 13,25 2,25 55% 73% 100% 54% 82% 100% 20% 

NEWR 4,5 1,5 3 9 3,75 1,5 4,5 9,75 0,75 50% 67% 100% 38% 54% 100% 8% 

ALCAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

BOM 0 0 0 0% 0% 0% 0% 0% 0% 0% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 0 0 0 0% 0% 0% 0% 0% 0% 0% 

Total 10,5 3,5 6 20 10,85 5,25 6,9 23 3 53% 70% 100% 47% 70% 100% 15% 

DAPP 0 0 0 0% 0% 0% 0% 0% 0% 0% 

NEWR 3 3 3 3 0 100% 100% 100% 100% 100% 100% 0% 

ALCAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

BOM 2 2 2,5 2,5 0,5 100% 100% 100% 100% 100% 100% 25% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 0 0 0 0% 0% 0% 0% 0% 0% 0% 

Total 5 0 0 5 5,5 0 0 5,5 0,5 100% 100% 100% 100% 100% 100% 10% 

DAPP 0 0 0 0% 0% 0% 0% 0% 0% 0% 

NEWR 5 1 6 5 1 6 0 83% 100% 100% 83% 100% 100% 0% 

ALCAN 1 1 1 1 0 100% 100% 100% 100% 100% 100% 0% 

BOM 5 5 5 5 0 100% 100% 100% 100% 100% 100% 0% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 6 6 6 6 0 100% 100% 100% 100% 100% 100% 0% 

Total 17 1 0 18 17 1 0 18 0 94% 100% 100% 94% 100% 100% 0% 


ALJOIN

45 

Task/Subtask 

(N°/title) 

WP4 Dynamic 

Modelling of 

Components and 

Structures 

WP5 New Joining 

Techniques and 

Joints 

WP6 Exploitation 

Products and 

Standards 

Partner 

(Name/ 

abbrev.) 

Table 5 Man Power and Progress Follow-up Table (continue from previous page) 


Actual 

Devia- 

Planned 


(MM) 

effort 

tion 

(%) 

(%) 

(%) 

(MM) 

(MM) 


Contract 


Month 




Year 3 Total Year 3 Total Totals Year 3 Year 3 Month 36 modifications of planned 

18-24 

18 18-24 

18 18-24 

18 18-24 

efforts. 

(a1+b1+c1 

(a+b+c) 

(a1+b1)/ 


a1/d1 

) (d1-d)/d 

/d 

d1 

/d1 


Month 1- 

18 

DAPP 19 19 0 38 21,6 24 0 45,6 7,6 50% 100% 100% 47% 100% 100% 20% 

NEWR 6 6 12 0 12 12 0 50% 100% 100% 0% 100% 100% 0% 

ALCAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

BOM 0 0,5 0,5 0,5 0% 0% 0% 0% 0% 0% 0% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 8,5 6,5 15 8,8 6,2 2,5 17,5 2,5 57% 100% 100% 50% 86% 100% 17% 

Total 33,5 31,5 0 65 30,9 42,2 2,5 75,6 10,6 52% 100% 100% 41% 97% 100% 16% 

DAPP 0 0 0 0% 0% 0% 0% 0% 0% 0% 

NEWR 0 0 0 0% 0% 0% 0% 0% 0% 0% 

ALCAN 1,9 1,1 3 1,9 1,1 3 0 63% 100% 100% 63% 100% 100% 0% 

BOM 0 0,5 0,5 1 1 0% 0% 0% 0% 0% 0% 0% 

DAN 0,7 0,3 1 0,7 0,3 1 0 70% 100% 100% 70% 100% 100% 0% 

TWI 2,5 2,5 5 2,5 2,5 2,5 7,5 2,5 50% 100% 100% 33% 67% 100% 50% 

Total 5,1 3,9 0 9 5,6 4,4 2,5 12,5 3,5 57% 100% 100% 45% 80% 100% 39% 

DAPP 0 0 0 0% 0% 0% 0% 0% 0% 0% 

NEWR 3 3 6 0,5 5,5 6 0 0% 50% 100% 0% 8% 100% 0% 

ALCAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

BOM 1,5 1,5 3 6 1,5 1 3,5 6 0 25% 50% 100% 25% 42% 100% 0% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 0,5 0,5 1 2 0,5 0,5 2,5 3,5 1,5 25% 50% 100% 14% 29% 100% 75% 

Total 2 5 7 14 2 2 11,5 15,5 1,5 14% 50% 100% 13% 26% 100% 11% 



46 

Task/Subtask 

(N°/title) 

WP7 Method for 

assessing 

crashworthiness 

WP8 Demonstrators 

WP9 Validation 

Partner 

(Name/ 

abbrev.) 



