采用数值分析的压痕法识别陶瓷材料断裂韧性的精度问题研究

Study on Accuracy Problem of Indentation Method Based on the Numerical Analysis to Evaluating the Fracture Toughness of Ceramic Materials

采用虚拟裂纹闭合法的基本原理对基于数值分析的压痕法识别陶瓷材料断裂韧性的精度问题进行研究,分析比较了3种典型基于数值分析的压痕法计算公式对陶瓷材料断裂韧性的测试精度.结果表明,Tang公式和Lee公式所测断裂韧性值与理论计算值的最大误差均随比功增加而增大,其最大误差分别为193.39%和81.99%;Hyun公式除对弹性模量E=70 GPa、We/Wt=0.7的材料测试误差高达-75.59%之外,其余材料范围测试误差均处于30.65%之内;相比Tang公式和Lee公式,Hyun公式明显具有较高的测试精度.本文工作为合理使用压痕法准确获得陶瓷材料断裂韧性值以及为下一步研究建立具有测试精度高、适用范围广的新型断裂韧性测试方法提供了一定的理论基础.

By using the virtual crack closure technique,the accuracy problem of indentation method,which is based on the numerical analysis to evaluating the fracture toughness of ceramic materials,is studied. The accuracy of three typical formulas established by numerical analysis are analyzed and compared. The results show that,for Tang and Lee formulas,the errors between measured and theoretical values increase with We/ Wtincreasing,and the maximum errors are 193. 39% and 81. 99%,respectively. The maximum errors of the Hyun formula are all within 30. 65% except the material with E = 70 GPa and We/ Wt= 0. 7（ errors up to- 75. 59%）. Compared with Tang and Lee formulas,Hyun formula has obviously higher test accuracy. This work provides a theoretical basis for reasonably using indentation method to obtain the values of ceramic materials＇ fracture toughness,and lays a foundation for establishing a new testing method with high accuracy and wide range of application.