Joining enabled by high velocity deformation
Three high velocity joining methods are presented. They are projectile spot impact welding, electromagnetic crimping, and electromagnetic impact welding. Projectile spot impact welding utilizes high-speed bullet to impact metal sheets to a recessed die to achieve a solid state bonding. The bullet velocity ranges from 160m/s to 280m/s. In electromagnetic crimping, aluminum tubes/rings are accelerated by electromagnetic pressure to impact the mandrel to form mechanical interference fit. Residual stress in the tubes/rings provides the crimping strength. In electromagnetic welding, flyer tubes are placed at a specified distance to the base tubes. When the flyer tube is accelerated by electromagnetic pressure to impact with the base tube at an adequate impact angle, high impact pressure will sweep off the surface oxide film to form atomic bonding between flyer and base tubes. Wavy interfaces are normally observed in successful welds. Finite element modeling is performed to aid the design and understanding of these processes. Three commercial software packages have been used throughout the research. AUTODYN is a nonlinear dynamics code. ABAQUS can handle both static and dynamic problems. MPone is a fully coupled electromagnetic-mechanical code. It has been found that both AUTODYN and ABAQUS are good at solving wave propagation problems, while MPone is able to provide a reasonable estimation of electromagnetic coupling and mechanical deformation. However, when modeling the electromagnetic crimping problem with each of the three codes, none of them produces fully satisfactory predictions of the process. The goal of this research is to investigate the joining capabilities of high velocity technologies using both numerical and experimental techniques. The experimental results demonstrate the great potential for using high velocity joining methods in production to save cost and extend current application limits. Although the numerical modeling provides some insight that is useful for developing commercial joining methods, further development is needed to fully capture the complex nature behind these high velocity joining techniques.
School:The Ohio State University
School Location:USA - Ohio
Source Type:Master's Thesis
Keywords:electromagnetic forming joinning dynamic simulation solid state welding
Date of Publication:01/01/2003