Modern Mechanical Engineering, 2011, 1, 38-46
doi:10.4236/mme.2011.12006 Published Online November 2011 (
Copyright © 2011 SciRes. MME
Virtual Prototype Modeling and Simulation of
Pipe Wa gon Articulating System
Ying Li1, Samuel Frimpong1, Wenyuan Liu2
1University of Missouri-Rolla, Rolla, USA
2Washington Uni versi t y in St . Loui s, St. Louis, USA
Received September 9, 2011; revised October 18, 2011; acc epted Octo b er 25, 201 1
Virtual prototype of pipe wagon articulating (PWA) system has been developed and simulated based on the
kinematics and dynamics of machinery and Automatic Dynamic Analysis of Mechanical Systems (A DAMS)
software. It has been integrated with real-time three dimensional (3-D) system simulations for detailed and
responsive interaction with dynamic virtual environments. By using this virtual model, the conceptual design
examination and performance analysis of the PWA system have been realized dynamically in virtual labora-
tory. System dynamic force, displacement and tension of pipe have been measured through verifying this 3-
D virtual prototype. By comparing the static tension and dynamic tension of pipe, the difference between the
two kind tensions has been found. The simulated dynamic tension is much greater than the static tension ob-
tained from the static theory. The results attained in this work suggest that the conceptual designed PWA
system can meet the requirements of the operation.
Keywords: Pipe Wagon Articulating, Dynamic Modeling, Virtual Prototype, Dynamic Simulation
1. Introduction
For efficient and economic extraction and haulage of oil
sands from production faces, the “at face slurrying (AFS)”
technology is currently being investig ated at the research
and technology development lev els. The AFS techno logy
will be used to create and transport oil san ds slurry from
production faces through flexible pipeline system to link
th e existing hydro-transpor t system. The three options have
been proposed to transport oil sands slurry from the face
to a fixed pipeline system based on preliminary economic
modeling, simulation and analysis of various conceptual
The PWA system is one of the three AFS options. A
lot of efforts have been invested to conceptualization of
the PWA mechanical system and detail numerical mod-
eling for investigation of oil sands multiple-phase prob-
lem in pipeline [1-4]. A conceptual design of the PWA
system has been proposed in our lab. In this proposal, the
PWA system is composed of linkages of pipe wagons
connected with flexible pipes. This flexible arrangement
accommodates the horizontal and vertical displacements
of the mobile system as it follows the hydraulic shovels in
the excavation process. In all research, a lot of attention
has been given to study the single-phase and multiphase
flow of oil sands slurry in PWA flexible pipe. The me-
chanics of oil sands slurry flow in PWA flexible pipeline
system has been formulated and simulated over an ex-
tended period [1]. A numerical simulator has been deve-
loped to provide nu merical solutions of the flow in flexi-
ble pipe as a 3-D multiphase problem [2]. However, im-
plementation of the PWA system in real-time and inside
a v irtual environment, has not been carried out. And, there
has not been investigation on system motion and engi-
neering performance analysis of the PWA system so far.
The continuing research will examine the handling per-
formance of the system to represent the motions and for-
ces of various components by modeling and simulateing
real-word PWA system in a virtual laboratory.
The literature that been reviewed in reference [5] in-
dicates a consistent viewpoint of the virtual prototype mo-
deling using to simulate the ground articulating pipeline
(GAP) system. Therefore, this methodology still will be
used in the simulation of the PWA system. Mechanical
system simulation (MSS) in ADAMS software can be
used for ongoing virtual modeling and simulation of the
PWA system. MSS can be employed to simulate the mo-
tion and force of the PWA systems based on machinery
Y. LI ET AL. 39
kinematics and dynamics. In o rder to realize dynamic mo-
deling of the PWA system, the kinematics and dynamics
models of the system are built in terms of the theory of
machines and mechanisms [6,7]. The principles of me-
chanics [8] can be used to static modeling mechanical
system. So, the solved kinematics and dynamics of ma-
chinery can yield equations for dynamic-motion, static-
force and dynamic-force analysis [9].
However, for the dynamic simulation of the PWA
system two key factors differ from the GAP system. One
of the key factors is system kinematics modeling. The
pipelines exhibit highly geometrically nonlinear behavior.
They are very flexible and undergo large displacements
before attaining their equilibrium configuration. Due to
this inherently nonlinear behavior, the flexible pipelines
do not fit the assumption of rigidity. They usually have
no effect on the kinematics of the system but do play a
role in supplying forces. The pipelines of the system are
usually ignored during kinematic analysis, and their force
effects are introduced during dynamic simulation [7].
Another of the key factors is pipeline modeling. The PWA
system is made up of linkages of wagons connected by
rubber pipelines. The rubber pipelines are used for trans-
mitting forces or displacements be tween wagons. Because
transmission paths are often convoluted, and the pipe per-
formance is dependent on phenomenon such as friction
and stretching, it is difficult to model pipelines using stan-
dard tools available in most mechanical system simula-
tion packages. The way to model fixable pipeline in AD-
AMS is to discretize th e pipe i n to seg ments. Th e seg ments
are then attached with a constraint.