Actual 

Devia- 

Planned 


(MM) 

effort 

tion 

(%) 

(%) 

(%) 

(MM) 

(MM) 


Contract 


Month 




Year 3 Total Year 3 Total Totals Year 3 Year 3 Month 36 modifications of planned 

18-24 

18 18-24 

18 18-24 

18 18-24 

efforts. 

(a1+b1+c1 

(a+b+c) 

(a1+b1)/ 


a1/d1 

) (d1-d)/d 

/d 

d1 

/d1 


Month 1- 

18 

DAPP 0 0 0 0% 0% 0% 0% 0% 0% 0% 

NEWR 3 3 6 0,5 5,5 6 0 0% 50% 100% 0% 8% 100% 0% 

ALCAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

BOM 3 3 6 4 3 7 1 0% 50% 100% 0% 57% 100% 17% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 0 0 0 0% 0% 0% 0% 0% 0% 0% 

Total 0 6 6 12 0 4,5 8,5 13 1 0% 50% 100% 0% 35% 100% 8% 

DAPP 0 0 0 0% 0% 0% 0% 0% 0% 0% 

NEWR 0 0 0 0% 0% 0% 0% 0% 0% 0% 

ALCAN 3,3 3 6,3 1,8 4,5 6,3 0 0% 52% 100% 0% 29% 100% 0% 

BOM 10 10 20 2 4 14 20 0 0% 50% 100% 10% 30% 100% 0% 

DAN 1 2 3 0,5 3,9 4,4 1,4 0% 33% 100% 0% 11% 100% 47% 

TWI 1 1 2 1 2 3 1 0% 50% 100% 0% 33% 100% 50% 

Total 0 15,3 16 31,3 2 7,3 24,4 33,7 2,4 0% 49% 100% 6% 28% 100% 8% 

DAPP 6 6 1 6 7 1 0% 0% 100% 0% 14% 100% 17% 

NEWR 6 6 6 6 0 0% 0% 100% 0% 0% 100% 0% 

ALCAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

BOM 3 3 3 3 0 0% 0% 100% 0% 0% 100% 0% 

DAN 0 0 0 0% 0% 0% 0% 0% 0% 0% 

TWI 0 0 0 0% 0% 0% 0% 0% 0% 0% 

Total 0 0 15 15 0 1 15 16 1 0% 0% 100% 0% 6% 100% 7% 



47 

Task/Subtask 

(N°/title) 

TOTALS 

Partner 

(Name/ 

abbrev.) 



(MM) 

Month 1- 

18 

Month 

18-24 

Year 3 Total 

Month 1- 

18 

Actual 

effort 

(MM) 

Month 

18-24 

Deviation 

(MM) 

Year 3 Total Totals 

Month 1- 

18 

Month 

18-24 


Year 3 

Month 1- 

18 

(a+b+c) 

/d 

a1/d1 

Month 

18-24 

(a1+b1)/ 

d1 

Devia-tion 

(%) 

Year 3 Month 36 

(a1+b1+c1 

) (d1-d)/d 

/d1 

DAPP 25 21 9 55 28,7 28,75 8,4 65,85 10,85 45% 84% 100% 44% 87% 100% 20% 

NEWR 18,5 14,5 15 48 11,75 15,5 21,5 48,75 0,75 39% 69% 100% 24% 56% 100% 2% 

ALCAN 2,9 4,4 3 10,3 2,9 2,9 4,5 10,3 0 28% 71% 100% 28% 56% 100% 0% 

BOM 8,5 14,5 19 42 12 9,5 23,5 45 3 20% 55% 100% 27% 48% 100% 7% 

DAN 0,7 1,3 2 4 0,7 0,8 3,9 5,4 1,4 18% 50% 100% 13% 28% 100% 35% 

TWI 17,5 10,5 2 30 17,8 10,2 9,5 37,5 7,5 58% 93% 100% 47% 75% 100% 25% 

TOTAL 73,1 66,2 50 189,3 73,85 67,65 71,3 212,8 23,5 39% 74% 100% 35% 66% 100% 12% 

*) Please note that the actual technical progress percentage and the updated remaining efforts must reflect the physically assessed status of the work. 

Planned 

(%) 

Assessed* 

(%) 



modifications of planned 

efforts. 

Contract Number G3RD-CT-2002-00829 



GROWTH PROJECT ALJOIN Contract N° G3RD-CT-2002-00829 


7.3 Work Plan 

48 

ALJOIN The Work Plan diagram is reported on next page. The only modification agreed with the 

partners was the extension of WP3, in order to complete the testing plan.

