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Available online at wwwsciencedirectOOm一一，：，ScienceDirectJ China Univ MinmgTeehnol 18(2008)0629-0633JOURNAL OF CHINA UNIVERSITY OFMINING&TECHNOLOGYiiiiii；iiiii|一WWWelseviercomlocatejcumtDynamic characteristics of conveyor beltsHOU You-fu，MENG QingruiSchool ofMechanical and Electrical Engineering，China University ofMiningTechnology，Xuzhou，Jiangsu 221116。ChinaAbstract：The dynamic characteristics of a beIt conveyor are determined to a large extent by the properties of the beItThis paperdescribes experiments designed to establish the dynamic properties of beIting materialThe dynamic elastic modulus，viscousdamping and theological constants of the belt were measuredSeveral properties were studied as a function of the tensile 10ading onthe beItThese included longitudinal vibrationthe natural vibration frequency iB the transverse direction and the response to animpulse excitationVibration response was observed under severaJ different excitation frequenciesMost of these properties havenot been tested previously under conditions appropriate for the ISO，DP9856 standardo types of belt were testeda steeI reinforced belt and a fabric reinforced beltThe test equipment was built to provide data appropriate for designing belt conveyorsItwas observed tIlat the stress wave propagation speed increased with tensile Ioad and that tensile load was the main factor influencing longitudinal vibrationsKey words：experimentai investigation；dynamic characteristics；conveyor belt1 IntroductionBelt conveyors are，incosteffective solution formost cases，the mosthandling bulk materialmass flows over short and medium conveying distancesThe belt is a key component of these conveyors and its dynamic characteristics determine theworking performance to a great extentAt present，experimental research on the dynamic characteristicsof conveyor belts is mainly concentrated on testingdynamic elastic modulus and viscous damping following the ISO，DP9856 standardLiule research onother dynamic parameters has been carried outE Langebrake et a1tested the breaking and splicestrength of steel cord belts by using a large magneticflux leakage testerI“Blazej et a1tested the tensilestrength of the belt and the strength parameters of therubber used for the adhesivebond ioint in splices byusing a ZP40 testing machine1Hou et a1reviewedthe experimental research work on the dynamic characteristics of the belt published over the past twodecadesThey considered that the test piece used inthe previous research work，based on theIS0，DP9856 standard，was too small(50 mmx300mm)to acquire reliable test data and suggested that alarger one should be adoptedplThis paper describes the design and constructionof an apparatus to investigate the dynamic characteristies of conveyor beltingTwo types of belta fabricbelt and a steel cord belt，commonly used in coalmines were examined2 Experimental21 ParametersThe main parameters studied by the experimentsa：1)The dynamic performance parameters of thebelt2)The relationship between the stress wave propagation speed and the tension force on the belt3)The dynamic response characteristics of the beltunder different tension forces and exciting frequencies4、The natural frequency of transverse vibration ofthe belt22 MethodsThe first step is pretreatment of the test piece，which includes the measurement of its size and peeling two ends off for grippingThen the test piece isinstalled on the test apparatus and kept in tension for24 hours under a given tension forceEach individualtest is repeated ten times and the average value is re-ported as the final test data1)By using the shock response method，the stresswave propagation speed C was found and used toReceived 12 March 2008；accepted 15 July 2008Corresponding authorTel：+8613805207270；Email address：hyfcumtsohucom登一万方数据calculate the dynamic elastic modulus局Acceleration sensors were fixed at certain points to record theresponse signalThe stress wave propagation time tcan be obtained by comparison of the signals of allimpact force and the response signals picked up bythe acceleration sensorsThe stress wave propagationspeed C can be calculated and Ed is then given bythe equation C=e-，where p is the density of theV PbeIt2)The rheoiogical constant_，of the belt is obtained by analyzing the shock and vibration signalsfrom displacement and acceleration sensors mountedat the sane placeThe viscous