7
SMMS Volume 16 Number 1 January/March 1996 ItandHns 15 Years of Conveyor Belt Nondestructive Evaluation Alex Harrison, USA Summary The year 1979 marked the beginning of a new technology that permitted the testing of conveyor belt damage and degradation For the first time, steel cord belts were tested for corrosion and this technology has now been in constant commercial use since 1981 fifteen years The invention of a method to test moving belts for damage and loss of strength led to more complex ap- plications including broken cable detection and splice signature analysis Fabric belt testing was developed next, followed by cable belt and pipe belt testing New advances have been made that provide a more sophisticated application of belt monitoring, including the development of safety factor (SF) analysis based on NDT signal analysis This paper will grve an historical over- view and describe the state-of-the-art 1. Introduction A great deal of knowledge has been gained dunng the past 17 years on the subject of conveyor belts and their modes of deg- radation This new knowledge was made possible through techniques developed to monitor the reinforcement of conveyor belts In retrospect the science of belt nondestructive testing (NDT) was bom in Australia in 1979 with the patenting of a system that came to be known as the "cbm" or conveyor belt monitor The research of Harrison [1,2] resulted in a series of papers and patent applications on the new technology Once the concept that a belt could be tested by non-contact methods was demonstrated, it became an established method for testing belts worldwide The ramifications to the manufac- turer in terms of quality assessment, and to the mine in terms of damage evaluation, have been quite profound Research con- tmues to discover new facts about belt and splice condition In this paper, the evolution of belt nondestructive testing into the science of safety factor (SF) analysis is discussed The natural direction for application of this research has been in evaluation of belting safety factors at a damage or defect site This procedure was developed for steel cord belts as early as 1981 [3,4] No longer is it acceptable to simply measure the lev- els of damage in the belting, but rather the industry requires an evaluation of belting strength at the location of greatest con- Prof Dr Alex Harrison President Scientific Solutions Inc , Managng Mem- ber Conveyor Technologies Ltd LLC 2200 Chambers Rd , Unit J, Aurora. CO 80011. USA Tel +1 303 344 9024 Fax +1 303 344 9102 Details about the author on page 149 cern. This thrust encompasses stress analysis of the belting as a composite material Finally, any analysis that does not con- sider the starting or stopping forces is lacking in terms of com- plete evaluation of belting condition These directions are considered to be the optimally correct ap- proach to evaluating belting condition Belt nondestructive test- ing applies to both steel cord [5] and fabric belting [6] Testing is designed to maximize information about the belting 2. State-of-the-Art in Testing Procedures Rg 1 shows the procedure used to obtain vital data for safety factor production based on belt damage or manufacturing qual- ity There are three distinct phases required in the evaluation of belting condition in relation to the conveyor system Phase 1 is considered to be the data collection phase, Phase 2 is the anal- Rg 1 Process used to analyze damage and anomalies in a steel cord belt O/>g/na/ Safery fecfor SF Phase* USED BELT NEW BELT f NDT Process J (cord Plane Scan Extract damage Information J C Detect Cord Plane Variations Calibration Calibration Compute Stress Concentrations at Problem Area Phase 2 Graphical Display (^De- rate Belt SFO SFf [Measure or > Model Belt Dynamic Factor J P/iase 3 (^De De-rate Bett SF1 13

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Page 1: 15yrs of Conv Belt Nondestructive Eveluation

SMMS Volume 16 Number 1 January/March 1996ItandHns

15 Years of Conveyor BeltNondestructive Evaluation

Alex Harrison, USA

Summary

The year 1979 marked the beginning of a new technology that

permitted the testing of conveyor belt damage and degradationFor the first time, steel cord belts were tested for corrosion andthis technology has now been in constant commercial use since

1981 - fifteen years The invention of a method to test movingbelts for damage and loss of strength led to more complex ap-plications including broken cable detection and splice signatureanalysis Fabric belt testing was developed next, followed bycable belt and pipe belt testing New advances have been madethat provide a more sophisticated application of belt monitoring,including the development of safety factor (SF) analysis based

on NDT signal analysis This paper will grve an historical over-

view and describe the state-of-the-art

1. Introduction

A great deal of knowledge has been gained dunng the past 17

years on the subject of conveyor belts and their modes of deg-radation This new knowledge was made possible throughtechniques developed to monitor the reinforcement of conveyorbelts

