Physically appropriate characterization of fatigue crack propagation rate in elastic–plastic materials using the $$J$$J-integral concept
Physically appropriate characterization of fatigue crack propagation rate in elastic–plastic materials using the $$J$$J-integral concept
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使用 $$J$$J 积分概念对弹塑性材料中的疲劳裂纹扩展速率进行物理适当的表征
DOI：
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
O. Kolednik
中科院分区：
文献类型：
--
作者：
W. Ochensberger;O. Kolednik
The current paper discusses the physically correct evaluation of the driving force for fatigue crack propagation in elastic–plastic materials using the $$J$$J-integral concept. This is important for low-cycle fatigue and for short fatigue cracks, where the conventional stress intensity range ($$Delta K$$ΔK) concept cannot be applied. Using the configurational force concept, Simha et al. (J Mech Phys Solids 56:2876–2895, 2008) , have derived the $$J$$J-integral for elastic–plastic materials with incremental theory of plasticity, $$J^{mathrm{ep}}$$Jep, which is applicable for cyclic loading and/or for growing cracks, in contrast to the conventional $$J$$J-integral. The variation of this incremental plasticity $$J$$J-integral $$J^{mathrm{ep}}$$Jep is studied in numerical investigations conducted on two-dimensional C(T)-specimens with long cracks under cyclic Mode I loading. The crack propagates by an increment after each load cycle. The maximum load is varied so that small- and large-scale yielding conditions prevail. Three different load ratios are considered, from pure tension to tension-compression loading. By theoretical considerations and comparisons with the variation of the crack tip opening displacement $$delta _{mathrm{t}}$$δt, it is demonstrated that the cyclic, incremental plasticity $$J$$J-integral $$Delta J_{mathrm{actPZ}}^{mathrm{ep}}$$ΔJactPZep, which is computed for a contour around the active plastic zone of the growing crack, is physically appropriate to characterize the growth rate of fatigue cracks. The validity of the experimental cyclic $$J$$J-integral, $$Delta J^{mathrm{exp}}$$ΔJexp, proposed by Dowling and Begley (ASTM STP 590:82–103, 1976), is also investigated. The results show that $$Delta J^{mathrm{exp}}$$ΔJexp is correct for the first load cycle, however, not fully appropriate for a growing fatigue crack.
The current paper discusses the physically correct evaluation of the driving force for fatigue crack propagation in elastic–plastic materials using the $$J$$J-integral concept. This is important for low-cycle fatigue and for short fatigue cracks, where the conventional stress intensity range ($$Delta K$$ΔK) concept cannot be applied. Using the configurational force concept, Simha et al. (J Mech Phys Solids 56:2876–2895, 2008) , have derived the $$J$$J-integral for elastic–plastic materials with incremental theory of plasticity, $$J^{mathrm{ep}}$$Jep, which is applicable for cyclic loading and/or for growing cracks, in contrast to the conventional $$J$$J-integral. The variation of this incremental plasticity $$J$$J-integral $$J^{mathrm{ep}}$$Jep is studied in numerical investigations conducted on two-dimensional C(T)-specimens with long cracks under cyclic Mode I loading. The crack propagates by an increment after each load cycle. The maximum load is varied so that small- and large-scale yielding conditions prevail. Three different load ratios are considered, from pure tension to tension-compression loading. By theoretical considerations and comparisons with the variation of the crack tip opening displacement $$delta _{mathrm{t}}$$δt, it is demonstrated that the cyclic, incremental plasticity $$J$$J-integral $$Delta J_{mathrm{actPZ}}^{mathrm{ep}}$$ΔJactPZep, which is computed for a contour around the active plastic zone of the growing crack, is physically appropriate to characterize the growth rate of fatigue cracks. The validity of the experimental cyclic $$J$$J-integral, $$Delta J^{mathrm{exp}}$$ΔJexp, proposed by Dowling and Begley (ASTM STP 590:82–103, 1976), is also investigated. The results show that $$Delta J^{mathrm{exp}}$$ΔJexp is correct for the first load cycle, however, not fully appropriate for a growing fatigue crack.
影响因子：
5.4
作者：
M. Metzger;T. Seifert;C. Schweizer
通讯作者：
M. Metzger;T. Seifert;C. Schweizer