Recent Research and Development Into Vehicle Technology

PERSPECTIVE

Recent Research and Development into Vehicle Technology Recent Research and Development into Vehicle Technology Yasushi UJITA Vehicle Structure Technology Division (Former) Yasushi UJITA Vehicle Structure Technology Division (Former) RTRI was involved in approximately 300 research themes in the ﬁscal year 2018 to 2019.RTRI Among was involved them, 48 in were approximately related to rolling300 research stock technology,themes in the covering fiscal yeara wide 2018 range to 2019. Amongof themes, them, in 48 practical, were related applied to rolling and fundamental stock technology, research, covering such as: a widethe increase range of in themes, train in practical,running applied speedRecent andand Research improvementfundamental and ofresearch, rideDevelopment comfort, such as: applied theinto increase researchVehicle in suchTechnologytrain asrunning running speed andstability improvement and reliability of ride comfort,of rolling applied stock, andresearch elucidation such as of running the mechanisms stability leadingand reliability to of rollingwheel wear.stock, The and three elucidation topics fromof the amongst mechanismsYasushi this UJITA research leading andto wheel described wear. in The this three paper topics from amongst this research and described in this paper are: “Evaluation of bogie hunting sta- are: " Evaluation of bogie hunting stability,” “Active bogie frame steering system bility,” “Active bogie frameVehicle steering Structure system Technologyensuring both Division running (Former) stability and curving per- ensuring both running stability and curving performance,” and “Technique for formance,” and “Technique for predicting bogies vibration according to running conditions basedpredicting on the transfer bogies characteristics vibration according between to axle running boxes conditions and evaluated based Points.” on the transfer characteristicsRTRI wasbetween involved axle inboxes approximately and evaluated 300 Points.”research themes in the ﬁscal year 2018 to 2019. Among them, 48 were related to rolling stock technology, covering a wide range Keywords : rolling stock, running safety, speeding up, hunting motion test, steering system, Keyof words themes,bogie: rolling in vibration practical, stock, applied running and safety, fundamental speeding research, up, hunting such motion as: the test,increase steering in train system, bogie vibrationrunning speed and improvement of ride comfort, applied research such as running stability and reliability of rolling stock, and elucidation of the mechanisms leading to 1. Introduction wheel wear. The three topics from amongst thisWh researchen class if andyin g described the num b ine r this of v paperehicle related areas are: " Evaluation of bogie hunting stability,”covere d “Active in FY 2 bogie018 ( 4 frame8 case s steering at the b systemeginni ng of the fiscal 1. AIntroductions part of its lo ngensuring-term vi si bothon“ R runningISING” (R stabilityesearc h andIni- curvingyear) ac performance,”cording to the R andeofse FY)a “Techniquerch & Dev el foropm ent direction, t iative and Strategy predicting- Innovat iv bogiese, Ne u vibrationtral, Glo b accordingal) which to4 0 running%When invo l v conditions classifyinge“ Improv e based theme n numbert onof s thea fe of t y transfer, vehicle” as sh o relatedwn in areasFig. 2, sets Asthe partfutu r ofe d itsir e longccharacteristicstion-term to b e vision tak eb netween “RISING” by re axlesea r (Researchcboxesh, an andd i n evaluated covereda trend Points.” inge n FYer a 2018l ly r e (48flec t casesed th atro u thegh o beginningut RTRI, ofin thepar t fiscalicula r, oInitiativerder to r andeali z Strategye this v is-i oInnovative,n , the Rai lw Neutral,ay Tec h Global)nical R e whichsearc h year)artic le accordings regard i tong theim p Researchrovemen t & o f Develrunnopmenting saf e direction,ty & coll i- sets the future direction to be taken by research, and in order to 40% involve “Improvement of safety,” as shown in Fig. 2, a Institute (hereinafteKeyr re f wordserred :t orolling as RT stock,RI) d r runningew up th safety,e s io speedingn safety , up,and hunting diagno s motiontic and test,asse s steeringsment t e system,chnolog bogieies. In 5realize-year b thisasi c vision, plan“ theRE S RailwayEARCH Technical 2020 - C r Researcheating I n Institutenovativ e trendvehi cl generallye system s reflected researc h throughout the perce n RTRI,tage o f in t ot particular,al numbe r (hereinafter referred tovibration as RTRI) drew up the 5-year basic plan articles regarding improvement of running safety & collision Technol ogies” for the fiscal years (FY) 2015 to 2019. Dur- of themes related to“ harmony with the environment” and i“RESEARCHng the fourth 2020year o- f Creatingthis five - Innovativeyear plan i Technologies”n 2018, each d foriv i- “safety,impr oandvem diagnosticent of us eandr c oassessmentnvenience technologies.” was