In retrospect the science of belt nondestructive testing (NDT)was bom in Australia in 1979 with the patenting of a system that

came to be known as the "cbm" or conveyor belt monitor The

research of Harrison [1,2] resulted in a series of papers and

patent applications on the new technologyOnce the concept that a belt could be tested by non-contact

methods was demonstrated, it became an established method

for testing belts worldwide The ramifications to the manufac-turer in terms of quality assessment, and to the mine in terms of

damage evaluation, have been quite profound Research con-

tmues to discover new facts about belt and splice condition Inthis paper, the evolution of belt nondestructive testing into the

science of safety factor (SF) analysis is discussed

The natural direction for application of this research has been in

evaluation of belting safety factors at a damage or defect site

This procedure was developed for steel cord belts as early as

1981 [3,4] No longer is it acceptable to simply measure the lev-

els of damage in the belting, but rather the industry requires an

evaluation of belting strength at the location of greatest con-

Prof Dr Alex Harrison President Scientific Solutions Inc, Managng Mem-

ber Conveyor Technologies Ltd LLC 2200 Chambers Rd,Unit J, Aurora.

CO 80011. USA Tel +1 303 344 9024 Fax +1 303 344 9102

Details about the author on page 149

cern. This thrust encompasses stress analysis of the belting as

a composite material Finally, any analysis that does not con-

sider the starting or stopping forces is lacking in terms of com-

plete evaluation of belting condition

These directions are considered to be the optimally correct ap-proach to evaluating belting condition Belt nondestructive test-

ing applies to both steel cord [5] and fabric belting [6] Testing is

designed to maximize information about the belting

2. State-of-the-Art in TestingProcedures

Rg 1 shows the procedure used to obtain vital data for safetyfactor production based on belt damage or manufacturing qual-ity There are three distinct phases required in the evaluation of

belting condition in relation to the conveyor system Phase 1 is

considered to be the data collection phase, Phase 2 is the anal-

Rg 1 Process used to analyze damage and anomalies in a steel cord belt

O/>g/na/ Safery fecfor SFPhase*

USED BELT NEW BELT

f NDT Process J (cord Plane Scan

Extract damageInformation J C Detect Cord Plane

Variations

Calibration Calibration

Compute StressConcentrationsat Problem Area

Phase 2

GraphicalDisplay (^De-rate Belt SFO SFf

[Measure or >Model Belt

Dynamic Factor J

P/iase 3

(^DeDe-rate Bett SF1

13

Page 2: 15yrs of Conv Belt Nondestructive Eveluation

Nondestructive Conveyor Belt Testing

ysis of the data in terms of actual belting SF relative to the ong-mal design value, and Phase 3 considers the ramifications of the

starting or stopping forces on the actual belting SF value at lo-cations of damage or cord plane defect

In an analysis of the true belting factor SF, the following equa-tions are applied

(D

*2 (2)where SFq =10 (fabric belt - nominal) and SFq = 6 67 (steel cordbelt), where /(., is the computed stress concentration factor atthe damage site or at the irregularity in the reinforcement (usu-ally /c, > 1 2) and /Cg is the ratio of the highest dynamic belt force

Tpeak to the highest static belt tension 7"^Based on the procedure outlined in Fig 1, computation of /c,has been described in detail by Harrison in [7] Analytical meth-ods are used here to determine the stress concentration factorsat damage sites (broken reinforcement) and at manufacturingdefect locations (buckles) In other words, the factor /c, is di-

rectly related to the damage or defect magnitude as detectedby non-contact NDT methods Application of this theory usingcomputer generated stress fields is discussed in a later sectionof this paper

Finally, the computation of /Cg is directly related to the dynamicoverstress in the belting, based on the highest belt tension foreither starting or stopping according to the equation

f = 7 / 72 peak max'

0 (3)

in which kg is either directly measured or modeled on a com-

puter [8] The application of this method is also discussed laterin the paper

3. NDT Systems for Steel Cord Belts -

Phase 1 Testing

3.1 General Background

During Phase 1, the belt is tested by non-contact NDT meth-ods Sensors available for testing steel reinforced belting includemagnetic, eddy current, electromagnetic, x-ray and vibrationsensor systems Sensors available for testing fabric belts in-

elude force transducers, electric field devices, vibration measur-

ing systems and x-rays Each of these systems are employed totest the continuity of the belting reinforcement

