The viscoelastic behavior of the principal compliance matrix of a unidirectional graphite/epoxy composite

Abstract A testing program was conducted to determine the time‐temperature response of the principal compliances of a unidirectional graphite/epoxy composite. It is shown that two components of the compliance matrix are time and temperature independent. In addition, the compliance matrix is found to be symmetric for the viscoelastic composite. The time‐temperature superposition principle is used to determine shift factors. It is shown that shift factors are independent of fiber orientation for fiber angles that vary from 10 to 90° with respect to the load direction.