冲击载荷作用下平板玻璃穿孔机理(2)

60振动与冲击 2007年第26卷

158 J OURNAL OF V IBRAT I ON AND S HOCK V o.l26N o.12007

t h e syste m are d iscussed using Lyapunov theories.F i n ally,the effects of the m ass and stiff n ess para m eters of the syste m and exciter para m eters are i n vesti g ated w it h nu m erical si m ulations.

K ey w ords:self synchronous v i b rati o n,stab ility,b ifurcati o n

C HAO S CONTROL ANALYSIS

FOR MATH I EU EQUAT I ON BY THREE M ETHODS

L i X ianf eng, Chu Yandong, L iu X iaojun, D eng J in

(School o fM athema ti cs,P hys i cs&So ft w are Eng i neeri ng,L anzhou Jiaotong U n i versity,Lanzhou 730070)

Abst ract By m eans of num erica l si m ulati o ns,the autho rs st u dy b ifurcati o ns and chao tic behav i o rs in non linear M athieu equati o n.The route to chaos is revea led by g l o ba l b ifurcation graph.Phase d iagra m s,ti m e response and po w er spectra m are used to sho w dyna m ic behav i o r of a syste m.By se lecti n g proper control para m eters accord i n g to the b ifurca ti o n graphs,the chaotic m oti o ns o f the syste m can be successfu lly converted to the stab le peri o dic orbits after three m eth ods wh ich are coup led contr o lm ethod,x|x|contro lm ethod and period ic exc iting force one are used to contro l effecti v ely chaotic behav i o rs ofM ath ieu equation.

K ey w ords:M athieu equati o n,bifurcati o n,chaos,chaos contro,l po w er spectrum,Po i n care m ap

ADAPTI VE RES ONANCE DE MODULAT I ON M ETHOD AND I TS APPL I CATI ON TO FAULT D I AGNO SIS OF FRE I GHT CAR ROLL I NG BEARI NGS

L iu J inzhao1, D ing X ia w an2, W ang Chengguo1

(1.Cente r o f R esearch and D evelopment,China A cademy o f R a il w ay Sc ience,Beiji ng 100081

2.Schoo l o fM athe m atics and Co m puter Sc i ence,the Central U niversity for N ationa lities,Be ijing 100081)

Abstract Resonance de m odu lati o n m ethod,other than AR m ode lm ethod,w avelet transfor m m ethod and so on,is adopted by eng ineers to d iagnose faults o f rolling bearings o f a fre i g ht car.But its effecti v eness depends to a great exten t on how to choose the cen ter frequency and the bandw idth of its filter.The difficulty to choose the band pass filter can be avo i d by the adaptive resonance de m odulati o n m ethod presented here.The key point o f the m ethod is to separate high fre quency resonance si g na ls caused by i m pu lse and the l o w frequency ones w ith h i g h ener gy.The au t h ors firstly do ti m e fre quency transfor m on the ti m e si g na l and t h en auto m atica lly ex tract the ti m e energy signal fr o m the ti m e frequency spectrum w it h out filteri n g.I n additi o n,a un if o r m fra m e is proposed to ex tract the ti m e energy si g nalw hich is si m ilar to ti m e edge fro m the ti m e frequency spectr um,w hich is a lso called L p nor m criterion.The nu m erical resu lts show that the adaptive resonance de m odu lation perfor m s e ffecti v ely i n fau lt diagnosis o f fre i g h t car r o lli n g beari n gs w ith outer race faults,inner race ones and rolli n g e le m ent ones and it perfor m s m ore effecti v ely than conventional de m odu lated resonance techniques.

K ey w ords:adaptive resonance de m odulation,ti m e frequency analysis,L p nor m,refined Fourier techn i q ue,fre i g h t car r o lli n g beari n gs,fau lt diagnosis

THE PERFORATI ON M ECHANIS M OF FLAT GLASS UNDER I M PACT LOAD

F ang W eif e ng, Yu X iaoqing

(A i rfie l d Eng i neer i ng Depart m ent o fX uzhou A ir Force A cade m y,Xuzhou 221000)

Abstract G lass,as lighti n g m ateri a,l i s w i d ely used i n buildi n gs,veh i c les,sh i p s,and furnit u re.But it is a typi ca l k i n d o f brittle m ateri a l and ex tre m ely easy to break.Under i m pact load,da m age for m s of g l a ss p late have close re la ti o n to the acti o n types o f the load,w hich can be classified i n to si m p l e break,m i x ed break and perforati o n.H ere,a g lass plate w ith P VC plate as a backboard is used i n shooting perforati o n experi m ents to record perforation fo r m i n g under the i m

pact l o ad .The H ertz t h eo r y is used to calcu late the stress d i s tribution o f the g lass p late under the i m pact load .The for m i n g m echan is m o f break cone angles is analyzed .For the double layered plate consisti n g of g lass and PVC w ith var i o us t h icknesses ,the re l a ti o n bet w een t h e thickness of g lass and break cone ang les is descri b ed under the sa m e experi m ental conditions .

