Analytical Prediction Model for Fatigue Crack Propagation Rate under Tension-Compression Loading

2013 ◽  
Vol 842 ◽  
pp. 455-461
Author(s):  
Yu Sha ◽  
Shi Gang Bai ◽  
Ya Hui Wang
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Plastic Zone ◽  
Crack Propagation ◽  
Compressive Stress ◽  
Fatigue Crack Propagation ◽  
Crack Tip ◽  
Plastic Zone Size ◽  
Zone Size ◽  
Compression Loading

Elastic–plastic finite element analyses have been performed to study the compressive stress effect on fatigue crack growth under applied tension–compression loading. The near crack tip stress, crack tip opening displacement and crack tip plastic zone size were obtained for a kinematic hardening material. The results have shown that the near crack tip local stress, displacement and reverse plastic zone size are controlled by the maximum stress intensity factors Kmax and the applied compressive stress σmaxcom under tension–compression. Based on the finite element analysis results, a fatigue crack propagation model using Kmax and σmaxcom as a parameters under tension–compression loading has been developed.The models under tension–compression loading agreed well with experimental observations.

scholarly journals The Variation Law of Mechanical Parameters of Type I Fatigue Crack Tip Under High Frequency Resonant Loading

2015 ◽  
Vol 9 (1) ◽  
pp. 379-387
Author(s):  
Gao Hong-Li ◽  
Zheng Huan-Bin ◽  
Qiu Xin-Guo ◽  
Liu Huan ◽  
Liu Hui
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
High Frequency ◽  
Crack Tip ◽  
Type I ◽  
Mechanical Parameters ◽  
Stress Cycle ◽  
Fatigue Crack Propagation Test

This work explores the variation law of mechanical parameters at fatigue crack tip of compact tension specimen with type I pre-notch based on dynamic finite element method (FEM) in the high frequency resonant fatigue crack propagation test. The displacement fields, the strain fields and the stress intensity factors (SIF) at CT specimen fatigue crack tip in one stress cycle and at different crack lengths under constant amplitude high frequency sinusoidal alternating loading condition are calculated and the related variation laws of mechanical parameters are analyzed. In order to calculate the dynamic SIF at fatigue crack tip, the static SIF has been calculated first. The compared results of the static finite element analysis with the theoretical calculation show that finite element modeling and calculating method and respective results are accurate. Secondly, the variation law of SIF at crack tip during the process of fatigue crack propagation test is studied by dynamic FEM. Finally, the high frequency resonant fatigue crack propagation test has been performed and the dynamic strain gauge is used to measure the strain at crack tip during one stress cycle. The research results show that during crack stable propagation stage, the displacement, strain and SIF at type I fatigue crack tip are in the same form having high frequency resonant load, and the displacement, strain and SIF amplitude increase with the crack growth. The error of static SIF between the calculated result by FEM and the theoretical result is 2.51%. The maximum error of the strain at crack tip between the FEM calculating result and the experimental result is 2.93%.

A Study on the Relationship between Fatigue Crack Opening Behavior and Reversed Plastic Zone Size

2005 ◽  
Vol 297-300 ◽  
pp. 66-71 ◽  
Author(s):  
Hyeon Chang Choi
Keyword(s):  
Finite Element Analysis ◽  
Fatigue Crack ◽  
Plastic Zone ◽  
Crack Opening ◽  
Crack Tip ◽  
Plastic Zone Size ◽  
Zone Size ◽  
Element Analysis ◽  
Element Size ◽  
The Relationship

A relationship between fatigue crack opening behavior and the reversed plastic zone size is studied. An elastic-plastic finite element analysis (FEA) is performed to examine the opening behavior of fatigue crack. The contact elements in this analysis are adopted in the mesh of the crack tip area. The smaller element size than reversed plastic zone size is used for evaluating the distribution of reversed plastic zone. In the author’s previous results, the FEA could predict the crack opening level, which the size of crack tip elements was in proportion to the theoretical reversed plastic zone size. It is found that the calculated reversed plastic zone size is related to the theoretical reversed plastic zone size and crack opening level. The calculated reversed plastic zone sizes are almost equal to the reversed plastic zone size considering crack opening level obtained by experimental results. It is possible to predict the crack opening level from the reversed plastic zone size calculated by the FEA. We find that the experimental crack opening levels correspond with the opening values of crack tip contact nodes on the calculated reversed plastic zone.

scholarly journals Quantitative measurement of plastic strain field at a fatigue crack tip

2012 ◽  
Vol 468 (2144) ◽  
pp. 2399-2415 ◽  
Author(s):  
Y. Yang ◽  
M. Crimp ◽  
R. A. Tomlinson ◽  
E. A. Patterson
Keyword(s):  
Fatigue Crack ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Strain Distribution ◽  
Pure Titanium ◽  
Crack Tip ◽  
Plastic Zone Size ◽  
Uniaxial Tensile ◽  
Commercially Pure Titanium ◽  
Zone Size

A novel approach is introduced to map the mesoscale plastic strain distribution resulting from heterogeneous plastic deformation in complex loading and component geometries, by applying the discrete Fourier transform (DFT) to backscattered electron (BSE) images of polycrystalline patches. These DFTs are then calibrated against the full width at half the maximum of the central peak of the DFTs collected from the same material tested under in situ scanning electron microscopy uniaxial tensile conditions, which indicates a close relationship with the global tensile strain. In this work, the technique is demonstrated by measuring the residual strain distribution and plastic zone size around a fatigue crack tip in a commercially pure titanium compact tension specimen, by collecting BSE images in a 15×15 array of 115 μm square images around the fatigue crack tip. The measurement results show good agreement with the plastic zone size and shape measured using thermoelastic stress analysis.

Finite Element Analysis of the Effect of the Compressive Loading on Fatigue Crack Growth under Different Loading

2009 ◽  
Vol 16-19 ◽  
pp. 269-272 ◽  
Author(s):  
Yu Sha ◽  
Hui Tang ◽  
Xin Song ◽  
Jia Zhen Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fatigue Crack ◽  
Compressive Stress ◽  
Compressive Loading ◽  
Crack Tip ◽  
High Strength ◽  
Stress Cycle ◽  
Element Analysis ◽  
Compression Loading

In this paper, elastic-plastic finite element analysis has been performed in order to obtain the fatigue crack tip parameters under tension-compression loading. Two centre-cracked high-strength aluminum alloy with a crack length of 2mm under different tension-compression loading are analyzed. The analysis shows that the compressive loading has a significant contribution towards the crack tip plasticity and the crack tip stress. In a tension-compression loading the crack tip displacement increases with the increase of the compressive stress and the crack tip compress stress increases with the increase of the compressive stress. The maximum stress intensity Kmax in the tension part of the stress cycle and the maximum compressive stress in the compression part of the stress cycle are the main factors controlling the near crack tip parameters.

Influence of compressive plastic zone at the crack tip upon fatigue crack propagation

2008 ◽  
Vol 30 (1) ◽  
pp. 67-73 ◽  
Author(s):  
Y XIONG ◽  
X HU ◽  
J KATSUTA ◽  
T SAKIYAMA ◽  
K KAWANO
Keyword(s):  
Fatigue Crack ◽  
Plastic Zone ◽  
Crack Propagation ◽  
Fatigue Crack Propagation ◽  
Crack Tip
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