=Paper=
{{Paper
|id=Vol-2485/paper61
|storemode=property
|title=Visualizing the Process of Forming a Shock Pulse in the Deformation Zone
|pdfUrl=https://ceur-ws.org/Vol-2485/paper61.pdf
|volume=Vol-2485
|authors=Andrey Kirichek,Sergey Barinov,Maria Ryzhkova,Alexandr Yashin
}}
==Visualizing the Process of Forming a Shock Pulse in the Deformation Zone==
https://ceur-ws.org/Vol-2485/paper61.pdf
Visualizing the Process of Forming a Shock Pulse in the Deformation
Zone
A.V. Kirichek1, S.V. Barinov2, M.N. Ryzhkova2, A.V. Yashin2
avk@tu-bryansk.ru |box64@rambler.ru
1
BSTU, Bryansk, Russia;
2
VLSU, Vladimir, Russia
The article raises the problem of visualizing fleeting processes occurring as a result of wave strain hardening (WSH). The features
of this method are unique capabilities for controlling the parameters of the shock pulse. This allows, in contrast to other dynamic
methods of the surface plastic deformation, forming the desired microhardness distribution diagram in the surface layer at a depth of 6-
8 mm, while ensuring the required uniformity of hardening. The need to visualize this method is explained by the complexity of the
analytical description of the ongoing wave processes in the shock system and the loading medium. Developing a visualization technique
based on a model of the process of wave strain hardening consists of several stages. The stages include setting the initial and boundary
conditions of the simulated elements, their physical-mechanical properties, loading conditions, the type of the mesh, the process
conditions. The created model allows you to visually track the shock pulse movement after the striker hits the statically pressed
waveguide against the loading medium, and at the same time to see the generation of the reflected deformation wave (the tail of the
shock pulse) and its effect on the shock system elements and the loading medium. The results will make it possible to develop shock
systems with the highest efficiency.
Key words: finite element method, wave strain hardening , visualizing of simulation.
1. Introduction 2. Visualizing the formation of a shock pulse in
To improve the efficiency and reliability of machine parts in
the deformation zone
mechanical engineering technology, methods of surface plastic For visualizing fleeting shock processes (of the order of 10 -5
deformation (SPD) are successfully applied [6]. It is known that s), the finite element method has proven itself [8-10]. The tools
from an energetic point of view, the dynamic force during SPD of the modern engineering analysis are based on the principle of
is more advantageous than the static force, especially when this method. The leader in this area is the software package
forming a large hardening depth. At the same time, a significant Ansys.
drawback of dynamic (impact) methods is that the impact energy Developing a visualization technique, based on the model of
is spent on plastic deformation irrationally. This is due to the fact a shock pulse in a deformation zone, is divided into four stages
that, increasing the loading speed, the flow time of plastic in the process of wave strain hardening.
deformation decreases, therefore its value will depend not only At the first stage, in the Workbench section of the Ansys
on the impact force, i.e. the amplitude of the shock pulse, but also program, model elements are created in the graphics module: a
on its duration, which has not usually been considered before striker, a waveguide and loading medium. The striker and the
when hardening using SPD [1-2]. Accounting for this fact waveguide are rods with flat ends, and the loading medium has
became possible with the advent of wave strain hardening the form of a rectangle. Then they are positioned relative to each
(WSH). A feature of the method is generating deformation waves other, according to Figure 1. To significantly speed up the
by a shock system with an intermediate link and their calculation using the Split Body element, the model is cut along
communication to the deformation zone to strengthen critical the symmetry axis and only half of the model is left for
surfaces of machine parts. The method effectiveness is ensured calculation.
by a more complete use of the energy of the deformation wave in Then, in the Engineering Data module, models of the
the hardening process [3,4,7]. This is achieved due to preliminary materials of the shock system and the loading medium are
static preloading of the tool-waveguide system to the surface to created. The basis for this is the value of the physical-mechanical
be treated and subsequent dynamic loading by the striker. Static properties of real materials obtained as a result of the preliminary
preloading provides recovery of the reflected deformation waves. laboratory studies using the appropriate equipment. In the
As a result of processing, the depth of the hardened layer is 6-8 Symmetry Region section, the boundary of the model symmetry
mm, and the degree of hardening reaches 150% [5]. plane is indicated. The breakdown of the created model into finite
Since the WSH process has been developed quite recently, elements – tetrahedrons (triangular pyramids) is performed in the
most studies were carried out only experimentally. For Mesh section. There, the type of mesh is selected and its size is
comprehensive understanding of the WSH process, it is set. In the Contacts section, the type of Frictional contact
necessary to know in detail what occurs in the shock system after between model elements is set and the value of the coefficient of
striking the statically pressed waveguide against the loading friction is indicated. Using the Contact Tool, contact interactions
medium, how the deformation wave is formed, which affects the between model elements are generated.