damping r，of the beltcan be calculated by the relationship between f，rand目3)The response signals of the belt were tested under different tensile loads and exciting frequencies bymounting two displacement and two accelerationsensors at specified places and then analyzing theinteraction between the respective signals41 The natural frequency for transverse vibration ofthe belt was identified by using a swept sinewaveexcitation23 ApparatusThe data from the experiments carried out in thispaper are intended to assist in engineering applicationsTo acquire reliable test data，the apparatus isbuilt to simulate a real belt conveyorThe main fea-tures of the apparatus are as follows(see Fig1)：1)The test piece is supported on carrying idlers，just as real conveyor belts are2、The distance between two carrying idlers is ap-proximately the same as in actual belt conveyors31 The test piece is placed horizontally so that thesag is similar to that of actual belt conveyors41 The test piece is tensioned by a screw nut51 The longitudinal exciting force is applied by avibration exciterThe signals were recorded with a TEAC MR 30tape recorder and were analyzed with an HP3562Adynamic signal analyzer111e test pieces includedfabric belts and steel cord belts commonly used incoal minesThe cross sections of the belts are shownin Fig2The design parameters of the belts are giveninTable 1Fig2 Cross section of the beltsT曲le 1 Parameters of tlle belts!兰!竺 !竺!：!：笠鐾 塞兰 !：竺!竺Steel cord belts STl000 32 025 1000 NmmFabric belts 800+4 32 025 70 Nmmlayer3 Results31 Propagation speed of a stress wave along thebeltThe stress wave propagation time can be obminedfrom the recorded impact force and response signalsThe stress wave propagation speed can be calculatedfrom the timeThe results are shown in Table 2The data in Table 2 show that the stress wavepropagation speed varies with tIle belt type and withtensile loadThe speed increases nonlinearly with anincrease in tensionUnder lower tension the stresswave propagation speed increases more quicklyAsthe tension force increased above a threshold thestress wave propagation speed changed only slightlyThe stress wave propagation speed in the steel cordbelts is greater tIlan that of the fabric belts for a giventensile loadTable 2 Stress wave propagation speed under different tensile Ioads rms)Tensionforce 00N1 6 8 10 12 14 16 18 20Steel cofd belts 11075 13045 15348 15252 15387 15541 15006 15828Fabric belts 8354 9469 10081 10737 10854 1 1066 1 1872 1 147732 Dynamic parameters of the beltsThe dynamic elastic modulus of the belts call be c砌捌胁c=序讪灿wnm万方数据HoUYoufuet al Dynamic characteristics of conveyor beIts 631Table 3The rheological constant of the belts Call be foundby analyzing the acceleration and displacement fromall impact；the results ale shown in Table 4Viscous damping coefficients can be calculatedusing the relationship between dynamic elastic mod-ulus，the rheological constant and the viscous damp-ing；the results ale shown in Table 5Table 3 Dynamic elastic modulus under different tensile loads(Nmm)Tensionforcc(kN) 6 8 10 12 14 16 18 20Stcel cord beIts 257344 357087 494162 488381 496743 507132 472506 525572Fabric belts 27889 35796 40642 46053 47089 48929 51358 52624Table 4 Rheological constants under different tensile loads (s)Tensionforce(kN) 6 8 10 12 14 16 18 20Steel cord beIts 0207 017l 0，151 o，155 0149 0，147 0145 o140Fabric beIts 0255 0245 O250 0253 0248 O26l O249 0246Table 5 Viscous damping under different tensile loads (Nsram)Tensionforce(kN) 6 8 10 12 14 16 18 20Steel cord belts 53269 61061 74618 75699 74014 74548 68512 73579Fabric belts 7109 8768 10160 11651 11675 12768 14031 12944From Tables 3，4 and 5it carl be seen that the dynamic performance parameters of the belts vary overa large range as the tensile load changesThis indicates that because of viscoelastic behavior the dynamic characteristics of the belt vary under differentboundary conditions33 Natural frequency of transverse vibration ofthe beltThe natural，transverse，vibration frequency is thatfrequency where the response of the belt to a sweptsine wave excitation is greatestThe results of sweptsine wave tests are shown in T-lble 6The data in Tlble 6 show that t11e natural frequencyfor transverse vibration in tIle two types of belt increases slightly with all increase in the tensile force ina nonlinear wayThe natural frequency for transversevibration of the steel cord belt is