Fatigue Fracture of the Stem–Cement Interface With a Clamped Cantilever Beam Test

2000 ◽  
Vol 122 (6) ◽  
pp. 647-651 ◽  
Author(s):  
D. A. Heuer ◽  
K. A. Mann
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Cantilever Beam ◽  
Crack Tip ◽  
Beam Test ◽  
Cement Interface ◽  
Cocr Alloy ◽  
Pmma Cement

A clamped cantilever beam test was developed to determine the fatigue crack propagation rate of the CoCr alloy/PMMA cement interface at high crack tip phase angles. A combination of finite element and experimental methods was used to determine the fatigue crack growth rates of two different CoCr alloy/PMMA cement surfaces. A crack tip phase angle of 69 deg was found, indicating that loading at the crack tip was mixed-mode with a large degree of in-plane shear loading. The energy required to propagate a crack at the interface was much greater for the plasma-sprayed CoCr surface when compared to the PMMA-precoated satin finish p<0.001. Both interface surfaces could be modeled using a Paris fatigue crack growth law over crack propagation rates of 10−4 to 10−9 m/cycle.[S0148-0731(00)01306-6]

scholarly journals An Integral Formulation of Two-Parameter Fatigue Crack Growth Model

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Jianguo Wu ◽  
Shan Jiang ◽  
Wei Zhang ◽  
Zili Wang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Closure ◽  
Crack Tip ◽  
Integral Form ◽  
Crack Growth Behavior ◽  
Crack Growth Model ◽  
Two Parameter

A two-parameter fatigue crack growth algorithm in integral form is proposed, which can describe the continuous crack growth process over the time period. In this model, the fatigue crack propagation behavior is governed by the temporal crack-tip state including the current applied load and the physical condition due to the previous load sequence. The plasticity-induced crack closure, left by the historical loading sequence, controls the following fatigue crack growth behavior and typically leads to the interaction effects. In the proposed method, a modified crack closure model deriving from the local plastic deformation is employed to account for this load memory effect. In general, this model can simulate the fatigue crack growth under variable amplitude loading. Additionally, this model is established on the physical state of crack tip in the small spatial and temporal scale, and it is used to evaluate the macroscopic crack propagation and fatigue life under irregular tension-tension loading. A special superimposed loading case is discussed to demonstrate the advantage of the proposed model, while the traditional two-parameter approach is not proper functional. Moreover, the typical various load spectra are also employed to validate the method. Good agreements are observed.

Atomistic Simulations of Fatigue Crack Growth in Single Crystal Aluminum

2013 ◽  
Author(s):  
Enqiang Lin ◽  
Yongming Liu
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Single Crystal ◽  
Crack Growth ◽  
Crack Tip ◽  
Loading Path ◽  
Crack Model ◽  
Cleavage Crack ◽  
Crack Tip Opening Displacement

The behaviors of model-I fatigue crack propagation behaviors under different strain cycles in single crystal aluminum have been systematically investigated by molecular dynamic and quasicontinuum method with embedded atom potential. Four different crack orientations: (010)[001], (111)[11-2], (110)[001] and (101)[10-1] are investigated by using the edge-crack model. Different fatigue crack growth mechanisms such as cleavage crack propagation, twinning and dislocation emission are observed. Premature crack surface contact during the unloading path is also observed for the (010)[001] crack, which is consistent with the crack closure hypothesis in the classical fatigue theory. The relationship between local deformation and crack growth kinetics are identified by using crack tip increments and crack tip opening displacement (CTOD) profiles at the selected stress cycle. The results show that crack only grows during part of the loading path and no crack growth during the unloading path, which are well in agreement with our previous in-situ SEM observations.

scholarly journals Numerical Simulation of Fatigue Crack Growth Rate and Crack Retardation due to an Overload Using a Cohesive Zone Model

2014 ◽  
Vol 891-892 ◽  
pp. 777-783 ◽  
Author(s):  
Sarmediran Silitonga ◽  
Johan Maljaars ◽  
Frans Soetens ◽  
Hubertus H. Snijder
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Crack Tip ◽  
Zone Model ◽  
Cohesive Elements

In this work, a numerical method is pursued based on a cohesive zone model (CZM). The method is aimed at simulating fatigue crack growth as well as crack growth retardation due to an overload. In this cohesive zone model, the degradation of the material strength is represented by a variation of the cohesive traction with respect to separation of the cohesive surfaces. Simulation of crack propagation under cyclic loads is implemented by introducing a damage mechanism into the cohesive zone. Crack propagation is represented in the process zone (cohesive zone in front of crack-tip) by deterioration of the cohesive strength due to damage development in the cohesive element. Damage accumulation during loading is based on the displacements in the cohesive zone. A finite element model of a compact tension (CT) specimen subjected to a constant amplitude loading with an overload is developed. The cohesive elements are placed in front of the crack-tip along a pre-defined crack path. The simulation is performed in the finite element code Abaqus. The cohesive elements behavior is described using the user element subroutine UEL. The new damage evolution function used in this work provides a good agreement between simulation results and experimental data.

