Aluminium Design and Construction John Dwight

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Table 4.2 Temper designations for non-heat-treatable material quarter, half, three-quarter and fully-hard. The official system specifies the temper by means of an H-number, such as H14, for example. Table 4.2 lists the H-numbers in common use. The second digit after the H is the important one, since this defines the actual hardness. Usually this is an even number, the corresponding hardness being obtained by dividing by 8 (e.g. H16=6÷8=3/4 hard). For special requirements, material can be supplied to an intermediate level of hardness, in which case the second digit is odd (e.g. H13). The first digit after the H is of less direct interest, as it merely shows the procedure used by the manufacturer to bring the material to its final hardness. Possible procedures are: Temper-rolled (H1x). The material is cold reduced to the required hardness, with no subsequent heating. Temper-annealed (H2x). The material is over-worked in the final pass, and is then brought back to the required hardness by a partial anneal. Stabilized (H3x). The material is cold reduced to the right hardness, and its properties are then stabilized by a relatively low temperature application of heat. Such treatment may be necessary to prevent the age-softening to which some work-hardened alloys are prone. 4.1.4 The O and F conditions There are two other possible conditions in which material can be supplied, defined as follows: O, annealed; F, ‘as-manufactured’. The O condition defines material that has been fully annealed (i.e. softened) by heating. The stronger F condition applies to products that are hot-formed to their final shape, without any subsequent cold-work or heat-treatment. It typically applies to hot rolled plate, or to sections in the as-extruded condition. The properties of F condition material cannot be controlled to the degree that is possible with other conditions, and material specifications only quote ‘typical’ strength values for such material, rather than guaranteed minima. In the case of extrusions, the F condition strength Copyright 1999 by Taylor & Francis Group. All Rights Reserved.
will be only slightly above that for O. With plate, it is often considerably higher, but not reliably so. Often material ostensibly in the O condition gets very slightly cold worked after annealing, as might occur in a straightening or flattening operation. Such material is officially referred to as being in the H111, rather than the O condition. However, the quoted properties are not usually any different, and the use of the designation O for all such material is unlikely to cause confusion. 4.1.5 Relation between temper and tensile strength For work-hardened sheet material, there is a fairly consistent relation between temper designation (H-number) and minimum tensile strength (fu ), as laid down in BSEN.515. The fully-hard temper (H18, H28 or H38), referred to as Hx8, is described as the ‘hardest temper normally produced’, and for any given alloy it is defined in terms of a specific amount by which fu exceeds the value fuo for the same alloy in the annealed (O) condition. The intermediate tempers are then defined by taking equal steps in fu between the two extreme conditions (O and Hx8). The resulting value for fu is effectively given by the following expression (plotted in Figure 4.1): f u =Pf uo +Q (4.1) in which the coefficients P and Q are a function of the temper (Table 4.3). This expression is based on the BSEN.515 rules and is valid for any composition having an annealed tensile strength greater than about 90 N/ mm 2 (i.e. excluding pure aluminium). In practice the actual material standard Figure 4.1 Relation between temper and minimum tensile strength (f u ) for work-hardened materials. f uo =minimum tensile strength in the O condition. Copyright 1999 by Taylor & Francis Group. All Rights Reserved.
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Aluminium Design and Construction C
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First published 1999 by E & FN Spon
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2.2.1 Rolling mill practice 2.2.2 P
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5 Limit state design and limiting s
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8.2.6 Use of interpolation for semi
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10.3.2 Inertias for a section with
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Preface Aluminium is easily the sec
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List of symbols The following symbo
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uu, vv principal axes w effective s
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1.1.3 The industrial metal It is on
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where A is the section area (mm 2 )
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1.3.1. The good points about alumin
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Deflection Because of the lower mod
Page 27 and 28: 1.4.4 Establishment of the alloys I
Page 29 and 30: 1.5.2 New technology Most of alumin
Page 31 and 32: large span, where self-weight is a
Page 33 and 34: These tend to be in all-aluminium c
Page 35 and 36: Close-up of the M-dec system, which
Page 37 and 38: Aluminium glazing system for commer
Page 39 and 40: Nat West Media Centre, Lords Cricke
Page 41 and 42: The main requirements for the produ
Page 43 and 44: in which t and w are in mm. These a
Page 45 and 46: Figure 2.1 Extrusion process (direc
Page 47 and 48: Figure 2.2 Typical extrusion die. t
Page 49 and 50: Figure 2.6 ‘Semi-hollow’ profil
Page 51 and 52: especially the stronger alloys in t
Page 53 and 54: Figure 2.9 Conventional profiles. 2
Page 55 and 56: 2.4 TUBES By tubes we mean hollow s
Page 57 and 58: CHAPTER 3 Fabrication 3.1 PREPARATI
Page 59 and 60: Figure 3.1 Alternative designs for
Page 61 and 62: Figure 3.2 Thread insert. a coil-sp
Page 63 and 64: 3.3 ARC WELDING 3.3.1 Use of arc we
Page 65 and 66: adjusted. The technique is claimed
Page 67 and 68: For welds of minimum or fatigue qua
Page 69 and 70: Figure 3.5 Friction-stir welding: s
Page 71 and 72: are, and the designer/fabricator mu
Page 73 and 74: cartridge, and mixing takes place a
Page 75 and 76: 3.7.4 Painting Alloys having durabi
Page 77: Where a range is given, as for the
Page 81 and 82: heating the metal to a temperature
Page 83 and 84: Table 4.4 Characteristics of differ
Page 85 and 86: softening in the heat-affected zone
Page 87 and 88: 60 alloys, are: BSEN.485 plate and
Page 89 and 90: Firure 4.3 Nominal composition and
Page 91 and 92: popular alloys in the series are: 6
Page 93 and 94: Figure 4.6 Variation of tensile str
Page 95 and 96: undercarriages of aircraft. They ar
Page 97 and 98: Figure 4.11 Minimum stress-strain c
Page 99 and 100: AC.51400 This is another non-heat-t
Page 101 and 102: times that of the actual pits) prod
Page 103 and 104: The severity of bimetallic corrosio
Page 105 and 106: Nominal loading. Nominal loads are
Page 107 and 108: 2. Material factor (� m ). In the
Page 109 and 110: design does not, because stress at
Page 111 and 112: Table 5.2 Summary of limiting stres
Page 113 and 114: Figure 5.4 Plastic strain at workin
Page 115 and 116: example, a reduced value might be t
Page 117 and 118: The parameter � depends purely on
Page 119 and 120: CHAPTER 6 Heat-affected zone soften
Page 121 and 122: area of softening. With 7xxx-type m
Page 123 and 124: Figure 6.3 Typical hardness plots a
Page 125 and 126: 6.4 SEVERITY OF HAZ SOFTENING 6.4.1
Page 127 and 128: Figure 6.6 Categories of welded joi
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Figure 6.10 One-inch rule, extent o
