Simulation of assembly and disassembly behavior of ring-type snap fits:

In many plastics engineering applications, fastenings are typically realized by means of snap fits instead of conventional types of fasteners such as screwed fits or rivets. Snap fits can be easily integrated into injection molded parts and enables later assembly without additional fasteners. When disassembling a ring-type snap fit, the viscous deformation resulting from the hysteresis behavior of the polymeric material can reduce the holding force and the disassembly force. In a conventional finite element analysis of the assembly and disassembly process, the hysteresis behavior is usually not taken into account. After loading and unloading a part, a permanent set after the removal of the load is found, which is due to the viscous material deformation of the polymeric material and yields the accompanying change in deformation behavior under sequence of loading procedures. The first assembly can already lead to mechanical damage of the polymeric part. Consequently, in return it explains why the disassembl...