Structural and thermal optimization of a composite electronics enclosure for spacecraft applications

An existing composite electronics enclosure has been optimized with respect to structural and thermal loading. A thermal model of the enclosure with printed circuit boards was created using a finite difference code, and the maximum board temperature from existing spacecraft enclosure data was used as the thermal criterion. A structural model of the same enclosure with printed circuit boards was created using the finite element code ABAQUS. Random vibration loads were reduced to quasi-static loads and imposed on the enclosure. Tsai-Wu,failure criteria were used to assess failure. The structural and thermal models were iterated until an optimum stress and temperature state could be achieved. This was done by varying the number of plies, ply orientation, and ply location. Two different high-thermal-conductivity fibers (YS90 and XN70) were used in conjunction with an intermediate-modulus fiber (T300) in different quantities and different locations. Both weight and cost were considered in evaluating the models. Two designs had the same positive margins of safety, the same board temperatures, and the same weights; however, one design cost 1/10th as much as the other.