Virtual Prototype Modeling and Simulation of Pipe Wagon Articulating System

doi:10.4236/mme.2011.12006

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Modern Mechanical Engineering, 2011, 1, 38-46

doi:10.4236/mme.2011.12006 Published Online November 2011 (http://www.SciRP.org/journal/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

E-mail: [email protected]

Received September 9, 2011; revised October 18, 2011; acc epted Octo b er 25, 201 1

Abstract

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

models.

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

Y. LI ET AL.

(a)

(b)

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).



 (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

qxyz







,. The appropriate

dynamic model of the system [8] is given by Equation (3).



,,, T

TT T

qqq q



mna

ijk

qqq





 



 







(3)

Restriction equations are written as









 (4)

uq

 (5)



qt0



(6)



,,, 0

kk n

Ffqut



 (7)

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).









 (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).









 





 (9)

211

kl kl

qqq q

qqtqqt

t

















 



 





 













 

(10)

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.

qtqq







 

 



 

 







 





 (11)

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) .

Y. LI ET AL.

Figure 3. Simply supported pipe with uniformly distributed load along the hori zontal projec tion of the span.



TH Lx







 















(12)

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

TTH L







 















(13)

The length of the pipe, l, can be expressed as

8d 32d

135

lL LL





 

 



 

 















(14)

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

LL L



 

 (15)

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.

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)

Pipeline

Angle range  (degree) 0 - 60

Material Steel

Length (m/u ni t ) 15

Width (m/unit) 4

Height (m/unit) 7

Wagon

Displacement (m/unit) 7

Material Steel

Length (m) 20

Width (m) 6

Mobile Slurry

System

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

Y. LI ET AL.

(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

above.

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.

(a)

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.

Y. LI ET AL.

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.

8. References

[1] S. Frimpong, R. M. M. Changirwa, E. Asa and J. Szy-

manski, “Mechanics of Oil sands Slurry Flow in a Flexi-

ble Pipeline System,” International Journal of Surface

Mining, Vol. 16, No. 2, 2002, pp. 105-121.

doi:10.1076/ijsm.16.2.105.3401

[2] S. Frimpong, O. R. Ayodele and J. Szymanski, “Nu-

merical Simulation Software for Oil sands Slurry Flow in

Flexible Pipelines,” SCSC 2003 of the Society for Model-

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