A note on the plastic zone size ahead of the propagating fatigue crack

1966 ◽  
Vol 2 (3) ◽  
Author(s):  
Takeo Yokobori ◽  
Masabumi Tnaka
Keyword(s):  
Fatigue Crack ◽  
Plastic Zone ◽  
Plastic Zone Size ◽  
Zone Size

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.

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.

Understanding Crack Tip Plasticity – a Multi-Experimental Approach

2011 ◽  
Vol 70 ◽  
pp. 153-158 ◽  
Author(s):  
Rachel A Tomlinson ◽  
Ying Du ◽  
Eann A Patterson
Keyword(s):  
Fatigue Crack ◽  
Plastic Zone ◽  
Experimental Approach ◽  
Crack Tip ◽  
Thermoelastic Stress ◽  
Plastic Zone Size ◽  
Image Correlation ◽  
Zone Size ◽  
Thermoelastic Stress Analysis ◽  
Crack Tip Plasticity

Crack tip plasticity has been investigated using thermoelastic stress analysis (TSA) and digital image correlation (DIC). The plastic zone size at the tip of a propagating fatigue crack was measured using both techniques. At longer crack lengths, the results compared well with Dugdale’s and Irwin’s models for crack tip yielding. The TSA methodology requires careful observation of the adiabatic assumption.

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