Licentiate Thesis Print Ver

7/28/2019 Licentiate Thesis Print Ver

1/24

Modelling, Simulation andExperimental Investigation of aRammer Compactor Machine

by

ANDERS JNSSON

Division of Computer Aided DesignLule University of Technology

SE-871 87 Lule, Swedenand

Department of Mechanical EngineeringBlekinge Institute of Technology

SE-371 79 Karlskrona, Sweden

Karlskrona 2001


2/24

2

Acknowledgements

This work was carried out at the Department of Mechanical Engineering,Blekinge Institute of Technology, Karlskrona, Sweden. It was supervised by

Associate Professor Gran Broman. I wish to express my sincereappreciation to my supervisor. Working together with Gran Broman hasbeen a grand privilege; his exemplary support and great knowledge will

continue to influence me in all future work.

I also wish to acknowledge my gratitude to Associate Professor Mikael

Jonsson and Professor Annika Stensson at the Division of Computer Aided

Design, Department of Mechanical Engineering, Lule University ofTechnology, Lule, Sweden.

I would also like to thank all my colleagues and friends for valuable

discussions and their support during this work. Working together with the

staff of Svedala Compaction Equipment AB has been most inspiring. I

would particularly like to thank Anders Engstrm for his support.

The financial support from the Foundation of Knowledge and Competence

Development in Sweden is gratefully acknowledged.

And finally, I wish to express my thanks to my family and particularly tomy beloved life-companion, Louise.

Anders Jnsson


3/24

3

Abstract

This licentiate thesis considers the modelling, simulation and experimentalinvestigation of a rammer compactor machine. The purpose is to develop an

efficient and verified method for simulation of rammer compactor machines

to be used in the product development process. The experience gained

through this work is also intended to be useful for studying other types of

dynamic compactor machines.

Rammer compactor machines perform impact soil compaction. This is more

efficient than static compaction. The machines are often used in places

where a high degree of compaction is needed, and where the space foroperation is limited. The complexity of this type of machine makes design

optimisation through traditional prototype testing impractical. This has

pointed to the need for a theoretical model and simulation procedure for

predicting the dynamic behaviour of the machine. To be useful for

optimisation the theoretical model and simulation procedure must be

verified.

By concurrently working with theoretical modelling, simulations,

experimental verifications, and optimisation an efficient analysis support for

product development is achieved. This co-ordination works both ways in an

iterative manner: experimental investigations are used to verify theoretical

models and simulations; and theoretical models and simulations are used to

design good experiments. This Complete Approach concept enables better

decisions to be made earlier on in the development process, resulting in a

decrease in time-to-market and improved quality.

In this thesis, the Complete Approach concept is applied to a rammer soilcompactor machine. An introductory iteration is described. The good

agreement between theoretical and experimental results indicates that the

theoretical model and simulation procedure should prove useful in

introductory optimisation studies. The thesis discusses reasons for the

remaining discrepancy and suggests improvements in both the theoretical

model and the experimental set-up for future iterations.

Keywords: Soil Compaction, Non-linear Dynamics, Theoretical Modelling, Numerical

Simulation, Experimental Verification, Complete Approach.


4/24

4

Thesis

This thesis comprises an introductory part and the following papers.

Paper A

A. Jnsson, G. Broman & A. Engstrm,Modelling of a Soil CompactionTamping Machine using Simulink, Proceedings of the MATLAB DSP

Conference, Espoo, Finland, 1999.

Paper B

G. Broman & A. Jnsson, The Nonlinear Behavior of a Rammer SoilCompactor Machine, Proceedings of the EM2000 ASCE Fourteenth

Engineering Mechanics Conference, Austin, Texas, 2000.

Paper C

A. Jnsson & G. Broman, Experimental Investigation of a Rammer SoilCompactor Machine on Linear Spring Foundation, Accepted to the

NAFEMS 2001 World Conference, Como, Italy, 2001.