highe rIn t hvehican tleha t stheion fiscal/labo ryearsatory (FY) eng a2015ged toin 2019.resea r cDuringh linke thed t ofourth rolli nyearg st ofoc k systemsin othe r research RTRI r theese a percentagerch divis io ofn s total, i.e . numberprojec ts of i n themescludin g rthisevi 1.e fivew e-dIntroductionyear th e planir p r inog 2018,re ss, eachwith division/laboratorya view to priori t engagedize wor k relatedtopics tosu “harmonych as ene withrgy stheav ienvironment”ngof m FY)easu res andor t“improvementrackside nois e ainn d research target o linkedutcom toes t rollingo mee t stock railw revieweday opera t theiror n e progress,eds. Th e ofre d useructi o convenience”Whenn, and classifyingincrea s wasing ther higherun n numberin g than sp e ofe thatd s vehicle a innd otherri d relatede co RTRImf o areasr t, cwithhan g ae view iAsn t h part toe t prioritize o ofta l itsnu m long workber-term o andf R e vision targetsearc h outcomes “RISING” & Dev e tol o (Researchp meetmen t researchetc.covered divisions, in FY i.e. 2018 projects (48 cases including at the topics beginning such as of energy the fiscal trailwayhemInitiativees operatorat R T andRI , needs. a Strategynd c h aThe n-g eInnovative, changein the n inu mthe Neutral,b e totalr of R Global)numberesearc h ofwhich & savingyear)A n measure e x accordingampsl e or o f trackside toth i thes t y Research p noisee of c reduction,r o &ss - Develcutt i andnopmentg c increasingoop e direction,ratio n DResearchevsetselop them &e nfutureDevelopmentt the directionmes un themesd toer beta ktaken eatn RTRI,b yby v research,e handicle change sy andste minin lorderathebo - to runningcan40% be fspeeds oinvolveund iandn “Improvementw rideork comfort,relating of etc.to safety,” safety oasf vshownehicle sin a Fig.gain s2,t a rnumberatorealizeries ofin thisResearchRT R vision,I fo r &t h the Developmente p Railwayast 5 ye a Technical r themess are s h undertaken Researchown in F Institutei g by. 1 . crostrends win d generallys and fir e reflected prevent io throughoutn, where th RTRI,e veh ic inle s particular,ystems vehicle system laboratories in RTRI for the past 5 years are Ther(hereinaftere are 9 ve hreferredicle sy stote asm RTRI)labora drewtorie sup in the to t5a-lyear, in cbasludicin plang diviarticlession w o regardingrks in co oimprovementperation wi tofh trunninghe Env isafetyronm e&nt acollisionl En- shown in Fig. 1. There are 9 vehicle system laboratories in the “RESEARCHVehicle Struc t 2020ure T -e cCreatinghnology InnovativeDivision, V Technologies”ehicle Contro l for ginesafety,ering ,and Ma diagnosticterial Tec handno lassessmentogy, Disas ttechnologies.er-preventio nIn Tvehicech-le total, including the Vehicle Structure Technology Division, Techtheno lfiscalogy D yearsivisi o(FY)n an 2015d Ra itolw 2019.ay D y nDuringamics Dtheiv ifourthsion. yearBe- of nolosystemsgy, Hu m researchan Scie n thece, percentageetc. divisio n ofs i totaln th e number course ofof t themesheir Vehicle Control Technology Division and Railway Dynamics tweethisn t h fiveem-,year the y plan hav ine e 2018,ngag e eachd in a division/laboratorybout 40 themes a engagedt the worrelatedk. to “harmony with the environment” and “improvement Division. Between them, they have engaged in about 40 begiinnn researching of e a linkedch fis ca tol y rollingear. T h stocke tot a reviewedl numbe r their of t h progress,emes ofA s user exa m convenience”ples of rec e wasnt a c higherhieve m thanen ts that in v ine h othericle s RTRIys- themes at the beginning of each fiscal year. The total number covewithred a at viewRTR I to s h prioritizeown by p workoint s and joi n targeted b y outcomes a line in toF i meetg. temresearchs resea rdivisions,ch in th ii.e.s r eprojectsgard, t includinghe follow topicsing s esuchctio nas g energyives of themes covered at RTRI shown by points joined by a line in 1 flurailwayctuate s operator betwe e needs.n 270 toThe 29 0 change, and t inh ethe ve h totalicle numbersystem of a brsavingief ov e measurer view so f or th tracksidee outcom noisees to :“reduction, Evalua ti andon o increasingf bogie Fig. 1 fluctuates between 270 to 290, and the vehicle system themResearches corre s&p oDevelopmentnd to about 1themes5% of tath eRTRI, total nandum changeber. in the hunrunningting st speedsability and,”“ rideAct icomfort,ve bogi eetc. fr ame steering system themesnumber correspond of Research to about & 15% Development of the total themesnumber. undertaken by vehicle system laboratories in RTRI for the past 5 years are shown in Fig. 1. There are 9 vehicle system laboratories in total, including the Vehicle Structure Technology Division, Vehicle Control Technology Division and Railway Dynamics Division. Between them, they have engaged in about 40 Fig. 2 Classification of themes according to R&D themes at the beginning of each fiscal year. The total number direction of 9 vehicle system laboratories in FY of themes covered at RTRI shown by points joined by a line in 2018