energy transfer of the shock pulse. Solving these tasks is possible At the second stage, the Static Structural module sets the
only in combination, this is due to the fact that the factors under preliminary static compression of the loading medium by the
consideration are interconnected and affect each other. It is best waveguide. At the beginning, to limit the displacement of the
to visually evaluate the degree of influence of one or another loading medium under load, the boundary condition Fixed
factor on forming a shock pulse. Support is applied to its lower end. The boundary condition
The aim of this study is to develop a methodology for Displacement introduces a ban on moving the waveguide along
visualizing the process of wave strain hardening, based on the the Z axis, which avoids its displacement, under load, from the
model of forming a shock pulse in the deformation zone, using symmetry axis. To account for the effect of gravitational forces
the tools of the modern engineering analysis. on model elements, the Standard Earth Gravity module is added
to the calculation. To set the value of the static load, in the Force
section, the waveguide is assigned the value of the force of its
preloading to the loading medium measured in Newtons. The
Copyright © 2019 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
final setup of this stage is completed in the Analysis Settings
section by setting the duration of the static loading process.
1
2
Fig. 1. The scheme of the shock system:
1 – striker; 2- waveguide; 3- loading medium (sample).
At the third stage, the simulation of fleeting shock loading in
the LS-Dyna module takes place. As in the previous stage, the
model setup begins with assigning the boundary conditions:
Fixed Support is a ban on moving the lower end of the loading
medium and Displacement is a ban on displacing the striker and
waveguide relative to the symmetry axis. The effect of
gravitational forces on model elements is taken into account by 3
adding the Standard Earth Gravity module to the calculation. The
addition of the Dynamic Relaxation function is necessary to
consider in computing the effect of the preliminary static load on
the loading medium, calculated in the Static Structural module.
The action of the shock load of the striker is realized through the
speed in the Velocity section, which is more correct from the
energy point of view than the task given through the force
parameter. In the Analysis Settings section, the value of the End
Time parameter is configured. This parameter includes the sum
of the time of static loading, impact and unloading after the
impact.
At the fourth stage, in the Solution module, processing and
visualizing the simulation results takes place. The module allows 4
you to visualize in the model the actions of various types of
deformations, stresses, etc
The developed technique made it possible to visually assess
the propagation of the deformation wave in the shock system and
the loading medium in the case of a single striking. Visualizing
the shock pulse propagation in the elements of the model for a
time equal to the period of the shock pulse duration is shown in
Figure 2.
3. Conclusion
The developed visualization technique, based on the model
of shock pulse propagation, will allow you not only to identify
the features of its propagation in different types of shock systems,
but also to establish their types that will more fully transfer the
shock load to the loading medium. The data obtained on
propagating the shock pulse in the elements of the shock systems
and the loading medium will allow selecting more efficiently the
elements of the shock systems for specific hardening tasks.
4. Acknowledgments
The reported study was funded by RFBR according to the Fig. 2. Shock pulse:
research project No. 18-38-20066. 1 - rise front; 2 - period of the shock pulse action; 3- front
of recession; 4 - repeated action of the reflected shock pulse
(tail).
5. References
[1] Eremjants V.E., Niu V.V. Two-layer plate stress condition
under longitudional impact by tools resting on the plate //
Modern problems of theory of mashines. North Charleston.
GreateSpace 2016. № 4(1). P. 123–127.
[2] Eremyants V.E., Nju V.V. About selection of parameters of
hydraulic vibro-impact machines for surface cleaning // Journal
of Advanced Research in Technical Science. 2016. Issue 2. P.
20–24.
[3] Hustrulid W.A., Fairhurst C. A theoretical and experimental
study of the percussive drilling of rock // Intern. J. Rock Mech.
and Mining Sci., 1971, № 8. - P. 311-333.
[4] Hustrulid W.A., Fairhurst C. A theoretical and experimental
study of the percussive drilling of rock // Intern. J. Rock Mech.
and Mining Sci., 1972, № 9. - P. 335-356.
[5] Kirichek А.V., Barinov S.V., Aborkin A.V., Yashin А.V.,
Zaicev A.А. Strengthening of the surface layer of the material by
wave deformation multi-contact loading,
Materials Science and Engineering, 2017.
[6] Kirichek А.V., Barinov S.V., Yashin А.V., "Patterns of
Wave Deformational Multicontact Half-Subspace Loading", Key
Engineering Materials, Vol. 736, pp. 12-17, 2017. DOI
10.4028/www.scientific.net/KEM.736.12.
[7] Lundberg B. Some basic problems in percussive rock
destruction. - Geteborg, 1971.
[8] Mechanics of plastic deformation in metal processing /
Erich Gottfried Thomsen, Charles T. Yang, Shiro Kobayashi. –
1965. – 486 p.
[9] Shiro Kobayashi, Soo-Ik Oh, Taylan Altan, Metal Forming
And The Finite Element Method / New York: Oxford University
Press, 1989. ISBN: 0-19-504402-9. 377 p.
[10] Strang G. and Fix G. J., “An Analysis of the Finite Element
Method,” Prentice-Hall, Inc., Englewood Cliffs, 1973.