−Table of Contents
Simple contact
by Dr. Dušan Gabriel
Problem description
Consider the two bodies shown acted on by uniformly distributed pressure p. Perform contact analysis and calculate the pressure distribution over the contact plane.
Material properties
E=2×105 MPa, ν=0.3.
Support
None.
Loading
p=−10 MPa.
Solution
The contact search is performed at external Gauss integration points accessed by the FE algorithm. Contact constraints are enforced by the penalty method. Thus, the unknown contact pressure pIG is approximated by the penalty function pIG=ξπIG, where ξ denotes the value of the penalty parameter and πIG is the penetration determined at the Gauss integration point IG. The essential part of the analysis is a good choice of the penalty parameter ξ, whose value can be estimated from the stiffness of a cubic element ξ=fsK√detJS, where fs is the inverse of relative displacement error, K the bulk modulus and JS the surface Jacobian. For example, if we require the relative displacement error to be 0.01 (i.e., the ratio of penetration to the displacement of the contact plane should not exceed 0.01), we set the penalty parameter to ξ=1013 N/m3.