Fig. 1 fluctuates between 270 to 290, and the vehicle system

themes correspond to about 15% of the total number. An example of this type of cross-cutting cooperation can

be found in work relating to safety of vehicles against cross

winds and fire prevention, where the vehicle systems division

works in cooperation with the Environmental Engineering, Fig.Fig. 1 1 Number Number of themes of themes researched researched in vehicle in vehicle related Material Technology, Disaster-prevention Technology, Human related laboratorieslaboratories being being implementedimplemented (beginning (beginning of Science,Fig.Fig. 2 eClassification 2tc. divisions Classification in theof themescourse of themes of according their work.according to R&D to direc R&D- FY) directiontion of 9 of vehicle 9 vehicle system system laboratories laboratories in FY 2018in FY 2018

QR of RTRI, Vol. 60, No. 4, Nov. 2019 An example of this type of cross-cutting cooperatio2n2 can9

be found in work relating to safety of vehicles against cross

winds and fire prevention, where the vehicle systems division

works in cooperation with the Environmental Engineering, Fig. 1 Number of themes researched in vehicle Material Technology, Disaster-prevention Technology, Human related laboratories being implemented (beginning Science, etc. divisions in the course of their work.

As examples of recent achievements in vehicle systems compare running stability with different bogie specifications, research in this regard, the following section gives a brief over fixed excitation conditions were used. However, with the view of the outcomes to: “Evaluation of bogie hunting results above, it is possible to adjust the excitation conditions stability”, “Active bogie frame steering system ensuring both so that the initial amplitude becomes constant and make a running stability and curving performance”, and “Technique comparison with reduced variation in the limit speed for predicting bogie vibration according to running conditions evaluation values. based on the transfer characteristics between axle boxes and The next objective is to develop an analytical or evaluated Points.” numerical method that quantitatively estimates the relationship between the running speed and the upper limit of the initial amplitude and build a running stability evaluation method that 2. Evaluation of bogie hunting stability [1] does not require a large-scale stationary rotation test using the roller rig. It is possible to evaluate the running stability (hunting elimitnsur ispeed)n gAs bo examples tofh rau nbogieni nofg throughsrecenttabili tachievements ystationary and cur vrotationin ing pvehicleer ftestsorm asystemsusingnce,” compare running stability with different bogie specifications, athendresearch“ rollerTech nin testiq thisu e rig fregard,o r in p r RTRIed theict i followingn (Fig.g bo g 3).ie vsection However,ibrati ogivesn a thec cao rbrief criticalding over to fixed excitation conditions were used. However, with the rhuntingunviewnin g ofspeedco n thed it canio outcomesn s vary ba sdependinge d to:on t “Evaluationhe ontra hownsfe r initial ofch a bogier a shakingct er huntingist i iscs results above, it is possible to adjust the excitation conditions bappliedetstability”,ween (e.g.,axl e“Active bo excitationxes abogiend ev conditionsframealuat esteerid P o ofingn t thessystem.” rollers). ensuring If theboth so that the initial amplitude becomes constant and make a evaluationrunning stabilityresult of andcritical curving hunting performance”, speed is sufficiently and “Technique higher comparison with reduced variation in the limit speed thanfor thepredicting running bogiespeed vibrationof bogies according in commercial to running operation, conditions this evaluation values. 2kind. basedEv a ofl u on variationat i theon transferof doesbog i characteristicse not hu n intterfere.ing st a between Inbi li orderty [1 axle ] to boxesevaluate and The next objective is to develop an analytical or stabilityevaluated in Points.” more detail, work is underway to elucidate the numerical method that quantitatively estimates the relationship conditions It is po thatssib generatele to eva huntingluate th oscillation.e running s tability (hunting between the running speed and the upper limit of the initial lim it speed) of a bogie through stationary rotation tests us- amplitude and build a running stability evaluation method that ing2. t hEvaluation e roller test rofig bogiein RTR huntingI (Fig. 3) stability. Howeve r[1], th e critical does not require a large-scale stationary rotation test using the hunti ng speed can vary depending on how initial shaking roller rig. is app liIte d is ( e possible.g., exci t toat i evaluateon cond i thetio n runnings of the stabilityrollers) . (hunting If the evalimitlu at speed)ion re soful ta obogief cri tthroughical hu nstationaryting spe erotationd is su ftestsficie nusingtly higthehe r rollerthan t testhe r rigun n inin g RTRI spee d (Fig. of b o 3).gie s However, in comm theerc ia criticall op- erahuntingtio n, th speedis kin d can of varyvari adependingtion does onno t how int e initialrfere. shakingIn orde r is to appliedeva lua te (e.g., sta bi excitationlity in m o conditionsre detail, w ofo r thek i s rollers).underw a Ify t theo Fig.Fig. 4 Occurrence4 Occurrence conditions conditions of hunting of hunting oscillation eluevaluationcid ate the result cond iofti ocriticalns tha thunting genera speedte hu nist isufficientlyng oscillat ihigheron. oscillation thanW h theen runningthe rot speedation ofsp bogieseed o fin r ocommercialllers is g roperation,adually ithisn- Th e next objective is to develop an analytical or nu- crekindas ed ofw it variationhout ex c doesitati o notn, h inunterfere.ting o s Inci ll orderation tooc c evaluateurs at m3.e r Activeica l me th bogieod th at frame quant it steeringatively e st systemimates th ensuringe relation - a cstabilityert ain s inpe e mored (“ o detail,ccurre n workce s p ise e underwayd”), and if to t h elucidatee rotati o then sbothhip b e runningtween th e stabilityrunning sp andeed a curvingnd the u p performanceper limit of th e speed is gradually decreased from the occurrence speed, initial amplitude and build a running stability evaluation conditions that generate hunting oscillation. [2] the h unting oscillation converges at a certain speed (“con- method that does not require a large-scale stationary rota- vergence speed”). In the range of speed between the con- tion tes t using the roller rig. Fig. 3 Rotation tests using the roller test rig A bogie frame steering system was developed that vergence and the occurrence speed, the excitation condi- As examples of recent achievements in vehicle systems featurescompare bothrunn ing running stability stability with and different curving bogie performance. specifications, It tions of the roller determine whether the bogie will reach researchWhen in thethis rotation regard, speedthe following of rollers section is gradually gives a increabrief oversed accomplishesfixed excitation this by conditions controlling were the used.turning However, angle of the with bogie the hunting oscillation or not. Therefore, various excitation 3. Act ive bogie frame steering system ensuring both withoutview of excitation, the outcomes hunting to:oscillation “Evaluation occurs ofat a bogie certain hunting speed frameresults relative above, toit isthe possible body, which to adjust reduces the excitation the lateral conditions force in conditions were tested to experimentally determine the run ning stability and curving performance [2] (“occurrencestability”, “Active speed”), bogie and frame if the steeri rotationng system speed ensuring is gradually both curvedso that sections, the initial and amplitudeby operating becomes as a passive constant yaw and damper make in a conditions under which hunting oscillation occurs (Fig. 4). decreasedrunning stability from the and occurrence curving performance”, speed, the hunting and “Technique oscillation highcomparison-speed straight with reduced sections. variation Unlike the in wheelset the limit steering speed The results indicate that the amplitude of lateral dis- A bogie frame steering system was developed that fea- convergesfor predicting at a bogie certain vibration speed (“convergenceaccording to running speed”). conditions In the method,evaluationFig. this values. 