Innovative Stainless Steel Applications in transport ... - Euro Inox

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can be calculated using relatively simple formulas, which, together with some values for these factors, for various core geometries, are given in Kujala et al. (2003). Deflections It is typical of space-critical structures that deflection is one of the dimensioning criteria. In such cases the elastic, global deflection of the structure must at no location exceed its set maximum value. A typical deflection criterion in design is L/300, where L is the web spacing of the structure. Plastic failure The core may also fail locally as a result of local loads. There are calculation formulas for dimensioning for plastic failure in the literature reviewed in Romanoff & Kujala (2002). 3.2.5 Structural optimisation The key task in any structural optimisation process is formulating the optimisation task itself, including defining the limits for the core dimension range to be optimised and defining strength and deflection criteria. In practice, the starting data includes the main dimensions of the structure, the loading applied to the panel and the boundary conditions (Kujala et al. 2003). From an optimisation point of view, it is essential to minimise the number of variables. The optimisation task solution depends on how accurately details are calculated. A preliminary idea of core dimensions can usually be obtained by using analytical formulas, calculating through all the design alternatives possible with the parameters and finding the best solution in terms of weight or cost, for example. For more accurate analysis, 3D FEM can be used, but the optimum found may not be the global optimum. An optimised solution usually lies close to the limits of the design criteria, so these limits have to be defined carefully. For example, the manufacturing technique defines the core thickness in an I-core panel – optimised core would be too thin to laser weld. Improving manufacturing techniques also leads to lighter-weight panels (Kujala et al. 2003). Figure 52 shows an experimental strucure manufactured for gaining practical experience with sandwich panels in actual service conditions (Alenius et al. 2002). 68
Figure 52. An experimental, sandwich-panel bus floor element, in grade 1.4003, assembled using laser welding (Alenius et al. 2002). 3.2.6 Design tools Several methods can be used for all-steel sandwich panel design, depending on the desired accuracy and speed. Available design methods and tools in ascending accuracy and time consumed are (Kujala et al 2003): • readily available calculated design curves • beam theory together with analytical expressions for strength • 2D plate theory together with analytical expressions for strength • 3D FEM calculation for structural response together with analytical expressions for strength • 3D FEM calculation for structural response and strength The use of prepared design curves is by far the quickest design method. The designer needs to know the main dimensions and loading case of the panel. A suitable panel can be selected from several alternatives. A key benefit with design curves is that a rough estimate of a panel’s dimensions and geometry is available quickly and easily. On the other hand, the curves are connected to a particular core geometry and availability is limited (Kujala et al. 2003). Panel response and strength can be solved with reasonable accuracy and in a reasonable time by using beam theory together with analytical expressions for strength. These make it possible to program formulas in closed form with a computer and enable the use of an optimisation programme that calculates through all the possible core parameter combinations defined (Kujala et al. 2003). 69
Page 1 and 2:
Preface This publication is the mai
Page 3 and 4:
Contents Preface ..................
Page 5:
List of symbols Mechanical properti
Page 8 and 9:
Figure 1. Rear view of El Capitan.
Page 10 and 11:
In Japan and the Asia-Pacific areas
Page 12 and 13:
12 Figure 13. Delhi metro coach (Go
Page 14 and 15:
1.3 Bus and coach applications 14 A
Page 16 and 17:
1.4 Future potential Future prospec
Page 19 and 20: 2. Materials By definition, stainle
Page 21 and 22: use higher nitrogen contents in aus
Page 23 and 24: Grade 1.4318 stainless steel was su
Page 25 and 26: MPa). Table 7 shows the format and
Page 27 and 28: 1. Design using minimum specified v
Page 29 and 30: Table 9. The most common stainless
Page 31 and 32: Table 10. Physical properties of so
Page 33 and 34: for example, in the case of lap joi
Page 35 and 36: to develop new de-icing chemicals,
Page 37 and 38: (a) (b) Figure 30. Photograph from
Page 39 and 40: Austenitic CrNi and CrNiMo stainles
Page 41 and 42: Figure 33 shows the behaviour of fe
Page 43 and 44: (a) (b) Figure 35. Localised corros
Page 45 and 46: visual and not detrimental to struc
Page 47 and 48: Reduction factor 1 0.9 0.8 0.7 0.6
Page 49 and 50: It is typical of cold-worked stainl
Page 51 and 52: Thermomechanical treatments can be
Page 53 and 54: Table 17. The minimum values for co
Page 55 and 56: 3. Lightweight structures and desig
Page 57 and 58: K joints The requirements for K joi
Page 59 and 60: Figure 42. Overlapping joint (Yrjö
Page 61 and 62: Another typical way to join a hollo
Page 63 and 64: There are some disadvantages with a
Page 65 and 66: New challenges have to be met in bo
Page 67: Stiffness parameters Despite the li
Page 71: 71 Figure 53. Stainless steel sandw
Page 74 and 75: values are shown in Table 20. A com
Page 76 and 77: Springback was determined by measur
Page 78 and 79: A “three-roll” (pyramid-type) b
Page 80 and 81: angle of 180 °. Figure 58 shows th
Page 82 and 83: design and the manufacture of the t
Page 84 and 85: Combined with modern pulsing techni
Page 86 and 87: possibility of transferring the bea
Page 89 and 90: 5. Properties of lightweight struct
Page 91 and 92: Table 28. Fusion welding results fo
Page 93 and 94: welding mechanical treatments. Howe
Page 95 and 96: performance of a weld-joint detail
Page 97 and 98: 2400 N. Thus, the specified fatigue
Page 99 and 100: limited number of static bending te
Page 101 and 102: material strengths or manufacturing
Page 103 and 104: section at a velocity of 3.0 m/s. F
Page 105 and 106: (a) (b) (c) Figure 65. (a) Deflecti
Page 107 and 108: Figure 67. Panel sections after lon
Page 109 and 110: 6. Life cycle issues The transporti
Page 111 and 112: and services, occurring throughout
Page 113 and 114: 100 % 80 % 60 % 40 % 20 % 0 % Mater
Page 115 and 116: (especially in the case of lower-al
Page 117 and 118: Acknowledgements The following orga
Page 119 and 120:
References Ala-Outinen, T. 1996. Fi
Page 121 and 122:
DIN 6935. 1975. Kaltbiegen von Flac
Page 123 and 124:
Federation of metals industries. ME
Page 125:
UNEP 2002. Industry as a partner fo
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