Critical Assessment of a Local Strain-Based Fatigue Crack Growth Model Using Experimental Data Available for the P355NL1 Steel

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Abílio M. P. De Jesus ◽  
José A. F. O. Correia
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Element Analysis ◽  
R Ratio ◽  
Crack Growth Model

Fatigue crack growth models based on elastic–plastic stress–strain histories at the crack tip region and strain-life damage models have been proposed in the literature. The UniGrow model fits this particular class of fatigue crack propagation models. The residual stresses developed at the crack tip play a central role in these models, since they are used to assess the actual crack driving force, taking into account mean stress and loading sequence effects. The performance of the UniGrow model is assessed based on available experimental constant amplitude crack propagation data, derived for the P355NL1 steel. Key issues in fatigue crack growth prediction using the UniGrow model are discussed; in particular, the assessment of the elementary material block size, the elastoplastic analysis used to estimate the residual stress distribution ahead of the crack tip and the adopted strain-life damage relation. The use of finite element analysis to estimate the residual stress field, in lieu of a simplified analysis based on the analytical multi-axial Neuber's approach, and the use of the Morrow's strain-life equation, resulted in fatigue crack propagation rates consistent with the experimental results available for P355NL1 steel, for several stress R-ratios. The use of the Smith–Watson–Topper (SWT) (=σmax.Δɛ/2) damage parameter, which has often been proposed in the literature, over predicts the stress R-ratio effects.

Assessment of Fatigue Crack Growth Data Available for the P355NL1 Steel Using a Local Strain-Based Approach

2011 ◽  
Author(s):  
Abi´lio M. P. de Jesus ◽  
Jose´ A. F. O. Correia
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Local Strain ◽  
Element Analysis ◽  
R Ratio

Fatigue crack growth models based on elastic–plastic stress–strain histories at the crack tip region and strain-life damage models have been proposed in literature. The UniGrow model fits this particular class of fatigue crack propagation models. The residual stresses developed at the crack tip play a central role in these models, since they are used to assess the actual crack driving force, taking into account mean stress and loading sequence effects. The performance of the UniGrow model is assessed based on available experimental constant amplitude crack propagation data, derived for P355NL1 steel. Key issues in fatigue crack growth prediction using the UniGrow model are discussed; in particular, the assessment of the elementary material block size, the elastoplastic analysis used to estimate the residual stress distribution ahead of the crack tip and the adopted strain-life relation. The use of finite element analysis to estimate the residual stress field, in lieu of a simplified analysis based on the analytical multiaxial Neuber approach, and the use of the Morrow strain-life equation, resulted in fatigue crack propagation rates consistent with the experimental results available for P355NL1 steel, for several stress R-ratios. The use of the SWT parameter for the local strain-life relation, which has often been proposed in the literature, leads to overprediction of stress R-ratio effects.

Modeling of Fatigue Crack Closure by Finite Element Method

2012 ◽  
Vol 544 ◽  
pp. 145-150
Author(s):  
Zhen Yu Ding ◽  
Xiao Gui Wang ◽  
Zeng Liang Gao
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Closure ◽  
Fe Simulation ◽  
Crack Tip ◽  
Cyclic Plasticity ◽  
Stress And Strain

Crack closure concept is often used to explain the crack propagation behavior in cracked components. The effective stress intensity factor range is considered as a driving force of fatigue crack growth based on the traditional crack closure concept. The crack closure process and the plastic deformation near the crack tip were discussed in this paper. The standard compact tension specimen with the plane-stress condition was used to study the crack closure. A dynamic crack propagation method was proposed to simulate the effect of previous fatigue crack growth on the successive crack growth behavior. To obtain the accurately numerical results of stress and strain components, the Jiang and Sehitoglu cyclic plasticity model was implemented into ABAQUS as UMAT. With the detailed stress and strain response taken from the finite element (FE) simulation, the whole process of crack closure was described by the load curve. The load corresponding to maximum crack closure length is firstly proposed to describe the effect of fatigue damage. According to the results of FE simulation, the cyclic plasticity of the material near the crack tip persists during the crack closure period and should not be ignored.

scholarly journals Effect of Electropulsing Treatment on the Fatigue Crack Growth Behavior of Copper

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2168 ◽  
Author(s):  
Yan Yin ◽  
Haibo Chen ◽  
Yasuyuki Morita ◽  
Yuhki Toku ◽  
Yang Ju
Keyword(s):  
Fatigue Crack ◽  
Fatigue Life ◽  
Fatigue Crack Growth ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Tip ◽  
Cyclic Stress ◽  
Crack Growth Behavior ◽  
Electropulsing Treatment ◽  
Two Sides

