Interrelationship of the parameters controlling the boundaries of the area of self-simulating crack growth on the fatigue failure curve

1982 ◽  
Vol 18 (2) ◽  
pp. 166-171
Author(s):  
V. S. Ivanova ◽  
L. I. Maslov ◽  
S. A. Kunavin ◽  
M. Arita
Keyword(s):  
Crack Growth ◽  
Fatigue Failure ◽  
Failure Curve

Fatigue

2020 ◽  
pp. 529-546
Author(s):  
Lallit Anand ◽  
Sanjay Govindjee
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Failure Analysis ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Miner’S Rule ◽  
Miner's Rule ◽  
Repeated Loads

This chapter introduces methods for analysing fatigue failure of materials under repeated loads. The notions of defect-free and defect-tolerant failure analysis are discussed. For defect free analysis the notion of S-N curves is introduced and Coffin-Mason low cycle as well as Basquin high cycle relations are discussed. Miner’s rule is also introduced. For a defect-tolerant approach Paris’s law for fatigue crack growth is presented.

scholarly journals Characterization and Quantitative Analysis of Crack Precursor Size for Rubber Composites

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3442 ◽  
Author(s):  
Hao Guo ◽  
Fanzhu Li ◽  
Shipeng Wen ◽  
Haibo Yang ◽  
Liqun Zhang
Keyword(s):  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Theoretical Formula ◽  
Uniaxial Tensile ◽  
Rubber Composites ◽  
Economic Output ◽  
Average Size ◽  
Crack Growth Model

In the field of engineering, the annual economic loss caused by material fatigue failure reaches 4% of the total economic output. The deep understanding of rubber fatigue failure can help develop and prepare rubber composites with high durability. The crack precursor sizes within the rubber composites are vital for the material mechanical and fatigue properties. In this study, we adopted three different characterization methods to analyze crack precursor sizes and their distribution. First, based on the theoretical formula of fracture mechanics, the size of the crack precursor was deduced from 180 μm to 500 μm by the uniaxial tensile experiment combined with tear test (nicked angle tear, planar tear and trouser tear). Second, by combining the uniaxial fatigue test of dumbbell specimen with the fatigue crack growth rate test, the average size of the crack precursor was calculated as 3.3 μm based on the Thomas fatigue crack growth model. Third, the average size of the crack precursor was 3.6 μm obtained by scanning electron microscope. Through theoretical calculations and experimental tests, the size and distribution of the crack precursors of rubber composites were systematically presented. This work can provide theoretical guidance for the improvement of fatigue performance of rubber composites.

A Theory for Fatigue Failure under Multiaxial Stress-Strain Conditions

1973 ◽  
Vol 187 (1) ◽  
pp. 745-755 ◽  
Author(s):  
M. W. Brown ◽  
K. J. Miller
Keyword(s):  
Experimental Data ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Physical Interpretation ◽  
Tensile Strain ◽  
Multiaxial Fatigue ◽  
Fatigue Data ◽  
Principal Strains

A new theory for multiaxial fatigue is presented that is based on a physical interpretation of the mechanisms of fatigue crack growth. It may be represented graphically by contours of constant life, which are expressed mathematically by where ε1, ε2 and ε3 are the principal strains, •ε1 ≥ ε2 ≥ ε3. This equation underlines the importance of strain parameters in correlating fatigue data. It illustrates the effect of both the shear strain and the tensile strain normal to the plane of maximum shear. The theory is compared with several classical and recent theories, which are briefly reviewed. It is shown that classical theories of fatigue failure cannot correlate experimental data, and may be dangerous if used for design purposes.

A Theory for Fatigue Failure under Multiaxial Stress-Strain Conditions

1973 ◽  
Vol 187 (1) ◽  
pp. 745-755 ◽  
Author(s):  
M. W. Brown ◽  
K. J. Miller
Keyword(s):  
Experimental Data ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Physical Interpretation ◽  
Tensile Strain ◽  
Multiaxial Fatigue ◽  
Fatigue Data ◽  
Principal Strains

A new theory for multiaxial fatigue is presented that is based on a physical interpretation of the mechanisms of fatigue crack growth. It may be represented graphically by contours of constant life, which are expressed mathematically by where ε1, ε2 and ε3 are the principal strains, •ε1 ≥ ε2 ≥ ε3. This equation underlines the importance of strain parameters in correlating fatigue data. It illustrates the effect of both the shear strain and the tensile strain normal to the plane of maximum shear. The theory is compared with several classical and recent theories, which are briefly reviewed. It is shown that classical theories of fatigue failure cannot correlate experimental data, and may be dangerous if used for design purposes.

scholarly journals Fatigue Life Assessment of Refill Friction Stir Spot Welded Alclad 7075-T6 Aluminium Alloy Joints

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 633
Author(s):  
Andrzej Kubit ◽  
Mateusz Drabczyk ◽  
Tomasz Trzepiecinski ◽  
Wojciech Bochnowski ◽  
Ľuboš Kaščák ◽  
...  
Keyword(s):  
Fatigue Crack ◽  
Aluminium Alloy ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Spot Welding ◽  
Lap Joints ◽  
Life Assessment ◽  
Loading Conditions ◽  
Friction Stir ◽  
Lap Shear