5/24

5

Contents

1 Introduction............................................................................................61.1 Compaction of Soil......................................................................6

1.2 Compactor Machines...................................................................7

1.3 Non-linear Dynamics...................................................................8

1.4 Product Development ..................................................................9

2 Aim and Scope of the Present Work ..................................................12

3 Summary of Papers..............................................................................15

3.1 Paper A ......................................................................................153.2 Paper B ......................................................................................15

3.3 Paper C ......................................................................................16

4 Conclusions...........................................................................................17

5 References.............................................................................................18

Enclosures

Paper AA. Jnsson, G. Broman & A. Engstrm, Modelling of a Soil Compaction TampingMachine using Simulink, Proceedings of the MATLAB DSP Conference, Espoo,

Finland, 1999.

Paper B

G. Broman & A. Jnsson, The Nonlinear Behavior of a Rammer Soil CompactorMachine, Proceedings of the EM2000 ASCE Fourteenth Engineering Mechanics

Conference, Austin, Texas, 2000.

Paper CA. Jnsson & G. Broman, Experimental Investigation of a Rammer Soil CompactorMachine on Linear Spring Foundation, Accepted for the NAFEMS 2001 World

Conference, Como, Italy, 2001.


6/24

6

1 Introduction

1.1 Compaction of SoilSoil has been used as a construction material since early civilisations for

constructing roads, canals, embankments for dwellings and fortifications [1].

The knowledge of how to use the material was initially passed on from

generation to generation by word of mouth. Later on, the written word

became important as a means of increasing knowledge about soil properties

and handling. The Dschou-Li, a book about the customs of the Dschou

Dynasty written in China about 3000 B.C., contains instructions for the

construction of roads and bridges [2]. The Ten Books on Architecture is oneof the oldest purely technical texts describing soil-based construction. This

text was written by the Roman engineer Vitruvius in the first century B.C.

[3].

During the mid-1600s, France initiated a large civil engineering program for

roads, canals and border fortification systems. This resulted in the first

engineering school in Europe, Ecole des Ponts et Chausses, established in

Paris in 1747. This school was to influence all future scientific development

in civil engineering. The building of railway lines at the beginning of the1800s raised demands on the underlying structure and demonstrated the need

for a scientific approach. During the first half of the 1900s, soil compaction

tests and the relationship between density, moisture, strength,

compressibility and other soil properties were studied and developed; see,

for example, [4,5].

There have been major developments in construction equipment since the

early days of civil engineering. In ancient times, humans and animals were

used for compaction and hauling. Developments were rapid during the

industrial revolution; and in 1859, M. Louis Lemoine of Bordeaux, France,

was granted a patent for a steamroller. In 1906, a patent was issued for a so-

called sheep foot roller, which increased the efficiency of soil compaction.

Compaction was limited to the surface layer because it was believed that the

fill would settle by itself.


7/24

7

The evolution of the infrastructure brought about by mainroads during the

1920s resulted in the use of higher embankments. The latter required the fill

to be compacted from the ground to the surface. This necessitated larger and

heavier compaction equipment with a higher capacity.

1.2 Compactor Machines

Compactor machines are designed to consolidate earth and paving materials

to sustain loads greater than those sustained where there is no compaction.

The machines range in size from small hand-held tampers to large machines

weighing more than 50 tons. Static loading for compaction is an old

technique. To make the compaction more effective many machines include

vibratory action so that compaction is achieved by impact force rather thansheer weight; see, for example, [6-11]. All early works focused on

experimental investigations. This is not sufficient, however, to support an

efficient product development process. For more extensive parameter

studies, theoretical models are also needed.

Theoretical modelling of soils and compactor machines started to appear in

the 1950s [12-14]. By using modern computers for simulations, it ispossible to simulate more complex behaviours [15-19]. Most of the

simulations performed during the last decades have focused on vibratoryrollers.

Published descriptions of measurements on rammer compactor machines are

rare. In 1963, Borchert [20] made some measurements on large rammer

compactors. Filz and Brandon [21] performed force measurements on a

rammer compactor in 1993.

The design of compactor machines now concentrates to a high degree on

modifications of established designs to increase speed, efficiency, accuracy,

and operator comfort and safety. An introductory optimisation study of a

rammer compactor machine has been performed by Broman et al. [22].

The need for civil engineering equipment is still an important feature of

modern society since major changes occur in the infrastructure all the time.

