Cryogenic-thermal-vibration coupling residual stress relief method and regulation mechanisms analysis of M55J-CF/CE laminates

Carbon fiber-reinforced polymer (CFRP) composites are widely used in the essential structural for spacecraft. However, the uneven distribution of internal residual stress (RS) significantly reduces the pointing accuracy and service life of these products. This research presents an innovative cryogenic-thermal-vibration stress relief (CTVSR) method, and the RS regulation equipment with high-low temperature (−196 to 220 °C) and vibration frequency (16.7–133 Hz) were developed. Taking M55J carbon fiber/cyanate ester (M55J-CF/CE) composite laminates as the research object, and the RS regulation experiment with 15 groups of CTVSR parameters was carried out. Then the measured strain (MS) result along the layer thickness were collected based on incremental hole-drilling (IHD) method. The gradient RS distribution under different parameters is derived by the calibration coefficient matrix used FEM to solved. The research results show the RS peak value reduces effect between 25% and 65%. Subsequently, the relationship between RS and mechanical properties, microstructure, and interface characteristics were deeply analyzed, the RS regulation mechanism by different CTVSR parameter was revealed. The coupling effect of cryogenic-thermal-vibration promotes the microflow and relaxation of fiber-interface-matrix. The uneven distribution of RS between CF and CE components of the composites was broken, and the RS peak value of the whole laminate was reduced. It has been demonstrated that the CTVSR method has obvious effect on RS regulation of CFRP.