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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0.2mm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。
Based on the principle of load separation, a method to determine the explicit expression of load-displacement (PV) curve of compact cracked (CT) specimens with different crack lengths and blunt cracks was proposed. By comparing with the PV curves of sharp crack specimens, Direct Load Demarcation (LSDC) method was developed to directly determine the real - time crack length of sharp cracked specimens. This method eliminates the need for any physical measurement of crack length on the cross-section of the specimen. The CT sample made of Cr2Ni2MoV steel verifies the feasibility and effectiveness of the LSDC method. The results show that the J resistance curve obtained by the LSDC method is more reasonable and accurate than the flexibility and regularization methods. The LSDC method can also obtain the critical fracture toughness which can truly reflect the material cracking from the PV curve separation point of the blunt crack and sharp crack CT sample under the same initial crack length. Compared with the pass point of 0.2mm passivation bias line The established traditional cracking initiation toughness value is more reasonable and has a smaller data dispersion.