Hello,

I am working on a thermal-stress/expansion analysis of a laser diode array using the following half unit-cell geometry which comes from the red outlined portion of the repeated unit cell structure shown at bottom left. This half-unit cell has symmetry down one plane and a linear periodic condition across the top and bottom surfaces, reflecting the repeating geometric unit for stacked laser diode bars. These boundary conditions are shown in the bottom right sketch of the half unit cell model.

The thermal load comes from the results of a steady state thermal analysis and is not my concern here. My major concern is getting the right boundary constraints in the structural model to allow free thermal expansion in the boundaries shown above with the above symmetries while preventing rigid body motion and rotation, as well as mitigating artificially induced boundary stresses from those constraints. I am familiar with the 3-2-1 approach; however, I do not know how it would apply in the case of a one plane symmetry (U_x = 0, U_y = U_z = free) and linear periodic conditions across two other faces.

I would appreciate some tips/pointers. Thanks!