In this work, the theoretical modeling and virtual pro-
totype simulation of the PWA have been focused on.
Using the virtual model developed in this work, the fol-
lowing work has been carried out: 1) realization of dy-
namic simulation; 2) creation of 3-D solid visualization
models with 3-D motion for the PWA system; 3) de-
termination of important engineering data, such as maxi-
mum force necessary to drive the PWA machinery using
reality and virtual prototypes; 4) analysis of the distri-
bution of tension along pipe and comparison of static
tension with dynamic tension.
2. Concetual Design of the PWA System
The PWA system will facilitate the conveyance of oil
sands slurry to joint a fixed pipeline or existing hydro-
transport train (HTP). This system has been designed and
developed to withstand the oil sands mechanical and che-
mical characteristics and handle oil sands slurry rate or
flow rate of 6100 tph. It must accommodate production
face advance of 60 m/day or 400 m/week w ith a robu st sys-
tem components interfaces. The slurry component sizes
must be a fraction of minus 80mm with a specific gravity
of 1.6. The PWA concept is illu strated in Figure 1(a). This
system will work with a shovel, mobile slurry system with
slurry pump system, PWA system and fixed pipeline sys-
tem. The PWA system consists of linkages of wagons con-
nected by FlexRite flexible pipelines. In this combined
system the shovel excavates and feeds dry oil sands lumps
into the mobile slurry system and with the addition of hot
water into the system, oil sands are slurried. The result-
ing oil sands slurry is then pumped through the PWA
system to join the fixed pipeline or existing HTP.
Figure 1(b) indicates that the PWA system will consis t
of a series of rigid truss frames on castors and will be al-
lowed to swivel relative to each other. Each frame will
support concentrated 24” diameter slurry and 18” diamete r
fresh water lines. A flexible pipeline assembly is required to
allow flow of both slurry and fresh water while permitting
the position changes between adjacent trusses. FlexRite
pipes are more flexible than conventional steel pipes and
provide maximum bending with smooth flow of materials.
The flow across the FlexRite pipeline can change in any
direction due to the flexible nature of the pipeline system.
The flexible pipe can bend to a maximum angle of 60˚.
Two types of particles or mixtures impingement can oc-
cur including straight horizontal flexible pipe and bend
(from 0˚ to 60˚ deflection) flexible pipe.
A mining sequence can be established for a movement
of a shovel within the pit. The mobile slurry system is
designed to follow the shov el as it traverses the pit. Dur-
ing this operation, the pipe will move as they follow the
movements of the shovel as illustrated in Figure 1(a). To
accommodate a shovel advance, the PWA arms will be
added at various advance rates as illustrated . As the mine
face advances the stretching PWA will follow shovel.
The PWA movement will be automated and robotized
through computer vision systems. In this case, the PWA
can accumulate or un-accumulate allowing the effective
working envelope between the mine face and fixed pipe-
line to be varied.
3. Theoretical Models of the PWA System
3.1. Motion Model of the PWA Wagon
The requirement by the PWA system is that of causing
an output member to move from one position to another.
In analyzing motion, the first and most basic problem
encountered is that of defining and dealing with the con-
cepts of position and displacement. Since motion can be
thought of as a time series of displacements between suc-
cessive positions, it is important to analyze exactly the
positions of mechanism in the PWA system. Figure 2 is
a schematic drawing of the PWA system including the
Copyright © 2011 SciRes. MME
Copyright © 2011 SciRes. MME
Figure 1. (a) Conceptual components of the PWA technology [1]; (b) Conceptual views of the PWA system [1].
Figure 2. Schematic diagram of the PWA system.
Y. LI ET AL. 41
ground, two pipe units and three wagons. Furthermore,
th is mechanism is a multi-loop linkage combined of same
two or more pipe wagon units. To simplify design, one pipe
wagon unit has only been studied. If it is assumed that
the velocity of every wagon is constant, the displacement
of every wagon is Equation (1).
vt (1)
where vi is the wagon velocity value, t is the operation
time. If the PWA system consists of N pipe wagons, the
total displacement of system is Equation (2).
3.2. Dynamic Model of the PWA System
In the PWA system, the desired motions of the mecha-
nisms are specified in advance by production requirement.
Even though the wagon is driven at constant speed, this
does not mean that all points of the pipelines have con-
stant velocity vectors or even that other parts of the sys-
tem will operate at constant speeds; there will be accel-
erations and therefore system with moving parts will not
be in equilibrium. Analytical methods for investigating
dyna mic forces in the PWA system employ mathematical
models that are solved for unknown forces associated
with known mechanism motion. Solving this problem
requires definitions of the actual shapes, dimensions, and
material specifications to determine the centers of mass
and mass moments of inertia of the parts, which will be
given in section 4.0. Then, the Lagrange method of mul-
tirigid-body system is used to establish the equations of
kinematics and dynamics of the PWA system. The dis-
placement, velocity, acceleration and force can be obtained.
Cartestian coordinate of the center of mass for rigid
body i and Euler angle or generalized Euler angle of ri-
gid body a re regarde d as generate d coordinates,
,,,,, T
,. The appropriate
dynamic model of the system [8] is given by Equation (3).
,,, T
qqq q
 
