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Fracture Mechanics of Brittle Matrix Composites with Imperfect Interfaces
Final rept. 1 Jul 95-31 Aug 97
UNIVERSITY OF SOUTH FLORIDA TAMPA DEPTOF MECHANICAL ENGINEERING
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In understanding the complexity of the fracture mechanics of brittle matrix composites, knowing reliable values of the mechanical properties of the fiber-matrix interface are important. Since all experiments designed to evaluate the mechanical properties of the fiber-matrix interface rely on curve fitting experimental measurements to analytical results, accurate physical modeling of these tests is imperative. In this final report, two common tests, namely the push-in test and the slice compression test, were analytically simulated. In the push-in test, the effect of extrinsic factors such as indentor shape and size, and push-through radius hole, and intrinsic factors such as transverse isotropy of fibers on load-displacement curves was studied. All factors except the push through hole-radius were found to affect the load-displacement curves. In the slice compression test, comparison was made for the values of maximum protrusion, residual protrusion and debond lengths for a simple shear-lag analysis and a finite element analysis model. Large differences ranging from 15 to 70 were found by using the two different models. Hence, the importance of accurate modeling of the test cannot be ignored. The study also gives tools to an experimentalist for designing reliable experiments for evaluating reliable values of the mechanical properties of the fiber-matrix interface.
APPROVED FOR PUBLIC RELEASE