Study of the Mechanical Behavior of a 2-D (Two-Dimensional) Carbon-Carbon Composite

摘要

The objective of this study was to observe and characterize the out-of-plane fracture of a 2-D carbon-carbon composite and to gain an understanding of the factors influencing the stress distribution in such a laminate. Finite element analysis of a two-ply carbon-carbon composite under in-plane, out-of-plane, and thermal loading were performed. The results indicated that under out-of-plane loading sigma sub x and tau sub xz were strongly dependent on stacking sequence, undulation aspect ratio, and undulation offset ratio, but sigma sub z and sigma sub y were relatively independent of geometry. Under in-plane loading all components of stress were strong functions of geometry. Additionally, large thermal stresses were predicted. Out-of-plane tensile tests revealed that failure was interlaminar, and that cracks propagated along the fiber-matrix interface. An elasticity solution was utilized to analyze an orthotropic fiber in an isotropic matrix under uniform thermal load. The analysis reveals that the stress distributions in a transversely orthotropic fiber are radically different from those predicted assuming the fiber to be transversely isotropic.