Abstract:Stitched foam sandwich panel is a newly developed sandwich structure used in various structural applications. The sandwich skins are made of glass-fiber/epoxy-matrix composite; their interior layers are connected with glass yarn called piles. This paper investigates the effect of pile orientation on the shear strength of stitched foam sandwich panel. Four types of pile orientation are used; 90º, 45º, 90 º/45 º and 90º/45º/90º.The results are compared with a non-stitched sandwich panel. From the results of the … Show more
“…For example, Han 18 analysed the effects of the impact energy and stitch density on low-velocity impact damage to stitched foam sandwich composites through experiments and numerical studies. Lascoup B 19 and Ramraj 20 studied the effects of the stitch angle on the shear properties of foam sandwich composites. The study of a single stitch thread could reveal the bridging force and fracture mode of the stitched foam sandwich composites.…”
Sandwich composites are susceptible to interfacial delamination, owing to the mismatches in the material properties between the face sheets and core. Previous studies have shown that stitching can improve the performance of sandwich composites. In this study, an analysis approach was developed to investigate the fracture behaviour of stitched foam sandwich composites. The stitched foam sandwich composites were manufactured by a vacuum-assisted resin transfer moulding process. Interlaminar tension tests revealed the effects of the linear thread density on the failure mechanisms of the stitched foam sandwich composites. Asymmetric double cantilever beam tests were performed to investigate the influences of the stitch thread reinforcement on the fracture behaviour. An analytical approach combining extended finite element method and nonlinear spring elements was proposed to predict the failure behaviour of the stitched sandwich composites. Experiment and simulation approaches were employed to investigate the influences of the stitch parameters (stitch pitch and linear thread density) on the ultimate load and energy absorption. The results show that stitched method can significantly enhance the mechanical properties of sandwich composites. The energy absorption and ultimate load values of the specimens tend to increase with an increase in the linear thread density or a decrease in the stitch pitch.
“…For example, Han 18 analysed the effects of the impact energy and stitch density on low-velocity impact damage to stitched foam sandwich composites through experiments and numerical studies. Lascoup B 19 and Ramraj 20 studied the effects of the stitch angle on the shear properties of foam sandwich composites. The study of a single stitch thread could reveal the bridging force and fracture mode of the stitched foam sandwich composites.…”
Sandwich composites are susceptible to interfacial delamination, owing to the mismatches in the material properties between the face sheets and core. Previous studies have shown that stitching can improve the performance of sandwich composites. In this study, an analysis approach was developed to investigate the fracture behaviour of stitched foam sandwich composites. The stitched foam sandwich composites were manufactured by a vacuum-assisted resin transfer moulding process. Interlaminar tension tests revealed the effects of the linear thread density on the failure mechanisms of the stitched foam sandwich composites. Asymmetric double cantilever beam tests were performed to investigate the influences of the stitch thread reinforcement on the fracture behaviour. An analytical approach combining extended finite element method and nonlinear spring elements was proposed to predict the failure behaviour of the stitched sandwich composites. Experiment and simulation approaches were employed to investigate the influences of the stitch parameters (stitch pitch and linear thread density) on the ultimate load and energy absorption. The results show that stitched method can significantly enhance the mechanical properties of sandwich composites. The energy absorption and ultimate load values of the specimens tend to increase with an increase in the linear thread density or a decrease in the stitch pitch.
“…It was also reported that stitched core increased the ultimate shear strength and shear modulus of the sandwiches. 34 Foam-filled corrugated cores, i.e. steel facings/Al foam–steel core webs, 35 and glass/epoxy facings/PVC foam core-glass/epoxy core webs, 36 in the form of rectangular, trapezoidal and triangular also contributed to improving bending load capacities and flexural stiffness of the structure.…”
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.
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