Search Results (5)

This paper investigates the design of aluminium I-beams under major axis bending, fabricated by MIG welding three plates to form the section. The study focuses on beam sizes relevant to pedestrian bridges, with depths ranging from 508 mm to over 2540 mm. The analysis is limited to local buckling behaviour. A total of 600 geometrical material non-linear imperfection analysis-GMNIA and linear buckling analysis-LBA reference numerical results were obtained from validated non-linear shell finite element models. The influence of the heat-affected zone (HAZ) is shown to be pronounced and detrimental to the resistance of welded aluminium beams. Unlike in steel beams, where buckling often governs, local buckling modes in aluminium members may arise but are typically dominated by HAZ-related failure. The effect of strain hardening on the behaviour and resistance of aluminium alloys is examined and compared with current design approaches, which typically assume an idealised plastic plateau similar to steel. The results show that strain hardening significantly enhances resistance and is not captured by existing design methods. The effect of residual stresses in welded aluminium members is also investigated. The results indicate that MIG-induced residual stresses are sufficiently small and have a negligible influence on both structural behaviour and strength. Their effect can be conservatively accounted for by increasing the amplitude of initial geometric imperfections. The study shows that current design recommendations are inconsistent and mostly unsafe for welded aluminium beams bridge sections governed by local buckling. The findings provide improved insight into the behaviour and resistance of such members and contribute to more accurate and efficient design methods. Full article

Welding aluminium alloys presents several challenges, most notably strength reduction in the heat-affected zone and pronounced welding-induced deformations. Current design provisions for welded connections, such as those in Eurocode 9, can result in substantial reductions in the structural capacity of welded components. With the ongoing development of welding processes that enable metal fusion with reduced heat input and potentially less degradation in the heat-affected zone, re-evaluation of these provisions is essential. This paper presents the results of hardness measurements conducted on butt-welded connections made from EN AW-5083-H321 aluminium alloy to qualify and quantify the extent of the heat-affected zone. The experimental programme included 12 specimens with plate thicknesses of 10 mm, 8 mm, and 6 mm, fabricated using DC-MIG-P and AC-MIG-P welding processes. The measured extents of the heat-affected zone were between 1.73 and 2.64 times smaller than the Eurocode 9 values for the DC-MIG-P welding process and between 2.29 and 4.62 times smaller for the AC-MIG-P process. Significant variability in the measured extents of the heat-affected zone was observed. Full article

One of the main challenges in welding aluminium concerns structural integrity and a significant reduction in mechanical properties in the region adjacent to the weld. Design provisions can result in a drastic reduction, which may exceed 50% of the base metal resistance. This research aims to evaluate the accuracy of the HAZ extent values codified in Eurocode 9 for T-connections fabricated from artificially aged 6082 aluminium alloy, which is widely used in load-bearing structures. Three plate thicknesses (6, 8 and 10 mm) and two pulsed MIG welding processes (DC-MIG-P and AC-MIG-P) were used to fabricate 20 T-connection specimens (10 different configurations) in accordance with EN 1090-3. The study focuses on characterising the welding zones through hardness testing and metallographic examination. Results show that AC-MIG-P offers better control over thermal input and may reduce structural distortion, while DC-MIG-P provides more robust fusion and metallurgical continuity. Findings related to HAZ extent (12.77 mm and 15.36 mm maximum measured for AC-MIG-P and DC-MIG-P, respectively) suggest that Eurocode 9 may be overly conservative for pulsed MIG welding processes, particularly for greater plate thicknesses where a HAZ extent of 22.50 mm or more is specified. Consequently, adopting more precise, process-specific HAZ characterisations could lead to more realistic connection design and structural behaviour. Full article

In this work, AA1070 aluminium alloy sheets are joined using TIG and MIG welding after three different edge preparations. Shearing, water jet and plasma-cut processes were used to cut sheets, subsequently welded using ER5356 and ER4043 filler metals for TIG and MIG, respectively. Mechanical properties of the obtained sheets were assessed through tensile tests obtaining a relation between sheet preparation and welding tightness. Micro-hardness measures were performed to evaluate the effects of both welding and cutting processes on the micro-hardness of the alloy, highlighting that TIG welding gives rise to inhomogeneous micro-hardness behaviour. After tensile tests, surface fractures were observed employing scanning electron microscopy to highlight the relation between tensile properties and edge preparations. Fractures show severe oxidation in the water jet cut specimens, ductile fractures and gas porosities. Full article

The thermo-elastic fracture problem and equations are established for aluminium alloy Metal Inert Gas (MIG) welding, which include a moving heat source and a thermoelasticity equation with the initial and boundary conditions for a plate structure with a crack. The extended finite element method (XFEM) is implemented to solve the thermo-elastic fracture problem of a plate structure with a crack under the effect of a moving heat source. The combination of the experimental measurement and simulation of the welding temperature field is done to verify the model and solution method. The numerical cases of the thermomechanical parameters and stress intensity factors (SIFs) of the plate structure in the welding heating and cooling processes are investigated. The research results provide reference data and an approach for the analysis of the thermomechanical characteristics of the welding process. Full article