Research Article
Numerical Simulation of Mixed-Mode Fatigue Crack Growth for
Compact Tension Shear Specimen
Yahya Ali Fageehi and Abdulnaser M. Alshoaibi
Department of Mechanical Engineering, Jazan University, P. O. Box 706, Jazan 45142, Saudi Arabia
Correspondence should be addressed to Abdulnaser M. Alshoaibi; alshoaibi@gmail.com
Received 30 January 2020; Revised 3 March 2020; Accepted 20 March 2020; Published 23 April 2020
Academic Editor: Davide Palumbo
Copyright © 2020 Yahya Ali Fageehi and Abdulnaser M. Alshoaibi. is is an open access article distributed under the Creative
Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the
original work is properly cited.
is work concentrates on the fracture behaviour of the compact tension specimen under mixed-mode loading, and numerical
investigation using ANSYS Mechanical APDL 19.2 finite element program with different modes of mix angles is carried out. e
prediction of mixed-mode fatigue life under constant amplitude fatigue loading for the compact tension shear specimen (CTS) is
employed using Paris’ law model for two different loading angles with agreement to the experimental results. e predicted values
of ΔK
eq
were compared with the experimental and analytical data for various models. Depending on the analysis, the findings of
the present study show consistency with the results achieved with similar models of predicting the equivalent stress intensity
factor. In addition, the direction of crack growth derived from the analysis was observed to follow the same trend of the literature
experimental results.
1. Introduction
is work describes the use of ANSYS Mechanical APDL
19.2 finite element program in crack analysis of the engi-
neering structures containing discontinuities and holes. In
the proposed study of the cracks throughout elastic mate-
rials, linear elastic fracture mechanics are employed where
the crack driving force called stress intensity factor (SIF) is
used as a measure of fracture associated with the materials
threshold SIFs (K
th
) for dynamic loading. e accuracy of a
crack propagation simulation depends highly on the accu-
racy achieved for the calculated SIFs. Engineering structures
are generally used under periodic and cyclic loading con-
ditions [1] [2–7] [6]. e periodic as well as cyclic loading
decreases the load limit required to initiate deformation in
the material under static loading and results in progressive
fracture leading to catastrophic failures of the material
known as fatigue failures [6]. It has been estimated that 60%
to 80% of the failures of mechanical components are as-
sociated with fatigue [8]. Various problems concerning
fatigue crack growth can be found in the literature using
different approaches for simple and complex geometries in
two and three dimensions [9–13]. Combined action of
tensile stress, cyclic stress, and plastic strain initiates failure
due to fatigue phenomena. If any of these three does not
exist, it will not trigger and spread a fatigue crack growth
[14]. As environmental loads are also multidirectional in
nature, the fatigue cracks may propagate under mixed-mode
conditions [15–18]. e majority of failures in service is of
mixed-mode type, where the cracks do not propagate in the
direction normal to the applied load. However, the majority
of fatigue crack growth behavior studies focus on mode I
cracks, whereas the cracks and defects in actual engineering
components (e.g., pressure vessels, pipelines, and fan blades)
tend to be plane-stress mixed-modes I–II cracks [19]. In
reality also mixed mode can be observed, for example, in
turbine shafts or railway tracks by a sudden change of the
loading direction. e crack will initiate due to the plastic
strain occasioning from the cyclic stress, whereas the
propagation steps of the cracks result from the tensile stress.
Furthermore, the cause of local tensile stresses happens to be
the fact that compressive loads may not lead to the initiation
of fatigue crack [20]. To prevent failure due to fatigue, ex-
tensive research has been performed to get developed and
Hindawi
Advances in Materials Science and Engineering
Volume 2020, Article ID 5426831, 14 pages
https://doi.org/10.1155/2020/5426831