The Influence of Gravitational Stiffening and De-stiffening on Nonlinear Dynamic Behavior of Vertical Beams with Cracks

Dynamics of vertically oriented blades is an important topic of research as it replicates the physical behaviour of several real-time applications such as horizontal axis wind turbine blades. It is observed that available literatures explaining the effects of gravity on the dynamic behaviour of vertical beams/blades did not focus on the various operational adversities such as geometric nonlinearities, possibilities of crack initiation due to adverse conditions. Therefore, in present study, an attempt is made to capture reverberations of gravity on cracked vertical blades including geometric nonlinearity. A computationally efficient numerical model for nonlinear dynamic analysis of vertically oriented cracked blades is developed. Efficacy of proposed model is verified by several case studies. Subsequently, parametric investigation is performed for combined effects of crack and gravity on the dynamic response. Crack and gravity dominant regions based on slenderness ratio are identified for the first time . Furthermore, influence of nonlinearities on such behaviour provides useful insights to anticipate the mechanics of the dynamic behaviour of a vertical cracked cantilever beam. Proposed work may be useful for developing a robust vibration-based condition monitoring for a given application which involves hanging beams with a possibility of crack such as rotor blades.