Thermal Stress Distribution in CF/EP Composite in Low Earth Orbit

Thermal cycle in low earth orbit environment has a negative influence on thermal stress distribution in carbon fiber/epoxy (CF/EP) composite. In our experiment a 3D finite element analysis method was used to analyze thermal stress distribution and failure mechanism in CF/EP composite. Thermal stress distribution was characterized using Von Mises stress, composite potential failure zone was analyzed using parabolic failure criterion, and composite micro-cracking distribution was studied using birth and death technique. Results indicated that thermal stress at different parts of the composite are different: at composite free end zone, the maximum thermal stress 179.9 MPa located at fiber surface with the longest distance between two fibers; while in composite inner zone, the maximum thermal stress is 29.5 MPa located in EP matrix with the shortest distance between two fibers. Thermal stress concentration at composite free end zone induces micro-cracking between fiber and the matrix, besides as thermal cycle increase micro-cracking progress from composite free end zone to composite inner zone, which will degrade the mechanical performance.