4 system Occurrence does not conditions require a of special hunting linking placement of the wheelset, which occurs immediately after tures both running stability and curving performance. It rangbasede of on speed the transfer between characteristics the convergence between and theaxle occurrence boxes and mechanismThe next to be objective mounted oscillation on is the to un develop-sprung an masses analytical i.e. axle or excitation (“initial amplitude”) has an upper limit at which accomplishes this by controlling the turning angle of the speed,evaluated the Points.” excitation conditions of the roller determine boxenumerical s, which method prevents that increasing quantitatively the mass estimates of the the bogie. relationship the vibration converges. If the initial amplitude does not bogie frame relative to the body, which reduces the lateral whether the bogie will reach hunting oscillation or not. between3. This Active the bogie running bogie frame speed framesteering and steeringsystem the upper is composed system limit of the ensuring of initialthree reach this upper limit (marked by circles in Fig. 4), after force in curved sections, and by operating as a passive Therefore, various excitation conditions were tested to elements:amplitudeboth running theand steering build stability a running control device,st andability curving whichevaluation detects performance method a curve that eexperimentallyxcitat ion, the determine vibratio nthe co connveditionsrges. Oundern th ewhich othe huntingr hand , yaw damper in high-speed straight sections. Unlike the 2. Evaluation of bogie hunting stability [1] anddoes[2] calculates not require the a large steering-scale command, stationary the rotation hydraulic test using steering the woscillationhen e xci toccursation (Fig.cond 4).itio n s exceed this limit (marked by wrollerheel srig.et steering method, this system does not require a actuator, which can also operate as a passive yaw damper, and crosseThes in F resultsig. 4) , t indicatehe vibr at thation d theive rg amplitudees and re ac ofh es lateral hunt - specia l linking mechanism to be mounted on the un-sprung ItFig. is possible3 Rotation to evaluate tests theusing running the roller stability test (hunting rig a mechanicalA bogie bogie frame angle steering detection system mechanism was developed that prevents that indisplacementg oscillation of, a thend twheelset,he regul awhichr amp occurslitude immediatelyrapidly incr eafterases masse s i.e. axle boxes, which prevents increasing the mass limit speed) of a bogie through stationary rotation tests using reversefeatures steering both and running miss -steering stability in and straight curving sections performance. (Fig. 5). It cexcitationlose to th (“initiale limit ,amplitude”) where it c ohasnt aanct supper the flimitlang ate. whichAlso, tthehis of the bogie. the rollerWhen test the rigrotation in RTRI speed (Fig. of rollers 3). However, is gradually the increa criticalsed accomplishes this by controlling the turning angle of the bogie uvibrationpper lim converges.it decrease Ifs sthetea initialdily a amplitudes the rota tdoesiona notl sp reacheed o fthis the This bogie frame steering system is composed of huntingwithout speed excitation, can varyhunting depending oscillation on occurs how initial at a certain shaking speed is frame relative to the body, which reduces the lateral force in wupperheels limit incr e(markedases fro bym tcircleshe co ninve Fig.rgen 4),ce safterpee dexcitation, to the oc ctheur - three elements: the steering control device, which detects a applied(“occurrence (e.g., speed”), excitation and conditions if the rotation of the speed rollers). is gradually If the curved sections, and by operating as a passive yaw damper in rvibrationence spe e converges.d. Before th Onis te thest , t othero co m hand,pare r whenunnin g excitation stability curve and calculates the steering command, the hydraulic evaluationdecreased result from of the critical occurrence hunting speed, speed the is sufficiently hunting oscillation higher high -speed straight sections. Unlike the wheelset steering wconditionsith differ exceedent bo gthisie slimitpeci f(markedications ,by fi xcrossesed exc iinta Fig.tion 4),co nthedi - steeri ng actuator, which can also operate as a passive yaw thanconverges the running at a speed certain of speed bogies (“convergence in commercial speed”). operation, In this the method, this system does not require a special linking tvibrationions wer ediverges used. H o andwe v reaer, cheswith huntingthe res u oscillation,lts above, i andt is p theos - damp er, and a mechanical bogie angle detection mecha- kindrang e of of variation speed between does not the in convergenceterfere. In orderand the to occurrence evaluate mechanism to be mounted on the un-sprung masses i.e. axle sregularible to amplitudeadjust th erapidly excita increasestion con dcloseition tos stheo t hlimit,at th wheree init iita l nism that prevents reverse steering and miss-steering in stabilityspeed, in the more excitation detail, conditionswork is underway of the to roller elucidate determine the boxe s, which prevents increasing the mass of the bogie. acontactsmplitud thee b flange.ecomes Also, cons tthisant upper and mlimitake decreases a compa steadilyrison w asith straig ht sections (Fig. 5). conditionswhether that the generate bogie will hunting reach oscillation. hunting oscillation or not. This bogie frame steering system is composed of three rtheedu c rotationaled variat io speedn in t h ofe l im theit sp wheelseed ev a increasesluation v a fromlues. the A bogie turning test that simulated a bogie running Therefore, various excitation conditions were tested to elements: the steering control device, which detects a curve convergence speed to the occurrence speed. Before this test, to throu gh a curve, conducted on a commercial line, con- experimentally determine the conditions under which hunting and calculatesFig. 5 the Bogie steering frame command, steering the system hydraulic steering firmed that it is possible to reduce the bogie turning mo- oscillation occurs (Fig. 4). actuator, which can also operate as a passive yaw damper, and ment by approximately 77% through steering control (Fig. 6). The results indicate that the amplitude of lateral a mechanical bogie angle detection mechanism that prevents Also, a steering stability test confirmed that the system displacement of the wheelset, which occurs immediately after reverse steering and miss-steering in straight sections (Fig. 5). could ensure running stability equivalent to that of current excitation (“initial amplitude”) has an upper limit at which the

