Structural abstraction in snap-fit analysis

Snap-fit design has always been more of an art instead of an engineering ac tivity. Research in this area focuses on generating finite element models f or predicting the performance of snap-fit features. Such research typically uses fixed-end conditions at the base of the snap-fit feature. Often this is an unrealistic assumption, because snap-fits are usually molded on plast ic parts with significant flexibility. The performance of snap-fits can be significantly influenced by this additional flexibility. To predict this pe rformance of snap-fits it often becomes necessary to analyze the entire par t, which can be a costly and time consuming process. There is no general me thodology, in the open literature to incorporate base-part flexibility into the design of snap-fit features. Existing work in this area is inaccurate and limited to certain base-part and snap-fit topologies. This paper propos es a new methodology called structural abstraction for incorporating base-p art flexibility into snap-fit feature models. This methodology abstracts ba se-parts as spring elements with various stiffnesses. The underlying theory and the relevant relationships are developed and the approach is validated using several test cases. independence of the approach to both base-part a nd snap-fit topologies is established and shown to be a major advantage of this technique. Use of this methodology will improve snap-fit anal? sis and give a more accurate estimation of retention strength, It is shown that in certain cases the improvement in accuracy over conventional finite element models of snap-fits can be as high as 70 percent. [S1050-0472(00)02504-6].