Parasitic vibration attenuation in ultrasonic welding of battery tabs

The effect of interface reaction on vibration evolution and performance of aluminium to steel high power ultrasonic spot joints

“…In addition, the signal control system may not deliver consistent power to piezoelectric components resulting in amplitude stepping in a bimodal manner [12,22,25]. Fig.…”

“…Firstly, the energy delivered to the transducer might not be enough for long welding cycles. Secondly, local melting of the zinc coating layer after~1.0 s of vibration could affect the power delivery to the welds [1,12,22,25]. However, this would be expected to lead to an increase in amplitude if the control system tries to maintain a constant power delivery.…”

“…A pause will happen by not providing an energy source input to transducers for a few moments and therefore, system response is expected to be attenuated. Amplitude stepping takes place when the amplitude of the vibration is modulated [12].…”

“…High Power Ultrasonic Spot Welding is an energy efficient technique for joining dissimilar materials, minimizing many problems caused by comparable fusion welding processes, such as intermetallic phase formation at the interface [3,4,8,9]. However, to date this technique is more applied to the welding of thin gauge foils in electronics and battery applications [10][11][12][13][14] than in automotive body structure applications [15][16][17][18]. A considerable advantage of this welding method is that various dissimilar material combinations, such as metals to ceramics, glasses and composites, as well as dissimilar metals including aluminium sheets to steel, can be produced [19][20][21].…”

“…The power can ramp-up with increasing welding time as the interface contamination can be removed and scattered around the weld periphery by cyclic shearing forces from the welding sonotrode [3,24]. In high power ultrasonic spot welding, three possible scenarios of phase-shift, pause and amplitude stepping can be considered for defective vibration [12]. In the 180°-phase shift, the direction of sonotrode vibration is changed in the middle of the welding process.…”