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2022 Vol. 41, No. 8
Published: 2022-04-28
 
1 Gas-liquid flow states and vibration characteristics of a double-blade centrifugal pump during self-priming process
WU Denghao1，ZHANG Ting1，ZHU Zhibing2，QIAN Heng3，REN Yun4，MOU Jiegang1
The self-priming process of pump contains a complex gas-liquid two-phase flow structure, which induces vibration and noise and is not conducive to the stable operation of the pump. At present, the research on the pump self-priming process mainly focuses on the self-priming mechanism and the evolution of the gas-liquid flow states, and rarely involves the vibration characteristics of the self-priming process. In order to reveal the vibration induction mechanism of the self-priming process of centrifugal pump, the experimental research on the gas-liquid flow states and vibration characteristics of the pump is carried out by constructing the self-priming performance test rig with a double-blade centrifugal pump, and using high-speed photography technology and vibration testing technology. Meanwhile, five backflow holes in different positions are designed to study the effect of the position of backflow hole on self-priming performance and vibration performance. The results show that during the self-priming process, the drastic changes in the flow of gas and liquid inside the impeller aggravate the unstable radial loads of the impeller-rotor system, resulting in an increase in vibration intensity. During the self-priming process, the vibration excitation frequency is distributed in the medium frequency band of 700Hz-1200Hz, and the broadband vibration is the main contributor. There is a big bubble inside the impeller is observed. At the end of the self-priming process, the primary excitation frequency is the blade passing frequency, with the excitation frequency concentrated in the low frequency band of 25Hz-400Hz. The position of the backflow hole has a significant effect on the self-priming time, but less effect on the vibration intensity.
2022 Vol. 41 (8): 1-6 [Abstract] ( 2417 ) HTML (1 KB)  PDF (1680 KB)  ( 1401 )
7 Application of refined composite multiscale fluctuation dispersion entropy in hydraulic pumps fault diagnosis
JIANG Wanlu1,2，ZHAO Yapeng1,2，ZHANG Shuqing3，LI Man1,2
The vibration signal of hydraulic pump has the characteristics of non-linearity and non-stationarity. Entropy algorithms have a unique advantage in this kind of signal analysis. However, the traditional entropy algorithms still have shortcomings of slow calculation speed, inaccurate entropy value and unstable entropy value in hydraulic pump vibration signal feature extraction. To extract fault feature information more effectively and improve fault diagnosis accuracy, the refined composite multiscale fluctuation dispersion entropy(RCMFDE) is introduced into the fault feature extraction of hydraulic pumps. A hydraulic pump fault diagnosis method based on RCMFDE and particle swarm optimization support vector machine(PSO-SVM) algorithm is proposed. Firstly, the RCMFDE values of different fault vibration signals are calculated and the multi-RCMFDE values are selected at appropriate scales as feature vectors to form feature samples. Then the feature samples are input to PSO-SVM for fault diagnosis. Through analyzing the simulation signals and hydraulic pump experiments signals, the proposed method is compared with the fault diagnosis methods based on multiscale sample entropy(MSE), multiscale permutation entropy(MPE), multiscale symbolic dynamic entropy(MSDE), multiscale dispersion entropy(MDE), refined composite multiscale dispersion entropy (RCMDE) and multiscale fluctuation dispersion entropy(MFDE). Experimental results show that the proposed method can accurately identify multiple types of hydraulic pump faults and effectively evaluate the performance degradation degree of hydraulic pump.
