aluminium in commercial vehicles - European Aluminium Association

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58 EUROPEAN ALUMINIUM ASSOCIATION ALUMINIUM IN COMMERCIAL VEHICLES CHAPTER VI 1. Introduction The new European design code for aluminium structures is used as a basis for this chapter. The name of this standard is: EN 1999 Eurocode 9: Design of aluminium structure Part 1-1 General structural rules Part 1-2 Structural fire design Part 1-3 Structures susceptible to fatigue Part 1-4 Cold-formed structural sheeting Part 1-5 Shell structures Part 1-1 is used for all static design and Part 1-3 for all fatigue design shown in this chapter. A new European standard for the execution of structural aluminium is under development and is soon ready for publication. It is recommended to use relevant parts of this standard for execution of aluminium components for use in commercial vehicles. The name of this standard is: EN 1090-3: Execution of steel structures and aluminium structures – Part 3: Technical requirements for aluminium structures 2. Possibilities with aluminium The advantages of designing with aluminium are: • High strength-to-weight ratio • Possibilities to create your own cross-sections with the extrusion technique • Good corrosion resistance • Long vehicle life • Easy to work with • Easy to repair Especially for product design, the use of tailor-made profiles is a great advantage for aluminium compared with other metals. In profile design the material can be placed where the effect of the material is optimal regarding resistance. Details can be made in such a way that it will ease the fabrication and assembling of the components. 3. Symbols Frequently used symbols are defined in this section: f characteristic value of 0.2 % o proof strength f characteristic value of ulti- u mate tensile strength f characteristic ultimate tensile ub strength of bolt E modulus of elasticity d bolt diameter d hole diameter o t wall thickness A cross section area W section modulus γ partial safety factor for resist- M ance (see the definitions in section 5.2), in EN 1999-1-1: Subscript is used for factored Ed load effects. It may be on axial force (N ), bending moment Ed (M ), shear force (V ), torsion Ed Ed (T ) and forces in connection Ed with bolted connections (F for v,Ed shear force and F for tension t,Ed force).
EUROPEAN ALUMINIUM ASSOCIATION ALUMINIUM IN COMMERCIAL VEHICLES CHAPTER VI 59 4. Aluminium versus Steel Both steel and aluminium are metals with relatively high strength. Both materials are incombustible and will not contribute to a fire. For structural purposes the main differences are: Elasticity: The modulus of elasticity (E-modulus) of aluminium is 1/3 of that of steel. This means that an aluminium beam with the same cross-section and the same loads as a steel beam will have a deflection 3 times that of the steel beam. Weight: The density of aluminium is 1/3 of that of steel. This means that a steel beam will weigh 3 times more than an aluminium beam with the same cross-section. Welding: When welding a hardened aluminium alloy some of the hardening effects will be lost. The strength in the heat affected zone (HAZ) will be reduced. This reduction depends on the alloy, temper, type of product and welding procedure. Ordinary steel has no strength reduction after welding. Thermal elongation: The coefficient of thermal elongation of aluminium is twice that of steel. This means that an aluminium member will get twice the thermal elongation as a similar steel member with the same temperature difference. Since the elastic modulus of aluminium is 1/3 of steel, the stresses in an aluminium member with fixation are 2/3 of that in a similar steel member. Most of the structural aluminium alloys have relatively high “strength-to-E modulus” ratio. This effect is especially clear when the aluminium alloy is strain-hardened or heat-treated. Structural aluminium alloys have roughly twice the “strength-to-E modulus” ratio than standard steel. However, when compared with high strength steels, structural aluminium alloys have about the same “strength-to-E modulus” ratio. It should also be noted that the elastic modulus of an alloy mainly depends on its parent metal. In other words, all aluminium alloys have very similar Emodulus, but this is also valid for steel alloys. Consequently, the so called “high strength steels” don’t have better elastic properties than mild steel. Steel designers often use the strength of the material as governing criteria when desig ning a steel struc ture and check afterwards whether the deflection is within the requirement. When designing an aluminium structure, it will often be the deflection criterion that will be governing. For that reason, the design procedure will start with the deflection criterion and it will be checked afterwards if the stress or the resistance of the structure is within the limits. The deflection of members under bending load depends on the modulus of elasticity (E) and on the moment of inertia (I) together with the load and the span. With the same span and load, it will be the product E x I that will determine the deflection. To get the same deflection of steel and aluminium beams in bending, the moment of inertia of the aluminium beam must be three times that of steel. If the increase in the moment of inertia is to be done only by increasing the thickness of the web and flanges, the aluminium beam will have the same weight as the steel beam.
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ALUMINIUM IN COMMERCIAL VEHICLES
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Aluminium in Commercial Vehicles ha
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VII. FABRICATION . . . . . . . . .
Page 7 and 8: CHAPTER II ALUMINIUM IN TRANSPORT 1
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Page 15 and 16: CHAPTER III WHY USING ALUMINIUM 1.
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EUROPEAN ALUMINIUM ASSOCIATION ALUM
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CHAPTER IX OTHER JOINING TECHNIQUES
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CHAPTER X DECORATION AND FINISHING
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Cell wall EUROPEAN ALUMINIUM ASSOCI
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CHAPTER XI CORROSION RESISTANCE 1.
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CHAPTER XII CLEANING OF ALUMINIUM C
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CHAPTER XIII REPAIR OF ALUMINIUM CO
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