确定现代陶瓷材料断裂韧度的人字形裂纹法

Defination of the fracture toughness of modern ceramic materials with chevron notch

人字形裂纹法是测量脆性材料平面应变断裂韧度K_1值最有效的方法。试验期间,裂纹在人字形切口的端部形成,随着载荷的增加而稳定地扩展。人字形切口法的优点是在加载试验的早期阶段就自然形成了一个锐型裂纹,而不再需要制作预裂纹。对于特定的试样和裂口几何形状,最大荷载与裂纹长度有关,而与材料无关。用此最大荷载可以确定断裂韧度,而不再需要测量裂纹的长度。

The chevron norch specimen is especially useful for measuring the plane strain fracture toughness K_(lc) of brittle materials. During testing, a crack develops at the notch tip and extends stably as the load is increased. Chevron notch specimens have the advantage that a sharp natural crack is introduced in anearly stage of the test loading so that no pre-cracking is required. For a given specimen and notch configuration, maximum load is always dependent on the crack length and independent of the material. Fracture toughness is determinedfrom the maximum load with no need for crack length measurement.