Multiscale numerical and experimental investigation into the evolution of process-induced residual strain/stress in 3D woven composite

The process-induced residual strain and stress have a significant impact on the forming quality and service performance of 3D woven composites (3DWC). A multiscale model of 3DWC is developed to predict the residual strain and stress after the manufacturing process. Representative volume element at fiber scale and yarn scale are developed according to the geometric characteristics of 3DWC, and the modulus-development model is developed with respect to finite element based micromechanics method. An equivalent temperature load method is proposed to develop the cure shrinkage strain model. A thermal-chemical-mechanical coupling analysis of 3DWC curing process is carried out by integrating the abovementioned models, and the evolutions of temperature, degree of cure and residual strain/stress are obtained. Fiber Bragg Grating sensors are hybridized into the fabrics before Resin Transfer Molding (RTM) processing. The signal from sensors during RTM shows that the residual strain evolution is in good agreement with our modeling prediction.