2022 Vol. 41 (8): 7-16 [Abstract] ( 1035 ) HTML (1 KB)  PDF (2140 KB)  ( 580 )
17 The performance of cable’s multi-mode vibration control based on an eddy current damper
XIAO Xiao1,2，HUANG Zhiwen1,2，CHEN Zhengqing1,2，HUA Xugang1,2
The performance of a new type of ball screw type axial eddy current damper (BS-ECD) on cable’s multi-mode vibration control is investigated. Firstly, the expression of BS-ECD’s equivalent linear damping coefficient is calculated based on the equal energy dissipation in every vibration periods, and then the expression of the cable’s additional modal damping ratio after installing the BS-ECD is derived by using the equivalent linearization theory. Based on this, the BS-ECD’s parameter optimization is carried out for the cable’s multi-mode vibration control. Meanwhile, the BS-ECD’s optimal critical speed and peak damping force as well as the cable’s additional modal damping ratio are obtained when the interested modes in the cable focus on 1-4 and 1-8, and the BS-ECD’s vibration control performance is evaluated based on these optimal parameters. Finally, the sensitivity of BS-ECD’s optimal parameters and displacement amplitude of damper’s location towards damper’s control performance is analyzed. The results show that there is a set of BS-ECD parameters, which can make any two modes of the cable’s additional damping ratio reach the maximum at the same time. When the working stroke of the damper is specified, the cable’s multi-mode vibration control performance of BS-ECD’s performance in cable’s multi-mode vibration control is better than that of both linear viscous dampers and nonlinear liquid viscous dampers counterparts after parameters optimization and BS-ECD’s control performance is not sensitive to changes in optimal parameters’ deviation. Like other nonlinear dampers, the BS-ECD’s additional modal damping ratio provided by BS-ECD is also dependent on amplitude obviously. When the working stroke of the damper deviates from the design value, its damping effect will be significantly reduced, which should be carefully studied in the follow-ups.
2022 Vol. 41 (8): 17-24 [Abstract] ( 655 ) HTML (1 KB)  PDF (1633 KB)  ( 404 )
34 Mechanism study on the effect of a stabilizing plate on vortex induced vibration performance of a cable stayed bridge with a side main girder of a belt conveyor
LI Chunguang，YAN Hubin，LIANG Aihong，HAN Yan，ZHOU Xuhui
In order to study the mechanism of the effect of stabilizing plate on vortex induced  vibration (VIV) performance of side girder cable-stayed bridge with belt conveyor installed on bridge deck, the pressure time-histories date of the edge girder was obtained through the section model pressure test. The mean value of the pressure coefficient, standard deviation ,the power spectrum, and the correlation between local aerodynamic force and overall aerodynamic force of the cross-section on different number of lower stabilizers are comprehensively compared and analyzed, which reveals the vibration suppression mechanism of the edge girder by lower stabilizers. The research results indicated that the cause of the vertical VIV resonance are the strong pressure fluctuation in the front separation and reattachment area of the upper surface, the strong correlation between the front aerodynamic force and the overall aerodynamic force of the lower surface, and the strong pressure fluctuation of the strong correlation in the rear part of the lower surface. Arranging a stabilizer in  the bottom of beam can significantly reduce pressure fluctuation, and arranging two stabilizers can further reduce the pressure fluctuation, which can greatly suppress VIV; Three stabilizers arranged at the bottom of beam promote the reattachment of airflow at the downstream faring, the cross-section pressure fluctuation is greatly weakened, and the correlation between the local aerodynamic force and the overall aerodynamic force is significantly destroyed, thus the VIV is suppressed effectively.
2022 Vol. 41 (8): 34-44 [Abstract] ( 512 ) HTML (1 KB)  PDF (2260 KB)  ( 257 )
45 Experimental analysis on energy absorption effect of energy absorption device for a suspension type crossing frame
MENG Fanhao，XIA Yongjun，MA Yong，WAN Jiancheng
For improving the impact resistance performance of the suspension crossing frame, the hydraulic energy absorption device suitable for the crossing frame is designed based on the load-bearing characteristics of the suspension crossing frame under the accident state, and the energy absorption effect verification test is carried out. Firstly, based on the analysis of the load-bearing characteristics of the suspension crossing frame under accident conditions, several different types of energy absorption principles are compared, and finally the hydraulic energy absorption device is selected for design. Then, the energy absorption effect of the energy absorption device is tested through the small-scale vertical state test of the load-bearing cable of the suspension frame. The result shows the energy absorption effect of the hydraulic energy absorption device is 71.05%. In order to further verify the energy absorption effect of the energy absorption device under real working conditions, the large-scale impact test technology is carried out, and the impact response law of the load-bearing cable with and without energy absorption device is tested. The experimental results show that under the conditions of 110m span, 0.5T heavy load and 0.5m impact height, the energy absorption effect of the hydraulic energy absorption device reaches 32.10%, which can effectively improve the impact resistance of the suspension type crossing frame.