Crack propagation was quantitatively evaluated to investigate the effect of electropulsing treatment (EPT) on fatigue crack growth of copper specimens. Varying fatigue cycles were obtained under six different load levels. The crack lengths were measured under two load levels to examine the effect of cyclic stress. The microhardness was measured around the vicinity of the crack tip. Furthermore, the fracture surface was observed by scanning electron microscopy. Results show that EPT with electric current density of 150 A/mm2 enhances the high-cycle fatigue life, and the effect tends to increase with the decrease in cyclic stress. Vickers microhardness (HV) near the crack tip decreases to normal levels after treatment, and the approaching cracks on two sides can be observed. Local annealing and recrystallization occur around the fatigue crack tip. Accordingly, crack propagation can be delayed, and fatigue life can be prolonged by EPT.

scholarly journals Study on the Influence of the Gurson–Tvergaard–Needleman Damage Model on the Fatigue Crack Growth Rate

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1183
Author(s):  
Edmundo R. Sérgio ◽  
Fernando V. Antunes ◽  
Diogo M. Neto ◽  
Micael F. Borges
Keyword(s):  
Growth Rate ◽  
Fatigue Crack ◽  
Crack Growth Rate ◽  
Fatigue Crack Growth ◽  
Plastic Strain ◽  
Crack Growth ◽  
Damage Model ◽  
Crack Tip ◽  
Strength Parameter ◽  
Stress Intensity Factor Range

The fatigue crack growth (FCG) process is usually accessed through the stress intensity factor range, ΔK, which has some limitations. The cumulative plastic strain at the crack tip has provided results in good agreement with the experimental observations. Also, it allows understanding the crack tip phenomena leading to FCG. Plastic deformation inevitably leads to micro-porosity occurrence and damage accumulation, which can be evaluated with a damage model, such as Gurson–Tvergaard–Needleman (GTN). This study aims to access the influence of the GTN parameters, related to growth and nucleation of micro-voids, on the predicted crack growth rate. The results show the connection between the porosity values and the crack closure level. Although the effect of the porosity on the plastic strain, the predicted effect of the initial porosity on the predicted crack growth rate is small. The sensitivity analysis identified the nucleation amplitude and Tvergaard’s loss of strength parameter as the main factors, whose variation leads to larger changes in the crack growth rate.

Finite Element Simulation of Stable Fatigue Crack Growth Using Critical CTOD Determined by Preliminary Finite Element Analysis

2014 ◽  
Vol 891-892 ◽  
pp. 1675-1680
Author(s):  
Seok Jae Chu ◽  
Cong Hao Liu
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Finite Element Simulation ◽  
Crack Growth ◽  
Crack Tip ◽  
Stress Intensity Factor Range ◽  
Crack Tip Opening Displacement ◽  
Element Analysis ◽  
Element Simulation

Finite element simulation of stable fatigue crack growth using critical crack tip opening displacement (CTOD) was done. In the preliminary finite element simulation without crack growth, the critical CTOD was determined by monitoring the ratio between the displacement increments at the nodes above the crack tip and behind the crack tip in the neighborhood of the crack tip. The critical CTOD was determined as the vertical displacement at the node on the crack surface just behind the crack tip at the maximum ratio. In the main finite element simulation with crack growth, the crack growth rate with respect to the effective stress intensity factor range considering crack closure yielded more consistent result. The exponents m in the Paris law were determined.

Characterization of Crack Tip Damage Zone Formation on Alloy 625 During Fatigue Crack Growth at 750°C by Transmission EBSD Method

2017 ◽  
Author(s):  
Yuji Ozawa ◽  
Tatsuya Ishikawa ◽  
Yoichi Takeda
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Power Plants ◽  
Crack Path ◽  
Damage Zone ◽  
Crack Tip ◽  
Loading Frequency ◽  
Zone Formation ◽  
Alloy 625

In order to clarify the mechanism of fatigue crack growth in alloy 625, which is a candidate material for use in advanced ultra supercritical power plants, the crack tip damage zone formation after a crack growth test conducted in high temperature steam was investigated. It was observed that the oxide thickness at the crack tip tended to increase with decreasing cyclic loading frequency. The crack path was a mix of transgranular and intergranular fractures. According to the grain reference orientation deviation (GROD) maps, it was revealed that the density of geometrically necessary dislocations (GNDs) in the matrix along the crack path and ahead of crack tip increased with an increase in the fatigue crack growth rate (FCGR) due to environmental effects. It was observed that (1) mobile dislocations at the crack surface were blocked due to the thick oxide layer, resulting in an increase in the density of GNDs, and (2) an increase in the density of GNDs might induce stress concentration at the crack tip, deformation twinning, and the acceleration of FCGRs.

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