There are a number of steel cord NDT systems that have beendeveloped over more recent years as alternatives to the originalConveyor Belt Monitoring system ("cbm") invented in Australiaby Harrison in 1979 (US Patents 4,439,731) During 1990, an

array sensor system was developed at The University of New-castle, Australia These sensors are used by Conveyor Technol-

ogies Ltd (CTL) and TUNRA USA Inc to monitor steel cordbelts

Other less well known alternative monitors include an eddy cur-

rent system developed in Germany, a modified wire rope testingdevice (also developed in Germany) and a steel cord monitoringsystem developed in Canada that displays NDT data in graphi-cal form on a computer screen Many of these alternative mon-itonng systems need to develop a track record in order to pro-vide the industry with the necessary confidence that the data is

being correctly interpreted

Clearly, there are a number of systems that can test steel cordbelts Fabric belts can also be tested but in many cases thetesting is not cost effective The belt monitoring system used byCTL in the USA (BeltScanner) lends itself to diverse applica-tions, including the testing of cable belts, pipe belts, flexowall-type belts and belts with any physical shape

Transmitter Receiver Processor

Magnetic Pocket

Mass

Break

NDT Signal and Signature

OUTPUT

Breaks

Y

Steel Cord

time

time

Fig 2 Schematic of a modern steel cord NDT system

3.2 Damage Monitoring

In general, sensing systems similar to those shown in Fig 2 are

used to test conveyor belts The system in Fig 2 has been de-veloped to monitor corrosion and broken cables in steel cord

belting without the need to magnetize the belt This techniquehas significant advantages over earlier monitoring systems in

that belt magnetization or pre-conditioning is not required to re-

move spurious signals (magnetic pockets) from the belting (USPatent 4,864,233)

Fig 3 shows typical raw data recorded from a test rig designedto simulate a 4 m length of belting The data was obtained froma system described in Fig 2 Full scale deflection of the signalthat represents one broken cable depends on the sensor geom-etry, as is the case with "cbm" systems Nevertheless, the mon-itoring system is highly immune to magnetization in the belting,making it an ideal testing system particularly when some of the

belting is magnetized and some is new and unmagnetised Thissystem removes the complexities associated with magneticconditioning and data interpretation

Some typical NDT signals of damage in a steel cord belt are il-lustrated in this paper Similar types of signal may be recordedfrom fabric belt tests

Fig 3 Outputs of a monitoring system immune to belting fields

14

Page 3: 15yrs of Conv Belt Nondestructive Eveluation

SOlidS Volume 16 Number 1 January/March 1996handling

Nondestructive conveyor Belt Testing

BaitingPressLength

NOT

TrackingEdge of Belt

i->u__J,I Broken Cords-^I

inner Edge at Press Overlap

lot End

Direction of fabrication

Fig. 4: Typical NDT signals of broken cables and a faulty splice snowrtg the

effect on belt mistracking

Fig. 4 shows a record of a steel cord belt magnetic break signal,together with the tracking data, in a region of a faulty and failingsplice. This data was collected with a system shown in Fig. 2.

The splice exhibited considerable edge sag and mistracking,along with an irregular splice signature. Fig. 5 shows a steel

cord belt with periodic damage that results from either rock

spillage or ice lumps traveling around a pulley in the system.

3.3 Testing Manufacturing Quality -Commissioning Scans

A commissioning scan of a new belt will generally discover anyanomaly that is related to belting fabrication. Fig. 6 shows a

cord plane signature with fringing magnetic fields every 30 ft,which happens to be the press length in manufacture. These ef-

Fig. 7: NDT signals showing deterioration at manufacturing defect sites

fects are in fact small vertical displacements of some cables and

their existence has been reported for many years [9]. This typeof departure from a flat plane of reinforcing cables is a defect

that is responsible for cable breakdown over a period of time. A

mechanism that describes the generation of these defects has

been published [10].The greatest problem with defects that involve cable or fabric

layer displacements is reduced belt life and increased stress

concentrations at the defect site, lowering belt SF. Its detection

is therefore just as important as the detection of damage to re-

inforcement in the belting.

