STRESS-ANALYSIS IN UNIDIRECTIONAL COMPOSITE PLATES UNDER TORQUE LOADINGS - EXPERIMENTAL-OBSERVATION

Analysis of the stress state in a composite plate under torque loading s and some practical information are necessary for the engineering des ign. The large rotation displacement has been taken into account for t he stress analysis and the experimental results have shown a good agre ement with the analytical results. It is found that the normal stress due to the fiber deformation is no longer negligible if the rotation a ngle becomes important and we notice also that there exists a compress ion zone in the middle of the plate and two tension zones in each side , the ratio of the compression zone width to the total width is about 0.58. The maximum tension stress in the plate is double its compressio n stress. The experimental observations have shown that the shear stre sses tau12max and tau13max seem responsible for the material degradati on under torque loadings, and the determination of these shear stresse s has to use the effective torque (M(eff)) instead of the applied torq ue (M(a)).