Study of failure in 3-D carbon-carbons
A program of experiments and analysis was performed to examine failure criteria for 3-D carbon-carbon composites. Specimens from an FMI 2-2-1 weave and an AVCO 2-2-5 weave were investigated using off-axis tests in tension and compression. The stress strain responses were analyzed to provide composite stiffness and yield strength as a function of yarn angle. Estimates of the material shear stiffness were calculated. The data for yield strength versus yarn angle were fitted with Tsai-Hill and Tsai-Wu failure criteria. Values of the shear strength for yield and ultimate failure were found. The general off-axis nonlinear stress strain curves were condensed to a single equation using the theory of anisotropic plasticity. A simple criterion was found to predict the onset of yielding for 3-D weaves subjected to off-axis loading. Validation of the failure criteria and plasticity models was made by analyzing stress fields in the region of a hole and comparing with experimental data. Observations of microscopic material damage and failure surfaces were made for specimens subjected to on-axis compression and off-axis tension. The spread of damage in on-axis compression specimens is explained in detail.
- Research Organization:
- Purdue Univ., Lafayette, IN (USA)
- OSTI ID:
- 6422104
- Resource Relation:
- Other Information: Thesis (Ph. D)
- Country of Publication:
- United States
- Language:
- English
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