Modeling contact dynamics with ANSYS

Problem Description: This is a 3-D analysis of a steel pin contacting a smooth pinhole in a block. Because of the inherent symmetry of the model, the analysis is performed on a quarter symmetry model. Two different load steps are defined. The objective of the first load step is to observe the interference fit stresses of the pin which is geometrically thicker than its pinhole. The objective of the second load step is to observe the stresses, contact pressures and reaction forces due to the motion of the pin being pulled out from the block.

Given: The dimensions of the model are as follows: PIN radius = 0.5 units, length = 2.5 units. BLOCK width = 4 units, length = 4 units, depth = 1 unit. PINHOLE radius = 0.49 units, depth = 1 unit. Both solids are made of structural steel (stiffness = 30e6) and are assumed to be flexible.

Approach and Assumptions: A quarter symmetry model is appropriate to simulate the contact phenomena. Two load steps are used to set up the analysis: Load Step 1: Interference Fit -- solve the problem with no additional displacement constraints. The pin is constrained within the the pinhole due to its geometry. Stresses are generated due to the general misfit between the target (pinhole) and the contact (pin) surfaces. Load Step 2: Pull-out -- move the pin by 1.7 units out of the block using DOF displacement conditions on coupled nodes. Explicitly invoke Automatic Time Stepping to guarantee solution convergence. Read results for every 10th substep during solution.