Experimental Verification of the Criterion of Strain Energy Density Ratio

Correctness of the strain energy density ratio criterion , which predicts the direction of crack growth in composites , has been verified by tests . Two test methods - the moire method and the photographic method were used . Materials tested include 3 different kinds of glass fibre fabric reinforced polyesters involving difierent degrees of anisotropy. The test results are in good accord with the results as predicted by the criterion .