AN EXPERIMENTAL INVESTIGATION OF STIFFNESS REDUCTION AND CRACKS GEOMETRY IN A UNIDIRECTIONAL BRITTLE-MATRIX COMPOSITE

The nonlinear mechanical behavior of a unidirectional ceramic matrix c omposite is investigated by means of an ultrasonic method. This paper presents measurements of all the stiffness tensor coefficients during each step of a tensile test, and consequently the variation of all the components of the anisotropic damage tenser. A description in terms o f compliance makes possible comparison between mechanical and ultrason ic measurements of the composite deterioration and the re-construction of the stress-strain curve from ultrasonic data. Good agreement betwe en both experimental and predicted compliances of an anisotropic mediu m with distributed slit cracks is found. From this comparison, the cra ck density parameter is estimated and the matrix cracks geometry is ch aracterized.