Modeling, understanding and enhancing the mechanical response of the HAWTB composite structure through the nonlinear FE analysis of a proposed sub-model

The high demand of low cost wind energy needs to design large scale HAWTB with reduced weight, which poses a great challenge to their durability. Composite materials are being employed in many wind structures such as wind energy applications. In fact, external wind loads can cause damage mechanisms and large-deflection bending leading to test the ability of long composite WT blades. The paper is a comprehensive research on structural integrity of HAWTB by testing the structural part section cutted from the blade. The 3D complex geometry part represents the critical and structural part and it supports the main local failures initiation and progressive. The present part has been used for several analysis to investigate the coupled stiffness-strength and durability performance, using ANSYS, at extreme load conditions. The most advanced results obtained from nonlinear FEA of composite structural part concern the effect of fiber material on flap-wise displacement compared to Glass fibers and kevlar49 with 42% in stiffness gain. The FE results indicates that the high critical regions are localized near the root at the bottom skin of the structure, which are driven by typical damage mechanisms. The buckling analysis confirms the compressive regions applied and revealed high local deformed in structure, which generates important rotational moment at the adhesive layers. The stress analysis of out-of-plane shear stress is presented. Besides, the results of contact evaluation between bottom skin and rib show good agreements with the predicted, consequently, the gap and frictional stress indicate serious risk of adhesive layers damage. The most local failure mode predicted is also delamination’s because extreme local out-of-plane stress is generated. In fact, the modal analysis and random vibration are conducted for the fatigue life prediction using PSD indicator. Moreover, the vibration of bottom and top skin are evaluated and good results is agreed with the anticipated. A reinforcement method has been proposed for the blade structural part by incorporate locally circular Carbon/Epoxy laminates at the failed zones and the results show important gain on strength. Graphic Abstract