Fracture toughness of composite materials disciplines are presented and described at their various levels of sophistication and attendant scales of application. In this paper, an investigation on the influence of various kinds of fibre and elevated temperature on fracture toughness is presented for the materials of polyester and epoxy resins as thermosetting plastics and E-Glass as a fibre composite material. Chopped Strand Mat (CSM), Plain Woven Glass Fabrics (PWGF) and Unidirectional Laminate (UL) were used as fibre material. For CSM and both PWGF and UL materials, the fibre volume ratio was selected 20percent, 25percent, 30percent and 30percent, 40percent, 50percent respectively. The Glass Reinforced Plastics (GRP) materials having above fibre volumes and 4, 6, 8,, and 10 mm thickness, were manufactured by the Cold Molding Technique in the metallic molds. The compact Test specimens (CT) prepared according to ASTM E-399, were used in the experiments. To comply with this standard, the geometrical ratio of a/W=0.5 selected and CT specimens were machined to satisfy the condition of W=4B which stands for 1<=W/B<=4. The fatigue precracking was created such that R=0. Fracture toughness was performed at 25, 50, 75, 100, and 125 deg C by using Schenk-Trebel servo hydraulic tensile machine. The fractured surface photographs were taken by SEM and crack growth was inspected by optical microscope. At the end, fracture toughness of all specimens was calculated and plotted versus temperature and fibre volume ratio.
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机译：复合材料学科的断裂韧性以其复杂程度和相应的应用规模进行了介绍和描述。本文针对聚酯和环氧树脂（热固性塑料）和电子玻璃（E-Glass）作为纤维复合材料，研究了各种纤维和高温对断裂韧性的影响。短切毡（CSM），平纹玻璃纤维织物（PWGF）和单向层压板（UL）被用作纤维材料。对于CSM以及PWGF和UL材料，纤维体积比分别选择为20％，25％，30％和30％，40％，50％。具有以上纤维体积且厚度为4、6、8和10mm的玻璃纤维增强塑料（GRP）材料通过冷模技术在金属模具中制造。实验中使用了根据ASTM E-399制备的紧凑型试样（CT）。为了符合该标准，选择a / W = 0.5的几何比率，并加工CT试样以满足W = 4B的条件，即1 <= W / B <= 4。产生疲劳预裂，使得R ＝ 0。使用Schenk-Trebel伺服液压拉伸机在25、50、75、100和125℃下进行断裂韧性。通过SEM拍摄断裂的表面照片，并且通过光学显微镜检查裂纹的生长。最后，计算所有样品的断裂韧性，并绘制温度与纤维体积比的关系图。
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