K ey w ords :g lass ,perforati o n ,cone ang le ,i m pact load

ANALYSIS OF AXI ALLY PULS ED CHARACTERISTI C OF SCRE W

FOR DYNA M I C PLAS T I CS I NJECT I ON MOLD I NG M ACH I NES

W ang Quan 1,2, Qu J inp ing 2

(1 D epart ment o f E lectro m echanical Eng i nee ri ng ,Zhong K ai U niversity of A gr i culture and T echno l ogy ,G uangzhou 510225,China ;2 T he N a ti ona l Eng ineer i ng R esearch Center of N ove l Equ i p m ent for P o l yme r P rocess i ng ,The K ey L aboratory o f Po ly m er P rocessi ng

Eng i nee ri ng ofM inistry o f Education ,Sou t h Ch i na U n i versity o f T echno l ogy ,Guangzhou 510640,Ch i na)

Abst ract A novel self m ade hydraulic v i b rato r used as t h e driving i m petus of a m oti o n m echan is m to realize ax ial pulse of an injection scre w is adopted .Itm akesm e l,t plasticati n g ,injection and ho ldi n g pressure corse go on i n the state of v i b rating peri o dically .The dyna m ic response ,a m p litude and frequency characteristic of the pu lsed scre w i n the injec ti o n course are ana l y zed .Th is st u dy show s that the a mp litude of the pu lsed i n jecti o n is s m aller t h an tha t of v i b ration source ,but the v i b ration frequency keeps fro m vary i n g .Analyzi n g the ax ia lly pulsed characteristic o f the i n jecti o n scre w is he l p fu l for eng i n eers to desi g n pulsed pressure induced i n jection m o l d i n g m ach i n es .

K ey w ords :v ibration force field ,ax ia l pulse ,i n jecti o n scre w ,pu lsed characteristic

NE W M ETHOD FOR DETER M I NI NG THE SECOND CR I TI CAL SPEED

OF TH I N WALL CYLI NDRI CAL S HELLS UNDER AXI AL I M PACT

Chen Yong tao 1, Zheng Gang tie

2(1.Institute o f F luid Phy si cs ,Ch i na A cade m y of Eng i neer i ng Physics ,M ianyang 621900

2.H arbi n Institute o f T echno l ogy ,H arb i n 150001)

Abstract Study i n g on dyna m ic buckling m odes of th i n w all cylindrica l shells is helpful to desi g n anti i m pact struc tures .There ex ists a secondary critica l speed beyond w hich the ax isy mm etric buck ling m ode of a th i n w all cylindrical shell under ax ial i m pactw ou ld be converted a nonax isy mm etric one ,m oreover when the ax ial i m pact speed is beyond the second critical speed ,the ax isy mm etr i c buckli n g m ode appears firstly ,and then the buck ling mode c hanges to the nonax isy mm et ric one g radually w ith the i m pact response ti m e .A ccor d i n g to the theory described above ,by co m paring the ti m e histo ri e s of the k i n etic energy and the buckling defor m ation based on the fi n ite e le m entm ode l of the i m pact syste m ,an ener gy itera ti v e m ethod to deter m i n e the second criti c al speed is presented.U sing this ne w m ethod to desi g n anti i m pact structures o f t h e th i n w all cy li n drica l she ll can reduce test ti m es and cost effecti v ely .The feasibility and va li d ity o f this m ethod are de m onstrated by a dropp i n g ha mm er experi m en.t

K ey w ords :cy li n drical shel,l i m pac,t buckli n g ,cr itical speed

ANALYSIS OF I M PACT EFFECTS OF MOVI NG VEH I CLES ON A CONTI NUOUS BRI DGE

Bu J ianqing 1, Lou Guoc hong 1, La w S iuseong 2

(1.Schoo l of T ransporta ti on Eng i neering ,Sh ijiazhuang R a il w ay Institute ,Sh iji azhuang 050043

2.D epart m ent of C i v il and S tructural Eng i nee ri ng ,H ong K ong Po l y technic U n i versity ,H ong K ong )

Abst ract To st u dy e ffects of para m e ters of a veh icle bri d ge syste m on dyna m ic m agn ification factor ,a si m ply sup 159V o.l 26N o .12007 J OU RNAL OF V IBRAT I ON AND S HO CK

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