Battery housing (BH) in modern electric vehicles must meet demanding functional requirements. The design and geometry of the BH become intricate to prevent damage during collisions and to ensure absolute impermeability to gases and water during operation. Moreover, in the pursuit of a lightweight BH, manufacturers rely on high-strength 6xxx aluminium alloys, posing significant challenges for the welding processes. It is estimated that up to 30 m of weld length is required during the construction of battery housings including joining the lid and under-shield to the main structural frame and joining the ribs to the frame for standard vehicles. Due to the increasing use of thin sheets for lightweighting the structure, thermal-induced buckling may occur and generate critical dimensional unconformities going beyond design tolerances. This underpins the need to optimise fixturing design to control thermal-induced buckling.This paper goes beyond the state-of-the-art “N-2-1” approaches for fixturing thin and deformable parts and proposes the new principle of “unilateral N-2-1 fixturing”. The driving idea is adding unilateral restraints to the direction of thermal contraction, which ultimately causes buckling; and, keeping the direction where the thermal expansion occurs in a free state. The methodology is based on three main steps: (1) physics-based modelling of parts and fixtures using a thermo-mechanical FEA simulation; (2) calibration of the weld heat source using metallographic data; (3) validation using optical scanning technology. The methodology was demonstrated during the laser beam welding of a high-strength aluminium 6xxx thin deformable lid to a rigid high-strength 6xxx aluminium extrusion frame. Results indicated that the thermal induced buckling deformation was reduced from 15 mm, when using the state-of-the-art fixturing approach, to approximately 2 mm with the proposed methodology.

Investigation of the joining technology of 3D-printed parts into a large physical model has become an important research topic. Rotary friction welding (RFW) is one of the friction welding methods. Understanding the weld interface temperature changes in the weld center zone during RFW is critical because it is related to the weld quality of the welded parts using RFW. Traditionally, the number of revolutions is constant in the RFW. However, rare investigations focus on the fatigue specimen fabricated by RFW with variable rotational speed. This study used RFW with varying rotational speeds to fabricate fatigue specimens. The ANSYS software was used to predict the temperature history of rotary frictionally welded dissimilar polymer rods fabricated by a computer numerical control (CNC) turning machine with variable rotational speed. The RFW experiment of ABS/PC dissimilar polymer rods was conducted to investigate the temperature history and compared with the simulation results. It was found that the temperature history profiles were in good agreement with the experimental and simulation results. Compared with the weld interface heating rate obtained from the experimental results, the simulation results has average discrepancy rate about 4.48 %. Compared with the maximum temperature of the weld interface obtained from the experimental results, the simulation results has average discrepancy rate about 3.16 %. The fatigue life can be increased by approximately 1.4 times. Finally, a database of rotary frictionally welded dissimilar polymer rods fabricated by a CNC turning machine with variable rotational speed was proposed. The average Shore A surface hardness at the weld interface was enhanced by approximately 18 % compared to the base ABS material.

Friction stir welding is a modern welding technology with which the joining partners are welded in the solid state. The technology is often employed in the aerospace industry due to the excellent mechanical properties of the weld. Process disturbances can cause irregularities in the weld quality. It is still a challenge to avoid part fit-up deviations as a result of part misalignments and tolerances. Several publications have investigated the effect of alignment discrepancies on the weld quality, for example, by introducing a gap between parts, a tool offset, or linearly misaligned sheets. Depending on the application, the effects of simultaneously occurring alignment discrepancies on the weld quality could be critical. In this work, three alignment discrepancies were investigated (gap, linearly misaligned sheets, tool offset). The weld quality was determined using tensile tests. Process data such as the process forces and the spindle torque were also measured during the welding experiments. The results showed that each of the alignment discrepancies had a negative impact on the weld quality. The simultaneous occurrence resulted in an even lower weld quality. Some alignment discrepancies can probably be detected in the future using process data (e.g., the lateral force).