Shear-Normal Coupling Effects on Composite Shafts Dynamic Behaviour

This paper concerns the dynamic analysis of rotating composite shafts and focuses on the formulation of the shear-normal coupling effect using Equivalent Single Layer Theory (ESLT) and Layerwise Shaft Theory (LST). On the one hand, ESLT consists in considering the laminated shaft made of several orthotropic layers as an equivalent single layer having equivalent mechanical properties of all the layers. On the other hand, LST aims on modelling configurations where different layers may consist of materials with different properties of several orders of magnitude. Thus, different layers may have different slopes. In fact, the shear-normal coupling term is introduced directly in both formulations unlike the development available in the literature where the equivalent longitudinal Young’s modulus expression is modified to consider the shear-normal coupling effect. Results are compared with those available in the literature using different formulations. Obtained results prove that the developed theories can be efficiently used for rotating laminated shaft dynamic analysis. Indeed, obtained results prove that laminate parameters such as: fiber orientation and stacking sequence have an important influence on the shear-normal coupling and show the significant effect of the shear-normal coupling on dynamic behaviour of rotating composite shafts.