Most civil engineering projects have high associated costs. This means that

an increase in efficiency during the construction phase is usually highly

advantageous from an economical point of view.


8/24

8

1.3 Non-linear Dynamics

The classical study of a mechanical system often starts with the use of

Newtons Law F=ma. For the three centuries after the publication ofNewtons Principia in 1687 (a reproduction in Swedish can be found in [23])it was believed that the behaviour of every system described by particles

could be predicted indefinitely if their initial conditions were known.

However, it has also been recognised for some time that complex systems

exist that cannot be studied deterministically, for example, turbulent flow.

The problem is the large number of degrees of freedom, and the complexity

of the relationships between the particles. Systems with different kinds of

non-linearities have also proved difficult to simulate due to the problem offinding analytical solutions.

The introduction of fast computers has recently increased the study of non-

linear systems. These studies have revealed that even very simple systems

can exhibit highly complex behaviour that cannot be predicted far into the

future. Such motions have been labelled chaotic. Their topicality value as a

research area is increasing with the growing capacity of computer

simulations. In current publications, chaotic is defined as the motions in

deterministic systems whose time history has a sensitive dependence oninitial conditions [24]. Some examples of systems known to exhibit chaotic

vibrations are: systems with sliding friction, non-linear acoustic systems,

feedback control devices, flow-induced problems, and mechanical systems

with play or backlash.

Impact compactor machines are included in the last group. Broman and

Jnsson have proved that the rammer machine of this work is capable ofexhibiting chaotic behaviour; see paper B. The study of non-linear systems is

often more complicated than that of linear systems; and the intuition gained

from many years of studies of linear systems can often be misleading when it

comes to studying non-linear systems.

Understanding non-linear systems places greater demands on the underlying

theoretical knowledge of the system when doing simulations since the

system is often sensitive to parameter changes. By slightly changing a

parameter value, completely different behaviour can be produced; such is not


9/24

9

the case for linear systems. Ignoring non-linearities will in some cases give a

completely false description of the real system.

1.4 Product DevelopmentHigh quality, low price and short time-to-market are essential aspects of the

modern manufacturing industry. Customer requirements are rising at the

same time as the products are becoming more and more complex.

Suggestions for a successful product development process can be found

widely in a large number of publications; see, for example, [25-27].

Although there is a great variety of strategies, a common conclusion is that

changes in product design introduced late in the product development

process are extremely costly and should be avoided.

The paradox of the design process is that knowledge about the problem and

its potential solutions is gained throughout the process and, conversely,

design freedom is lost as the project proceeds. This is demonstrated

schematically in figure 1.

Designfreedom

Knowledge aboutthe design problem

Time into design process

Per cent

100

0

Figure 1. The design process paradox, reproduced from [25].

During the design process, design decisions constrain the design, as

illustrated by the Design freedom curve. The Knowledge about the designproblem curve is a learning curve for the problem. It is obvious that thelearning curve should be as steep as possible so that maximum knowledge


10/24

10

about the problem is obtained as early as possible in the design process,

while the freedom of design is still large.

Modern simulation techniques enable one to test many different designconcepts early on in the design process. Of course, simulation procedures

must be verified in some way if they are to be useful as a basis for design

decisions.

At the Department of Mechanical Engineering at Blekinge Institute of

Technology, a concept for modelling, simulation, verification, and

optimisation has been implemented in both research and education; see

figure 2.

Figure 2. Complete Approach for analysis support in product development.

In short, theoretical models describing interesting product characteristics are

developed. The models are used for simulations. Adjustments are madebetween the modelling and simulation parts until the simulation yields

reasonable results. The simulations are then verified experimentally.

Theoretical models and simulations are also used to design good

experiments. This process is repeated until good agreement is achieved

between theoretical and experimental results.

Optimisation(Re)designing

ExperimentalVerification

ProjectCoordination

Market ChangesNew Technology

New/ModifiedProduct

TheoreticalModelling

Simulation


11/24

11

Simulation of the theoretical models can then be used as an effective tool for

optimisation in the product development process. Should optimisation entail

design changes that significantly change the relevance of the assumptions of

the theoretical models, the entire procedure is repeated. In this way,increasingly detailed descriptions of the product are created where necessary

alongside development of the product.

