基于双悬臂梁试样的柔度方法

COMPLIANCE METHOD BASED ON DOUBLE CANTILEVER BEAM

NACE TM0177—96标准推荐的双悬臂梁DCB(double cantilever beam)试样主要用于测试硫化物腐蚀条件所产生的平衡载荷与裂纹扩展的相互关系,进而评估材料抗应力腐蚀开裂临界强度因子的优劣,但未提供确定裂纹长度的方法。文中通过有限元分析法提出计算V形裂纹长度的统一柔度公式,该公式在满足有效性条件下,与试样几何尺寸无关,可用于通过测试试样加载线和端面裂纹张开位移计算柔度,进而实现裂纹长度预测。文中采用30CrMo钢DCB试样和已有文献的试验数据对统一公式进行有限元模拟和试验结果对比。研究表明,所提出的柔度公式对不同V形裂纹DCB试样的裂纹长度预测结果与有限元分析结果之间的相对误差不超过2%,与试验结果之间的相对误差不大于5%。

The double cantilever beam（DCB） is widely used to determine the relationship between equilibrium load and crack growth in sulfide corrosion as a testing specimen to evaluate the resistance to stress corrosion cracks in NACE TM0177—96.However,it doesn＇t provide any formula to calculate crack growth or propagation length.An unified formula with dimensionless characteristic was presented based on finite element（FE） method to determine crack length by a compliance of chevron specimens.It can be used to predict a crack growth length by crack opening displacement（COD） and force on the crack mouth or load line.Furthermore,it carries out a numerical simulation and tests for DCB of 30CrMo and the formula to be checked by the data of reference.The results indicate that there is less than about 2% relative error between FE results and predictive value,as well as is not over than about 5% error between test result and predictive value.