Fig. 7 shows the inter-relation between cord plane defects and

the resulting NDT signal when displaced cables fatigue and

break [9]. This figure shows the general location of cable planeanomalies in relation to the press length. A similar process mayoccur in fabric belt fabrication.

iiiiiiiiiiii?ii- H 1 1 1 1 1 1 1-

No. B1 1 1 1 1 1 1

Fig. 5: NDT signals of a belt with damage from rock and ice lumps

Fig. 6: NDT signals for a belt with manufacturing anomofies at a press length

mi BB

BjiBll

-;:

iBSfl

HiS

::::.

rrtr

h:. Mi

kt:::

nH

,7Tnr"T!ilJlfir:

1

fl

I;..

i

= :|!

::' i

tt::

tl:.

Illrj-|,

n

BE 11

s

IT'rrllir?

15

Page 4: 15yrs of Conv Belt Nondestructive Eveluation

Nondestructive Conveyor Belt Testing Volume 16 Number 1 January/March 1996

Stage 3

Fig 8 Computer generated reference signatures of example splices

At this point, both arms of Phase 1 in Fig 1 are completed froman analysis perspective With regard to steel cord belting, the

problems associated with cable displacement during the curingprocess are not restricted to one particular belt supplier Tosolve this problem the belt manufacturer needs to first be ableto compute the magnitude of the cable pre-tension, based on

time-dependent, thermally-induced strain during vulcanisationThe general equations for determining a steel cord cable pre-tension necessary to prevent buckling are

o- P(K, A7", a, /_) > 0 (4)

where Fq is the initial pre-tension in the cables prior to embed-

ding covers, P is the Euler buckling load for a cable stiffness Kbased on a thermal expansion coefficient a and a temperaturechange A7~ in the press heating cycle, and for an initial cable

length L Buckling will usually be initiated at the exit end of the

press rather than at the entry end Cable buckles are locked-into the rubber matrix once rubber curing takes place

3.4 NDT of Splices

As part of the NDT process outlined in Phase 1 testing, con-

veyor belt splices are also monitored because splices are a po-tentially weak link in a steel cord belt A technology has been

Fig 9 Measured NDT splice signatures of typical stage 1 2 and 3 splices

developed to aid in the interpretation of splice NDT signatures[11, 12] This involves the computer generation of referencemagnetic signatures of the particular splice lay-up or geometryReference signatures are unique to each splice design Stage 1,stage 2 and stage 3 splice reference signatures for a particularsplice lay-up pattern are shown in Fig 8 A BeltScanner mon-

itonng system was used to measure these splices

Fig 9 shows some examples of splice signatures recorded frombelts with stage 1, 2 and stage 3 signatures, respectively De-

parture from the ideal signature indicates either a small lay-updifference or the existence of damage In addition, splices thatare in the process of failing have distinctive changes in their NDTsignatures Another use of this technology is in determining an

unknown splice lay-up based on signature matching

4. Phase 2 - Safety Factor AnalysisUntil belts could be nondestructive^ tested, there was no

knowledge available to begin analysis of the effect of damageand defects on the actual working stresses in a belt This prob-lem was particularly relevant to the high tension steel cord beltsbecause of the possibility of lowered safety factors (SF) to re-

duce capital costs

As discussed in Fig 1, the natural step after the detection ofweak locations in a belt is to analyze their relative importance in

terms of potential early failure From 1985 to 1991, a number of

papers were initiated from the above NDT research that mvesti-

gated SF issues [13-17] A notable paper was published in 1990on "Safety Factor Calculations for High-Strength Inclined Beltsbased on NDT Analysis" [16] This paper showed how stressconcentration factors can be developed and used to generatecomputer-based tension distributions across the width of a beltat sites of damage or loss of reinforcement tension

Fig 10

CSF

2 464

i a

B 8

Model result for a 46 cord system with 4 broken cables

CSF = Cord Stress Factor1 sisna T(i) = 1 8888

1,1

Coda data AH 8Composite Non-edge Break ModelNo of Breaks - 4 (fro cord 2 >

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 II 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