Restriction equations are written as
,,, 0
kk n
where L is Lagrangian = T – V, T is the kinetic energy of
system, V is the potential energy of system, is the
constraint equations, r is the application point of force, f
is the function defining the forces, p is the momentum, u
is the velocity, q is the displacement,
is the Lagrange
Multiplier, and F is the externally applied force.
At time tn, the position of parts are calculated by New-
ton Raphon iteration using Equation (8).
where 1
qq q
, j denotes the j-th iteration.
Solving the first derivative and the second derivative
of restriction Equation (6), instant velocity and accelera-
tion at tn [10] are given by Equations (9) and (11).
kl kl
qqq q
 
 
 
 
From the Lagrange equation with multiplier, the instant
reaction forces in the PWA multi-body system are given
by Equation (11) along each of generalized coordinates.
These are introduced as holonomic algebraic constraint
functions. Therefore, the assembly of parts can be repre-
sented mathematically in a manner that conforms to the
required dynamic functions of the system.
 
 
 
 
 
3.3. Static Model of the PWA Pipeline
The static model of pipeline will be developed using the
governing equation for freely hanging flexible cable [11]
in order to compare the static tension with the dynamic
tension of pipe. In the PWA system, the pipes between
two wagons are freely handing pipes. In the following,
the Equation [11] are presented for freely hanging pipes
when the load is distributed uniformly along the pipes, as
shown in Figure 3. The supports are both at same level.
The span is L from lift-hand support to right-hand sup-
port. The position of maximum pipe sag d occurs when x
= L/2. When pipe of length L subjected to a load w L,
where w is the intensity of the distributed load along the
horizontal projection of the pipe at any distance x from
the left-hand support, the tension, Tx, in the pipe with a
distance x from the left-hand support can be found from
Equation (12) .
Copyright © 2011 SciRes. MME
Figure 3. Simply supported pipe with uniformly distributed load along the hori zontal projec tion of the span.
 
where H = wL2/8d.
From Equation (12) it follows that the pipe tensions,
TA and TB, at the supports of A and B are given by
 
The length of the pipe, l, can be expressed as
8d 32d
 
 
 
 
The values of H, d and L will change to (H + H), (d
+ d) and (L + L) due to horizontal movements of the
supports. If assumed that the length of the pipe does not
alter due to changes in tension, the change in d may be
found by differentiating Equation (14) with respect to L.
This eventually yields
422 4
120 320d2304d
d640d 3072d
 
