Crack Growth Rate Model under Constant Cyclic Loading and Effect of Different Singularity Fields

Shi, Kun; Liu, Cai; Bao, Chen

doi:10.1016/j.mspro.2014.06.253

Cited by 8 publications

(4 citation statements)

References 30 publications

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“…The second type is the Kujawski-Ellyin field (Kujawski and Ellyin, 1984; Ellyin, 1986). The effect of these singularity fields was examined in the paper Shi et al (2014). The study (Shi et al , 2014) evaluates the common FCG model, which is based on energy balance during growth of the crack.…”

Section: The Crack Growth Ratementioning

confidence: 99%

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Unification proposals for fatigue crack propagation laws

Kobelev

2017

MMMS

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Purpose The purpose of this paper is to propose the new dependences of cycles to failure for a given initial crack length upon the stress amplitude in the linear fracture approach. The anticipated unified propagation function describes the infinitesimal crack-length growths per increasing number of load cycles, supposing that the load ratio remains constant over the load history. Two unification functions with different number of fitting parameters are proposed. On one hand, the closed-form analytical solutions facilitate the universal fitting of the constants of the fatigue law over all stages of fatigue. On the other hand, the closed-form solution eases the application of the fatigue law, because the solution of nonlinear differential equation turns out to be dispensable. The main advantage of the proposed functions is the possibility of having closed-form analytical solutions for the unified crack growth law. Moreover, the mean stress dependence is the immediate consequence of the proposed law. The corresponding formulas for crack length over the number of cycles are derived. Design/methodology/approach In this paper, the method of representation of crack propagation functions through appropriate elementary functions is employed. The choice of the elementary functions is motivated by the phenomenological data and covers a broad region of possible parameters. With the introduced crack propagation functions, differential equations describing the crack propagation are solved rigorously. Findings The resulting closed-form solutions allow the evaluation of crack propagation histories on one hand, and the effects of stress ratio on crack propagation on the other hand. The explicit formulas for crack length over the number of cycles are derived. Research limitations/implications In this paper, linear fracture mechanics approach is assumed. Practical implications Shortening of evaluation time for fatigue crack growth. Simplification of the computer codes due to the elimination of solution of differential equation. Standardization of experiments for crack growth. Originality/value This paper introduces the closed-form analytical expression for crack length over number of cycles. The new function that expresses the damage growth per cycle is also introduced. This function allows closed-form analytical solution for crack length. The solution expresses the number of cycles to failure as the function of the initial size of the crack and eliminates the solution of the nonlinear ordinary differential equation of the first order. The different common expressions, which account for the influence of the stress ratio, are immediately applicable.

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Section: The Crack Growth Ratementioning

confidence: 99%

“…The effect of these singularity fields was examined in the paper Shi et al (2014). The study (Shi et al , 2014) evaluates the common FCG model, which is based on energy balance during growth of the crack. A new parameter was introduced in this study.…”

Section: The Crack Growth Ratementioning

confidence: 99%

Unification proposals for fatigue crack propagation laws

Kobelev

2017

MMMS

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“…Because of its simplicity and wide general applications, Paris law remains to be the most popular fatigue model to quantify fatigue crack growth, 9 and it offers a sound base for modifications and improvements. To account for the effects of various factors on da/dN prediction, a number of modifications to the Paris model have been proposed, for instance, as follows: (1) the fracture toughness of material and the stress ratio during fatigue test were suggested to incorporate in the Paris model as reported in Forman et al; 10 (2) based on theoretical research and experimental validation, Barter et al proposed the following form: da/dN = C 1 a (1 2 m*/2) (DK eff ) m* (C 1 , a*, m* are constants); [11][12][13] and (3) an effective DK (DK eff ) was used instead of DK to account for the effect of crack closure.…”

Section: Introductionmentioning

confidence: 99%

Effects of heterogeneity and load amplitude on fatigue rate prediction of a welded joint

Zhang

Jiang

Lü

et al. 2016

Advances in Mechanical Engineering

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It is a contradiction to homogeneous material fatigue behavior characterized by widely used linear Paris law, welded-joint fatigue issues need to be reassessed because fatigue crack growth behavior going through heterogeneous region will be different. For a welded joint, log(da/dN) is no longer linearly related to log(DK) in heterogeneous region because of the change in fatigue properties resulting from the welding process. Theoretical model of the fatigue crack growth rate without artificial adjustable parameters was proposed by considering the effects of heterogeneity in a welded joint and load-amplitude variation on fatigue crack growth curve. In this fatigue heterogeneous region, the relationship between log(da/dN) and log(DK) is similar to a concave-down parabola. Predicted results from the proposed model agreed better with the experimental data obtained from fatigue tests conducted in this study and open published literatures for welded joints in comparison to the widely used Paris model.

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“…Theoretical and experimental results can be found in Figs. 1-2 for 2024-T351 Aluminum alloy [5,8,33] and 7075-T651 Aluminum alloy [4,8,9,34], respectively.…”

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confidence: 99%

Mode-II Fatigue Crack Growth Model from Shear-Type Low Cycle Fatigue Properties

Shi

Cai

et al. 2016

AMM

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The inherent law between fatigue behaviors of shear-type representative volume element and mode-II fatigue crack growth is found in the range of cycle plastic zone near the crack tip. Prediction model for mode-II fatigue crack growth rate is then proposed by utilizing shear-type low cycle fatigue properties, plastic strain energy criterion, and effective cycle stress-strain field. Experimental data of two Aluminum alloys, 2024-T351 and 7075-T6, are used for the model verification. Good agreement between experimental and theoretical results is obtained.

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Crack Growth Rate Model under Constant Cyclic Loading and Effect of Different Singularity Fields

Cited by 8 publications

References 30 publications

Unification proposals for fatigue crack propagation laws

Unification proposals for fatigue crack propagation laws

Effects of heterogeneity and load amplitude on fatigue rate prediction of a welded joint

Mode-II Fatigue Crack Growth Model from Shear-Type Low Cycle Fatigue Properties

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