Refill Friction Stir Spot Welding (RFSSW) shows great potential to be a replacement for single-lap joining techniques such as riveting or resistance spot welding used in the aircraft industry. In this paper, the fatigue behaviour of RFSSW single-lap joints is analysed experimentally in lap-shear specimens of Alclad 7075-T6 aluminium alloy with different thicknesses, i.e., 0.8 mm and 1.6 mm. The joints were tested under low-cycle and high-cycle fatigue tests. Detailed observations of the fatigue fracture characteristics were conducted using a scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The locations of fatigue failure across the weld, fatigue crack initiation, and propagation behaviour are discussed on the basis of the SEM analysis. The possibility of predicting the propagation of fatigue cracks in RFSSW joints is verified based on Paris’s law. Two fatigue failure modes are observed at different load levels, including shear fracture mode transverse crack growth at high stress-loading conditions and at low load levels, and destruction of the lower sheet due to stretching as a result of low stress-loading conditions. The analysis of SEM micrographs revealed that the presence of aluminium oxides aggravates the inhomogeneity of the material in the weld nugget around its periphery and is a source of crack nucleation. The results of the fatigue crack growth rate predicted by Paris’s law were in good agreement with the experimental results.

Effect of Load Ratio on Fatigue Failure Micromechanisms of Railway Axle Steel

2015 ◽  
Vol 770 ◽  
pp. 209-215
Author(s):  
Pavlo Maruschak ◽  
Andriy Sorochak ◽  
Sergey V. Panin
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Fatigue Crack Growth ◽  
Intensity Factor ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Stress Ratio ◽  
Load Ratio ◽  
Railway Axle

The paper presents the basic regularities of fatigue failure of the railway wheelset axle material – OsL steel (C - 0,40—0,48 %; Mn - 0,55—0,85 %; Si - 0,15—0,35 %; P < 0,04%; S < 0,045 %; Cr < 0,3 %; Ni < 0,3 %; Cu < 0,25 %). It was revealed that under loading stress ratio R = 0, fatigue crack growth is 2 ... 4 times lower than that at the asymmetry R = -1. In doing so, amplitude of stress intensity factor vary in the range of 20 – 35 MPa√m. The micromechanisms of fatigue crack growth are described and systematized, while physical-mechanical interpretations of the relief morphology at different stages of its growth are offered.

Two-parameter mechanistic model for the fatigue crack growth of metals

2019 ◽  
Vol 12 (2) ◽  
Author(s):  
Tawqeer Zada
Keyword(s):  
Experimental Data ◽  
Fatigue Crack ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Fatigue Failure ◽  
Mechanistic Model ◽  
Model Development ◽  
Two Parameters ◽  
Crack Growth Model ◽  
Two Parameter

In this paper, a two-parameter mechanistic model for the fatigue crack growth has been developed. Fatigue failure is the major causes of mechanical structural failure. The fatigue failure progress in three stages crack initiation, crack growth and final failure. The fatigue crack growth has been modelled by different approaches, however these approaches are generally empirical. In this paper, a mechanistic fatigue crack growth model is proposed. The striation and its relation to the cyclic load is used for the model development. Scanning electronic microscope results are used to establish relation between striation and crack growth. The developed model is two-parameters. The model has been implemented and validated using experimental data from the literature. The model prediction is satisfactory in region II of the crack growth curve. However, in region I and region III the model deviates from experimental data. It is suggested to incorporate interaction of monotonic and cyclic loading in the mechanistic modelling for the fatigue growth.

Predicting Catastrophic OD Initiated Fatigue Failure of Thick-Walled Cylinders Using Low Cycle Fatigue Data

1983 ◽  
Vol 22 ◽  
Author(s):  
Joseph A. Kapp
Keyword(s):  
Crack Growth ◽  
Fatigue Failure ◽  
Low Cycle Fatigue ◽  
Cycle Fatigue ◽  
Analysis Method ◽  
Life Data ◽  
Fatigue Data ◽  
Concentration Factors ◽  
Crack Initiation Life ◽  
Stress Concentration Factors

ABSTRACTA procedure is presented to predict fatigue failure of thick-walled cylinders containing discontinuities at the OD. Both crack initiation life and crack growth are considered. The elastic-plastic strains at an OD discontinuity are estimated using an elastic analysis and stress concentration factors. The strain estimates are then used in conjunction with low cycle fatigue data to determine the initiation life. Crack growth life is estimated by integration of a power law relationship. The results obtained by using this analysis method compared to measured fatigue life data for several OD initiated failures in thick-walled cylinders agrees to within about 10 percent.

Crack Initiation and Propagation in Model Cord-Rubber Composites

1989 ◽  
Vol 62 (4) ◽  
pp. 709-731 ◽  
Author(s):  
Y. S. Huang ◽  
O. H. Yeoh
Keyword(s):  
Crack Growth ◽  
Fatigue Failure ◽  
Pure Shear ◽  
Strain Energy Release ◽  
Growth Characteristics ◽  
Approximate Theory ◽  
Rubber Composites ◽  
Basic Premise ◽  
Test Pieces ◽  
Tearing Energy

Abstract The present study suggests that the development of penny-shaped cracks at cord ends is the first stage of fatigue failure of cord-rubber composites. An approximate theory for calculating the strain-energy release rate (tearing energy) for the propagation of penny-shaped cracks and predicting the life of model composites has been outlined. The basic premise of this theory is that the rate of propagation of these penny-shaped cracks is governed by the usual crack-growth characteristics of rubber vulcanizates customarily determined using simple test pieces such as the pure-shear test piece. Fatigue studies on two model composites show experiment and theory to be in semiquantitative agreement. Breidenbach and Lake have already established the relationship between the crack-growth characteristics of the rubber material to interply crack propagation, a later stage in the fatigue failure of cord-rubber composites. Therefore, it is clear that the crack-growth characteristics are an important screening criterion for compound development aimed at improving the life of cord-rubber composites.

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