The Complete Approach enables better decisions to be made earlier on in the

development process, resulting in decreased time-to-market and improved

quality. When a completely new product is developed, a number of complete

iterations are usually needed. When a new variant of a product is developed,

much prior work can be re-used. The Complete Approach concept gives the

company a framework with which to structure such experience.


12/24

12

2 Aim and Scope of the Present Work

The aim of this work is an efficient and verified method for simulatingrammer compactor machines to be used in the product development process.

The experience gained should also be useful in studying other types of

dynamic compactor machines.

The complexity of the machine makes design optimisation through

traditional prototype testing impractical. This has pointed to the need for a

theoretical model and simulation procedure for prediction of the dynamic

behaviour of the machine as well as for a procedure for optimisation. In this

work, a model of a rammer compactor machine is described. The model isused for simulations. The simulation results are compared with measured

results.

The rammer compactor machine LT70 from Svedala Compaction Equipment

AB, Karlskrona, Sweden, is studied. Many other manufacturers and models

of rammer compactor machines exist. All such machines are basically

designed in the same way. A sketch of the machine showing the main parts

is presented in figure 3.

Figure 3. Principal sketch of a rammer soil compactor machine.

Engine house

Connecting rod

Piston

SoilFoot

Engine

Cam disc

Cylinder


13/24

13

Although the mechanism seems to be rather simple, the machine conceals

considerable inherent complexity. Descriptions of the soil and the interaction

between the machine and the soil are also non-trivial problems. To make

efficient simulations, simplifications must be made. The simplified modelused in this work is shown in figure 4. All assumptions, simplifications and

notations are described in the enclosed papers.

Enginem3 , J

Pistonm2

ci ki

cs ks

u3

u1

u2

Foot

m1

M

r

SoilReplace-ment

Figure 4. Theoretical model of the rammer

machine and soil replacement.

The most questionable simplification of the combined system is the

representation of the soil as a linear spring and a viscous damper. However,

since the aim of the present work is an efficient model of the machine itself,

this simplification is justifiable. Parallel work is currently being carried out

to find better soil models. Combining the machine model suggested in this

work with other soil models should not present any major difficulties.


14/24

14

The dynamic system is non-linear due to the angle of the cam disc and the

jumping behaviour, which makes it hard to solve the equations analytically.

Standard ordinary differential equation solvers in Matlab and Simulink are

used for the simulations.


15/24

15

3 Summary of Papers

The three papers included in this thesis represent a description of how towork iteratively with modelling, simulations and measurements.

3.1 Paper A

In this paper, a theoretical model for the dynamic behaviour of a rammer

compactor machine is described, and a simulation procedure is established.

The model was suggested by Moshin [14] and has been applied also in

papers B, C and [28-30]. The soil is modelled by a linear spring and a

viscous damper. In this paper the foot of the machine and the soilreplacement are not allowed to lose contact with each other. In contrast to

earlier works on compactor machines of this kind [12, 14, 28], the equations

of motion are solved numerically for an arbitrary time period in this work.

This also makes it possible to study the transient and non-harmonic

behaviour of the machine, and to reach a steady state. The Matlab toolbox

Simulink is used to solve the equations of motion. Experimental results from

[28], where the rammer compactor machine was run on simulated soil

material, are used for a preliminary verification. The agreement between the

simulation and the experiment is good, which implies that the level of detailin the theoretical model is sufficient for further studies.

3.2 Paper B

In this paper, the complexity of the theoretical model used in paper A is

increased by allowing the foot of the machine to lose contact with the soil

replacement. The contact conditions between the foot of the machine and the

soil replacement are investigated and described. The simulation procedure is

complemented by these conditions. The differential equations of the modelare solved numerically by using Matlab. The dynamic behaviour is analysed

for different driving torque values. Simulation results are presented as time

series, phase plane diagrams, mappings and bifurcation diagrams. The results

show that the system is highly non-linear and indicate that harmonic, sub-

harmonic and chaotic behaviour are present within the parameter variations

used. This phenomenon has also been observed while operating the machine

under real-life conditions. The parameter sensitivity emphasises the need to

include such simulations in the product development process.


