Poly epoxy is a high performance room temperature cured epoxy system which provides excellent physical and mechanical properties. However, the effects of post curing of this resin system on the properties of different sandwich structures are unknown. This study aims to evaluate the effect of post curing (at 70°C for 2 hr) on the edgewise compressive and flexural strengths of a sandwich structure, constructed with Styrofoam and honeycomb as core materials and a plain weave carbon fabric as face sheet. Tested factors evaluated from edgewise compressive tests were as follows: peak load, compressive strength, and crash energy absorption of sandwich structures while core shear stress and bending stress of sandwich structures were determined and compared with flexural tests. It was observed that post curing affects significantly on the bending and compressive strengths of the sandwich structures. However, the data obtained for crash energy absorption suggested that the effect of post curing on the core shear strength and the total deflection was statistically insignificant. The matrix polymer was also inspected using dynamic‐mechanical thermal analysis to assess the changes in glass transition temperature and degree of conversion due to post cure. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

The advanced composite materials are increasingly being used in the automotives for their ultralight physical properties and super strong mechanical properties. This research examines the cost‐effective single‐step liquid resin infusion manufacturing process for developing all composite car body as the generally used sheet molding compound manufacturing process is highly capital intensive. Three different scaled down models of the Eco car were developed focusing on minimal weight and air drag coupled with aesthetics. Structural design and analysis was carried out using the Pro/E and Ansys tools. The Pro‐E model was scaled up to generate computer‐aided drafting drawings for tool development. Different stations were marked on the model and sliced virtually for development of pattern. Moreover, the mold was manufactured from carbon and glass/polyester composites for prototype manufacturing of the car body. This involved manual placement of desired number of carbon layers as preform on female side of the mold. The vacuum sucked the resin through a number of carefully selected entry ports which ensured effective resin distribution and impregnation. Polycarbonate wind shield was thermoformed in the convection oven according to streamlined geometry of car body and hinged. The car body was integrated with the compatible floor panels and accessories. The crumble zone shock absorber in the bumper was manufactured using successive layers of nomax honeycomb and polyvinyl chloride rigid foam to dampen the accidental shock. The car performed remarkably well in the Eco marathon race held at Malaysia, 35:97–104, 2014. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

The hygrothermal effect on the flexural, interfacial and glass transition behaviors of 977-2A carbon/epoxy composites cured in an autoclave and by using Quickstep were evaluated in the previous paper. This article concerns with the hygrothermal effect on the mode I and mode II delamination resistance of the samples cured in an autoclave and by Quickstep. It was observed that the mean initiation and propagation GC values (i.e. GIC and GIIC) of both autoclave and Quickstep 60 cured specimens were apparently reduced after hygrothermal conditioning; however, the data obtained from both autoclave and Quickstep 60 cured specimens in dry and wet states were not statistically significant. The scanning electron micrograph confirmed the enhancement of matrix ductility; however, no effect of this matrix ductility was observed in the GIC and GIIC data.

An aerospace grade prepreg 977-2A carbon=epoxy composite was processed using traditional oven=autoclave and relatively new technique, Quickstep (QS). The manufacturer's recommended autoclave cure cycle was employed for oven=autoclave processing while due to greater flexibility to control the cure cycle temperature in order to manipulate the resin viscosity, several cure cycles were employed for Quickstep processing. Optimization methodology and effect of these cure schedules and their comparison with traditional oven=autoclave curing is presented in previously published article. However, in order to reduce the total cycle time of QS AD (QS-60) cure schedule, an attempt was made to facilitate the excess resin to squeeze out during QS-35 and QS-45 cure. This attempt was based on the incorporation of double vacuum bagging (DVB) technique into Quickstep processing. Statistical analysis was performed to investigate any effect of DVB in Quickstep processing and it was observed that incorporation of DVB in Quickstep processing is not found to be significantly effective, however, it is believed that small resin rich patches of QS-45 cured panels can be removed with controlled application of external pressure using DVB. POLYM. COMPOS., 34:942-952,

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Delamination is the most common failure mode in laminated composites due to the weaker strength in the through‐the‐thickness direction. Air‐jet texturing is used to produce bulk and loops in the yarn which provides more contact surface between fibers and resin. The development and characterization of core‐and‐effect textured glass yarns and the effect of texturing on the mechanical properties of laminated composites were presented in previous papers. This article describes the optimization of textured composites by varying the type and combination of constituent yarns for improving the mechanical properties. Composites with combinations of various textured yarns and non‐textured yarns were made. It was observed that the composites made from fabrics having non‐textured yarn in the warp and core‐and‐effect textured yarn in the weft had the best combination of mechanical properties. They maintained the tensile and flexure properties of composites with non‐textured yarns but had significantly higher interlaminar shear strength. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

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