Aluminium Design and Construction John Dwight

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3xxx, 5xxx same as for MIG; 6xxx reduce MIG value by 0.05; 7xxx reduce MIG value by 0.2. 6.8.3 Extent of the softened zone for TIG welding With the present dearth of information, we would tentatively suggest that the extent of the nominal HAZ at a TIG weld should be found by making the following arbitrary adjustment to the predicted extent for MIG: Welds on thin material. Increase Az by 50%. Welds on thick material. Increase s by 25%. A problem arises when an original MIG weld is repaired using TIG. This will locally increase the width of the HAZ by an amount that is very hard to quantify. 6.9 HAZ AT FRICTION-STIR WELDS At the time of writing, it is too soon to provide comprehensive HAZ data for joints made by the new friction-stir process. However, from a study of some hardness surveys provided by Hydro-Aluminium in Norway, using 6xxx-series specimens, it is possible to make the following observations for material welded in the T6 condition. 1. The pattern of softening will be of the same general form as that shown in Figure 6.2. 2. The severity of softening is comparable to that with MIG. 3. The extent of the softened zone relates to the shoulder radius of the welding tool. 4. The softened area will tend to be rather less than that obtained with MIG. Note, however, that it is possible to FS-weld together extruded sections in the T4-temper, and then apply post-weld ageing to bring them up to full T6 properties. Then there is no HAZ region worth speaking of and the ductility is good. Such a procedure is readily carried out in an extrusion plant where long ageing furnaces already exist. Copyright 1999 by Taylor & Francis Group. All Rights Reserved.
CHAPTER 7 Plate elements in compression 7.1 GENERAL DESCRIPTION 7.1.1 Local buckling In aluminium design it is often economic to employ wide thin sections, so as to obtain optimum section properties for a minimum weight of metal. The extrusion process makes this possible. The limit to which a designer may thus go in spreading out the material depends on local buckling of the individual plate elements comprising the section. If the section is made too wide and thin, premature failure will occur with local buckles forming in elements that carry compressive stress (Figure 7.1). The first step in checking the static strength of a member is to classify the cross-section. Is it compact or slender? If it is compact, local buckling is not a problem and may be ignored. If it is slender the resistance will be reduced, with interaction occurring between local buckling of individual plate elements and overall buckling of the member as a whole. 7.1.2 Types of plate element Two basic kinds of element are recognized, namely internal elements and outstands. An internal element is attached to the rest of the section at both Figure 7.1 Local buckling. 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
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1.4.4 Establishment of the alloys I
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1.5.2 New technology Most of alumin
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large span, where self-weight is a
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These tend to be in all-aluminium c
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Close-up of the M-dec system, which
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Aluminium glazing system for commer
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Nat West Media Centre, Lords Cricke
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The main requirements for the produ
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in which t and w are in mm. These a
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Figure 2.1 Extrusion process (direc
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Figure 2.2 Typical extrusion die. t
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Figure 2.6 ‘Semi-hollow’ profil
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especially the stronger alloys in t
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Figure 2.9 Conventional profiles. 2
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2.4 TUBES By tubes we mean hollow s
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CHAPTER 3 Fabrication 3.1 PREPARATI
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Figure 3.1 Alternative designs for
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Figure 3.2 Thread insert. a coil-sp
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3.3 ARC WELDING 3.3.1 Use of arc we
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adjusted. The technique is claimed
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For welds of minimum or fatigue qua
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Figure 3.5 Friction-stir welding: s
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are, and the designer/fabricator mu
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cartridge, and mixing takes place a
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3.7.4 Painting Alloys having durabi
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Where a range is given, as for the
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will be only slightly above that fo
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heating the metal to a temperature
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Table 4.4 Characteristics of differ
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softening in the heat-affected zone
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60 alloys, are: BSEN.485 plate and
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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
Page 129 and 130: Figure 6.10 One-inch rule, extent o
Page 131 and 132: e allowed for in design by replacin
Page 133 and 134: Figure 6.13 Predicted area (A z ) o
Page 135 and 136: Figure 6.15 Overlapping HAZs. nomin
Page 137 and 138: In determining A zp , an appropriat
Page 139 and 140: failure plane in the HAZ, close to
Page 141: With MIG welding, an electrode-posi
Page 145 and 146: (a) Compression member elements The
Page 147 and 148: Table 7.1 Classification of element
Page 149 and 150: Figure 7.4 Slender internal element
Page 151 and 152: Figure 7.7 shows curves of � ° p
Page 153 and 154: (7.9a) (7.9b) The strain gradient c
Page 155 and 156: (through the centroid) for ß S . F
Page 157 and 158: Figure 7.13 Outstands under strain-
Page 159 and 160: Figure 7.15 Reinforced elements. Th
Page 161 and 162: Figure 7.18 Stiffener location for
Page 163 and 164: Figure 7.20 Slender reinforced inte
Page 165 and 166: CHAPTER 8 Beams 8.1 GENERAL APPROAC
Page 167 and 168: 8.2.2 Section classification The di
Page 169 and 170: that for the gross section. It woul
Page 171 and 172: the usual manner. Line 1 in the fig
Page 173 and 174: 1. Fully compact sections. The limi
Page 175 and 176: Figure 8.8 Transverse and longitudi
Page 177 and 178: 8.3.4 Shear resistance of bars and
Page 179 and 180: Figure 8.12 Tension-field action. i
Page 181 and 182: Figure 8.14 Moment/shear interactio
Page 183 and 184: depending on the estimated degree o
Page 185 and 186: where a is the stiffener spacing an
Page 187 and 188: plates (if fitted), p v =limiting m
Page 189 and 190: ending moment diagram. Two cases ar
Page 191 and 192: 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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