隨機(jī)干擾下碰撞振動(dòng)系統(tǒng)的動(dòng)力學(xué)分析_圖文

1、 Vol . 28 No. 9 2009 JOURNAL OF V I B RATI ON AND SHOCK 221 chines . The cracks in different positions of a shaft were regarded as different classes of fault, and were diagnosed by the grid support vector machines . The results showed the new m ethod distinctly i m p roved the fault recognition accu

2、racy and the diagnosis speed, and it was more suitable for p ractical app lication of m ulti2class fault diagnosis . ( Key words: fault diagnosis; support vector m achines SVM ; multi2class; grid support vector machines ( pp: 155 - 158 D ynam ic v iscoela stic ana lysis of a spha lt pavem en ts ZHAO

3、 Yan 2qing , ZHON G Yang 1 2 ( 1. Depart m ent of Transportation Engineering, Dalian University of Technology, Dalian 116024, China; 2. School of Civil and Hydraulic Engineering, Dalian University of Technology, Dalian 116024, China Abstract: A sphalt m ixtures are typ ical viscoelastic m aterials a

4、nd pavem ents are subjected to dynam ic loads under high 2speed traffic. Thus, behavior of asphalt pavements can be more realistically described by conducting dynam ic viscoe2 lastic analysis . In this study, a three 2dim ensional dynam ic viscoelastic model was developed for a typ ical asphalt pave

5、2 ment, and dynam ic viscoelastic response of surface deflection and its influencing factors were evaluated. The results showed that the deflection peak value and tim e of its occurrence were affected by the distance betw een the point of interest and app lied load. Damp ing ratio had negligible inf

6、luence on deflection peak value, while it had significant influence on the decaying rate of deflection vibration. The vibration decayed more rap idly w ith an increasing damp ing ratio. Tempera2 ture had great effects on both the deflection peak value and decaying rate. Decaying rate increased w ith

7、 increasing temper2 ature. Comparisons were made bet w een the peak values of deflection obtained through dynam ic and quasi2static analyses . The results indicated that the peak values obtained from dynam ic analysis were about 12% larger than those obtained from quasi2static analysis, and the perc

8、entage of increase in the peak value varied w ith horizontal distance. Key words: viscoelastictiy; dynam ic analysis; damp ing ratio; three 2dim ensional finite element method; quasi2static ( pp: 159 - 162 analysis; temperature D ynam ic ana lysis of a v ibro 2im pact system w ith random d isturbanc

9、e T I AN Ha i2yong, L I U W ei2hua, ZHAO R i2xu ( School of M echatronic Engineering, Lanzhou J iaotong University, Lanzhou 730070, China Abstract: A one 2degree 2 of2freedom vibro 2impact system w ith clearance was established. The analytic exp ression of Poincar map of the system was derived, and

10、the spectrum of Lyapunov exponents of the system was calculated numerical2 ly, the effects of the dynam ic behavior of the vibro 2impact system w ith random disturbance were analyzed. A t last, w ith the largest Lyapunov exponent, the stochastic bifurcation of the random non 2smooth system was studi

11、ed. Num erical sim ula2 tions showed that period 2doubling bifurcation also exists in the random non 2s mooth system , but is different from that in the deter m inistic system. Key words: vibro 2impact system; stochastic bifurcation; Lyapunov exponent ; random disturbance ( pp: 163 - 167 Performance

12、 ana lysis of dua l2cham ber pneuma tic v ibra tion isola tor XU D eng 2feng, ZHU Yu, YOU Z heng, J I A S ong 2tao (Departm ent of Precision Instruments and M echanology, Tsinghua University, Beijing 100084, China Abstract: V ibration isolator can insulate or weaken vibration from the ground or load

13、 and it help s to ensure the de2 sired ulti m ate p recision. Therefore, vibration isolator has been w idely app lied in lots of subsystem s which are used in the field of ultra 2 p recision machining, inspection and op tics . Among most of vibration isolators, pneumatic vibration isolator is very popular due to its high cost2efficiency ratio and its natural frequency doesn t depend on the load. B ased on C. Erin s study, orifice number as a parameter was introduced and the theoretical model of air bearing through derivation was im