Assessment method of allowed CTOD based on modified load ratio of BS7910
WU Nan;MIAO Zhangmu;ZENG Zheng;XIA Ziyu;School of Transportation,Wuhan University of Technology;
The assessment method of high-strength steel welded joint CTOD( crack tip opening displacement)value in BS7910 Standard,i. e.,the guidance of metal structural defects acceptability evaluation method,can be used to effectively overcome differences in values allowed in different countries. However,the conservativeness of the assessment has always been of concern. To solve this problem,this paper uses the CTOD test data to obtain the true stress of the crack tip by applying the finite element method to δ5simulation. Based on the 2A level assessment method of BS7910,we revised the abscissa,that is,the load ratio,of the assessment points of the failure assessment curve. The results show that the abscissa is less than 1 after revision,the evaluation points are within the safety domain of the failure assessment curve,and the revision gives higher safety evaluation points. At the same time,the critical toughness is significantly lower than δmin,the allowable value of CTOD before correction,thus making the method of acquiring the allowable value of CTOD based on failure assessment curve more accurate.