柔度法测算三点弯曲试样疲劳裂纹长度的影响因素  

Factors affecting the calculation of fatigue crack length in three-point bending specimens using the flexibility method

作　　者：高宇昊 王佳 朱官朋 房坤 翟建飞 GAO Yuhao;WANG Jia;ZHU Guanpeng;FANG Kun;ZHAI Jianfei(Luoyang Ship Material Research Institute,Luoyang 471023,China)

机构地区：[1]中国船舶集团有限公司第七二五研究所,洛阳471023

出　　处：《理化检验（物理分册）》2024年第3期4-9,15,共7页Physical Testing and Chemical Analysis(Part A:Physical Testing)

摘　　要：使用柔度法对不同厚度三点弯曲试样的疲劳裂纹长度进行测算,结合有限元仿真分析方法,研究了试样厚度、柔度函数关系式的适用条件、材料的弹性模量、裂纹前缘弯曲程度、引伸计标距等因素对柔度法测算裂纹长度准确性的影响。结果表明:归一化实际裂纹长度不小于0.3是保证柔度法测算结果准确性的必要条件;用有限元方法模拟平直的贯穿型裂纹,归一化模拟裂纹长度不小于0.3时,柔度函数关系式与模拟结果的吻合程度较高;当试样厚度不大于40 mm时,在柔度函数关系式中使用材料的弹性模量可以获得较为准确的测算结果;随着试样厚度的增加,裂纹前缘圆弧角度增大,裂纹平直度降低,导致测算裂纹长度比实际裂纹长度偏小。The flexibility method was used to calculate the fatigue crack length of three-point bending specimens with different thicknesses.Combined with the finite element simulation analysis method,the influence of factors such as specimen thickness,applicable conditions of the flexibility function relationship,material elastic modulus,crack front edge bending degree and extensometer gauge length on the accuracy of the flexibility method in calculating crack length was studied.The results show that a normalized actual crack length of no less than 0.3 was a necessary condition to ensure the accuracy of the flexibility method calculation results.When using the finite element method to simulate a straight through type crack and normalizing the simulated crack length to be no less than 0.3,the compliance function relationship had a high degree of agreement with the simulation results.When the thickness of the specimen was not greater than 40 mm,using the elastic modulus of the material in the flexibility function relationship could obtain a more accurate calculation result.As the thickness of the specimen increased,the angle of the crack leading edge arc increased,and the crack flatness decreased,resulting in the calculated crack length being smaller than the actual crack length.

关 键 词：三点弯曲试样 柔度法 裂纹长度 有限元模拟 疲劳裂纹扩展试验 

分 类 号：TB31[一般工业技术—材料科学与工程] TG115.5[金属学及工艺—物理冶金]