4. Virtual Prototype of the PWA System
Figure 4 shows a virtual prototype of the PWA system
developed in ADAMS environment. The PWA model,
including the oil sands terrain, mobile slurry system, wa-
gon subassembly, water line subassembly and slurry line
subassembly, is modeled as a multi-body system. The de-
sign parameters for the PWA simulation will comprise
basic dimension and calculation data as shown in Table
1. In this table, the flexible pipe system material of Flex-
Rite is used to PWA pipeline material based on the con-
ceptual design of the flexible pipeline system [1]. This
flexible pipe can bend to a maximum degree of 60. The
specific gravities and pipeline diameters of slurry and
water given in this table have been derived from Section
2. The unit length of pipeline and wagon listed in the
table is assigned by the results of the PWA system syn-
thesis. To accommodate a shovel advance of 400 m per
week, the maximum displacement of every wagon is 7m.
In order to operate the system, the drive force has to be
applied to fourteen wagons, respectively. 3-step proce-
dures for building the PWA model are described below.
The first step involves the creation of 3-D component
models of the oil sands terrain, mobile slurry syste m, wa-
gon subassembly, water line subassembly and slurry line
sub assembly. The mobile slurry system contains one body
and two crawler geometries. The wagon model includes
one body and four crawler geometries. The water and slurry
models consist of a series of smaller rigid pipe sections
as show in Figure 4. The second step defines the connec-
tions of the components with joints. Figure 5 gives the
topological structure and restriction among components
of the PWA multi-body system. The oil sands terrain B0
and mobile slurry crawler B1 and wagon crawler B2 are
connected by translational joints H1 and H2, respectively.
The mobile slurry crawler B1 and mobile slurry body B3
are connected by revolute joint H3. The wagon crawler
B2 and wagon body B4 are connected by revolute joint
H4. The mobile slurry body B3 and water line B5 and
slurry line B6 are connected by ball joints H5 and H6,
respectively. The wagon body B4 and water line B5 and
slurry line B6 are connected by ball joints H5 and H6,
respectively. The flexible water pipeline B5 and slurry
pipeline B6 are separated a lot of small sections that are
connected by ball joint H7 and spring-damper H8, re-
spectively. The third step defines the appropriate alge-
braic variables, which represent the movements of the
mobile slurry system. This means that the varying ang les
applied to the water and slurry pipelines are introduced
during operation.
Copyright © 2011 SciRes. MME
Y. LI ET AL. 43
Table 1. Main PWA design parameters [1-3].
Material FlexRite
Specific gravity 1.6 (slurry); 1 (water)
Length (m/u ni t ) 15
Diameter (m) 0.62(slurry); 0.45(water)
Angle range (degree) 0 - 60
Material Steel
Length (m/u ni t ) 15
Width (m/unit) 4
Height (m/unit) 7
Displacement (m/unit) 7
Material Steel
Length (m) 20
Width (m) 6
Mobile Slurry
Height (m) 9
Viscous damping coefficient 0.3
Coulomb friction c on s t a n t 0.5
Figure 4. Virtual prototype of the PWA system.
B3 B1 B5
B2 B4 B8
H1 H3 H5
H8 H2 H4 H6
Figure 5. Topological and restriction among parts of the
PWA system.
5. Dynamic Simulation of the PWA System
Visualizing system motion can be realized by simulating
the PWA system. The PWA virtual prototype shown in
Figure 4 has been moved on a hard homogeneous oil sands
terrain. In the 3-D solid model, the mass, inertial proper-
ties and gravity of components are given in Table 2.
For one complete cycle of the PWA system, every wa-
