PROCEEDINGS OF THE INSTITUTE OF VEHICLES
(12pt)
3(89)/2012
(12pt)
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2
Grzegorz Służałek , Marek Kubica , Mateusz Służałek
3
(12pt)
COMPUTER METHODS IN STUDY OF HISTORICAL ASSYRIANS CHARIOT
(12pt)
1. Introduction
Assyrian chariots are exceedingly short, but apparently, they must have been of a
considerable width. They contain two, three or even four persons. The warrior who
fights from a chariot is necessarily attended by his charioteer [1]. Today's technology
allows to recreate the battle chariot in the virtual CAD environment applications of the
ancient model, as well as completing the analysis of materials in terms of stress, strain
and displacement. In modern CAE programs engineering simulations could be
performed. To modelling the battle chariot used a reverse engineering (RE) technique
and computer image analysis (CIA).
2. Computer image analysis of the battle chariot
For better analyze and visualize detailed images of the battle chariot computer
image analysis (CIA) were done in the Met-Ilo and ImageJ applications. The computer
image analysis allowed to treatment images by reducing noise, enhance clarity of the
relevant factors. CIA was realized by using mathematical operations of gamma
correction process, adjust contrast and brightness, subtract background, enhance
contrast, the use of mean and median filters [2]. The images of Assyrian chariot before
[1] and after CIA are shown on the figure 1.
Fig. 1. Before and after CIA treatment
The 3D surface plot plugin was used (fig. 2.). This plugin creates interactive surface
plots from all kinds of image types. The luminance of each pixel in the image is
interpreted as the height for the plot. Selections, also non-rectangular, are supported. The
plot can be displayed in different color schemes: original colors, grayscale and different
LUT schemes. Scale, rotation, perspective and position can be adapted. Using a
smoothing option reduces noise. An adjustment of the lightning condition improves the
visibility of small differences.
Grzegorz Służałek, Ph.D., Assist. Prof., Department of Materials Science, Faculty of Computer and Materials
Science of University of Silesia
2
Marek Kubica, M.Sc., PhD student, the Faculty of Computer and Materials Science at University of Silesia
3
Mateusz Służałek,Student of University of Silesia
1
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a)
b)
Fig. 2. Showing interactive 3D Surface Plot: a) grayscale b) Thermal LUT
The surface plot supports four different drawing modes: dots, lines, meshes or a
filled surface [3]. The visualization process of 3D surface plot plug-in work is shown on
figure 3.
Fig. 3. Visualization process of the proposed 3D rendering scheme [3]
3. 3D model of the assyrian battle chariot
Autodesk Inventor software was used for the three-dimensional modeling and
rendering the virtual reconstruction of the battle chariot. This program is the Computer
Aided Design (CAD) tool for modeling in the 3D space, using solid model and surface
model. Inventor model is an accurate 3D digital prototype that enables to validate the
form, fit, and function of a design as you work, minimizing the need to test the design
with physical prototypes. By enabling to use a digital prototype to design, visualize, and
simulate models digitally, Inventor software helps communicate more effectively, reduce
errors, deliver more innovative product designs faster [4]. The screenshots while creating
the Assyrians battle chariot were showed on figures 4 and 5.
Fig. 4. The chosen elements of the battle chariot in CAD software
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Fig. 5. Wheals of the battle chariot
4. FEM analysis of the battle chariot
The finite element method (FEM) is a numerical technique for finding approximate
solutions of partial differential equations (PDE) as well as of integral equations. The
solution approach is based either on eliminating the differential equation completely
(steady state problems), or rendering the PDE into an approximating system of ordinary
differential equations, which are then numerically integrated using standard techniques
such as Euler's method, Runge-Kutta, etc. In a structural simulation, FEM helps
tremendously in producing stiffness and strength visualizations and also in minimizing
weight, materials and costs.
FEM allows detailed visualization of where structures bend or twist, and indicates
the distribution of stresses and displacements. FEM software provides a wide range of
simulation options for controlling the complexity of both modeling and analysis of a
system. FEM allows entire designs to be constructed, refined, and optimized before the
design is manufactured [5].
This powerful design tool has significantly improved both the standard of
engineering designs and the methodology of the design process in many industrial
applications. The introduction of FEM has substantially decreased the time to take
products from concept to the production line [6]. It is primarily through improved initial
prototype designs using FEM that testing and development have been accelerated. In
summary, benefits of FEM include increased accuracy, enhanced design and better
insight into critical design parameters, virtual prototyping, fewer hardware prototypes, a
faster and less expensive design cycle, increased productivity, and increased revenue
[7, 8].
a)
b)
Fig. 6. Boundary conditions: a) wheels torque, b) torque wheels and force of gravity
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Numerical analyses were carried out in Autodesk Inventor FEA integrated module.
Boundary conditions corresponding to the real were introduced to simulation. On the
axes of the vehicle assigned torque (Fig. 6a.), and geometry has been assigned to the
force of gravity (Fig. 6b. ).
On the figure 7 we can see position and the pressure of human feet (orange arrows),
force of gravity (red arrow) and torque wheels (yellow arrows).
a)
b)
Fig. 7. Battle chariot simulation: a) pressure of human feet, b) all of boundary conditions
The finite element mesh was applied on the modeled geometry consist of 119939
nodes and 70742 elements (fig. 8.). Local mesh control was made on the battle chariot
platform.
