Significance of crack opening displacement and crack tip plastic strain energy in fracture initiation
Significance of crack opening displacement and crack tip plastic strain energy in fracture initiation
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裂纹张开位移和裂纹尖端塑性应变能在断裂萌生中的意义
DOI：
10.1179/msc.1978.12.12.579
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发表时间：
1978
期刊：
影响因子：
--
通讯作者：
M. Suzuki
中科院分区：
文献类型：
--
作者：
T. Shoji;H. Takahashi;M. Suzuki
用再结晶技术研究了钝化裂纹尖端局部强应变区的发展过程，以及该区域内的等效塑性应变分布。结果表明，该区域内的等效塑性应变为ε<disp-formula><mml:math display='block'><mml:semantics><mml:mrow><mml:msup><mml:mover accent='true'><mml:mi></mml:mi><mml:mo><$</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:msup><mml:mo>=</mml:mo><mml:msub><mml:mover accent='true'><mml:mi>ε</mml:mi><mml:mo><</mml:mo></mml:mover><mml:mn>$0</mml:mn></mml:msub><mml:msup><mml:mrow><mml:mrow><mml:mo>（</mml:mo><mml:mrow><mml:mfrac><mml:mrow><mml:msub><mml:mi>δ</mml:mi><mml:mi></mml:mi></mml:msub><mml:mi>tcos</mml:mi><mml:mi>θ</mml:mi></mml:mrow><mml:msup><mml:mi>r</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:mfrac></mml:mrow><mml:mo>）</mml:mo></mml:mrow></mml:mrow><mml:mi>m</mml:mi></mml:msup></mml:mrow><mml:annotation encoding='MathType-MTEF'></mml:annotation></mml:semantics></mml:math></disp-formula>，其中r′为距裂纹尖端自由表面的距离，m为0.6-0.7。在此基础上，计算了强应变区塑性功密度和塑性功随裂纹张开位移的变化关系。证明这些参数的重要性与断裂起始，纤维和解理，裂纹张开位移的意义被强调。
The development of an intense strain region, formed locally at a blunting crack tip, and the equivalent plastic strain distribution within it were investigated in terms of crack opening displacement δt by means of the recrystallization technique. The results obtained showed that the equivalent plastic strain within the region was given by <disp-formula><mml:math display='block'><mml:semantics><mml:mrow><mml:msup><mml:mover accent='true'><mml:mi>ε</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mi>p</mml:mi></mml:msup><mml:mo>=</mml:mo><mml:msub><mml:mover accent='true'><mml:mi>ε</mml:mi><mml:mo>¯</mml:mo></mml:mover><mml:mn>0</mml:mn></mml:msub><mml:msup><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mfrac><mml:mrow><mml:msub><mml:mi>δ</mml:mi><mml:mi>t</mml:mi></mml:msub><mml:mi>cos</mml:mi><mml:mo></mml:mo><mml:mi>θ</mml:mi></mml:mrow><mml:msup><mml:mi>r</mml:mi><mml:mo>′</mml:mo></mml:msup></mml:mfrac></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow><mml:mi>m</mml:mi></mml:msup></mml:mrow><mml:annotation encoding='MathType-MTEF'></mml:annotation></mml:semantics></mml:math></disp-formula> where r′ was distance from crack-tip-free surface and m was 0.6–0.7 in this study. Furthermore, based on the above expression, the density of plastic working and plastic work done within the intense strain region were calculated as a function of crack opening displacement. Demonstrating the importance of these parameters with reference to fracture initiation, both fibrous and cleavage, the significance of crack opening displacement was emphasized.