Seminar by Wayne Cai

Multi-Scale and Multi-Physics Modeling of Multi-Material Ultrasonic Metal Welding

Wayne Cai

Staff Researcher

General Motors Global R&D Center

Ultrasonic welding is a solid-state bonding process using high-frequency vibration energy. It has been used in the semiconductor industry for several decades and more recently in the automotive industry for lithium-ion battery welding due to its advantages in joining multi-layer and multi-material metals (such as Cu and Al).

This talk presents some recent research advancements in ultrasonic metal welding, particularly in the context of integrated computational material engineering and process modelling.  At the structural scale, analytical and simulation models calculate the assembly system dynamics and resonances and thereby predict the structural failure during the ultrasonic welding.  At the macroscale, thermal-mechanical finite element methods are employed to simulate the cyclic and super-high-strain-rate welding process by means of both Lagrangian and Eulerian methods. At the mesoscale, phenomenological models are explored to describe the kinetics of dynamic recrystallization and thereafter the microstructure evolution at the multi-material bonding interface. Finally, an interfacial bonding model (from atomistic to μm scale) is proposed to predict the inter-material bonding layer atomistic/micro-structures, chemical compositions and subsequently the mechanical properties needed for weld quality evaluation. The talk will conclude with future work from both the science/knowledge and engineering/innovation points of view.

Dr. Wayne Cai is a Staff Researcher at General Motors Global R&D Center in Warren, Michigan, USA. His research area is in joining and assembly where mechanics, materials, and mathematics (statistics) are used to predict, optimize, monitor & control manufacturing processes and systems for improved quality, reliability and reduced cost. He has been a project leader, principle investigator and supervisor for a number of industrial, and/or governmental/university collaborative research programs. Dr. Cai is very active in contributing to world-wide knowledge and higher education by authoring over 70 peer-reviewed research papers and supervising graduate students. He is also recognized for his innovation with 30+ US and international patents (or patent pending) and numerous GM trade-secrets inventions. He serves as an Associate Editor for ASME Journal of Manufacturing Science and Engineering, SME Journal of Manufacturing Processes, chair of SAE Hybrid Electric Vehicle Committee, and guest professor at Shanghai Jiao Tong University (China). Dr. Cai received his Ph.D. degree from The University of Michigan in Mechanical Engineering.