Fig. 8. The finite element mesh on the battle chariot geometry
Material properties presented in table 1 entered into the simulation. Analyses were
taken for a battle chariot made of different wood birch or oak.
Tab. 1. Material properties
Parameter
Density
Young's modulus
Poisson's ratio
Yield
Tensile strength
Material
Wood – birch
0.55 g/cm3
10.3 GPa
0.426
56.3 MPa
6.3 MPa
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Wood – oak
0.56 g/cm3
9.3 GPa
0.350
46.6 MPa
5.5 MPa
The results of stress simulation are shown on figures 9 and 10. The arrows shows
wheels torque, gravity load and feet load.
Fig. 9. Results of FEM stress simulation - top view.
Fig. 10. Results of FEM stress simulation
Fig. 11. Results of FEM displacement simulation
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Stress maps indicate the places most vulnerable to damage and wear. Maximum
stress occurred in the tested model in the place where the axis contacts with the chariot
chassis. The results showed that stress in the model, made of oak are slightly smaller.
The results of analysis of displacement have been presented on the figures 11 and
12. By applying displacement magnification in graphical presentation shows that it is
possible deformation of the axis of the battle chariot.
Fig. 12. Results of FEM displacement simulation
5. Rendering of the battle chariot
Real-Time 3D Photorealistic Rendering was realized after designing the model of
the battle chariot in the software Autodesk Showcase application. Rendering takes into
account real materials and realistic lighting and the surroundings of the model [9]. The
effects of the work of the application Showcase illustrate figures 13 and 14.
Fig. 13. The model of the battle chariot after rendering in Autodesk Showcase
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Fig. 14. The model of the battle chariot after rendering
6. Summary
The present technology of CAx was used in this work to bring closer questions from
the ancient history. The realization of the 3D model allows see as objects looked, often
well-known few and only in the two-dimension. Virtual models can be analyzed by
using finite element method (FEM) in modern CAE programs, and give the answer to
many engineering problems, for example, what material should be constructed in the
proposed design. Computer simulation shown concentration of stress in a model, and
location of displacement. With a computer model using rapid prototyping techniques one
can print it on the printer 3D as an element of the equipment of historical study or can be
the object of farther scientific investigations.
References:
[1]
Rawlinson G.: The Seven Great Monarchies of the Ancient Eastern World
Babylonia, Media and Persia, 2002, New York, J. W. Lovell.
[2]
Tadeusiewicz R., Korochoda P.: Komputerowa analiza i przetwarzanie obrazów,
1997, Kraków, FPT.
[3]
Kai Uwe Barthe: 3D-Data Representation with ImageJ, International Media and
Computing, Berlin, Germany, 2011.
[4]
http://images.autodesk.com/adsk/files/inventor_professional_detail_bro_us.pdf
[5]
http://en.wikipedia.org/wiki/Finite_element_method
[6]
Hastings, J., Juds, M., Brauer, J.: Accuracy and Economy of Finite Element
Magnetic Analysis, 33rd Annual National Relay Conference, April 1985.
[7]
McLaren-Mercedes: Vodafone McLaren-Mercedes: Feature-Stress to impress,
2006.
[8]
Służałek G., Kubica M., Bąkowski H.: Modelowanie zmiennych warunków
eksploatacji dla skojarzenia kostka-płytka z wykorzystaniem MES. Mechanik
nr 7, Warszawa, 2010.
[9]
Kubica M., Służałek G, Służałek M.: Metody komputerowe w badaniu
historycznego wozu bojowego. Logistyka 3, Poznań, 2012.
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Abstract
This paper is about the Assyrian battle chariot, which is one of the most
characteristic element of the historical military. To modeling the battle chariot used a
reverse engineering (RE) technique in CAD – Solid Edge and computer image analysis
(CIA) in Met-Ilo and ImageJ applications. The numerical analysis which using finite
element method (FEM) for calculations, were made in Autodesk Inventor software. 3D
photorealistic rendering was realized after designed the model of the battle chariot in the
Autodesk Showcase.
Keywords: Battle chariot, Assyrian, three-dimensional model, modeling, computer
aided design, 3D, FEM, computer simulation, reverse engineering
(8pt)
METODY KOMPUTEROWE W BADANIU HISTORYCZNEGO WOZU
ASYRYJSKIEGO
(10pt)
Streszczenie
Artykuł traktuje o Asyryjskim wozie bojowym, który jest jednym z najbardziej
charakterystycznych militarnych elementów historycznych. Do zamodelowania wozu
posłużono się metodami inżynierii odwrotnej (IO) zrealizowanej w programie CAD –
Solid Edge, użyto również komputerowej analizy obrazu (KAO) wykorzystując
aplikacje Met-Ilo i ImageJ. Analizy numeryczne z zastosowaniem metody elementów
skończonych (MES) zostały wykonane w Autodesk Inventor. Fotorealistyczny rendering
zamodelowanej bryły wozu bojowego uzyskano w programie Autodesk Showcase.
Słowa kluczowe: Wóz bojowy, Asyryjski, model trójwymiarowy, modelowanie,
komputerowe wspomaganie projektowania, 3D, MES, metoda elementów skończonych,
symulacja komputerowa, inżynieria odwrotna
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