EXPERIMENTAL-DETERMINATION OF TSAI FAILURE TENSORIAL TERMS F-IJ FOR UNIDIRECTIONAL COMPOSITE-MATERIALS

Composite materials are being used more and more for components of lar ge thickness. For this kind component, two-dimensional failure criteri a do seem to be adequate to describe the mechanical behaviour of these structures. This paper presents an experimental determination (withou t reference to damage mechanisms) of the different terms of the streng th tensors of a three-dimensional polynomial failure criterion for two different composite materials (graphite/epoxy T300/914 and glass/epox y M10). The considered third dimension leads to some experimental diff iculties in the determination of out-of-plane parameters F-3, F-33, F- 44, and F-ij. A new testing fixture (double compression fixture), new experimental conditions (Iosipescu shear test) and a new specimen shap e (through-the-thickness tension test) are proposed to solve these pro blems. Finally, the two strength tensors F-i and F-ij are totally dete rmined to meet the requirements of engineers and designers.