vibration converges. If the initial amplitude does not reach this upper limit (marked by circles in Fig. 4), after excitation, the Fig. 4 Occurrence conditions of hunting vibration converges. On the other hand, when excitation oscillation conditions exceed this limit (marked by crosses in Fig. 4), the vibration diverges and reaches hunting oscillation, and the 3. Active bogie frame steering system ensuring regular amplitude rapidly increases close to the limit, where it both running stability and curving performance contacts the flange. Also, this upper limit decreases steadily as the rotational speed of the wheels increases from the [2]

convergenceFig. 3 Rotation speed to the tests occurrence using thespeed. roller Before test this rig test, to Fig. 3 Rotation tests using the roller test rig A bogieFig.Fig. frame5 Bogie Bogie steering frame frame systemsteering steering was system system developed that features both running stability and curving performance. It When the rotation speed of rollers is gradually increased accomplishes this by controlling the turning angle of the bogie without excitation, hunting oscillation occurs at a certain speed 230 frame relative to the body,QR owhichf RTR Ireduces, Vol. 6 0th, eN lateralo. 4, N oforcev. 20 in19 (“occurrence speed”), and if the rotation speed is gradually curved sections, and by operating as a passive yaw damper in decreased from the occurrence speed, the hunting oscillation high-speed straight sections. Unlike the wheelset steering converges at a certain speed (“convergence speed”). In the method, this system does not require a special linking range of speed between the convergence and the occurrence mechanism to be mounted on the un-sprung masses i.e. axle speed, the excitation conditions of the roller determine boxes, which prevents increasing the mass of the bogie. whether the bogie will reach hunting oscillation or not. This bogie frame steering system is composed of three Therefore, various excitation conditions were tested to elements: the steering control device, which detects a curve experimentally determine the conditions under which hunting and calculates the steering command, the hydraulic steering oscillation occurs (Fig. 4). actuator, which can also operate as a passive yaw damper, and The results indicate that the amplitude of lateral a mechanical bogie angle detection mechanism that prevents displacement of the wheelset, which occurs immediately after reverse steering and miss-steering in straight sections (Fig. 5). excitation (“initial amplitude”) has an upper limit at which the vibration converges. If the initial amplitude does not reach this upper limit (marked by circles in Fig. 4), after excitation, the vibration converges. On the other hand, when excitation conditions exceed this limit (marked by crosses in Fig. 4), the vibration diverges and reaches hunting oscillation, and the regular amplitude rapidly increases close to the limit, where it contacts the flange. Also, this upper limit decreases steadily as the rotational speed of the wheels increases from the convergence speed to the occurrence speed. Before this test, to Fig. 5 Bogie frame steering system

actualactual railway railway cars cars in in operation operation and and provided provided by by related related institutions of around the world.” Therefore, these values do AA bogie bogie turning turning test test that that simulated simulated a a bogie bogie runningrunning institutions of around the world.” Therefore, these values do not indicate whether vibrations were measured during actual throughthrough a a curve, curve, conducted conducted on on a a commercial commercial line, line, confirmed confirmed not indicate whether vibrations were measured during actual operation and under every possible condition, while thatthat it it is is possible possible to to reduce reduce the the bogie bogie turning turning moment moment by by operation and under every possible condition, while understanding this issue is important to prevent incidents such approximatelyapproximately 77% 77% through through steering steering control control (Fig. (Fig. 6). 6). Also, Also, a a understanding this issue is important to prevent incidents such as components becoming detached. Nevertheless, since it is steeringsteering stability stability test test confirmed confirmed that that the the system system could could ensure ensure as components becoming detached. Nevertheless, since it is not easy to measure vibrations of a running bogie on a runningrunning stability stability equivalent equivalent to to that that of of c urrentcurrent vehicles. vehicles. Also, Also, an an not easy to measure vibrations of a running bogie on a commercial line, it is necessary to develop a method that can runningrunning test test confirmed confirmed that that it it is is possible possible to to reduce reduce the the average average commercial line, it is necessary to develop a method that can easily identify and evaluate different vibration conditions. laterallateral force force when when passing passing through through a acurve curve with with a aradius radius of of 160 160 easily identify and evaluate different vibration conditions. With this background in mind, a method is being metersmeters by by approximately approximately 56% 56% (Fig. (Fig. 7). 7). With this background in mind, a method is being developed to estimate the acceleration of the evaluated points ThisThis system system is is effective effective for for rolling rolling stock stock used used on on intercity intercity developed to estimate the acceleration of the evaluated points of a bogie according to running conditions by numerical servicesservices that that may may be be subject subject to to large large lateral lateral forces forces when when of a bogie according to running conditions by numerical calculation. This method considers a transfer function that passingpassing through through sharp sharp curves curves or or when when the the curve curve passing passing speed speed calculation. This method considers a transfer function that takes axle box acceleration, which is considered to be highly isis increased, increased, and and it it can can be be installed installed in in existing existing vehicles vehicles takes axle box acceleration, which is considered to be highly correlated with track displacement (the main cause of bogie equippedequipped with with conventional conventional passive passive yaw yaw damper dampers.s. correlated with track displacement (the main cause of bogie ivibration),nvibration),cidents sas uas canh an ainput, sinput, com and pando nacceleratio eaccelerationts beconm nof iofn theg the d evaluatede tevaluatedached. pointsN pointsever - on the bogie as an output. This transfer function is determined thonel ethess, bogiesince asit anis noutput.ot eas yThis to mtransfereasur efunction vibrati oisn sdetermined of a run- nthroughing bo gai evibration on a co mmeasurementmercial lin etest, it conductedis necessa atry at odepot deve orlo p through a vibration measurement test conducted at a depot or amaintenance method th factoryat can (“ineas-ihousely ide test”ntif ybelow), and e vwhichaluat ise easierdiffer eton t maintenance factory (“in-house test” below), which is easier to vcarryibra t oution c thanond i largetions-.scale running tests. In the running test, carry out than large-scale running tests. In the running test, onlyonlyW the theit haxle axleth iboxs boxba accelerationc accelerationkground i nis is mmeasured measuredind, a m [5, [5,et 6].h 6].o d i s being de-