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e allowed for in design by replacin
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Figure 6.13 Predicted area (A z ) o
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Figure 6.15 Overlapping HAZs. nomin
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In determining A zp , an appropriat
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failure plane in the HAZ, close to
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With MIG welding, an electrode-posi
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CHAPTER 7 Plate elements in compres
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(a) Compression member elements The
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Table 7.1 Classification of element
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Figure 7.4 Slender internal element
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Figure 7.7 shows curves of � ° p
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(7.9a) (7.9b) The strain gradient c
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(through the centroid) for ß S . F
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Figure 7.13 Outstands under strain-
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Figure 7.15 Reinforced elements. Th
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Figure 7.18 Stiffener location for
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Figure 7.20 Slender reinforced inte
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CHAPTER 8 Beams 8.1 GENERAL APPROAC
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8.2.2 Section classification The di
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that for the gross section. It woul
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the usual manner. Line 1 in the fig
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1. Fully compact sections. The limi
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Figure 8.8 Transverse and longitudi
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8.3.4 Shear resistance of bars and
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Figure 8.12 Tension-field action. i
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Figure 8.14 Moment/shear interactio
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depending on the estimated degree o
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where a is the stiffener spacing an
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plates (if fitted), p v =limiting m
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ending moment diagram. Two cases ar
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Figure 8.23 Sections covered in Tab
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where: I yy , I vv =inertia about m
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post (Section 8.6.4) or by some oth
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Figure 8.26 Components of deflectio
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9.1.2 Classification of the cross-s
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hole. Alternatively, it might fail
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Figure 9.2 Limiting stress p b for
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The determination of l involves a c
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Figure 9.6 Monosymmetric section. I
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Figure 9.9 Limiting stress p b for
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where s=� s /� t s =slenderness
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Figure 9.11 Type-R sections covered
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Figure 9.14 Four standardized profi
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9.7.2 Secondary bending in trusses
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Table 9.5 Necessary checks for memb
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Figure 9.18 Axial load with biaxial
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1. Tension members. The localized f
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Figure 10.1 Symmetric plastic bendi
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We now turn to monosymmetric sectio
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distance of its centroid from the n
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Figure 10.6 Elements of sections. I
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10.3.3 Product of inertia The produ
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Usually the conditions are such as
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Table 10.2 Torsion constant. Factor
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Figure 10.12 Warping. Conventional
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where b, t=element width and thickn
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10.5.3 Evaluation of warping When t
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For sections where the position of
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(10.31) where: e=distance that S li
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10.5.9 Asymmetric sections Before s
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CHAPTER 11 Joints This chapter cons
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the use of limiting stresses taken
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and the summation is made for all t
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Figure 11.3 Interaction diagram for
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k in order to give a fair compariso
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3. The design is satisfactory if fo
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When the method of surface preparat
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11.3.3 Weld force arising In many c
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Table 11.6 Limiting stress p w (N/m
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where p a =limiting stress for unwe
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Figure 11.11 Interaction diagram fo
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Manufacturers of structural adhesiv
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11.4.6 Creep Shear strength figures
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Figure 11.15 Effect of glue-line th
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Table 11.7 and Figure 11.17 provide
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11.4.11 Resistance calculations for
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high value reflects the various unc
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therefore usually presented in term
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For example: The loading spectrum i
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act on the structure. However, BS.8
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Figure 12.4 Crack propagation: (a)
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12.5 CLASSIFICATION OF DETAILS 12.5
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i.e. a joint extending in the same
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when the design life is low or when
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Methods (2) and (3) are difficult t
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it reverts to line 1. The slope s o
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Aluminium Design and Construction John Dwight

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