Dynamic finite element analysis simulation of the terminal crimping process

The lead time in order to develop the ideal terminal crimp, for low energy applications, is quite extensive. The terminal grip must first be designed, prototype tooled and the crimp specification developed and tested prior to approval and release. The factors of grip design, terminal material and crimp tooling, that govern the formation of a ''good'' crimp are also not clearly understood. In this study finite element analysis was used to simulate the crimping process, in order to better understand the underlying factors that govern crimp formation. FEA models were created using the ABAQUS program. In order to simplify the study, this work was conducted using two (2) and three (3) dimensional models. The terminal grip cross section, the punch tooling and the wire strands were modeled. In the FEA simulation, the grip was forced into the punch while sitting on the anvil. This mimics the real life application. The initial results of the study have shown that the friction between the grip surface and the punch surface is crucial to the formation of a ''good'' crimp. The models also showed that the crimping process is a combination of both the plane stress and plane strain conditions. The initial models are currently being refined in several ways. Compressive stress versus strain properties of the various grip materials, that are presently used in automotive terminal crimps, have been measured. The dynamic coefficients of friction that exist between the various interfaces that are involved in the crimping process are being determined. A high speed video has also been taken of the crimping process in order to provide more accurate punch speed versus distance data for the FEA models. The video will also be used to correlate the FEA results with the crimping of actual parts. This study will assist in designing more robust grip designs with better serration features and reduces the time for the total crimp development process in the future. This study showed the importance of tool surface quality and tool wear to the formation of a good crimp.