Numerical and experimental analysis of the vibration propagation of ultrasonically welded cable-arrester connections

Abstract Ultrasonic metal welding (USMW) is widely applied in the transportation industry for the production of lightweight electrical connections, particularly in cable arrester joints for electric vehicles. While the process offers low joining temperatures and short cycle times, ultrasonic vibrations can interfere with previously welded joints, potentially causing degradation. Therefore, a mechanistic understanding of vibration propagation during USMW and its impact on existing joints is required to ensure process reliability. This study investigates vibration propagation and joint degradation in stranded wire to arrester connections welded at both ends using linear USMW. EN AW-1370 aluminum stranded wires with a cross section of 50 mm 2 and varying lengths between 150 and 1000 mm were welded to CW004A copper terminals. Experimental investigations included laser vibrometry, high-speed videography, and tensile shear testing. In parallel, a scaled finite element model was developed in ANSYS Workbench and validated against experimental data. Mechanical testing revealed a strong dependence of joint integrity on cable length, with robust joints at 300 mm, non-weldable behavior at 225 mm, and isolated failures at 150 mm and 375 mm, while longer cables exhibited no indications of joint degradation. Laser vibrometry indicated decreasing vibration amplitudes with increasing length due to damping, whereas critical lengths were characterized by pronounced amplitude and phase shifts associated with weld degradation. Finite element simulations reproduced these effects and identified elevated weld-zone stresses at critical lengths of approximately 130 MPa. Unsynchronized vibration transmission, expressed by relative phase shifts, was identified as the primary cause of joint failure.