General Mechanical

General Mechanical

Element distortion and unconverged solution issue with simulating snap-through in Mechanical APDL

    • CW62

      Hello all,

      I am attempting to simulate the qausi-static snap-through of a bistable composite laminate with an unsymmetric lay-up of [0_2/90_2]T. The simulation involves two parts: (1) simulating the cool down of the laminate from cure (temperature change = -180 degrees Celsius) to get the curved deformation of the laminate due to residual thermal stresses developing after cure (stable state 1), and (2) simulating the quasi-static snap-through of the laminate when the laminate is clamped at it's centre and 4 equal concentrated forces in the out-of plane direction on the laminate corners are applied to induce snap-through of the laminate to its second stable state (stable state 2).

      Below is an image of the square laminate after cool down from cure and the applied boundary conditions and loading for snap-through. The square laminate has an edge length of 250 mm with a mesh density of 50 x 50 SHELL181 reduced integration elements.

      With reference to section 8.11. Unstable Structures in the Mechanical APDL 2020 R1 Structural Analysis Guide, I know that there are the nonlinear stabilization and arc-length methods that can be used to simulate quasi-static snap-through events. I have attempted to use both methods but encounter the same issues of element distortion and unconvergence. I've set up the exact same models in Abaqus and had no issues at all with element distortion and convergence, yet I can't get the same model to converge in Ansys Mechanical APDL. I don't know what I'm doing wrong in Ansys Mechanical APDL to cause the errors I'm encountering. I've attached my APDL command list for the model using nonlinear stabilization for reference. Any help with rectifying my issues or guidance from people with experience modelling quasi-static snap-through events in Ansys would be much appreciated. Thank you.

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