46 Cords per Uidth

16

Page 5: 15yrs of Conv Belt Nondestructive Eveluation

SIMS Volume 16 Number 1 January/March 1996handlin

Nondestructive Conveyor Belt Testing

TENSION RE-OtSTRIBimON6 CORO BREAK IN A 96 CORD BELT

\MOTHOFBGLT(9n

Rg 11 Stress factors at a site of significant cable damage

During 1991 a partition model was developed to allow predic-tion of more complex stress patterns in a belt with damage A

partition model allows the broken reinforcement to reside at anyposition across the belt The research was experimentallytested on 4 and 5 ply fabric belting [17]

Fig 10 shows the application of "Cord Stress Factor" (CSF)modeling to determine the amount of overstress and stress re-

distribution near reinforcement damage This example shows

the stress distribution in a 46 cable steel cord belt with the 3rdto 6th cords broken The application also correctly predicts theCSF values for fabric belts with buckled plys

In Fig 10, the CSF is computed to be /c, = 2 464, which means

that the SF of the belt is SF, = 6 67/2 464 = 27 This loweredSF does not allow for any additional stresses from transitions,dynamic forces and loading stresses

Figs 11 and 12 show the results of modeling the stress redistn-bution both across and along the belt The decay of strain alonga belt depends on the relative ratio of the shear modulus of the

Fig 12 Compound breaks are analysed by interacting fields

Multiple Break Tension Analysis6 & 4 cord breaks on a 40 cord belt

Width of Belt

reinforcement and the rubber in the shear zone Analytical solu-tions used by Randall [18] for fabric belts have been developedto apply to steel cord belts Fig 11 shows that when significantbelt damage is detected, stress factors increase considerably in

adjacent unbroken cables, and in some cases result in operat-ing SF values that are close to unity

5. Phase 3 - Dynamic Safety Factor

AnalysisIn conveyor design, the highest belt running tension along a

conveyor is generally used as the basis for setting the beltstrength so that a SFq of between 6 67 (steel cord belt) and 10(fabric) is maintained Belt tensions based on these SF valuesare referred to as 7^ in earlier sections

Forces in the belt above 7"^ need to be predicted so that thevalue of /Cj can be used to further de-rate SF, according to Eq(3) This is achieved by dynamic analysis of the conveyor to ob-tain the highest tensions in the belt on either starting or stop-ping Conveyor profile determines the type of situation that is

likely to produce high forces

All attempts should be made to reduce transient stresses in

belts on starting or stopping [19] In braked downhill conveyors,for example, stopping stresses in the belt will most probablyovershadow any starting forces Take-up type and location hasa good deal of influence on dynamic stress amplitudes Certain

types of conveyor profiles will generate problems with either

high or low dynamic belt tensions on starting or stopping Anassessment of each conveyor on a case-by-case basis is nee-

essary to property evaluate the dynamics of the drive and thebelt as a mechanical system [20 - 24]Assuming that there are dynamic forces above 7"^, then the

dynamic analysis will permit the extraction of peak forces fromwhich /Cj and hence SF2 are calculated

Fig 14 shows a conveyor with a very small fall in elevation,driven at the tail and operated with a brake Braking stops the

conveyor in about 8 seconds There are no booster drives, anda winch at station 6 is locked on stopping This type of conveyormight feed coal to and from a stockpile at a power station

Major points of concern with this conveyor design are:

1 the amount of pretension needed to prevent drive slip on

starting,

Fig 13 Contour maps of the data in Bg 12

5SSS5SEII I 1II I 1II 1 1II I 1II 1II I 111 r 1

Mill 11 mi 11 mi 11 mi 11 IB 11 11 1in 1

j

i 1

11 111 l

I! III 1'I 11 1II 1

1II 1

1 Illll 1il IHII 1

Illll I1 Ulli 11 Illll 1I Illll 1

111II1I

I

11 11

17

Page 6: 15yrs of Conv Belt Nondestructive Eveluation

Nondestructive Conveyor Belt Testing jme 16 Number 1 January/March 1996 SOlidShandling

BELT PROFILE GRAPH - AH 1990 Uer 4 StatUaue

Project: tailflat Belt Lcc = 1353 n

Date: 11-28-1995 Lift = -6 n

Temp *C: © KXc = 10.402 hVwKXr = 0.800 N/nPnain = 263 kU

1

Belt Rating = 2200 kN/nLoad = 2500 T/hr

Velocity =3.50 m/s

KYc = 0.0203XVr = 0.0150Tl = 103 kN T2 = 28 kN

) = Hain Driue Brake = Station 1 TU = Station 6Md' 1 Driue 0 station 0 Power = 0 kU

Fig 14. Belt profile

2. belt forces when a braked stop is activated,

3. belt stresses under braking conditions if there is belting dam-age.