gon is commanded to execute the return and forward mo-
tions. The desired motion includes a return motion last-
ing 7 m within 500 s and a forward motion of 7 m during
500 s, and corresponds to the every wagon velocity of 0.014
m/s. When static and dynamic friction coefficient between
ground and crawler are set to 0.75 and 0.7, respectively,
the variations in response such as motion-generated forces ,
displacement of pipe wagon and angle
, have been ob-
tained as measures of the system performance.
5.1. Dynamic Motion Simulation of the
PWA System
Figure 6 shows that the motion of the PWA system is
visualized by plotting successive six positions on graphic
display over an extended period of time. The angles ,
displacement of wagon and sag of pipe are plotted in Fi-
gures 7 (a) and (b), respectively.
Figure 7(a) shows the plot of angle (see Figure 3)
versus time for one cycle. The angle
= 0˚ at time t = 0
corresponds to the initial static equilibrium position. in-
creases with time from 0 to 500 s followed by a de-
creases from 500 to 1000 s. It undergoes a maximum of
56˚ at time = 500 s, which corresponds to the end posi-
tion. The predicted from 0˚ to 56˚ for the system is in
the range from 0˚ to 60˚ allowed by the pipe material.
Figure 7(b) depicts the displacement of every wagon
and the sag of pipe for one cycle. Both displacement and
sag increase with time for the first 500 s and they are
subjected to the opposite trend for the last 500 s. The
maximum displacement locates at 7 m at a time of 500 s,
which meets the required value in Table 1. The corre-
sponding maximum sag of pipe is 6.8 m.
5.2. Dynamic Force Simulation of the
PWA System
The PWA prototype is simulated over an extended pe-
riod of time to study dynamic-force of the system. The
Table 2. Mass and properties in the PWA system.
Inertia Moments (kgm2)
Component Name Mass (kg) Ixx Iyy Izz
Water line ( each section)480 12 138 138
Slurry line ( each section)928 42 308 308
Wagon 1.97E+5 2.97E+5 3.65E+63.83E+6
Mobile Slurry 6.55E+6 4.64E+7 2.45E+82.38E+8
Copyright © 2011 SciRes. MME
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(a) (b) (c)
(d) (e) (f)
Figure 6. PWA motion sequence thr ough one extended period of time.
(a) (b)
Figure 7. Dynamic motion responses to time for the PWA system: (a) angle and (b) displacement and sag.
driving force an d non -d riving fo r ce app lied on w agon are
plotted in Figures 8(a) and (b).
Figure 8(a) illustrates the driving force applied on each
wagon for a wagon full motion cycle. It increases dra-
matically from 0 to ca. 1.5E+006N at a time range from
0 to ca.100s. Then, a constant po sitive force of 1.5E+006N
occurs in the time range from 100 to ca. 500 s . But, it dives
sharply from 1.5E+006N to ca. –1.6E+006N around a
time of 500s. Finally, it decreases slowly to –1.85E+
006N between 500 and 1000 s. The transient responses
around time of 0 and 500 s disappear quickly. It should
be noted that a p ositive force indicates retraction wh ile a
negative one does ex tension. This result indicates that the
maximum driving force is a little smaller when system
moves back than when it moves forth. The pipe gravity
accounts for this difference. It has a positive effect on
driving force when the wagon moves backward. How-
ever, it has a negative effect on driving force when the
wagon moves forward.
Figure 8(b) displays the non-driving force applied on
Y. LI ET AL. 45
(a) (b)
Figure 8. Dynamic force responses to time for the PWA system: (a) driving force applied on each wagon and (b) non-driving
force applied on each wagon.
each wagon with time for one cycle. It goes down a little
