Numerical analysis of thermal expansion behaviors and interfacial thermal stress of 3D braided composite materials

The objective of this investigation is to analyze the thermal expansion behaviors and interfacial thermal stress of 3D braided carbon/epoxy composite materials in various temperature fields ranging from similar to 100 degrees C to 140 degrees C. Two geometrical structure models, microstructure model and multi-unit cell model were established to investigate the thermo-mechanical behaviors of the 3D braided composites. The microstructure model has revealed the effect of braiding angle on the thermal expansion behaviors, interfacial stress and distribution. The multi-unit cell model was developed to analyze the nonlinear change of axial coefficient of thermal expansion (CTE) with braiding angle. We found that the interfacial normal thermal stress between braided yarns and resin increases with the braiding angle. The axial thermal strain exhibits thermal shrinkage for a small braiding angle and thermal expansion for a large braiding angle at high temperature. The critical braiding angle was found at which the axial CTE transited from negative to positive, i.e., the zero thermal expansion coefficient braided composite materials could be designed. (C) 2017 Elsevier B.V. All rights reserved.