Growth of the Shell/Transverse Defect in Rails

1989 ◽  
Vol 111 (4) ◽  
pp. 648-654 ◽  
Author(s):  
Maria Min-Hui Yu ◽  
L. M. Keer
Keyword(s):  
Fatigue Life ◽  
General Solution ◽  
Residual Stresses ◽  
Mixed Mode ◽  
Approximate Analysis ◽  
Stress Distributions ◽  
Mixed Mode Loading ◽  
Subsurface Crack ◽  
Defect Growth ◽  
Transverse Defect

An approximate analysis of the shell/transverse defect growth in steel rails during use is presented. A general solution for a single subsurface crack is presented first. A simpler approach, which considers the transverse defect alone, is examined as well. Residual stresses are included by introducing their stress distributions mechanically. A proposed mixed-mode loading growth law is used for fatigue life calculations and the crack length versus life curves are obtained. The life of the shell/transverse defect is found to be much shorter than that of the single transverse defect.

Low Cycle Fatigue Testing of Ball Grid Array Solder Joints under Mixed-Mode Loading Conditions

2004 ◽  
Vol 127 (3) ◽  
pp. 237-244 ◽  
Author(s):  
Tae-Sang Park ◽  
Soon-Bok Lee
Keyword(s):  
Fatigue Life ◽  
Mixed Mode ◽  
Room Temperature ◽  
Solder Joints ◽  
Low Cycle Fatigue ◽  
Ball Grid Array ◽  
Fatigue Tests ◽  
Test Method ◽  
Cycle Fatigue ◽  
Mixed Mode Loading

To give a proper and accurate estimation of the fatigue life of ball grid array (BGA) solder joints, a mechanical fatigue test method under mixed-mode loading is proposed. Experiments were conducted with 63Sn∕37Pb and Sn∕3.5Ag∕0.75Cu solder joints in room temperature. The mechanical low cycle fatigue tests were performed under several loading angles. The loading angle is controlled by several grips which have specific surface angle to the loading direction. Constant displacement controlled tests are performed using a micro-mechanical test apparatus. It was found that the normal deformation significantly affects the fatigue life of the solder joint. Throughout the whole test conditions at room temperature, Sn∕3.5Ag∕0.75Cu solder alloy had longer fatigue life than 63Sn∕37Pb alloy. Failure patterns of the fatigue tests were observed and discussed. A morrow energy model was examined and found to be a proper low cycle fatigue model for solder joints under mixed mode loading condition.

scholarly journals Adaptive Finite Element Prediction of Fatigue Life and Crack Path in 2D Structural Components

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1316
Author(s):  
Abdullateef H. Bashiri ◽  
Abdulnaser M. Alshoaibi
Keyword(s):  
Finite Element ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Crack Propagation ◽  
Crack Growth ◽  
Mixed Mode ◽  
Equivalent Stress ◽  
Circumferential Stress ◽  
Mixed Mode Loading ◽  
Linear Elastic

The existence of a hole near a growing fatigue crack can cause the crack trajectory to deviate. Unless the hole is too close to the crack, the crack is arrested at the edge of the hole and does not progress further. The purpose of this paper was to predict the crack propagation and lifetime of two-dimension geometries for linear elastic materials in mixed-mode loading using a finite element source code program written in Visual Fortran language. The finite element mesh is generated using the advancing front method. The onset criterion of crack propagation was based on the equivalent stress intensity factor which provides the most important parameter that must be accurately estimated for the mixed-mode loading condition. The maximum circumferential stress theory was used as a direction criterion. The modified compact tension (MCTS) was studied to demonstrate the influence of the hole’s presence on the direction of crack growth and fatigue life for different configurations. The Paris’ law model has been employed to evaluate the mixed-mode fatigue life for MCTS in different configurations under the linear elastic fracture mechanics (LEFMs) assumption. The framework involves a progressive crack extension study of stress intensity factors (SIFs), crack growth direction, and fatigue life estimation. The results show that the fatigue growth was attracted to the hole either changes its direction to reach the hole or floats by the hole and grows as the hole is missed. The results of the study agree with several crack propagation experiments in the literature revealing similar crack propagation trajectory observations.

scholarly journals The effect of residual stresses on the fracture behaviour of a cracked body under mixed mode loading

2011 ◽  
Vol 10 ◽  
pp. 3273-3278
Author(s):  
K. Sedighian ◽  
J. Mosayebnejac ◽  
H. Zakerhaghighi ◽  
H. Ehsasi
Keyword(s):  
Residual Stresses ◽  
Mixed Mode ◽  
Fracture Behaviour ◽  
Mixed Mode Loading

scholarly journals Asymptotic stress fields in the vicinity of the crack in perfectly plastic solids under mixed mode loading