velopAseAsd at oaresult eresultstim of aof tsuche such th eactivities, aactivities,ccelera ta i aomethod nmethod of th ewas wasev aproposed lproposeduated p othat ithatnt s

oestimatesfestimates a bogi e the theac c accelerationo accelerationrding to r PSDu PSDnni n atg at thec theon d evaluated evaluateditions b y points pointsnum e of r ofi c a a al running bogie. This method combines the transfer function carunninglculati o bogie.n. Th i Thiss m e methodthod c o combinesnsiders a the tr a transfernsfer fu functionnction tbetwehat tenak ethes a accelerationxle box acc eofle rtheati oaxlen, w boxhic hand is evaluatedconsidere dpoints to b e actualbetwe en railway the acceleration cars in operation of the axle and box provided and evaluated by related points hofig thehly bogie,correl aestimatedted with withtrac kthe d iinsp-lhouseacem etenstt (carriedthe ma ouin t catau as e institutionsof the bogie, of aroundestimated the with world.” the in Therefore,-house te st these carried values out doat a A bogie turning test that simulated a bogie running ocarfcar b witho withgie thev theib raxle aaxletio boxn box), aacceleration sacceleration an inpu tmeasured, measuredand acc ate atl ea r aacommercial tcommercialion of th e not indicate whether vibrations were measured during actual through a curve, conducted on a commercial line, confirmed elinevlineal u(Fig. a(Fig.ted 8 8pand oandin 9).t s9). oInitially, nInitially, the b oan gani impacte impactas a ntest testou int pin ua tastationary. stationaryThis tra staten statesfe r that it is possible to reduce the bogie turning moment by operationwas being and considered under for every the possible in-house condition, test, but it while was funderstandinguwasnct io ben ingis d e consideredthister missueined is t forimportanthro u thegh a in tov-house ipreventbrat io test,n incidentsm e butasu r itesuch m wasen t Fig.approximatelyFig. Fig.6 6Reduction 6 Reduction Reduction77% throughof turning of of steeringturning turning moment control moment moment in (Fig. bogie in in6). bogie bogierotationAlso, a tconfirmedeconfirmedst condu c that t thated thea thet a accuracy d accuracyepot or of m of a the i thent e estimation n estimationance fac t increases o increasesry “( in- h with o withus e steering stability test confirmedrotation that test the system could ensure asthe componentsuse of in-house becoming running detached. data. Also, Nevertheless, using the accelerations since it is test rotation test tnotethest ” easy usebe l ofo tow in) , measure-whousehich runningi s vibrations easi edata.r to ofcAlso,a r ar y runningusingout t hthea n bogieaccelerations larg e on-sc a al e running stability equivalent to that of current vehicles. Also, an in the left/right and forward/backward directions of the axle rcuommercialinn n theing left/right tes line,ts. I n it and tish e necessary forward/backwardrunning tote sdevelopt, on l directionsy tah methode axle ofb that o thex a canc axlece l- running test confirmed that it is possible to reduce the average box as inputs, in addition to the acceleration in the vertical eeasilyrboxatio n asidentify i s inputs, me aands u inr evaluatee d ad [dition5, 6] .different to the accelerationvibration conditions. in the vertical lateral force when passing through a curve with a radius of 160 direction, contributed to even more accurate results. direction,AWiths a r e thiscontributedsul t backgroundof su ctoh evenac ti inv morei ti mind,es ,accurate a m ae th method results.od wa s is p ro beingpose d meters by approximately 56% (Fig. 7). that e stimates the acceleration PSD at the evaluated This system is effective for rolling stock used on intercity developed to estimate the acceleration of the evaluated points point s of a running bogie. This method combines the trans- services that may be subject to large lateral forces when of a bogie according to running conditions by numerical fer fu n ction between the acceleration of the axle box and passing through sharp curves or when the curve passing speed calculation. This method considers a transfer function that evalua ted points of the bogie, estimated with the in-house is increased, and it can be installed in existing vehicles takes axle box acceleration, which is considered to be highly test ca rried out at a car with the axle box acceleration mea- equipped with conventional passive yaw dampers. correlated with track displacement (the main cause of bogie sured at a commercial line (Fig. 8 and 9). Initially, an im- vibration), as an input, and acceleration of the evaluated points pact te st in a stationary state was being considered for the on the bogie as an output. This transfer function is determined in-hou se test, but it was confirmed that the accuracy of the through a vibration measurement test conducted at a depot or estima tion increases with the use of in-house running data. maintenance factory (“in-house test” below), which is easier to Acarrylso, u out si n thang th e large acce-scalelerat irunningons in t htests.e le ftIn/r i theght runningand for wtest,ard /

bonlyack wthea raxled di boxrect accelerationions of the isax measuredle box as [5, in p6].ut s , in addition

