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].