In this study, flexural characteristics of low-density polyvinylchloride foam core sandwich structures consist of carbon fibre/epoxy facings hybridised with very thin stainless-steel wire mesh sheets were investigated. A comprehensive work was conducted considering the following design parameters: core thicknesses, wire mesh sizes, stacking sequences of wire mesh sheets and support span lengths for flexural tests. During the evaluation of flexural characteristics, experimental ASTM standards (C393, D3039, D7249 and D7250) were utilised. In addition, experimental flexural stiffness values were compared to analytically obtained results. By hybridisation of carbon fibre/epoxy facings with wire mesh sheets, significant improvements in flexural characteristics of sandwich structures were obtained. Besides improving bending behaviour and the larger amount of load-carrying capacity even at the same deflection values, the sandwiches with wire mesh sheets also prevented catastrophic sudden failure, which is the common case for carbon/epoxy/polymer foam core sandwiches. Response surface methodology was applied to evaluate the effects of the design variables on the load capacity of the sandwiches, and optimal solutions were revealed. The developed sandwiches can be good candidates in applications where both high stiffness-to-weight ratio and resistance to sudden failure are desired.

Fiber reinforced polymer (FRP) composites have significant potential for applications in many engineering fields in place of metallic materials, due to their low density, high strength to weight ratio, high stiffness, better corrosion resistance and durability. The fabrication of these composites requires careful design and appropriate process developments to improve the mechanical properties. This study aims to investigate the effect of the post-cure heat treatment on the tensile and impact toughness of FRP composites. FRP composites were fabricated by using woven carbon and glass fiber fabric plies and their respective hybrid laminates. Hand lay-up using vacuum bagging method was used for manufacturing the laminated composites. After curing, the specimens were subjected to the post-curing process at temperatures of 25, 62.5 and 100 °C for 1 hour. Impact toughness and tensile strength of post-cured FRP composite specimens were investigated by the Charpy impact test and tensile test, respectively... Kurzfassung Faserverstärkte Polymerkomposite (Fiber Reinforced Polymer (FRP) Composites) haben große Anwendungsmöglichkeiten in vielen Engineeringbereichen gegenüber metallischen Werkstoffen, und zwar aufgrund ihres geringeren spezifischen Gewichtes, eines hohen Festigkeit-Gewicht-Verhältnisses, einer besseren Korrosionsresistenz und einer besseren Haltbarkeit. Die Herstellung solcher Komposite erfordert ein sorgfältiges Design und geeignete Prozessentwicklungen, um die jeweiligen mechanischen Eigenschaften zu verbessern. Die diesem Beitrag zugrunde liegende Studie zielt darauf ab, die Auswirkung der Wärmenachbehandlung auf die Zugfestigkeit und die Kerbschlagzähigkeit von FRP-Kompositen zu verbessern. Hierzu wurden FRP-Komposite unter Verwendung von gewobenen Carbon- und Glasfasergewebelagen und ihrer entsprechenden Hybridverbunde hergestellt. Der manuelle Aufbau mit einem Vakuumeintauchprozess wurde zur Herstellung der laminierten Komposite angewandt. Nach dieser Behandlung wurden die Proben einer Wärme...

Sandwich structures offer innovative alternative solutions to many weight-critical industrial fields due to their lightweight and very high flexural rigidity compared to conventional materials. A vast number of sandwich configurations can be produced from a variety of materials for use as face sheets and core as well as matrix. Although there are many sandwich structures available in the literature to obtain the desired mechanical and physical properties, the usage of very low-density core materials is very limited. In this study, carbon and glass fiber fabrics having woven plain and ±45 ° fiber orientations and industrial PVC foam core having extremely low density of 40 kg × m⁻³ and 48 kg × m⁻³ were used for manufacturing the sandwich panels. Eight different configurations were constructed by hand lay-up followed by vacuum bagging. According to ASTM C393/C393M standard, the sandwiches were subjected to three-point bending (TPB) tests. After performing the TPB tests, the composite sandwich specimens were examined under a stereomicroscope to determine failure modes. The primary failure modes under quasi-static bending loading were found to be top face sheet failures due to fiber and matrix cracks and delamination, and core shear failures due to core crushing just below the top facing and core fractures. In addition, the consistency of the test results were verified and the effects of parameters were investigated by using statistical variance (ANOVA) and regression analysis. The study provides a valuable contribution to the literature regarding sandwich structures having extremely low-density foam core materials and may contribute to the material universe by introducing strong, stiff and lightweight sandwich composites. It provides a comprehensive comparison by considering the effect of different fiber types, fabric fiber orientations and core densities.