Fig. 7 Reduction of average lateral force in to thAse a ac cresultelera tofio nsuch in tactivities,he vertic a lmethod direct iwason, cproposedontribut ethatd t o Fig. 7 Fig. Reduction 7 Reduction of average of average lateral force lateral in running force in test even m ore accurate results. running test on test track. estimates the acceleration PSD at the evaluated points of a on test trackrunning test on test track. runningHo w bogie.ever, d Thisiffer e methodnt vehi c combinesle models theand transferrunnin g function section s resul te d in different levels of accuracy. This is thought to betwe en the acceleration of the axle box and evaluated points v e hicles. Also, an running tes t confirmed that it is possible be cau sed by the amplitude dependence caused by the non- of the bogie, estimated with the in-house test carried out at a t4.o4. re d Techniqueu Techniquece the ave r a forg fore la t predictinge predictingral force w h bogieen bogie pas s in vibrationg vibration through lin ear properties of the spring and anti-vibration rubber, car withFig. the8 axleOutline box acceleration of bogie vibration measured estimationat a commercial aaccording caccordingurve with a to tor a d runningi runningus of 16 0 conditionsm conditionseters by a p basedp basedroxim a onte onl y the5the6% blineut f(Fig.uFig.rth e8 8r and in vOutline 9).est iInitially,gatio ofn i bogiesan r eimpactqu ivibrationred test. in a estimationstationary state method ( transferFtransferig. 7). characteristics characteristics between between axle axle boxes boxes and and was L beasingtly , consideredconsiderin g for th methoda thet v ib inr-ahouse tions c test,an b bute c au its e wasd b y This system is effective for rolling stock used on in- t rack conditions and, depending on the evaluated points evaluatedevaluatedFig. 6 points Reduction points [3] [3] of turning moment in bogie confirmed that the accuracy of the estimation increases with tercity services that may be subject to large lateral forces in thHowever,e However,bogie, a l different s differento in th e vehicle vehicleelectr i modelsc modelsmoto r and, andco mrunning brunningustio nsections sectionsengine , rotation test the use of in-house running data. Also, using the accelerations when passing through sharp curves or when the curve aresultednresultedd dri vin ein udifferent ndifferentit, fut ulevels rlevelse p laof nof saccuracy. accuracy.are to i nThis cThisor pis ois rthoughta thoughtte the to iton bef lbeu - TheThe vibration vibration that that occurs occurs in in the the bogie bogie of of a a running running in the left/right and forward/backward directions of the axle passing speed is increased, and it can be installed in exist- ecausedncausedce of by tbyh ethe sthee amplitudef aamplitudectors in dependencet odependence a widen ecausedd caused scop eby byo fthe thean nona nonlys-lineari-slinear an d railwayrailway car car may may be be related related to to the the loosening loosening of of bolts bolts and and fatigue fatigue box as inputs, in addition to the acceleration in the vertical ing vehicles equipped with conventional passive yaw damp- ppropertiesrpropertiesovide m oof rofe the athec cspringu springrate eand sandtim anti aantiti-ovibration-nvibrations. rubber, rubber, but but further further inin parts parts and and components. components. Japanese Japanese Industrial Industrial Standards Standards [4] [4] direction, contributed to even more accurate results. ers. investigationinvestigation is is required. required. (JIS(JIS E E 4031, 4031, “JIS” “JIS” below) below) stipulate stipulate the the vibration vibration resistance resistance Lastly,Lastly, considering considering that that vibrat vibrationsions can can be be caused caused by by track track propertiesproperties required required in in vehicle vehicle components, components, but but the the values values of of conditionsconditions and, and, depending depending on on the the evaluated evaluated points points in in the the bogie, bogie, vibrationvibration acceleration acceleration specified specified by by JIS JIS were were “measured “measured from from 4. Technique for predicting bogie vibration accord-

ing to running conditions based on the transfer

characteristics between axle boxes and evaluated

points [3]

The vibration that occurs in the bogie of a running railway car may be related to the loosening of bolts and fatigue in parts and components. Japa nese Industrial Standards [4] (JIS E 4031,“ JIS” below) stip ulate the vibration resistance propFig.ertie s7 r eq Reductionuired in ve ofhic averagele compo nlateralents, b uforcet the inva lues of vibration acrunningceleration test spe conifi etestd by track. JIS w ere“ measured f rom actual railway cars in operation and provided by re- l ated institutions of around the world.” Therefore, these v4.al ue Techniques do not ind ic forate w predictinghether vibr ati bogieons w ere vibration measured during actual operation and under every possible condition, Fig.Fig. 8 8 Outline Outline of bogie of bogie vibration vibration estimation estimation method waccordinghile unde rs tota nd runninging this i conditionsssue is imp o basedrtant to on pr evtheen t transfer characteristics between axle boxes and method evaluated points [3] However, different vehicle models and running sections QR of RTRI, Vol. 60, No. 4, Nov. 2019 231 resulted in different levels of accuracy. This is thought to be The vibration that occurs in the bogie of a running caused by the amplitude dependence caused by the non-linear railway car may be related to the loosening of bolts and fatigue properties of the spring and anti-vibration rubber, but further in parts and components. Japanese Industrial Standards [4] investigation is required. (JIS E 4031, “JIS” below) stipulate the vibration resistance Lastly, considering that vibrations can be caused by track properties required in vehicle components, but the values of conditions and, depending on the evaluated points in the bogie, vibration acceleration specified by JIS were “measured from

