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V形缺口三点弯曲试样主要用于极脆性材料(如硬质合金、陶瓷等)平面应交断裂韧性(K_(iC))的测试。这种试样与传统的断裂韧性(K_(IC))试样相比,其优点是:(1)尺寸简单,易于加工;(2)不需用疲劳法预制裂纹;(3)不需测定裂纹长度(K_(iC)值可直接从载荷峰值计算而得);(4)其断裂韧性值分散性低,重复性好,可比性强。另外,本文还讨论了断裂韧性(K_(IC))与硬质合金主要结构参数的关系。结果表明:硬质合金的K_(IC)值与其结构参数λ/D_(WC)1/2存在着良好的线性关系。
V-notch three-point bending specimen is mainly used for the test of the fracture toughness (K i (iC)) of the extremely brittle materials (such as cemented carbide, ceramics, etc.) Compared with the traditional fracture toughness (K_ (IC)) specimen, this kind of specimen has the following advantages: (1) the size is simple and easy to process; (2) the fatigue crack propagation is not required; (3) Crack length (K_ (iC) value can be calculated directly from the peak load); (4) its fracture toughness value low dispersion, good repeatability, comparability. In addition, the relationship between fracture toughness (K_ (IC)) and the main structural parameters of cemented carbide is also discussed. The results show that there is a good linear relationship between the K_ (IC) value of the cemented carbide and its structural parameter λ / D_ (WC) 1/2.