2022 Vol. 41 (8): 45-54 [Abstract] ( 493 ) HTML (1 KB)  PDF (1988 KB)  ( 430 )
55 A track geometric irregularity reproduced method and its application based on 6DOF vibration test bench
ZHANG Jia，WU Pingbo，LIU Chaotao，SONG Ye，LI Fansong
It is considered to reproduce the track random irregularity on the test bench to simulate the vibration environment of the train and to test the vibration response of the whole or parts of the vehicle system. Combined with the characteristics of track geometric irregularity and the structure of vibration test bench, the motion control method of the test bench and the method to reproduce track geometric irregularity on the test bench are studied. Based on the full-scale virtual prototype model of the test bench, the measured irregularity signals of the high-speed railway from Wuhan to Guangzhou are successfully reproduced. On this basis, the rigid flexible coupling dynamic model of a certain type of train bogie under the condition of servicing is established. Modal analysis of the bogie frame is carried out with track geometric irregularity reproduced by virtual test bench as excitation. The analysis shows that under the excitation of track irregularity, the corresponding modes of 18Hz, 67Hz, 85Hz and 96.8 Hz of bogie frame will be excited when the bogie runs at 250km / h.
2022 Vol. 41 (8): 55-71 [Abstract] ( 559 ) HTML (1 KB)  PDF (2238 KB)  ( 494 )
72 Numerical simulation of multiphase flow field and trajectory characteristics of high-speed spinning projectile entry water in wave
LI Zhitao1,2，ZHAO Shiping1,2，LU Bingju1,2，YU Yong3
Based on the overlapping grid technique and 6-DOF algorithm, the numerical simulation of the water entry process of a high-speed pinning projectile in waves is carried out. The cavitation shape, trajectory characteristics and hydrodynamic load characteristics of the projectile at different positions of wave surface, such as wave crest, wave node 1, wave trough and wave node 2, are analyzed. The results show that the projectile body experiences water impact, cavitation formation, supercavitating and wetting under four cases, among which the tail of wave node 2 collides with the cavitation first, and the tail of wave node 1 collides with the cavitation last. At the end of the simulation, the lateral displacement and velocity change from large to small are wave node 2, wave crest, wave trough and wave node 1. In the initial stage of the four cases, the force and moment coefficients magnitude of the projectile sailing in the cavity are small. In the later stage of water entry, the surface of the projectile is wet in a large area. The force and moment coefficients under different cases are quite different. The nominal entry-water angle is 25 degree and the same under the four cases, but due to the existence of wave surface, the actual entry-water angle of the projectile change. The effective entry-water angle of the projectile from small to large are wave node 2, wave crest, wave trough and wave node 1, and the values are 10.3094 degree, 25.0032 degree, 25.0098 degree and 39.6620 degree respectively.
2022 Vol. 41 (8): 72-78 [Abstract] ( 451 ) HTML (1 KB)  PDF (4384 KB)  ( 360 )
79 A study on vibration suppression of a bridge in Sichuan—Tibet Railway and running safety of a train under floating ice collision
LI Penghao1，ZHAI Wanming2，HE Zhenxing1，SHI Guangtian1
The impact of floating ice is a common natural disaster of bridges in the complex and difficult mountainous areas of the Sichuan-Tibet Railway. To evaluate the effect of dynamic vibration absorbers (DVA) on vibration suppression characteristics of bridge and the running of trains on the bridge under impact loads. Based on the train-track-bridge dynamic interaction and the design method of DVA, the dynamics model of train-track-bridge-DVA considering the effects of floating ice impact loads is established. The vibration suppression of the bridge subject to the ice impact loads by DVA is investigated and the influence on the running of train on the bridge is analyzed. Results show that with the addition of DVA to the top of the bridge pier, the lateral vibration of the bridge structure under the ice impact loads can be effectively suppressed, and the dynamic indexes such as lateral acceleration of train, lateral wheel-rail force, derailment factor and wheel unloading rate are significantly reduced when the train crosses the bridge. When the speed increases to 200km/h, DVA still has a good damping effect on the dynamic response of the train. And the damping effect of train dynamic responses all increases with the increase of the mass ratio of DVA, while the running speed remains unchanged. It shows that the installation of DVA on the bridge is all beneficial to the resistance to ice impact of the railway bridge and the running of trains on the bridge.
