열응력으로 인한 크로스 플라이 유한적층판의 파손

Abstract

Thermal stress characteristics of laminated composites were investigated to study the effect of thermally induced stresses on failure. Thermal stress distributions in [0n/90n]s thick cross-ply laminates with finite size were analyzed using three-dimensional FEM. High thermal intralaminar tensile normal stress in transverse direction and interlaminar tensile normal stress were predicted in 90°C layer near free edge boundaries. These stress components resulted in transverse cracks of 90° layer. Experiments of damage developments due to thermally induced stresses were performed for the various layer thickness and geometries of [0n/90n]s, n=2,4,8 Carbon/Epoxy composites. The major failure modes and failure mechanisms due to thermal stresses were transverse cracks, local 0/90 interface delaminations due to transverse cracks in outer layer, and free edge delamination which were highly dependent upon the bonding conditions between fiber and matrix and the mechanical properties of matrix.