The objective of this research is to develop the woven/knitted hybrid composites for improved in plane as well as out of plane mechanical properties. Two different type of structures and two different materials were used in this study. Firstly, the woven and knitted fabrics were developed with glass and Kevlar yarn. Secondly, the laminated composite samples were fabricated with different stacking sequence of fabric plies. The epoxy resin was used as matrix. The cured samples were characterized for impact, tensile and dynamic mechanical properties. The behavior of composite materials was then analyzed with percentages of different fiber and fabric types. The samples with higher percentages of knitted reinforcement gave better impact strength but failed to provide better tensile properties. Moreover, the samples with higher percentages of woven structure and glass materials gives better modulus values.

The application of a sandwich structure made with composite facesheet and honeycomb core has increased rapidly due to high stiffness to weight ratio characteristics. There is a growing interest in using natural/synthetic hybrid composite to enhance the mechanical performance of natural fiber and reduce the environmental impact compared to synthetic materials. This study investigates the mechanical properties (tensile, edgewise compression, flexural) of the honeycomb sandwich structure with the hybrid composite facesheet, reinforced with different kenaf and glass fiber ratios. Non-hybrid kenaf and glass fiber composites were fabricated for comparison. The result showed that increasing the glass fiber ratio in a hybrid facesheet significantly improved the mechanical performance of the sandwich structure. Compared to the non-hybrid kenaf composite, the hybrid composite showed improved tensile and compression strength by up to 233% and 79%, respectively. The hybrid composite (glass/kenaf/glass) achieved 76% tensile modulus and 87% compression strength of glass fiber composite when the results were normalized. The specific flexural stiffness of the hybrid facesheet using glass fiber in the outer layer exhibited comparable performance by obtaining 89% flexural stiffness of non-hybrid glass composite sandwich structure.

This research is aimed at developing the sandwich structure with a hybrid composite facesheet and investigate its mechanical properties (tensile, edgewise compression, and flexural). The combination of renewable and synthetic materials appears to reduce the weight, cost, and environmental impact compared to pure synthetic materials. The hybrid composite facesheets were fabricated with different ratios and stacking sequence of flax and glass fibers. The nonhybrid flax and glass composite facesheet sandwich structures were fabricated for comparison. The overall mechanical performance of the sandwich structures was improved by increasing the glass fiber ratio in the hybrid composites. The experimental tensile properties of the hybrid facesheet and the edgewise compression strength and ultimate flexural facing stress of the hybrid composites sandwich structures were achieved higher when the results were normalized to the same fiber volume fraction of glass composite. The hybrid composite sandwich structure showed improved compression and flexural facing stress up to 68% and 75%, respectively, compared to nonhybrid flax composites. The hybrid composite using glass in the outer layer achieved the similar flexural stiffness of the nonhybrid glass composite with only a 6% higher thickness than the glass composite sandwich structure.