greater than that oftIIe fabric beltAccording to belt transverse vibrationt11eory,the steel cord belts are suitable for high speedbeIt conveyorsTable 6 Natural frequency of transverse vibration under different tensile loads(Hz)Tensionforce(kN) 6 8 10 12 14 16 18 20Steel cord belts 115 123 149 147 153 157 154 158Fabric belts 98 II，7 122 JJ8 121 119 J213 12234 Response characteristics under different ex-citing frequenciesHarmonic excitation was applied to the belt at dif-ferent frequencies(5 Hz，10 Hz，15 Hz，20 Hz，25 Hzand 30 Hz)under various tensile loadingsThe longitudinal vibration of steel cord belts was measuredThe results ale shown in Figs3 and 4From Figs3 and 4，it Call be seen that：1 1 The basic frequency of the longitudinal vibration of the belt is the same as the exciting frequency2)WAveform in the time domain varies with theexciting frequency under the same tension forceHigher-frequency harmonics decrease gradually with卸increase of the exciting frequencyAt arI excitingfrequency of 30 Hz the longitudinal vibration is closeto a first harmonic waveform3)By comparing the longitudinal vibration waveform shown in Fig3 with the one in Fig4 under thesame exciting frequency,it can be seen that the higher-frequency harmonic components are more obviouswhen the tension is greaterDifferent vibrationwaveforlns have different effects on dynamic stressHigher frequency harmonics intensify vibration of thebelt and lcad to increased dynamic stressTllis is alsothe hannful effect from excessive tension35 Response to shock excitationThe vibration response of steel cord belts to anirepulse excitation is shown in Fig5It call be seentllat the response decays exponentially,similar to theresponse characteristics of an elastic bodyThis indicates that the vibration characteristics of the belts alemainly determined by the elastic properties of theframework material of the belts万方数据邑3孚nol，2L5弓00b15f(ms)(a)Under exciting frequency of5 HzO 8020孚oo1215邑00一15O 80 160 240 320 400t(ms)(b)Under excmng fiequency of 10 Hz160 240 320 400 0 80t(ms)(c)Underexcitingfiequencyofl5 Hz0 80 160 240 320f(ms)32孚伽-3260 240 320 400f(ms)(d)Under exgitmg frequency of20 Hz0 80 160 240 320 400t(ms)(e)Under exciting frequency of25 Hz (0 Under exciting frequency of30 HzFig3 Longitudinal vibration of the belt in response to different excitation frequencies10 kN tensile load-o4一孚们一1220三吝03一14O 80 160 240 320 400t(ms)(a)Underexciting frequencyof5 H2_o1邑-04-09o5Z苦-05一150 80 160 240 320 4000 80 160 240 320 400 0，(ms)(c)Under excltmg厅equency of I 5 Hz0 80 160 240 320，(ms)(c)Under exciting rTequency of252OZ吝03一I4t(ms)(b)Underexcitingfrequencyofl0 Hz80 160 240 320 400f(ms)(d)Under exciting fiquency of20 H2400 0 80 160 240 320 400t(脚)(0 Under exciting freqtency of30 HzFig4 Longitudinal vibration of岫belt in response tO different excitation frequencies，20 kN tensile load”罟罟吨m屯一N)万方数据HOU 1rbufu et al Dynamic characteristics of conveyor belts 6336 Conclusionst(s)(”Shock response：10娴loadFig5 Response of steel cord belts to a shock excitation under different tensile loadsThe following conclusions Call be drawn from theresults of the experimentalinvestigation：l 1 Stress wave propagation speed increases nonlinearly with all increase in tension in the beltsFor thesame tension force，the stress wave propagation speedof the steel cord belt is greater than that of the fabricbelt2)The dynamic performance parameters of thebelts，including the dynamic elastic modulustherheological constant and the viscous damping，varywith tension force3)The natural frequency of the transverse vibrationin the belts slightly increases with the tensile lcad in anonlinear wayThe natural frequency of tlle transverse vibration in the steel cord belt is greater thantllat in the fabric belt41 Tension force on the belt is the main factor thatinfluences longitudinal vibration：The effect of excitation frequency iS smallerThis indicates that moreattention should be paid to controlling tensile lcadingin belt conveyor design5)Steel cord belts have the same response characteristic to shock excitation as an elastic bodyThisindicates that the vibration characteristics of a beIt aremainly determined by the elastic properties of itsframework materialAcknowledgementsThe authors would like to gratefully acknowledgeProfZhang Yong-zhong for his valuable contributionsReferences【l】L卸gebrake F，KIein J，Gronau ONondestructive testing of steelcord conve3for beltsBuIk Solids Handling1 9981 8(4)：565569【2】 Bla主cj R，Hardy96ra MModeling of shear sffesses inmultiply belt splicesBulk Solids Handling，2003，23(4)：234_-241 。