The present investigation was carried out to study the effect of fibre orientation and fibre loading on the flexural properties, free-vibration characteristics and moisture absorption behaviour of Sida acuta-fabric-reinforced epoxy matrix composites. S. acuta composites were fabricated to 0, 24, 28 and 32 wt.% fibre loadings with each having 0°/90° and ±45° fibre orientations using the hand lay-up method. The flexural strength and damping properties of the S. acuta composite were enhanced with fibre loading from 24 to 32 wt.% in both ±45° and 0°/90° fibre orientation composites. The maximum value of the flexural strength of the composites (43.3 MPa) was obtained at 32 wt.% fibre with a 0°/90° fibre orientation. The moisture absorption of the S. acuta composite was enhanced with increase in fibre content from 0 to 32 wt.%. The tensile strength and stiffness of the moisture-degraded S. acuta composite decreased with an increase in fibre loading from 24 to 32 wt.% after the equilibrium period (60 days) of moisture immersion. The nature of fibre and matrix material interface was investigated through scanning electron microscopy of a flexural fracture without moisture degradation and tensile fracture with moisture-degraded samples. The fracture surface morphology of the composite reveals that the fracture behaviour and fibre pull-out of the samples.

中文翻译：

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Sida acuta纤维聚合物复合材料的自由振动和吸湿性能

进行本研究以研究纤维取向和纤维负载对Sida acuta-织物增强的环氧基质复合材料的弯曲性能，自由振动特性和吸湿性能的影响。使用手工铺层法将S. acuta复合材料制成纤维含量为0、24、28和32 wt。％，每种纤维具有0°/ 90°和±45°纤维取向。在±45°和0°/ 90°纤维取向复合材料中，纤维负荷从24％到32 wt。％增强了S. acuta复合材料的弯曲强度和阻尼性能。复合材料的挠曲强度的最大值（43.3 MPa）是在纤维方向为0°/ 90°的纤维含量为32％（重量）时获得的。的吸湿性随着纤维含量从0增加到32wt。％，增强了S. acuta复合材料。湿气浸没的平衡期（60天）后，经湿气降解的金黄色葡萄球菌复合材料的拉伸强度和刚度随纤维负载的增加从24％降低到32％（重量）。纤维和基体材料界面的性质是通过扫描电子显微镜观察的，没有水分降解的弯曲断裂和有水分降解样品的拉伸断裂。复合材料的断裂表面形态揭示了样品的断裂行为和纤维拉出。