OS-E: 0155 Snap-Fit Analysis (CONSLI versus FINITE)

Snap-fit is a combination of two components namely mating and base part which form a mechanical attachment between them by means of locators, locks and enhancements. Nonlinear Static Analysis with large displacement theory is used to solve this example.

This model can be run with finite sliding and then compared with continuous sliding.
Figure 1. FE Model

Model Files

Before you begin, copy the file(s) used in this example to your working directory.

Model Description

Constrained in all degrees of freedom, the mating part is given. Imposed displacement along the assembly direction and contact is defined between mating and the base part. Also, SPCF forces are requested for calculating the applied load for the imposed displacement.
FE Model
Element Types
The linear material properties are:
MAT1 and MATS1
Young’s Modulus
2700 MPa
Poisson's Ratio
Initial Density
1.04E-9 Mg/mm3

Stress versus Strain curve is defined with MATS1.


Figure 2. Element Stress Contour

Concludes that the high stress concentration areas (Figure 2) are sensitive to the ramp-angle of the block, thickness of the flap and sharp corners. Such problem areas can be improved by means of notches, appropriate angles on the mating and base parts, respectively.

The continuous sliding is smoother comparative to finite sliding (Figure 3).
Figure 3. Finite Sliding versus Continuous Sliding