16/24

16

3.3 Paper C

In this paper, the theoretical model of paper A is thoroughly investigated

experimentally, and the resulting introductory iteration of the Complete

Approach concept is described. In the experimental set-up, the rammer foot

is attached to a linear spring foundation. This eliminates uncertainties

associated with soil modelling, and makes possible a check of the model of

the machine itself. The good agreement between theoretical and

experimental results indicates that the theoretical model and simulation

procedure are potentially useful in introductory optimisation studies.

Possible reasons for the remaining discrepancy are discussed, and

suggestions are given for improvements in both the theoretical model and the

experimental set-up for coming iterations.


17/24

17

4 Conclusions

In this work an efficient and verified method for simulation of a rammercompactor machine is presented. The method has been developed by using a

structural approach called Complete Approach, which includes theoretical

modelling, simulation, experimental verification, and optimisation. In this

way, a deeper understanding of the system has been gained.

The results of the simulations and the measurements deviate by

approximately ten per cent; a highly satisfactory result considering the

complexity of the machine studied, and the significant simplifications

introduced. The presented model and simulation procedure constitute auseful support in product development of compactor machines.

Although there is good agreement between simulation results and

experimental results, suggestions for improvements in both the theoretical

model and the experimental set-up have been given, and additional work in

the future is recommended.

Suggested improvements relate primarily to the modelling of internal

dissipation. In the present model, all internal dissipation is represented by a

viscous damper between the foot and the piston of the machine. It is

sometimes possible to estimate an equivalent damping constant, giving the

same dissipated energy per cycle as the combined friction and viscous

dissipation that are present in reality. Since the friction dissipation seems to

be significant compared to the truly viscous dissipation in this machine, a

new equivalent damping constant must be estimated for each new operating

condition. Considering this, the theoretical model can be improved by

including a friction element between the foot and the piston.

If necessary, stiffness, damping and friction between the foot and the house

can also be included. The experimental set-up can be improved by adding a

damper to the soil replacement foundation to produce a closer resemblance

to real operating conditions. It is also recommended that a more

sophisticated theoretical model of the soil is introduced, which includes the

non-linear behaviour of real soil materials.


18/24

18

5 References

1 WEBER, W. G. Jr., History of Embankment Construction, State ofthe Art Report 8, Transportation Research Board, National Research

Council, Washington, D.C., 1990.

2 SPECK, A., Der Kunststrassenbau, Ernst, Berlin, 1950.

3 GRANGER, F., Translation of Vitruvius Ten Books onArchitechture, Putnam, New York, N.Y., 1934.

4 PROCTOR, R. R., Fundamental Principles of Soil Compaction,Engineering News Record, Vol. 111, No. 9, pp. 245-248, 1933.

5 HOGENTOLER, C. A., Essentials of Soil Compaction, Proceedings Highway Research Board, Washington, pp. 309-316, 1936.

6 STEUERMANN, S., A New Soil Compacting Device, Engineering

News Record, pp. 87-88, July, 1939.

7 BERNHARD, R. K., Static and Dynamic Soil Compaction,

Proceedings from the Annual Meeting/Highway Research Board,

1951.

8 FORSSBLAD, L., Jordpackning genom vibrering, Teknisk Tidskrift,

No. 30, 1955.

9 LEWIS, W. A., A Study of Some of the Factors Likely to Affect the

Performance of Impact Compactors on Soil, Proceedings of the 4

th

International Conference on Soil Mechanics and Foundations,

London, 1957.

10 LEWIS, W. A., Recent Research into the Compaction of Soil by

Vibratory Compaction Equipment, Proceedings of the 5th

International

Conference on Soil Mechanics and Foundations, Paris, 1961.


19/24

19

11 D Appolonia, D. J., Sand Compaction with Vibratory Rollers,Journal of the Soil Mechanics and Foundations Division / Proceedings

of ASCE, Vol. 95, January, pp. 263-284, 1969.

