Welded aluminium alloy connections: a simplified plastic model

The heat from welding reduces the strength of heat-treatable aluminium alloy connections in the vicinity of the welds. This paper describes a model for the behaviour of welded cruciform connections with a reduced-strength zone and introduces a notional critical load based on a limiting strain to predict the ultimate loads. The model shows that a large proportion of the load is transferred through the transverse fillet weld at the end of the finger as compared with the longitudinal fillet welds along the finger. It also illustrates that the characteristic dish-like necking mode of failure is due to local straining at the reduced-strength zone. A parametric study shows that the single most important factor affecting the ultimate strength of these connections is the material strength in the over-aged zone.