As it goes I need to create a simulation fixture.  The best example I can use is a wood 2x4 place on a table.  Each end is overhanging the table.  I apply a force to each end.  As one would expect the center of the 2x4 bows off the table.  What fixture would I use for simulation.  I have choosen on flat face, but Simulation errors out, I think I am not constraining the model enough.