CONTACT 

PERSON 



COORDINATOR 

Andrea Barbagelata 

Maura Primavori 

Donato Zangani 

CONTRACTORS 

Mark Robinson 

George Kotsikos 

Denis Hofmann 

Christian Leppin 

Mick Roe 

Martin Wilson 

Mick Wood 

7.4 Updated contact details for the consortium 

PARTNER 

NAME 

D'Appolonia S.p.A. Via S. Nazaro 19 

16145 Genova 

Italy 

NEWRAIL 

ALCAN Fabrication 

Europe 

Bombardier 

Transportation 

Torben Lorentzen DanStir ApS 

Danish Stir Welding 

Technology 

John Davenport 

Weiguang Xu 

OTHER MEMBERS 

Aqeel Janjua Rail Safety & 

Standards Board 

EUROPEAN COMMISSION 

Dennis Schut European 

Commission Officer 

ADDRESS TEL./FAX/E-MAIL 

University of 

Newcastle 

Department of 

Mechanical & Systems 

Engineering 

Stephenson Building 

Newcastle upon Tyne 

NE1 7RU 

Alcan Technology & 

Management Ltd. 

Badische 

Bahnhofstrasse 16 

CH-8212 Neuhausen 

Switzerland 

Litchurch Lane 

Derby, DE24 8AD 

United Kingdom 

Park Allé 345 

Box 124 

DK-2605 Brondby 

Denmark 

TWI Limited Granta Park, 

Great Abington 

Cambridge CB1 6AL 


Floor 1 Evergreen 

House 

160 Euston Road 

London 

NW1 2DX 


European Commission 

DG RTD H2, Office-B7 

02/111, B-1049 

Rue Belliard 7, 

49 

ALJOIN tel. +39-010-3628148 

fax +39-010-3621078 

andrea.barbagelata@dappolonia.it 

maura.primavori@dappolonia.it 

donato.zangani@dappolonia.it 

Tel: +44 (0)191 222 5889 

Fax: +44 (0)191 2227679 

newrail@ncl.ac.uk 

George.Kotsikos@newcastle.ac.uk 

tel. +41-(0)-52 674 9523 

fax +41-(0)-52 674 9216 

mobile: +41 (0) 79 432 4841 

denis.hofmann@alcan.com 

tel. +41-(0)-52 674 9527 

christian.leppin@alcan.com 

tel. +44 (0)1332 266056 

fax +44 (0)1332 251840 

mobile +44 (0)7789 08779 

mick.roe@uk.transport.bombardier.com 

martin.j.wilson@uk.transport.bombardier.com 

mick.wood@uk.transport.bombardier.com 

tel: +45 4326 7035 

fax: +45 4326 7040 

mobile: +45 2330 3383 

tlo@danstir.com 

tel. +44-(0)-1223 891162 

fax +44-(0)-1223 892588 

john.davenport@twi.co.uk 

fax +44-(0)-1223 890689 

guang.xu@twi.co.uk 

tel. +44 (0) 20 7904 7966 

aqeel.janjua@rssb.co.uk 

Tel. +32 2 295 09 27 

fax: +32 2 296 33 07 

Dennis.SCHUT@cec.eu.int



Sandro Maluta Project External 

Assessor 

Brussels 

Belgium 

Via M. Lutero, 8 

20126 Milano, 

Italy 

50 

Tel. +30-333 9076104 

samaluta@tin.it 




8. RESULTS AND CONCLUSIONS 

51 

ALJOIN The introduction of double skinned construction, through the use of aluminium 

closed cell extrusions, has greatly improved the crash resistance of rail vehicles. 

On the other hand, the impact resistance of fusion welds that have traditionally 

been the joining technique of the extruded sections, had not received adequate 

consideration, in terms of the contribution of they make on the crash resistance 

of a rail vehicle. 

The ALJOIN project arose from the need to improve the crashworthiness design 

of aluminium rail vehicles and establish guidelines for the future build of such 

vehicles. 

Aluminium alloys derive their physical properties (i.e. strength, stress corrosion 

cracking resistance etc) through a range of elaborate heat treatments. The 

additional heat input introduced by the fusion welding process alters the 

microstructure at the weld region resulting in a reduction of strength there of up 

to 50% of that of the parent plate. This can have detrimental effects in the 

behaviour of such joints in high velocity impact situations. This effect has been 

demonstrated by the failure of the rail coaches in the Ladbroke Grove accident in 

the UK. 

ALJOIN has carried out a detailed investigation of the joining of components in 

rail vehicles by initially reviewing the current state of the art and assessing 

alternative joining techniques. 