also in the electric motor, combustion engine, and drive unit, Dynamics and Design Conference 2015, Hirosaki, Aomori, future plans are to incorporate the influence of these factors Japan, August 25–28, 2015, Paper 504 JSME (in Japanese). into a widened scope of analysis and provide more accurate [6] AKIYAMA, Y., TAKIGAMI, T., and YAMAMTO, K., estimations. “Predicting bogie vibration under running conditions,” RRR, Vol. 74, No. 10, pp. 12-15, 2017 (in Japanese).

RAuthorseferenc es

[ 1] YAMANAGA, Y. and KIDO, K.,“ Influence of Excita- Yasushi UJITA, Phototion Condition on Evaluating Critical Hunting Speed,” Quarterly ReportDirector, of RTRI Head, Vo ofl. 60, Vehicle No. 2, pp Structure. 97-102 , Technology Division (Former) 2019. [2] KOJIMA, TResearch., UMEH Areas:ARA ,Carbody Y. et al Structure,.,“ Devel oStructuralpment o f Integrity, Passive Safety of Rolling Stock. bogie frame steering system with active yaw damper,” th presented at 27 the Transportation and Logistics Con- th ference 2018 & 25 J-RAIL2018, Tokyo, Japan, Decem-

ber 5-7, 2018, Paper 2104 JSME (in Japanese). [3] TAKIGAMI, T., AKIYAMA, Y. et al.,“ Technique for predicting bogie vibration under running conditions based on the transfer characteristics between axle boxes and evaluated points,” RTRI Report, Vol. 31, No. 1, pp. 11- Fig.Fig. 9 9 Procedure Procedure ofof vibration estimation estimation method method 16, 2018 (in Japanese). (schematic diagram) [4] Japanese Industrial Standards Committee, Rolling (schematic diagram) stock equipment-Vibration and shock tests (2013 Edi- 5. Co nclusions tion), Japanese Industrial Standards E 4031, 2013. [5] ISHIMORI, A., TOMIOKA, T., et al.,“ Fundamental The findings presented in this article are examples of study on simplified approach to estimate bogie vibra- t5.he Conclusionsresults obtai ned from Research & Development con- tion in Railway Vehicle under arbitrary running condi- ducte d in the field of vehicle technology. Future work will tion,” presented at the Dynamics and Design Confer- continTheue ffindingsocus on presentedimprovin ing rthisunn articleing sa arefety examples as well aofs rtheide ence 2015, Hirosaki, Aomori, Japan, August 25-28, cresultsomfor tobtained, while ofromther Researchresearch &w iDevelopmentll concentra tconductede on them ines 2015, Paper 504 JSME (in Japanese). cthelar if fieldying ofra i vehiclelway-s p technology.ecific prob l e Futurems, im workprov e willmen t continue of non - [6] AKIYAMA, Y., TAKIGAMI, T., and YAMAMTO, K., dfocusestru oncti v improvinge inspect i runningon accu safetyracy, l asab o wellr-sa v asin rideg in comfort,mainte - “Predicting bogie vibration under running conditions,” nwhileance , otheretc., a researchnd deep ewillr co o concentrateperation w i onth r themeselevan t clarifying research RRR, Vol. 74, No. 10, pp. 12-15, 2017 (in Japanese). drailwayivision-sspecific. problems, improvement of non-destructive inspection accuracy, labor-saving in maintenance, etc., and deeper cooperation with relevant research divisions.

AReferencesuthor

[1] YAMANAGA, Y. and KIDO, K., “Influence of Excitation Yasushi UJITA Condition on Evaluating Critical Hunting Speed,” Quarterly Director, Head of Vehicle Structure Report of RTRI, Vol. 60, No. 2, pp. 97-102, 2019. Technology Division (Former) “ [2] KOJIMA, T.,R e UMEHARA,search Areas : Y.C a etrb o al.,dy StruDevelopmentcture, Structu r ofal ” bogie frame steeringIntegr it systemy, Pass iv withe Sa fe activety of R yawollin g damper,Stock presented at 27th the Transportation and Logistics Conference 2018 & 25th J-RAIL2018, Tokyo, Japan, December 5–7, 2018, Paper 2104 JSME (in Japanese). [3] TAKIGAMI, T., AKIYAMA, Y. et al., “Technique for predicting bogie vibration under running conditions based on the transfer characteristics between axle boxes and evaluated points,” RTRI Report, Vol. 31, No. 1, pp. 11-16, 2018 (in Japanese). [4] Japanese Industrial Standards Committee, Rolling stock equipment-Vibration and shock tests (2013 Edition), Japanese Industrial Standards E 4031, 2013. [5] ISHIMORI, A., TOMIOKA, T., et al., “Fundamental study on simplified approach to estimate bogie vibration in Railway Vehicle under arbitrary running condition,” presented at the

232 QR of RTRI, Vol. 60, No. 4, Nov. 2019