Studies on preform properties of multilayer interlocked woven structures using fabric geometrical factors

Structure property correlation is a critical textile research area explored by various researchers and many factors have been proposed over the years to predict/compare/design the woven fabrics. Cross-over firmness factor (CFF) and floating yarn factor (FYF) have been recently proposed as parameters to understand weave effect on fabric properties (Morino, H., Matsudaira, M. and Furutani, M. (2005). Predicting Mechanical Properties and Hand Values from the Parameters of Weave Structures, Textile Research Journal, 75(3): 252—257). Redefined CFF and FYF factors using fabric fields in terms of interlacement index (I) and float index (F), respectively have been proposed in this article. This new approach provides better understanding of the interlacements and floats in the woven structure and further they are applied on multilayer interlocked fabrics to quantify the structural influence on the properties. Multilayer interlocked woven fabrics with different interlacement patterns have been developed. Influence of fabric structure on preform properties relevant for resin transfer molding composite manufacture, such as compression, permeability, and tensile behavior were studied with respect to the interlacement and float indices. Tensile and compression tests were conducted on universal testing machine. Liquid permeability of these structures was evaluated based on horizontal wicking and contact angle wettability tests. Results show that influence of structural factor is greater on tensile and permeability properties than the compression properties of these multilayer fabricsThis work has been conducted within the Asia-Link Programme RPO1736, project no IN/ASIA-LINK/002 (82158). The authors wish to thank the European Commission for awarding research programme under the EU Asia-link project to the University of Minho (Portugal) and Indian Institute of Technology-Delhi (New Delhi, India)

Finite element analysis of Carbon composite sandwich material with agglomerated Cork core

AbstractComposite sandwich structures were developed for the hydrofoil sail boat hull using biaxial carbon fabric/epoxy composite facing and agglomerated cork core. These ultra-light weight structures were tested through four point bending tests to characterize their flexural behavior. The material exhibited an initial linear elastic behavior followed by non-linear elastic-plastic behavior. Finite element analysis of the sandwich beams was performed to analyze the flexural behavior of the structure. It was found that the transition from linear elastic to non-linear elastic-plastic behavior is the result of compressive yielding of core material which leads to indentation in the beam. This also causes initiation of failure in the core. A shift in the centroid axis of the beam towards the tensile face was also observed. The sandwich structures made of cross-linked PVC and PMI foam cores were also analyzed for comparison. Further, a parametric study on the effect of areal density and ply angle of the facing fabric and core thickness were performed using finite element method. The parametric study revealed that the transition from linear to non-linear trend is caused by different mechanisms with the change in the mentioned parameters