12 BATHELT, U., Das Arbeitsverhalten des Rttelverdichters aufplastisch-elastischem Untergrund, Bautechnik Archiv, Heft 12, Verlag

von Wilhelm Ernst & Sohn, Berlin, 1956.

13 RICHART, F. E. Jr., J. R. HALL Jr., and R. D WOODS, Vibration of

Soils and Foundations, Prentice-Hall, Inc., 1970.

14 MOSHIN, S. H., Untersuchungen des dynamischen Verhaltens von

Stampfsystemen, Baumaschine und Bautechnik, Jahrgang 14, Heft 1,pp. 11-17, 1967.

15 YOO, T. and E. T. SELIG, Dynamics of Vibratory-Roller

Compaction, Journal of the Geotechnical Engineering Division,

GT10, pp. 1211-1231, 1977.

16 PIETZSCH, D. and W. POPPY, Simulation of Soil Compaction with

Vibratory Rollers, Journal of Terramechanics, Vol. 29, No. 6, pp. 585-

597, 1992.

17 TATEYAMA, K. and T. FUJIYAMA, Study on the Vibratory Roller-

Ground Interaction and its Application to the Control of a Roller,

Proceedings of the 5th Asia-Pacific Regional Conference ISTVS,

1998.

18 ADAM, D., Continuous Compaction Control(CCC) with Vibrating

Rollers, Doctoral Thesis, Civil Engineering Department, TechnicalUniversity of Vienna, 1996.

19 KOPF, F., Continuous Compaction Control(CCC) during Compaction

of Soils by means of Dynamic Rollers with different kinds of

Excitation, Doctoral Thesis, Faculty of Civil Engineering, Technical

University of Vienna, 1999.


20/24

20

20 BORCHERT, G., Untersuchungen am Elektrostampfer-200kg, GroerBeleg TU Dresden, Institut fr Frdertechnik und Baumaschinen,1963.

21 FILZ, G. M. and T. L. BRANDON, Compactor Force and Energy

Measurements, Geotechnical Testing Journal, Vol. 16, No. 4, pp. 442-

449, 1993.

22 BROMAN, G., A. JNSSON, T. ENGLUND and J. WALL,Introductory Optimisation Study of a Rammer Soil Compactor

Machine, Proceedings of the NAFEMS World Congress, Como, Italy,

2001.

23 CHARLIER, C. V. L., Naturvetenskapens Matematiska Principer, A

reproduction of: NEWTON, I., Philosophiae Naturalis Principia

Mathematica, 1686, C W K Gleerups frlag, Lund, 1927.

24 MOON, F. C., Chaotic and Fractal Dynamics: An Introduction for

Applied Scientists and Engineers, John Wiley & Sons, Inc., 1992.

25 ULLMAN, D. G., The Mechanical Design Process, McGraw-Hill,

Inc., 1992.

26 PAHL, G. and W. BEITZ, Engineering Design. A Systematic

Approach, Springer, 1996.

27 ULRICH, K. T. and S. D. EPPINGER, Product Design and

Development, McGraw-Hill, Inc., 1995.

28 BORG, J. and A. ENGSTRM, Dynamic Behaviour of a SoilCompaction Tamping Machine, Master Thesis, Department ofMechanical Engineering, University of Karlskrona/Ronneby,

Karlskrona, Sweden, 1997.

29 JNSSON, A. and G. BROMAN, Dynamic Characteristics of a SoilCompaction Tamping Machine, Presented at the Swedish Days of

Mechanics 1999, Royal Institute of Technology, Stockholm, Sweden,

1999.


21/24

21

30 ARBIN, U., T. ENGLUND and J. WALL, Modelling and Optimising

a Rammer Soil Compactor Machine, Master Thesis, Department of

Mechanical Engineering, Blekinge Institute of Technology,

Karlskrona, Sweden, 2000.


22/24

22

Paper AModelling of a Soil Compaction Tamping Machine using Simulink


23/24

23

Paper BThe Nonlinear Behavior of a Rammer Soil Compactor Machine


24/24

Paper CExperimental Investigation of a Rammer Soil

Compactor Machine on Linear Spring Foundation

Licentiate Thesis Print Ver

Documents

Transcript of Licentiate Thesis Print Ver