SELECTION OF CRITICAL THERMAL STRUCTURAL DESIGN PARAMETERS FOR A METAL/COMPOSITE JOINT IN A COMPOSITE ELECTRONICS ENCLOSURE/

An experiment was designed to determine the critical design parameters for a metal/composite joint in a composite electronic enclosure where both thermal and mechanical performance are important. A combination bolted and bonded single-lap joint that simulates the interface betwee n the thermal wall and the card guide was studied under static loading with power supplied through a surface-mounted chip resistor. The foll owing parameters were varied: fiber orientation, type of thermally con ductive pitch fiber, type of adhesive, adhesive thickness. bolt spacin g, bolt size, and input power. Load, strain, and temperature from five thermocouples were collected during a tensile test with a 0.02 in/min . strain rate. A fractional factorial experimental design was used. A dual failure mechanism was consistently recorded: failure of the adhes ive bond followed by bolt shear failure. Initial screening results ind icated that a configuration can be achieved that significantly enhance s both mechanical and thermal performance.