No abstract

The objective of this study is to enhance the out-of-plane tensile and compressive performances of foam core sandwich composite via structural core modifications considering the ease of application and time consumption. The performances of single core perforated, single core stitched, divided core perforated, and divided core stitched sandwich composites are compared with each other and reference plain foam core sandwich composites. Results indicate that “perforated and stitched core” sandwich composites have superior strength, and in terms of performance modification, dividing the core is found very efficient for plain (non-perforated and non-stitched) core sandwich composites.

The aim of the study is to investigate the behavior of laminated composites under low velocity impact both experimentally and numerically. With this aim, the effects of wide range impact energy values between 10 J and 60 J were evaluated experimentally and numerically for the laminate of [±45/(0/90)2]S oriented unidirectional E-glass as reinforcing material and epoxy resin for matrix material. Different impactor velocities were used to maintain the impact energy values and experimental impact tests were generated with drop weight impact testing machine at room temperature. Numerical simulations were performed using LS-DYNA finite element analysis software with a continuum damage mechanics-based material model MAT058. Contact force between impactor and laminate, and transverse deflection at the center of laminate results were obtained as a function of time and used to plot contact force–time curves, contact force–deflection curves and absorbed energy-impact energy curves. Also, delamination area was examined. Finally, numerical results were compared with experimental results and a good correlation between them was observed.

In this study, various structural configurations such plain core, two-core, epoxy columns in the core, core stitched, and facesheet stitched were designed in the foam core sandwich composite with the aim to increase the absorbed energy and to decrease core/facesheet debonding area due to low-velocity impact. Glass fiber/epoxy and PVC foam were used as a facesheet material and a core material, respectively. The impact energy values were selected considering to penetration and perforation cases. The core stitching effect on low velocity impact behavior of sandwich composites were compared to facesheet stitching and it has been determined that the core stitching process can be an alternative to the facesheet stitching process in terms of the absorbed energy value. Impacted sandwich composites are investigated for core/facesheet debonding; the modifications through the thickness increased the failure path for core/facesheet debonding initiation and the results show that a significant decrease in the core/facesheet debonding area has been achieved.