It has been found that the use of Al-Mg filler wires in MIG welding results in 

superior performance welds in terms of strength, ductility and fracture toughness 

compared to Al-Si filler wires. Other joining techniques such as Laser Welding 

(LW) and Friction Stir Welding (FSW) have also been investigated with the 

former technique appearing attractive in terms of increased productivity and the 

latter in terms of a moderate increase in fracture toughness and improved 

surface finish, when they were compared to the traditional automated MIG 

welding process. 

ALJOIN has shown that the use of MIG welding with Al-Mg filler and FSW are 

both good candidates for future built of train vehicles. It has also been 

demonstrated that the design of the joint is equally important in the impact 

performance of the joint. 

Under-matching in an aluminium weldment is unavoidable due to the reduction in 

strength at that region even after moderate heat inputs (as in the case of FSW). 

After extensive testing both on small specimens and large demonstrators a 

significant output of the ALJOIN project has been the recommendation for the



52 

ALJOIN aluminium sheet thickness at the weld region to be increased, so that the 

resultant stress levels there are equivalent to those of the parent plate. The 

amount of thickening of the plate is a factor of the aluminium grade and welding 

process. 

Another joint design improvement realised by this project is the avoidance of 

partial penetration welds through appropriate shaping of the extrusions at the 

joint region. 

The validity of the design recommendations described above has been proved 

through large scale demonstrator tests which have shown that dynamic failure 

always takes place in the parent plate (that inherently possesses much higher 

toughness) rather than the weldments. 

Adhesive bonding of aluminium sections has also been investigated but has not 

proved attractive neither in terms of productivity nor strength or impact 

resistance. Furthermore, other issues such as the ease of carrying out NDE 

inspections for both quality control or to establish levels of damage and need for 

repair after minor impacts have proved impractical. 

A methodology to assess experimentally the performance of welded aluminium 

extruded sections was also developed during the ALJOIN project. 

The methodology measures the energy absorbed by the specimen and the 

displacement of the free end as it "tears away" from the clamped part of the 

specimen and provide a measure of the tearing resistance of the material when 

subjected to high loading rates. 

The term "tearing resistance" in this test is not to be confused with the fracture 

mechanics derived term. Since there is no sharp crack to initiate the failure the 

test can be considered as dynamic tensile test where the peak load describes the 

energy required to yield the cross-section and tear the material. The subsequent 

rate of load drop is a measure of how easily the tear propagates through the 

material. The results of this work have shown that the parent material (6005-T6) 

possesses substantial tearing resistance and have also demonstrated the 

benefits of increasing the cross-section thickness at the weld region in diverting 

failure (i.e. crack initiation and propagation) away from the weld and into the 

parent material. 

The tests also demonstrated that increasing this increase in the section thickness 

is a function of alloy grade and welding process. It is important here to note that 

there is an optimum increase in the section thickness at the weld region. Any 

further increase, although it improved the static strength of the joint, it reduced 

the dynamic loading response, resulting in a lower initiation load and tearing



53 

ALJOIN resistance. This was attributed to the increased thickness moving the failure 

mode from plain stress to plain strain failure. 

The ability to accurately model the collision behaviour of a rail vehicle has also 

been a major output of the ALJOIN project. The modelling efforts have been 

aided by detailed static and quasi-static mechanical property tests in order to 

derive the material parameters that can best describe failure. In addition to 

mechanical property and fracture mechanics tests, component tests were carried 

out to validate the resultant models. The Gurson-Tvergaard model used within 

the LS-DYNA finite element analysis code has provided very good predictions of 

failure under static, quasi-static and dynamic loading conditions. 

A model of a rail vehicle (class 165 by Bombardier, involved in the Ladbroke 

Grove accident) was constructed and subjected to a number of head on collision 

scenarios. The modelling exercise has demonstrated a notable improvement in 

the failure mode when the joint design recommendations developed through this 

project were implemented, (use of Al-Mg filler wire, increase of the sheet 

thickness at the weld region and full penetration welds throughout). 

ALJOIN has provided a number of results that have demonstrably improved the 

structural integrity of rail vehicles and their crashworthiness. It is important to 

note though that a collision between two rail vehicles or derailment cannot be 

accurately modelled as there is an infinite number of loading configurations that a 

rail vehicle and its individual structural components could be subjected to. Offaxis 

loads as well as extreme loading rates are possible and it is clear that there 

could still be a risk of fast fracture of weldments. The pipeline industry that for 

many years has encountered fast fractures that can run for kilometres 

understand the limitation in predicting this material behaviour. 

This project is nevertheless a major step forward in understanding the role of 

weldments in the crashwothiness of rail vehicles and produced recommendations 

to improve the performance of weldments subjected to dynamic loading.

ALJOIN Final Technical Report - Transport Research & Innovation ...

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