Effect of Core Joints on Axial Fatigue of Composite Sandwich Structures
Composite sandwich structures are commonly used in the spar caps and shear webs of wind turbine blades. These structural members are continuously subjected to fatigue loading. In practice, sandwich core sheets are joined with a simple butt-joint before infusion. When molded, this gap creates a resin rich area with significant stress riser when loaded in axial fatigue. The intensity of the axial load transferred thru core-to-core joint might influence the performance of the sandwich structure. This research work tends to examine this effect under static and fatigue loading. Sandwich panels with different PVC foam core joints were molded using vinylester resin reinforced with knitted E-glass fabric (biaxial/mat). Finite element analysis was used to validate the specimens’ geometrical configurations. Experimental results for butt-, finger- and scarf-type joints are presented and discussed. Based on the results from this work, it is concluded that the scarf-type joint outperformed other core joints with respect to axial stiffness and fatigue performance.
Authors: Elias A. Toubia, Md. Mahbubur Rahman and Ivan V. Sergeichev
Conference: CAMX 2016 – Anaheim