Postbuckling Response of Natural Fiber‐Based Functionally Graded Hybrid Composites: Experiments, Simulations, and Cutout Optimization Under In‐Plane Shear

ABSTRACT Natural fiber–reinforced polymer (NFRP) composites are increasingly being utilized in structural applications, prompting the need to determine their structural capacity under different loading situations. Among these loading conditions, the in‐plane shear load is particularly significant. An experimental and numerical investigation was conducted in this work to examine the buckling and postbuckling responses of NFRP composites and natural fiber‐based functionally graded hybrid (FH) composites. Hemp and carbon fibers were considered as reinforcement, epoxy mixed with hardener was used as matrix, and the composites were manufactured using the hand‐layup method with the help of a steel mold. A newly developed in‐plane shear test fixture was used for experimental analysis. Finite element‐based software ABAQUS was used for numerical analysis. For both studies, simply supported boundary conditions were used. Natural fiber‐based FH composites were made with different stacking sequences, such as cross‐ply (0/90) _4s , angle‐ply (−45/+45) _4s and quasi‐isotropic (−45/+45/0/90) _2s . Experimental and computational methods examined the composite plates critical buckling and first‐ply failure loads. Considering the sustainability and strength of FH composites, this study was expanded to determine the ideal dimension and shape of the cutout in FH composite plates by examining various cutout shapes and sizes. The findings of this study indicated that FH composite plates arranged in the (−45/+45) _4s sequence surpassed the performance of other stacking sequences. FH composite plates exhibited superior performance under negative in‐plane shear loads. This study revealed that small‐size diamond‐shaped cutouts performed better against other cutout sizes and shapes regarding FH composite plate buckling and postbuckling responses.