quickly from –2.045E+006 to –2.1E+006N around a
time of t = 0 s, indicating a tran sient response dies down
quickly around ti me t = 0. Then a constant negativ e force
of –2.1E+006N is established up to 1000 s.
The tension of the slurry pipe is simulated by using the
virtual prototype shown in Figure 4. The design parame-
ters used here are given in Section 5. The wagon back or
forth displacement of 7 m and the maximum pipe sag of
6.8 m have been derived from the dynamic motion tests
The relationship between displacement and dynamic
tension is investigated here. Po sitions 1 - 6 with an inter-
val of 1 are labeled by dividing a half pipe length from
left-hand support to mid point (see Figure 9(a)). The cor-
responding tensions acting at these positions are shown
in Figure 9(b) for a wagon movement from 0 to 7 m. It
is seen that the tension increases sharply from 0 to 4E+
005N with displacement in a very small range from 0 to
0.3 m followed by a sharp decrease of the tension to ca.
1E+005N within the displacement between 0.3 and 1 m.
Then, it decreases slowly with displacement. For a given
displace ment, tension decreases fro m positions 1 to 6. The
maximum tension appears at poison 1 (support) while the
minimum one does at position 6 (the center of pipe).
The relationshi ps of the displacement-static t ension and
the displaceme nt-dynamic tension are discussed here. The
variation of tension at support for a displacement from 0
to 7m is shown in Figure 10. The static tension calcu-
lated by Equations (13)-(15) decreases slowly with dis-
placement. By comparing the simulated dynamic tension
with the static tension, it can be noted that the dynamic
tension is greater than the static one owing to dynamic
effect, especially before a stable tension is established.
Figure 9. (a) Scheme of position distribution; (b) Displace-
ment-dynamic tensions relationship with different positions.
Figure 10. Stati c tension a nd dynamic ten sion at the su pport.
Copyright © 2011 SciRes. MME
6. Conclusions
The mechanical system of PWA has been simulated by
us ing virtual mo del, which is dev eloped by combinin g the
theory of machines and mechanisms and the multi-body
dynamic simulation software ADAMS. Important engi-
neering data of the PWA system have been determined
by simulating reality with a virtual prototype. Th e virtual
prototype model of the PWA system has been tested and
verified to be effective with real displacement value. The
results show this model is capable of kinematics com-
puting and offering computer-animated simulations of the
kinematics behavior. The results of dynamic-motion ana-
lysis indicate that the conceptual designed the PWA sys-
tem meets the requirement of the variation of angle from
0˚ to 60˚. The results of dynamic-force simulation have
given the maximum force of –1.85E+006N for driving
the system and the maximum non-driving force applied
on wagon (2.1E+006N) for calculating the bearing ca-
pacity of oil sands. The tension analysis of the pipe shows
that the distribution of tension along the pipe length is
not uniform. The maximum tensi on appears at the support.
The result of comparison between the static tension and
dyna mic tension illustrates that static tension is much smal-
ler than the dy namic tension. This work will allow further
benchmarking of the mechanical event simulation of the
PWA system s uch as examination of bearing capacity and
prediction of pipelin e stress.
7. Acknowledgements
The authors wish to express their gratitude to AERI/-
COURSE and Syncrude Canada Ltd. for the financial
support and field data for this study.
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