A test specimen capable of measuring the fracture resistance of bimaterial interfaces has been devised. A finite element approach has been used to characterize trends in the stress intensities and center point displacement with specimen dimensions, elastic properties, and crack length. The utility of the specimen has been demonstrated by conducting experiments on the model system, Al/PMMA.

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Woven unit-cell geometry functions are presented for a balanced plain weave fabric composite. Geometry models for polymer and ceramic matrix woven systems are developed. For polymer matrix woven systems, the space between bundles is fully occupied by the inter-bundle matrix phase which is modeled as a porous elastically isotropic medium. On the other hand, the woven unit-cell geometry model for ceramic matrix systems allows for the presence of both disperse porosity as well as large scale voids within the interbundle matrix region as needed to simulate the complex microstructure resulting from the Chemical Vapor Infiltration (CVI) processing technique. The geometry models take into account the existence of space between tows, the undulation of the tows, and the actual tow cross-sectional shape. Both the warp and transverse tows are modeled using piecewise continuous functions throughout the unit-cell domain. Equal accuracy in both the warp and fill directions, as required for biaxial and in-plane shear loading studies, is built into the geometry surface functions. The effects of the unit-cell geometry on the matrix and tow volume fractions for both the PMC and CMC systems are explored. Three-dimensional finite element meshes developed using these new mathematical geometry models are presented for both the porous matrix and matrix layer models.

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