收稿日期: 2017-01-13
修回日期: 2017-05-31
网络出版日期: 2017-05-31
基金资助
国家自然科学基金（11472228）
Load separation based direct calibration method for estimating J-resistance curves
Received date: 2017-01-13
Revised date: 2017-05-31
Online published: 2017-05-31
Supported by
National Natural Science Foundation of China (11472228)
基于载荷分离原理提出了确定不同裂纹长度钝裂纹紧凑拉伸（CT）试样的载荷-位移（P-V）曲线显式表达式的方法，进而通过与尖裂纹试样的P-V曲线进行对比分析，发展了直接确定尖裂纹试样实时裂纹长度的载荷分离直接标定（LSDC）法。该方法无需在试样断面上进行任何裂纹长度的物理测量。采用Cr2Ni2MoV钢制成的CT试样验证了LSDC法的可行性和有效性。研究结果表明，LSDC法得到的J阻力曲线相比柔度法和规则化法更加合理、精确。由LSDC法还可从相同初始裂纹长度条件下的钝裂纹和尖裂纹CT试样的P-V曲线分离点得到能够真实反映材料启裂的临界断裂韧度，相比根据0.2 mm钝化偏置线交点确定的传统条件启裂韧度值更为合理，且具有更小的数据分散性。
关键词： 载荷分离直接标定法; J阻力曲线; 断裂韧度; Cr2Ni2MoV钢; CT试样
巫元俊 , 包陈 , 何广伟 , 蔡力勋 . 用于J阻力曲线测试的载荷分离直接标定法[J]. 航空学报, 2017 , 38(10) : 221128 -221128 . DOI: 10.7527/S1000-6893.2017.221128
The explicit expression of P-V curves for blunt cracked Compact Tension (CT) specimens with different stationary crack lengths is proposed based on the principle of load separation.The load-displacement (P-V) curve of sharp cracked CT specimens is compared with that of blunt cracked CT specimen.The Load Separation based Direct Calibration (LSDC) method is developed to estimate the instantaneous crack length of the sharp cracked CT specimen.Any physical measurement of the crack length on the fracture surface of the broken specimen is unnecessary in this method.A group of CT specimens made of Cr2Ni2MoV steel are used to verify the feasibility and validity of the LSDC method.The results show that the J-resistance curves obtained by the LSDC method are more reasonable and accurate than those obtained by the unloading compliance method and the normalization method.The LSDC method can get critical toughness at the point of the P-V curve of sharp cracked CT specimen separating from that of the blunt cracked CT specimen,where the two specimens have the same initial crack length.The critical toughness can truly reflect the crack initiation.Compared with traditional critical toughness obtained by the intersection of 0.2 mm blunting offset line and J-resistance curves,the critical toughness corresponding to the separation point is more reasonable and has smaller data dispersion.
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