To calculate the mechanical response of the board & heat-sink assembly under various dynamic loads. To calculate the natural frequencies and mode shapes of the assembly. To calculate displacements and stresses under random vibration (PSD), constant acceleration and shock loads according to Mil-SPEC flight requirements.
The geometry of the model was generated in ABAQUS/CAE, a commercial FE preprocessor, using data supplied by MILPER. The geometry is shown in Figure 1, which included heat sink, PCB, electronic components and connector. The geometry was modeled with Solid Elements; the finite-element mesh is shown in Figure 2.
Using FEA in the preliminary design stage showed that no natural frequency of the analyzed assembly coincides with the known operating frequencies of the structure connected to it. Another benefit of the numerical study was the ability to determine the force that acts on the interface between the electronic components and the PCB under various dynamic loads. This value was then used to verify that no tearing of electronic components is likely to occur.