Citation: Han, J.; Wang, G.; Zhao, X.;
Chen, R.; Chen, W. Modeling of
Multiple Fatigue Cracks for the
Aircraft Wing Corner Box Based on
Non-ordinary State-based
Peridynamics. Metals 2022, 12, 1286.
https://doi.org/10.3390/
met12081286
Academic Editors: Alberto
Campagnolo and Alberto Sapora
Received: 26 June 2022
Accepted: 28 July 2022
Published: 30 July 2022
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Article
Modeling of Multiple Fatigue Cracks for the Aircraft Wing
Corner Box Based on Non-ordinary State-based Peridynamics
Junzhao Han
1
, Guozhong Wang
2
, Xiaoyu Zhao
3
, Rong Chen
1
and Wenhua Chen
1,
*
1
School of Mechanical Engineering and Automation, Zhejiang Sci-Tech University, Hangzhou 310018, China;
hanjz@zju.edu.cn (J.H.); rchen@zstu.edu.cn (R.C.)
2
Henghong Intelligent Equipment Co., Ltd., Hangzhou 310018, China; gzwang@hzjx.com.cn
3
China Ship Scientific Research Center, Wuxi 214028, China; zhxiyu123@126.com
* Correspondence: chenwh8@zju.edu.cn
Abstract:
In the current research, we propose a novel non-ordinary state-based peridynamics (PD)
fatigue model for multiple cracks’ initiation and growth under tension–tension fatigue load. In each
loading cycle, the fatigue loading is redistributed throughout the peridynamic solid body, leading
to progressive fatigue damage formation and expansion in an autonomous fashion. The proposed
fatigue model parameters are first verified by a 3D numerical solution, and then, the novel model is
used to depict the widespread fatigue damage evolution of the aircraft wing corner box. The modified
constitutive damage model has been implemented into the peridynamic framework. Furthermore,
the criteria and processes from multiple initiations to propagation are discussed in detail. It was
found that the computational results obtained from the PD fatigue model were consistent with those
from the test data. The angular errors of multiple cracks are within 2.66% and the number of cycles
errors are within 15%. A comparison of test data and computational results indicates that the fatigue
model can successfully capture multiple crack formations and propagation, and other behaviors of
aluminum alloy material.
Keywords:
non-ordinary state-based peridynamics; tension–tension fatigue load; multiple cracks;
aircraft wing corner box
1. Introduction
Extensive fatigue damage of aging aircraft structures has aroused widespread atten-
tion in the aerospace field. The prediction of the fatigue initiation and propagation of a
structure is complicated, tough work because of the uncertain loads and uncertainties in
material properties [
1
–
3
]. The fatigue damage law should be deduced to ensure flight safety
and to improve costs. After in-depth research, it was found that fatigue is the formation
and expansion of damage in a material under cyclic loads. Two stages can depict the whole
process based on the cumulative damage theory. The first stage is the crack formation, dur-
ing which damage nucleates in different locations of the material, and it can be impacted by
various mechanical, microstructural, and environmental factors
. The
second stage is crack
propagation, during which fatigue damage propagates stably until it exceeds the safety
margin, followed by rapid propagation that leads to catastrophic fracture
[4–7]. Therefore
,
the fatigue of metallic structures is a complex, irreversible process under repeated loading,
in which damage formation is controlled by the interaction of micro-cracks, trans-scale
effects on geometry and time, and unpredictable factors [
8
–
11
]. Vacancies are generated
when an atom or an ion is missing from its regular crystallographic site and new equi-
libriums are built. Under repeated loading, the new dynamic equilibriums are lost and
generate new balances, and fatigue damage initiates and accumulates naturally [
11
–
13
].
Therefore, the metal fatigue process includes complex submicroscopic and microscopic
damage propagation [
14
–
16
]
. The
fatigue life of metal structures under cyclic loading can
be accurately predicted from crack initiation to propagation, which is influenced by the
Metals 2022, 12, 1286. https://doi.org/10.3390/met12081286 https://www.mdpi.com/journal/metals
