A simple analytical crack tip opening displacement approximation under random variable loadings

Liu, Yongming; Lu, Zizi; Xu, Jifeng

doi:10.1007/s10704-012-9682-6

Cited by 19 publications

(9 citation statements)

References 12 publications

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“…Characteristic substructure crack growth test of cutterhead panel under variable amplitude loading. According to the statistics of cutter load and frequency, 21,22 the load frequencies of each cutter are relatively consistent, mainly concentrated in 0-5 Hz, with typical low-frequency characteristics. In order to facilitate the experimental study, the load applied on the characteristic sample is simplified.…”

Section: Weak Part and Characteristic Substructure Of Cutterhead Static Analysis Of Cutterheadmentioning

confidence: 99%

“…In Figure 4(b), the dashed line is the crack front at time t, the solid line is the crack leading edge at time t + dt, da is the length of crack propagation under cyclic loading, dd/2 is the length of crack opening (CTOD), u is the crack opening angle (CTOA), and the Based on a modified Dugdale strip yield model proposed by Liu et al 21 the crack opening displacement under plane stress is…”

Section: Theoretical Prediction Model Of Time Integration Crack Propamentioning

confidence: 99%

“…Based on a modified Dugdale strip yield model proposed by Liu et al 21 the crack opening displacement under plane stress is…”

Section: Theoretical Prediction Model Of Time Integration Crack Propagationmentioning

confidence: 99%

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Tunnel boring machine cutterhead crack propagation life prediction with time integration method

Li¹,

Zhang

Meng

et al. 2019

Advances in Mechanical Engineering

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Fatigue damage is one of the most common failure modes of large-scale engineering equipment, especially the full-face tunnel boring machine with characteristics of a thick plate structure bearing strong impact load. It is difficult to predict the location and propagation life of crack of cutterhead under strong impact load. Unseasonal maintenance of equipment caused by inaccurate prediction of life cycle of cutterhead seriously affects the construction efficiency of the equipment and the life safety of the operators. Determining the crack location of tunnel boring machine cutterhead structure under strong impact load and predicting the crack propagation life are difficult scientific problems. To solve them, first, the location of the stress concentration of the cutterhead is determined by using finite element analysis method of statics. Second, prediction model for crack propagation life of tunnel boring machine cutterhead characteristic substructure based on time integration is built. And the test of crack growth of cutterhead characteristic substructure is performed. The feasibility and accuracy of the prediction model are verified by contrasting crack prediction models and the results of the test. Finally, the life prediction of tunnel boring machine cutterhead of water diversion project in Northwest Liaoning Province is carried out by using crack propagation model based on time integration. Results show that the maximum error of theoretical prediction and experimental results of crack propagation is 16%. So the feasibility of crack propagation model based on time integration in predicting the crack growth of cutterhead is verified. It is predicted that the tunnel boring machine cutterhead panel can work normally for 5.9 km under the condition of ultimate load. Building the crack propagation model considering the influence of plate thickness and strong impact load has important research value for improving the working efficiency of engineering equipment, prolonging service time, and improving the working safety.

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Section: Weak Part and Characteristic Substructure Of Cutterhead Static Analysis Of Cutterheadmentioning

confidence: 99%

Section: Theoretical Prediction Model Of Time Integration Crack Propamentioning

confidence: 99%

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Tunnel boring machine cutterhead crack propagation life prediction with time integration method

Li¹,

Zhang

Meng

et al. 2019

Advances in Mechanical Engineering

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“…Based on the strip yield model proposed by Liu et al [30], the crack opening displacement during loading and unloading under a plane stress state is:…”

Section: ) Surface Crack Propagation Model Under Plane Stress Statementioning

confidence: 99%

A Time-Integral Crack Propagation Model Considering Thickness Effect

et al. 2019

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The crack propagation mechanism of thick plates is difficult to describe accurately, and thus, it is difficult to predict the lifetimes of thick plate structural cracks in extreme construction environments. In this paper, a theoretical model of the time-integrated crack propagation that accounts for the thickness effect is established. The constraint factor is introduced to characterize the thickness effect of crack propagation, and the constraint factor formula was obtained by fitting the experimental results. The results of the fatigue crack growth tests and the crack propagation theoretical predictions for Q345D specimens showed the time-integrated crack propagation model predicts the crack propagation more accurately in the initial stage and during the stable expansion stage of crack propagation. These results have guiding significance for the fatigue life prediction of equipment with thick plate structural features.INDEX TERMS Thick plate, crack propagation, crack closure, fatigue test, time integration method.

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“…A general CTOD approximation method under random cyclic loading is derived above. The detailed derivation can be found in the paper [6]. However, this model is over simple for the real fatigue crack growth analysis.…”

Section: A Ctod Estimation Algorithmmentioning

confidence: 99%

A time-based formulation for real-time fatigue damage prognosis under variable amplitude loadings

Zhang

Liu

2013

54th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference

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A time-based fatigue crack growth algorithm is proposed in this paper to calculate the fatigue crack growth under general random variable amplitude loading. This approach is based on the analytical crack tip opening displacement (CTOD) estimation and a subcycle fatigue crack growth model. The discussion is first given for fatigue cracks without considering the crack closure. Next, the model is extended to the growing crack with the crack closure. Following this, a general fatigue crack growth algorithm is proposed under general random variable loadings, which is combined the crack closure model and the geometrical relationship between the CTOD and the crack increment (da) at any time instant within a cycle. To validate this algorithm, a testing is performed for Al7075-T6 under "Christmas Tree" loading spectra, which cannot be easily handled by the classical cyclebased approaches. The predictions match the experimental data very well. A detailed discussion is given based on the current investigation. Nomenclature K= stress intensity factor ε y = tensile yield strain σ y = tensile yield strength E = Young's modulus σ = applied stress σ ref = crack closure stress a = crack length F,Y = geometry correction factor w = width of the specimen D = thickness of the specimen K = applied stress intensity factor  = CTOD

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A simple analytical crack tip opening displacement approximation under random variable loadings

Cited by 19 publications

References 12 publications

Tunnel boring machine cutterhead crack propagation life prediction with time integration method

Tunnel boring machine cutterhead crack propagation life prediction with time integration method

A Time-Integral Crack Propagation Model Considering Thickness Effect

A time-based formulation for real-time fatigue damage prognosis under variable amplitude loadings

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