To address these concerns, more than a static tension analysisis required. The dynamic tensions resulting from starting may bemodeled [25] to determine the amount of additional pre-tensionneeded to prevent drive slip on starting. Generally, a soft start

controller would be recommended in this situation.

Stopping can be more complex. The tensions at the output ofthe drive will rise and fall on stopping. Although the belting SFmay be based on the highest 7^ running tension, braking can

cause tensions in the belt to rise beyond predicted levels. Peak

dynamic forces of this nature will further reduce belt SF particu-larly in areas of the belt that are damaged.

Fig. 15 shows the 3D modeling of the tensions in the belt on

stopping. From the data produced by the model, the peakforces at the output of the drive (7g) rise from their static level of

103 kN to 190 kN on the second wave, approximately 6 sec-

onds after shutdown. Since the "T, or tight side running tension

Fig. 15. Dynamic analysis 3D plot showing peak overstress during the stoppingcycle

StoppingTensions

150000^120000g 90000tö 60000§ 30000" 0

Tail

2010

Time (sec)

T1

is 103 kN, the ^ tension rises from 28 kN to 190 kN during a

stop. The arrow in Fig. 15 shows the tension 7^used in the

analysis.In this case, an overstress at 7g of 190 kN, relative to the designtension of 103 kN, is the basis of the SF calculation. The calcu-lation produces a value of /^ = 1.84.

Suppose the belt parameters are similar to those described in

Fig. 10, then the following de-rating of the belt is made:

Original belt: SFq = 6.67

Belt with 4 broken cords: SF^ = SF/2.464 = 2.7

Addition of peak dynamics: SF = SF^/ZCg = 1.46.

The example illustrates the importance of the complete analysisof a belt SF when both damage and dynamic forces are

present. The complete procedure illustrated by Fig. 1 is now

completed, and shows that an analysis based on a system ap-proach is required on a case by case basis.

6. Conclusions

The importance of a systems approach to belt nondestructive

testing has been described in this paper. The methodology de-

veloped over the past 15 years encompasses all known aspectsof the problem of evaluating belting viability.A key element in the analysis of the ultimate belt SF has beenthe development of monitoring methods for testing steel cordand fabric belts. Application of the monitoring technology in itsown right has been beneficial to industry. Demand for this typeof information has led to the development of alternative monitor-ing systems, however the experience in belt nondestructive

testing application is usually essential. The use of belt nonde-structive testing has been developed beyond the simple testingphase.A most often asked question has been, "what does the damagedetected by a monitoring system really mean in terms of belt re-

liability?" To address this question, research was initiated on

safety factor (SF) analysis. Analytical tools have been developedand tested over many years, including software that permits the

analysis of NDT data from any sensor system. The coupling ofbelt stress distribution analysis at damage sites and belt dy-namic analysis methods, to the NDT problem, has resulted in a

technology that answers the vital question regarding belt reli-

ability.

18

Page 7: 15yrs of Conv Belt Nondestructive Eveluation

SOMS Volume 16 Number 1 January/March 1996luntfHnfl

Nondestructive Conveyor Belt Testing

References

[1] Harrison, A.: New development in conveyor belt monitor-

ing; Aust. Machinery & Production Eng., Vol. 32 (1979) No.12, p. 17.

[2] Harrison, A.: Determining conveyor belt serviceabilityusing signature analysis; Process Eng., Vol. 8 (1980) No. 6,pp. 22-25.

[3] Harrison, A.: Developments in bulk handling research in

Australia; Aust. Coal Miner, November 1981, pp. 62-65.

[4] Harrison, A.: Trends in the application of troughed con-

veyor belts; South African Mech. Engineer, Vol. 33 (1983)June, pp. 139-143.

