This experimental study investigates the flexural response of sandwich composites integrated with 3D multi-layer stitched core. Polypropylene 3D multi-layer woven fabric impregnated with an epoxy resin was selected as the core, while E-glass fiber reinforced epoxy was used for the sandwich composite face sheets. The sandwich composite exhibited a ductile behavior when loaded in three-point bending as the core layers increased. This is due to the drop in core shear strength with the increased number of core layers. The core layers that were not directly connected with the face sheets deformed most under shear, resulting in a more flexible plate behavior. The number of core layers, size of core unit-cell and stitching density were the critical design parameters determining the flexural strength and stiffness of the sandwich panel. The flexural modulus of sandwich composites with higher stitching density core stiffer than those of lower stitching density.

中文翻译：

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与 3D 多层缝合芯集成的夹层复合材料的弯曲响应

本实验研究调查了与 3D 多层缝合芯集成的夹层复合材料的弯曲响应。选择用环氧树脂浸渍的聚丙烯 3D 多层机织织物作为芯材，而夹层复合面板则使用 E​​-玻璃纤维增​​强环氧树脂。当芯层增加时，夹层复合材料在三点弯曲加载时表现出延展性。这是由于随着芯层数量的增加芯层剪切强度下降。与面板没有直接连接的芯层在剪切作用下变形最大，从而导致更灵活的板行为。芯层数、芯单元尺寸和缝合密度是决定夹芯板抗弯强度和刚度的关键设计参数。