【3】Hou Y F，Huang M，Zhang Y ZDynamic Performanceand Control Technology of Belt Conyeyor Beijing：Coalindustry Press，2004(In Chinese)万方数据Dynamic characteristics of conveyor belts作者： HOU You-fu， MENG Qing-rui作者单位： School of Mechanical and Electrical Engineering, China University of Mining &Technology, Xuzhou, Jiangsu 221116, China刊名： 中国矿业大学学报（英文版）英文刊名： JOURNAL OF CHINA UNIVERSITY OF MINING & TECHNOLOGY年，卷(期)： 2008，18(4)引用次数： 0次参考文献(3条)1.Langebrake E.Klein J.Gronau O Non-destructive testing of steel-cord conveyor belts 1998(4)2.Bla(z)ej R.Hardygra M Modeling of shear stresses in multiply belt splices 2003(4)3.Hou Y E.Huang M.Zhang Y Z Dynamic Performance and Control Technology of Belt Conveyor 2004相似文献(10条)1.外文会议 Kaldyumov. N. A.Kalihman. L. Ya.Kalihman. D. M.Polushkin. A. V.Nahov. S. F. TECHNIQUE AND DEVICES FOR EXPERIMENTAL INVESTIGATION OF LINEAR ACCELEROMETER DYNAMIC CHARACTERISTICSIn our paper we discuss the technique and devices for measuring dynamic characteristics of linear accelerometers which areapplicable to utilization at the manufacturing plants where accelerometers are being produced.2.外文会议 Kaldyumov N.A.Kalihman L.Ya.Kalihman D.M.Polushkin A.V.Nahov S.F.Scientific Councilof the Russian Academy of Sciences on the Problems of Motion Control and Navigation(RU);International Public Association-Academy of Navigation and Motion Control(ANMC); American Instituteof Aeronautics and Astronautics(AIAA); TECHNIQUE AND DEVICES FOR EXPERIMENTAL INVESTIGATION OFLINEAR ACCELEROMETER DYNAMIC CHARACTERISTICS In our paper we discuss the technique and devices for measuring dynamic characteristics of linear accelerometers which areapplicable to utilization at the manufacturing plants where accelerometers are being produced.3.外文期刊 Berthelot. JM.Sefrani. Y Damping analysis of unidirectional glass fiber composites withinterleaved viscoelastic layers: Experimental investigation and discussion The article investigates the damping of unidirectional glass fiber composites with a single or two interleaved viscoelasticlayers. The experimental damping characteristics are derived from flexural vibrations of cantilever beams as a function of the fiberorientation. The experimental results are analyzed considering the modeling developed in a previous article, Berthelot, J.-M. DampingAnalysis of Orthotropic Composites with Interleaved Viscoelastic Layers Modelling, Journal of Composite Materials (in press). Theanalysis considers the variations of Youngs modulus and damping of viscoelastic layers with the frequency. Finally, the articlepresents the effects of Youngs modulus and the damping of a viscoelastic layer interleaved in the middle plane of unidirectionallaminate. The results are also reported for the case of external viscoelastic layers.4.外文期刊 Ji BH.Wang LT.Yuan Q.Meng QJ.Liu DY.Zhang GH. Experimental investigation of thedynamic characteristics of the damped blade The test facility and measurement system for the investigation of the dynamic characteristics of a damped blade are described.The test results are analyzed, and some important conclusions are drawn. It is found that dry friction between the dampers(or betweendamper and blade) is a very effective means of reducing the vibration of a blade. The resonance frequency, the response amplitude andthe relative damping ratio can all be influenced by dry friction. High harmonic waves on the response ofthe blade which are caused bydry friction are observed in the test. However, the wave response of the damped blade is still basically harmonic. The normal forceacting on the rub surfaces of the damped blade will influence the dynamic characteristics of the blade. Since the damped blade systemis non-linear due to dry friction, the external exciting force can also influence the dynamic characteristics of the blade. (C) 1998Academic Press Limited. References: 55.期刊论文 宋强.孙逢春.马金奎 滑动轴承油膜参数识别的新算法及试验研究 -北京理工大学学报2002,22(6)提出一种滑动轴承油膜动力特性系数(油膜阻尼系数和油膜刚度系数)试验识别新算法.利用振动理论和最小二乘方法推导出识别算法的数学模型,并进行了试验研究.试验结果表明,该方法可以有效地抑制无用信号,具有较高的识别精度.利用该算法不需要事先测量基础刚度和阻尼,同时还可以识别轴颈的等效质量.6.会议论文 Zhu Changsheng Theoretical and experimental investigation into dynamic characteristics ofa rotor supported on a disk-type magnetorheological fluid damper 2007The dynamic characteristics of an overhung flexible rot