Aluminium Design and Construction John Dwight

Figure 11.9 Variation of a with � (equation (11.16)).
salient values being:
�=90° �=1.00
60° 0.82
45° 0.71
30° 0.63
0 0.58.
Appropriate values for certain cases of weld metal failure are therefore:
Transverse in-line butt (�=90°) �=1.00
Transverse fillet lap-joint (�=45°) �=0.71
Any case of longitudinal loading (�=0) �=0.58
‘Butt-fillet’ welds (Figure 11.7(d)) cause difficulty, because it is not
clear which value to take for k. When the preparation has been specified,
but the width of the deposit is uncertain, a safe procedure is to take
k=1.0 and g=g 1 (Figure 11.7(d)). Alternatively, if the size of the deposit
is clearly specified, it is acceptable to take k=0.85 and g=g 2 should this
prove more favourable.
11.3.5 Calculated resistance, fusion-boundary failure
At any weld there are two fusion-boundary planes, both of which may
need to be considered. The calculated resistance P¯c per unit length of
weld is found from:
P – c =ahpf (11.17)
where pf =limiting stress for fusion-boundary failure, h=width of failure
plane, and �=factor depending on joint geometry (as before).
The limiting stress pf is governed by the properties of the parent
metal. For heat-treated material it is given by:
p f =k z1 p a
Copyright 1999 by Taylor & Francis Group. All Rights Reserved.
(11.18a)