Experimental study of the strength of composite plates in bending

The strength of composite plates in bending and the effect of the angular parameters at the tips of the joint of the constituents on the strength are studied. An approximate experimental finite-stress curve $(\lambda=1)$ that separates the low-stress zone from the stress-concentration zone near the angular point of the joint is obtained in the plane of the angles $(\alpha,\beta)$ by analyzing the photoelastic patterns (isochromatic curves), fracture lines, and rupture moments. A comparison with the theoretical curve obtained from the solution of the corresponding problem is performed. An experimental relation between the strength of the plate and the angular parameters of the constituents is obtained for the stress-concentration and low-stress states near the joint tips.