2020 ◽  
pp. 73-89
Author(s):  
L. V Stepanova
Keyword(s):  
Asymptotic Solution ◽  
Plane Strain ◽  
Plane Stress ◽  
Mixed Mode ◽  
Full Range ◽  
Stress Conditions ◽  
Pure Mode ◽  
Stress Distributions ◽  
Mixed Mode Loading ◽  
Perfectly Plastic

In the paper presents the asymptotic stress fields in the vicinity of the crack tip in perfectly plastic Mises materials under mixed mode loading for a full range of the mode mixities. This objective is engendered by the necessity of considering all the values of the mixity parameter for the full range of the mode mixities both for plane strain and plane stress conditions to grasp stress tensor components behaviour in the vicinity of the crack tip as the mixity parameter is changing from 0 to 1. To gain a better understanding of the stress distributions, all values of the mixity parameter within 0.1 were considered and analyzed. The asymptotic solution to the statically determinate problem is obtained using the eigenfunction expansion method. Steady - state stress distributions for the full range of the mode mixities are found. The type of the mixed mode loading is controlled by the mixity parameter changing from zero for pure mode II loading to 1 for pure mode I loading. It is shown that the analytical solution is described by different relations in different sectors, the value of which is changing from 7 sectors to 5 sectors. At loadings close to pure mode II, seven sectors determine the solution whereas six and five sectors define the solution for the mixity parameter higher 0.33 and less than 0.89 and higher 0.89 respectively for plane strain conditions and seven sectors determine the asymptotic solution for the mixity parameter less than 0.39, while five sectors determine the solution for other values of the mixity parameter for plane stress conditions. The number of sectors depends on the mixity parameter. The angular stress distributions are not fully continuous and radial stresses are discontinuous for some values of the mixity parameter. It is interesting to note that the characteristic feature of the asymptotic solution obtained is the presence of a segment of values of the mixity parameter for which the solution does not depend on the mixity parameter (the solution does not depend on the mixity parameter for the mixity parameter from 0.89 to 1 and the solution coincides with the solution for mode I crack in perfect plastic materials for plane strain conditions). Thus, the salient point of the study is that the asymptotic solution is described by the same formulae for all values of the mixity parameter from 0.89 to 1 for plane strain. For plane stress conditions this segment can’t be observed. The solution in each sector corresponds to the certain value of the mixity parameter. The obtained solutions for plane strain and plane stress conditions can be considered as the limit solution for power law hardening materials and creeping power law materials.

scholarly journals Fatigue Crack Growth Analysis with Extended Finite Element for 3D Linear Elastic Material

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 397
Author(s):  
Yahya Ali Fageehi
Keyword(s):  
Finite Element ◽  
Fatigue Crack ◽  
Fatigue Life ◽  
Crack Propagation ◽  
Crack Growth ◽  
Mixed Mode ◽  
Propagation Path ◽  
Loading Conditions ◽  
Extended Finite Element ◽  
Linear Elastic

This paper presents computational modeling of a crack growth path under mixed-mode loadings in linear elastic materials and investigates the influence of a hole on both fatigue crack propagation and fatigue life when subjected to constant amplitude loading conditions. Though the crack propagation is inevitable, the simulation specified the crack propagation path such that the critical structure domain was not exceeded. ANSYS Mechanical APDL 19.2 was introduced with the aid of a new feature in ANSYS: Smart Crack growth technology. It predicts the propagation direction and subsequent fatigue life for structural components using the extended finite element method (XFEM). The Paris law model was used to evaluate the mixed-mode fatigue life for both a modified four-point bending beam and a cracked plate with three holes under the linear elastic fracture mechanics (LEFM) assumption. Precise estimates of the stress intensity factors (SIFs), the trajectory of crack growth, and the fatigue life by an incremental crack propagation analysis were recorded. The findings of this analysis are confirmed in published works in terms of crack propagation trajectories under mixed-mode loading conditions.

scholarly journals Selected Aspects of Cohesive Zone Modeling in Fracture Mechanics

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 302
Author(s):  
Wiktor Wciślik ◽  
Tadeusz Pała
Keyword(s):  
Cohesive Zone ◽  
Mixed Mode ◽  
Review Paper ◽  
Failure Process ◽  
Cohesive Zone Modeling ◽  
Mixed Mode Loading ◽  
Cohesive Models ◽  
Cohesive Modeling ◽  
Zone Modeling ◽  
Intensive Development

This review paper discusses the basic problems related to the use of cohesive models to simulate the initiation and development of failure in various types of engineering issues. The most commonly used cohesive zone models (CZMs) are described. Recent achievements in the field of cohesive modeling are characterized, with particular emphasis on the problem of mixed mode loading, the influence of the strain rate, the stress state triaxiality, and fatigue. A separate chapter of the work is devoted to the identification of cohesive parameters. Examples of the use of CZMs for the analysis of the fracture and failure process in various applications, both on the macro and microscopic scale, are given. The directions of CZMs development were indicated as well as the issues that are currently under particularly intensive development.

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