Characterization and simulation of the nonlinear thermal field of the aramid/bismaleimide composites caused by the dielectric heating effects of the microwave radiations

The aramid/bismaleimide composites are severely affected by the dielectric heating effects of the microwave radiations during use as the microwave functional materials. This study aims to characterize and predict the nonlinear thermal fields and thermal damages of the aramid/bismaleimide composites caused by the microwave radiations. The microwave radiation experiments were performed using a tailor-made system, and the equilibrium temperature and thermal damage threshold of the aramid/bismaleimide composites were experimentally determined. The temperature variation, thermal damage mechanism, and effect of the composite thickness associated with the dielectric heating were analyzed. Further, a simulation approach was developed to predict the nonlinear thermal fields of the composites caused by the microwave radiations. The dielectric heating process was considered an internal heat source, and a loop program was subsequently designed to implement the nonlinear thermal load. The developed simulation method efficiently predicted the equilibrium temperature and thermal damage of the composite materials due to the dielectric heating effect. The microwave radiation power was suggested to remain below 550 W for 3 mm thick aramid composites during service as a wave-transmitting material.