Modeling of Random Fatigue Crack Propagation

2013 ◽  
Vol 756-759 ◽  
pp. 105-107
Author(s):  
Xiao Li Zou
Keyword(s):  
Experimental Data ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Growth Process ◽  
Crack Size ◽  
Propagation Time ◽  
Fokker Plank Equation ◽  
Eigenfunction Method ◽  
Random Fatigue

A statistical model is proposed for the analysis of fatigue crack propagation, based on the theory of fracture mechanics and stochastic process. The fatigue growth process is approximated as a diffusive Markov process. The associated backward Fokker-Plank equation and boundary conditions are written, and the distribution of crack propagation time under a given crack size is obtained by using an Eigenfunction method. The sought distribution is expressed in the form of a convergent infinite series. An examples is presented to illustrate the application of the method. The predicted results seem to agree with the experimental data.

scholarly journals Effects of Crack Size, Stress Ratio and Hydrogen on the Near Threshold Fatigue Crack Propagation of High Strength Steel

2005 ◽  
Vol 54 (12) ◽  
pp. 1237-1243 ◽  
Author(s):  
Kazutoshi YANAGIHARA ◽  
Satoshi OHYANAGI ◽  
Masanobu KUBOTA ◽  
Chu SAKAE ◽  
Yoshiyuki KONDO
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
High Strength Steel ◽  
Stress Ratio ◽  
High Strength ◽  
Crack Size ◽  
Near Threshold

Simulation on Propagation and Coalescence of Fatigue Crack by Automatic Three-Dimensional Finite Element Crack Propagation System

2016 ◽  
Author(s):  
Hiroaki Doi ◽  
Kisaburo Azuma
Keyword(s):  
Experimental Data ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Test ◽  
Power Plants ◽  
Crack Size ◽  
Crack Coalescence ◽  
Initial Surface ◽  
Age Related ◽  
Bending Load

Verification analyses of the CRACK-FEM developed to predict the propagation of age-related cracks detected in complicated-shaped components of nuclear power plants are presented. Four fatigue crack propagation tests for plate specimens with one and two initial surface cracks subjected to cyclic tensile and bending load respectively are simulated using the CRACK-FEM, and the analysis results are compared with the experimental data of the tests in literature. For the specimens with one crack, the relation between the number of load cycles and the crack size obtained by the analyses agrees with the experimental data. For the specimens with two cracks, the analysis results until the crack coalescence and the timing of the crack coalescence obtained by the analyses agree with the experimental data. In tensile fatigue test for specimen with two cracks, the relation between the number of load cycles and the crack size after the crack coalescence obtained by the analysis almost agrees with the experimental data, although a little difference of analysis from the experimental data is seen. However, in bending fatigue test for specimen with two cracks, the analysis results for all the number of load cycles show good agreement with the experimental data.

scholarly journals Cycle-by-cycle simulation of variable amplitude fatigue crack propagation

2017 ◽  
Vol 8 (1) ◽  
pp. 8 ◽  
Author(s):  
Louis Muys ◽  
Jie Zhang ◽  
Nahuel Micone ◽  
Wim De Waele ◽  
Stijn Hertelé
Keyword(s):  
Experimental Data ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Numerical Models ◽  
Crack Tip ◽  
Variable Amplitude ◽  
Cycle Simulation ◽  
Crack Tip Plasticity ◽  
Variable Amplitude Fatigue

In variable amplitude fatigue of high strength low alloy (HSLA) steel components, overloads can severely retard subsequent crack propagation for a number of cycles. In order to be able to predict fatigue crack propagation with a reduced degree of conservatism, retardation has to be taken into account. Of all numerical models that have been developed over time, crack tip plasticity models are selected based on the need for a detailed and fast cycle-by-cycle simulation of high cycle. After introducing the load interaction zone concept, common to all crack tip plasticity models, the Wheeler and Willenborg models are discussed, implemented and compared to experimental data. It is concluded that the Modified Wheeler model provides the most promising results, whereas the main limitation of Willenborg models is the need for extensive experimental data.

scholarly journals A Study on Propagation Property of Fatigue Crack at Composite with Another Material

2017 ◽  
Vol 62 (2) ◽  
pp. 1363-1366
Author(s):  
K.K. Choi ◽  
J.U. Cho
Keyword(s):  
Experimental Data ◽  
Composite Material ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Experimental Result ◽  
Real Field ◽  
Propagation Property ◽  
Simulation Data ◽  
Safety Design

AbstractIn this study, the fatigue crack propagation in composite material is investigated by experimental result. When another material exists at fatigue crack propagation in case of composite, the durability against fatigue crack is smaller or greater than in case of matrix without another material. As another material is composite material, it refers to steel or material. Another material influences the crack propagation. As the experimental results can be agreed with simulation data, all experimental data in this study are verified. These experimental and analysis results can be applied into real field effectively. The estimation of safety design and life will be of great value industrially.

