Contact surfaces and shear force

Hello everyone,

I am currently performing a shear test on a sandwich panel which lies on top of two composite L-shaped side supports as shown below:

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Since the L-shaped side supports movement is fully constained, the sandwich panel would be expected to rest on top of them once the vertical load is applied when studying a linear static case. However, when running OptiStruct this is not the case and the sandwich panel just runs through the side supports like they are not even there. I tried creating contact surfaces at both the top of the L-shaped side supports and the bottom of the sandwich panel as well as an interface between them but the sandwich panel is still 'pushed down' and not sustained by the supports when running the analysis. Images below show Frames 0 and 1 from HyperView results; note how the sandwich panel just disappears down the screen while the side supports remain untouched.