The Mises Stress in the Contact Region of Materials with Soft
and Hard Phases in Frictional Process
M Wang
1,2
, S C Yang
1, *
and G L Lu
2
1
Engineering College, Changchun Normal University, Changchun 130032, China
2
Key Laboratory for Bionic Engineering (Ministry of Education), Jilin University,
Changchun 130022, China
Abstract. Composite polymers are a class of materials that have demonstrated superior
performance in various applications and thus been widely used in many industries. By
mimicking the soft and hard structure in natural materials, a kind of materials with soft and
hard phases based on flexible rubber /high rigidity ABS has been designed. In this paper, the
numerical simulation of frictional process of materials with soft and hard phases was
performed to analyse the Mises stress state in
the contact region. The results show that hard
phase support more load than soft phase, thus influence the frictional property of materials
with soft and hard phases.
1. Introduction
Natural materials such as nacre, bone or dentin, are biological composites in which soft and hard
element arranged in series, and provide a range of interesting properties, such as prevention of crack
propagation, flexibility and protection for biological armors, and even strain enhancement and signal
filtering for mechanosensing. Brick and mortar structure has been proposed[1] in 2000 to describe
materials such as nacre or the mineralized collagen fibril.[2] Such soft and hard structures exist at all
scales in natural materials,[3] can afford a mechanical performance better than each of soft or hard
element, and have huge potential capacity to enhance the mechanical performance of conventional
pure or simple materials.[4] Since the 1980s, Ren et al. [5, 6] has been dedicating to the study of the
cuticle morphologies and principles of soil animals such as dung beetles, black ants, and pangolins
and found that there were generally five kinds of simple structures on the cuticles, including convex,
concave, stria, bristle and squama. They are called non-smooth construction units, which have been
found to provide excellent anti-wear properties against soil. In this paper, the frictional process of the
materials with soft and hard phases was studied with a finite element analysis tool, and the Mises
stress state in the contact region was studied to analyze the frictional property of materials with soft
and hard phases.
2. Finite element model
To understand the frictional process of materials with soft and hard phases deeply, numerical
simulation of frictional process of materials with soft and hard phases was performed under
ABAQUS/Explicit environment. The finite element model of frictional process is shown in Figure 1.
Wang, M., Yang, S. and Lu, G.
The Mises Stress in the Contact Region of Materials with Soft and Hard Phases in Frictional Process.
In Proceedings of the International Workshop on Materials, Chemistry and Engineering (IWMCE 2018), pages 681-684
ISBN: 978-989-758-346-9
Copyright © 2018 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
681

The dimension of the material is 6 mm × 5 mm with the thickness 5 mm, and the material was
meshed by C3D8R element which is designed for large strains and deformations. The size of the
element is 0.01 mm × 0.01 mm × 0.01 mm, and a total of 152001 elements were used to model the
material.
Table 1. Material properties of soft phase and hard phase.
E (MPa)
μ
f
Soft material 270 0.4 0.1
Hard material 700 0.4 0.2
To simulate the friction boundary conditions between the material and the rubbing, surface-to-
surface contact mode was used, the friction coefficients (f) were 0.1 for soft phase and 0.2 for hard
phase, the Young’s model (E) is 270 MPa and 700 MPa for soft phase and hard phase respectively,
and the Poisson ratio for both soft and hard phases are 0.4. The material properties of the soft phase
and hard phase are listed in Table 1.
Figure 1. Numerical simulation of frictional process.
3. Results
The frictional process for materials with soft and hard phases is more complicated than the material
with only hard or soft material. The materials with integrated hard and soft phases will lead to the
redistribution of the loads, and change the frictional property of the material. Figure 2a shows the
contact region of materials with soft and hard phases in frictional process, in which blue is for hard
region and yellow for soft region. It can be found in figure 2b that the Mises stress in the contact
region is larger than the other region, and the Mises stress is large in the region with hard phase (blue
Soft phase
Hard phase
Rubbing
IWMCE 2018 - International Workshop on Materials, Chemistry and Engineering
682

region) and small in the region with soft phase (yellow region). This phenomenon shows the
redistribution of load, the hard phase support more load than soft phase, thus influence the frictional
property of the material with soft and hard phases.
Figure 2. Contact region of materials with soft and hard phases in frictional process.
4. Conclusions
Soft and hard structure which contains polymers with hardness differential can afford a mechanical
performance better than each of the composing polymers. The contact region of materials with soft
and hard phases in frictional process was present in this paper. It is obvious that the more load is
applied in the hard phase than the soft phase, and the redistribution of the load will influence the
contact state of two contact surface, thus change the frictional property of the materials with soft and
hard phases.
Acknowledgement
The authors would like to acknowledge the financial support provided by the National
Natural Science Foundation of China (Grant No. 51605187,Grant No.51605188),
Department of Education of Jilin Province (Grant No. JJKH20181163KJ, Grant No.
Contact region
h
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s
1
s
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s
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h
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s
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(a)
(b)
The Mises Stress in the Contact Region of Materials with Soft and Hard Phases in Frictional Process
683

JJKH20180093KJ), Jilin Provincial Science & Technology Department (Grant No.
20180201004GX), China Post Doctoral Science Foundation (Grant No. 2016M601382).
References
[1] Jäger I and Fratzl P 2000 Mineralized collagen fibrils: a mechanical model with a staggered
arrangement of mineral particles Biophysical Journal 79 1737-46
[2] Gao H, Ji B, Jager IL, Arzt E and Fratzl P 2003 Materials become insensitive to flaws at
nanoscale: lessons from nature Proceedings of the National Academy of Sciences of the
United States of America 100 5597-600
[3] Browning A, Ortiz C and Boyce M C 2013 Mechanics of composite elasmoid fish scale
assemblies and their bioinspired analogues Journal of the Mechanical Behavior of
Biomedical Materials 19 75-86
[4] Fratzl P, Kolednik O, Fischer F D and Dean M N 2015 The mechanics of tessellations -
bioinspired strategies for fracture resistance Chemical Society Reviews
[5] Ren L, Deng S, Wang J and Han Z 2004 Design Principles of the Non-smooth Surface of
Bionic Plow Moldboard Journal of Bionic Engineering 1 9-19
[6] Zhang Z H, Zhou H, Ren L Q and Tong X 2007 Tensile property of H13 die steel with convex-
shaped biomimetic surface Applied Surface Science 253 8939-44
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