Fracture toughness of unidirectional fiber reinforced composite is tested by photoelastic coating method combined with three-points bending test,the relation between the order of the isochromatic fringe and stress intensity factor is derived and the fracture toughness of Glass/epoxy composite plate as an example is easily detected.In this Experiment,a real-time monitoring of crack propagation is realized,and the fracture toughness of unidirectional fiber reinforced composite is effectively analyzed with P-V curve and photoelastic image.%结合金属材料三点弯曲试验方法,采用光弹贴片法实测纤维增强复合材料的断裂韧性。简要推导光弹条纹参数与裂尖应力强度因子的关系,并以玻璃纤维增强环氧单向板为实例探讨复合材料断裂韧性测试方法。实验表明,利用光弹图像可以实时观测试件裂纹扩展过程,并可结合P-V曲线判断开裂点,进而得到材料的断裂韧性。
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