[5] Harrison, A.: A magnetic transducer for testing steel-corddeterioration in high-tensile conveyor belts; NDT Int., Vol.18 (1985) No. 3, pp. 133-138.

[6] Harrison, A.: A new development in textile-ply belt mom-

tonng, bulk solids handling Vol. 8 (1988) No. 2, pp. 231-233.

[7] Harrison, A.: Performance of corded composites with

damaged and misaligned reinforcement; Proc. InauguralAsia/Pacific Composites Institutes Conference, Adelaide.Aust. 1989.

[8] Harrison, A.: Future design of belt conveyors using dy-namic analysis; bulk solids handling Vol. 7 (1987) No. 3,pp. 375-379.

[9] Harrison, A.: Internal fatigue mechanisms in steel cord

belting; bulk solids handling Vol. 11 (1991) No. 4, pp. 839-842.

[10] Kasper, S and Harrison, A.: Steelcord belting: Standards,measurement and field performance; SME Congress,Reno, NV, Feb., 1993, pp. 165-172.

[11] Harrison, A., and Ghys, S.: Evaluation of the inversemethod for NDT of steel cord belt splices; Proceedings12th World Conference on NDT, Amsterdam. 1989.pp. 330-335.

[12] Harrison, A.: Use of reference signature to monitor belt

splices; SME Conference, Phoenix, AZ, 1996.

[13] Harrison, A.: New techniques for monitoring defects in

underground steel cord belts; 21st International Confe-rence of Safety in Mines Research Institutes, Sydney, Aus-traha, 21-25 Oct. 1985, pp. 213-217.

[14] Harrison, A.: A failure model for corded composite plateswith edge fractures; J. Strain Analysis, Vol. 22 (1987) No.1,pp. 49-53.

[15] Harrison, A.: Stress distribution in steel cord belts withcord plane defects and inlaid repairs; bulk solids handlingVol. 8 (1988) No. 4, pp. 443-446.

[16] Harrison, A.: Safety factor calculations for high-strengthbelts based on NDT signal analysis, Proc. Coal Handlingand Utilization Conference, Sydney, June 19-21, 1990,pp. 289-295.

[17] Harrison, A.: Stress concentration prediction at a fracturesite in composite bimatenal plates under axial load; Pro-

ceedmgs International Conference on Fracture of Engi-neenng Materials and Structures, Singapore, 6-8 August,1991, pp. 277-282.

[18] Randall, R.B.: Theoretical stress distribution in splices in

rubber-fabric belts; Mechanical Engineering Transactions,Vol. 5. 1969, pp. 42-50.

[19] Harrison, A.: Transient stresses in long conveyor belts;Proc. Symposium on Belt Conveying of Bulk Solids, Uni-

versrty of Newcastle, November, 1982, pp. 9.1-9.8.

[20] Harrison, A.: Criteria for minimising transient stress in con-

veyor belts; Mechanical Engineering Transactions,IE(Aust),Vol. ME8, No. 3, 1983, pp. 129-134.

[21] Harrison, A.: Reducing dynamic loads in belts powered bythree wound rotor motors; bulk solids handling Vol. 5

(1985) No. 6, pp. 1153-1157.

[22] Harrison, A.: On the appropriate use of dynamic stressmodels for conveyor design; bulk solids handling Vol. 8

(1988) No. 6, pp. 677-680.

[23] Harrison, A.: Modern design of belt conveyors in the con-

text of stability boundaries and chaos; Philosophical Tran-sactions Royal Society, London, Vol. 338, 1992, pp. 491-502.

[24] Harrison, A.: Influence of belt creep and relaxation rateson the design of conveyor drives; Proceedings 5th Interna-tional Conference on Bulk Materials Storage, Handling &

Transportation, Newcastle, 1995, pp. 23-30.

[25] Harrison, A.: Simulation of conveyor dynamics; bulk solids

handling. Vol. 16 (1996) No. 1, pp. 33-36.

RD(TRANSPORTGUMMI GmbH

Made in Germany

STEEL CORD CONVEYOR BELTS

TEXTILE-PLY CONVEYOR BELTS

Rudolstädter Straße 23

D-07422 Bad Blankenburg

Phone: (004936741)5302Fax: (004936741)5440

Reader Service Card No. 719