Mechanical Behavior of 3D Woven Variable Thickness Composite Plate under Tensile Loading.

As a directly net-shaped structure, 3D woven variable thickness composite plate is different from the constant thickness structure in terms of the changing weft yarn sizes and resulting various warp yarn direction. To investigate the mechanical behavior of this structure, a finite element (FE) model was proposed in this paper on the basis of author's previous geometric model illustrating the characterized details. Mesh convergence was studied to determine the size of element in compromise of accuracy and efficiency. Linear displacement rather than periodic boundary conditions were applied due to the thickness change. For the validation of presented FE model, a sample variable thickness plate in 3D layer to layer weave style was tested under tensile load in warp direction whose thickness was changed in this direction by the change of weft yarn size. The strain was monitored with the help of Digital Image Correlation (DIC) system. The results showed that the predicted homogenized stiffness in warp direction decreased with the thickness increasing, in agreement with the observation from experiments. The maximum error between the predicted stiffness and the measurements of typical segment (TS) in variable thickness region of the plate is 12.05 % while the minimum error is 0.7 %. [ABSTRACT FROM AUTHOR]