Simulation of Fatigue Crack Growth Under Random Overloads with Retardation

2006 ◽  
Vol 324-325 ◽  
pp. 923-926
Author(s):  
Xiao Li Zou ◽  
Jian Hui Yang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Opening ◽  
Crack Size ◽  
Base Line ◽  
Yield Zone ◽  
Fatigue Crack Propagation Life

In order to study the behavior of fatigue crack propagation under random overloads, a Monte Carlo simulation scheme is proposed. Overloads of Poisson flow with uniform distribution on base-line constant-amplitude cyclic loads are considered. The retardation effect of overload is taken into account using crack closure model and the crack opening stress level is assumed to vary linearly in the yield zone produced by the overload. The fatigue crack growth curve from initial crack size till fatigue failure is simulated step by step. Through the large number of the simulated samples, the average fatigue crack propagation life is calculated. Finally, the influence of overload intensity and magnitude on fatigue crack propagation life is studied.

Method of Construction for High Cycle Fatigue Resistant Pressure Vessels in Hydrogen Service

2018 ◽  
Author(s):  
Pooya Mahmoudian
Keyword(s):  
Fatigue Crack ◽  
Fracture Mechanics ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Applied Pressure ◽  
Design Procedure ◽  
Fatigue Loading ◽  
Crack Size ◽  
Initial Crack ◽  
Pressure Vessels

Currently, pressure vessels that operate in hydrogen service and subjected to fatigue must be designed using a defect tolerant design procedure. This means that first the fracture mechanics properties of the material being considered must be measured in hydrogen at the maximum service pressure. The properties are fatigue crack propagation properties and threshold stress intensity factor for hydrogen embrittlement (KIHE). With these properties, a fatigue crack propagation life can be estimated assuming an initial crack size and geometry and growing this defect to failure. The property measurements are costly and can only be performed at a few laboratories. Furthermore, the resulting lives are usually very short because of the assumed initial crack size. These things limit the application of this design method to lower cycle or static loading applications. This work introduces a cost-effective method of design and construction of pressure vessels for high cycle use in hydrogen service at pressures below 40,000 psi that eliminates the need for determining fracture mechanics properties in hydrogen environment. The method uses shrink fit construction of a liner inside a jacket. The method requires that when the pressure is applied, the magnitude of the resultant stress at the pressure boundary of the liner is more compressive than the magnitude of the applied pressure and the maximum allowed size of defect in the jacket at the interface between the jacket and the liner is such that when the cyclic stress is applied the resultant fatigue loading of that defect at that location to be less than the threshold value for growth of that defect.

scholarly journals Comparative study of creep and fatigue crack growth in Poly (Vinyl chloride) pipe

2012 ◽  
Vol 9 (2) ◽  
pp. 359-366
Author(s):  
Baghdad Science Journal
Keyword(s):  
Experimental Data ◽  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Velocity ◽  
Rate Theory

The Rate theory of crack growth in PVC pipe has been studied for creep and fatigue crack propagation. Rate theory function parameters, (RTFP), were estimated theoretically from exponential function parameters, (EFP), to experimental data of crack velocity versus stress intensity factor ,(V-K) diagram, to creep crack propagation . Also (RTFP) were estimated theoretically from (EFP) to experimental data of (V-?K) diagram to fatigue crack propagation. Temperature effect with (RTFP) was discussed. Crack velocity function denoted with stress intensity factor and temperature degrees has been determined to fatigue and creep crack propagation theoretically and comparative results this function with experimental data of (V-K or ?K) diagram .

scholarly journals Fatigue Reliability Analysis of Tunnelling Boring Machine Cutterhead with Cracks

2020 ◽  
Author(s):  
jie li ◽  
bin zhang ◽  
chuang liu ◽  
jingbo guo
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Stress Amplitude ◽  
Crack Size ◽  
Initial Crack ◽  
Load Spectrum ◽  
Factors Affecting ◽  
Main Factors ◽  
Fatigue Crack Propagation Life

The cutterhead of tunnel boring machine is a large-scale metal welding structure, which is prone to problems such as wear and cracking during the tunnelling process. For the issue, the fatigue crack propagation rate model of cutterhead under different reliability was established, based on the damage tolerance of cutterhead. Its dangerous position of cutterhead failure was determined by using finite element method. According to the fatigue load spectrum, the fatigue propagation life of cutterhead under different reliability was calculated, the main factors affecting the reliability of cutterhead were analyzed and the engineering experiment is carried out. The results show that three dangerous positions of the cutterhead failure are the junction of the split plane, the maximum deformation of the block and the central cutter seat. The load stress amplitude and initial crack size are the main factors affecting the crack propagation life and the reliability of cutterhead. With the increase of load stress amplitude and initial crack size of cutterhead, the fatigue crack propagation life of cutterhead decreases and the reliability is worse. When the initial crack size of cutterhead is greater than 0.5mm, the fatigue crack propagation life of cutterhead decreases obviously. The research results provide a scientific basis for crack detection, life prediction and reliability evaluation of cutterhead structure.

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