Appendix A.11 - Argument #14: Matrix Post-Failure Stiffness Fraction

(Unidirectional composites only, not available for woven composites)

The 14th argument is a fraction used to define the damaged elastic moduli of the matrix constituent after matrix constituent failure occurs. Specifically, it is the ratio of the failed matrix constituent moduli to the unfailed matrix constituent moduli. A value of 0.10 would specify that after a matrix failure occurs at an integration point, all six of the matrix constituent moduli ( , , , , , ) are reduced to 10% of the original undamaged matrix constituent moduli. The matrix post-failure stiffness value must be greater than 0.0, and less than or equal to 1.0.

The value of the 14th argument can have a pronounced effect on the post-failure response of a multilayer composite structure. This constant is largely responsible for the rate at which local loads are redistributed after a localized matrix constituent failure occurs.