Anisotropic viscoelastic finite element analysis of mechanically and hygrothermally loaded composites

Abstract Quasi-static linear anisotropic viscoelastic responses of composite structures subjected to mechanical and hygrothermal loads are formulated in terms of finite element algorithms. Laplace and/or Fourier transforms rather than direct time integrations are used in this formulation, in order to improve the accuracy of results and save extensive computational time and storage. The present viscoelastic analyses require the same computer memory as is needed for corresponding elastic eigenvalue problems. Bending and stretching of composite plates for which analytical solutions exist are examined in order to evaluate the accuracy and effectiveness of the present approach. The time-dependent displacement fields in the transverse direction for the cross-ply and angle-ply laminates are calculated, and the stacking sequence effects of the laminates are discussed in detail. Creep responses for GY70 339 composite laminates with or without a circular hole are also studied. The numerical results compare favorably with analytical solutions, i.e. within 1.8% for bending and 10 −3 % for tension.