Greetings,
I am having a problem with a press-out analysis. I am using version 2022. The setup is as follows:
Objective
Preform a press out analysis of an aluminum bushing that has been assembled into an aluminum machined casting. I wish to obtain the force in which the bushing begins to slide and break free.
Two Load Case Setup
Load Step 1- Shrink fit the bushing into the casting with a given interference fit. The bushing is already in place, just the contacts need to be equivalenced and create the condition of a bushing that was press fit into the casting.
Load Step 2 - Perform an enforced displacement on the bushing to start generating a reaction force to determine when the load ramp starts to flatten out. Basically, finding the knee bend in the force deflection curve. This is the force that I am most interested in.
NLSTAT analysis for both Cases
Load Step 1 - This solves with no issues. I can get the initial shrink fit to work using a friction constant for the contact.
Load Step 2 - I apply the enforced displacement and get reasonable results. The solutions work with both large displacements turned on and off. However, this is still a quasi-static solution and not truly time dependent. I want to push out the bushing over a 2s time period.
NLSTAT for the Press fit and DTRAN for the Enforced Displacement
Load Step 1- The first solution works with NLSTAT and solves with no issues. I can get the initial shrink fit to work using a friction constant for the contact.
Load Step 2- I applied the enforced displacement, using a DTRAN load step, and the model will not converge. I have tried multiple combinations of options, time steps, variable changes, contact changes, etc. The most I can get is the first timestep to solve. When I post the results, the elements are distorted. It has to be the solver, trying to deal with the geometric non-linearity of the contact and sticking during the transient solution movement over a real timestep. I do this type of advanced nonlinear analysis in Nastran or Abaqus with no issues and get good results with basically the same model. I did try to run in version 2025 with no success.
This is a fairly straight forward analysis, and I just would like to be able to perform this type of solution directly within Opti struct without using those other solvers. Any thoughts, suggestions, or different approach would be appreciated.
