Large deformation analysis of a backside-supported snap-fit with nonlinear behavior

In this study, the large deformation of a backside-supported snap-fit was analyzed. The backside snap-fit pair consisted of mating part and base part. The mating part was a simple cantilever, and the base part had an opening with a supporting bar. The reaction force of the supporting bar was found to be an important parameter for the assembly and separation of the snap-fit. During our analysis, the supporting bar experienced a large deformation with nonlinear elasticity or plastic damage. Finite element analysis was performed. Stress concentration was observed at the root of the supporting bar and at the bent edge of the base part. Three types of specimens were designed and fabricated for experimental verification. The first specimen was a reference design that was fabricated according to the same design concept as the actual product. The second specimen was designed to reduce the stress concentration. The third specimen had an enriched design to increase the supporting force. The reaction force corresponding to the applied displacement was measured using a testing machine. The load exhibited a highly nonlinear behavior and reached a maximum peak value without causing any apparent damage, after which it decreased with plastic damage. Through numerical and experimental analyses, it was found out that the design of the backside-supported snap-fit could be improved by reducing the stress concentration and increasing the stiffness of the supporting bar.