2022 Vol. 41 (8): 79-85 [Abstract] ( 578 ) HTML (1 KB)  PDF (1890 KB)  ( 439 )
86 Design of a low-frequency noise suppression periodic pipe and its acoustic performance test
SHEN Huijie1，ZHANG Tao1，TANG Zhiyin1，YU Dianlong2
To control the transmission of low-frequency noise in the ventilation and air conditioning pipelines, a periodic pipe equipped with a 1D array of Helmholtz mufflers is constructed. Such a periodic pipe has a set of screw holes distributed in the axial direction with identical spacing such that the Helmholtz mufflers could be seated into the holes via the matching screw on the Helmholtz neck, thereby forming periodic pipes with various lattice constants. Numerical simulation results predict that there are two types of low-frequency band gaps existed in the periodic pipe system, i.e., the resonant and the Bragg type band gaps, respectively. These two types of gaps can be coupled by modulating the geometric parameters e.g., the lattice constant, via an exactly coupling condition. The experimental test of noise reduction (NR) and insertion loss (IL) further validate the theoretical prediction. Experimental results shows that within the band gap frequency ranges, the propagation of acoustic waves in the periodic system will be prohibited, exhibiting a good suppression effect on the transmission of low-frequency pipe noise, particularly in the resonant gap frequency range. Moreover, increasing the installing space of Helmholtz mufflers, the Bragg type gap will be move towards the lower frequency range. Under a certain condition, the Bragg and the resonant gaps could be combined together, giving rise to a low-frequency and broadband coupled gap with heavy attenuation effect. The experiment test reveals that the proposed strategy possesses a good control effect on the low-frequency noise transmission in the ventilation and air conditioning pipeline, thus providing a possible technical way to deal with the low-frequency noise problem in ship ventilation and air conditioning pipeline systems.
2022 Vol. 41 (8): 86-92 [Abstract] ( 383 ) HTML (1 KB)  PDF (1244 KB)  ( 204 )
86 A study on low frequency sound absorption performance of structure embedded local resonant scatters
LUO Yingqin，LOU Jingjun，ZHANG Yanbing
A simplified finite element method (SFEM) was established to calculate the acoustic characteristics for the periodic axisymmetric local resonant scatter structure. The influence of cross-section shape, core material and coating thickness on sound absorption was discussed. The sound absorption mechanism was analyzed through the displacement and energy dissipation density fields. It shows that the sound absorption peaks are caused by the resonances of the scatter. The first and second sound absorption peaks are closely related to the resonance of core and coating respectively. The average sound absorption coefficient was optimized by genetic algorithm while considering the variable cross-section parameters. The optimized results show the variable cross-section scatter can excite more matrix movement at the sound absorption peaks, promoting more wave mode conversion which is conducive for energy dissipation and improving the sound absorption. So it provides a new idea for low frequency broadband sound absorption structure design.
2022 Vol. 41 (8): 86-92 [Abstract] ( 289 ) HTML (1 KB)  PDF (2326 KB)  ( 180 )
93 An experimental investigation of an inertial viscous damper and its damping effect on a cable
LIU Jing1，LIANG Dong1,2
A prototype of the inertial viscous damper for stay cables, composed of rack and pinion, inertial element, and viscous damping element, is fabricated, and detailed experimental investigation of stay cables' vibration control is carried out. A cable-damper system considering sag, internal damping characteristics, pinion's inertia, shaft's inertia, and bearing's damping characteristics was established. The numerical analysis was carried out using the Improved Galerkin method. The novel damper's performance parameters, energy dissipation capacity, and vibration control effect on cables are discussed. The comparison between experimental and numerical investigation shows that the inertial viscous damper produces apparent negative stiffness in the vibration damping of the cable, and the displacement amplification effect has a significant positive impact on the vibration damping effect. The Improved Galerkin method can be adopted in the analysis of cable-inertial viscous damper system, and the algorithm does not depend on the selection of initial values. The theoretical results are in good agreement with the experimental results, verifying the calculation method's accuracy in this study. The inertial viscous damper has a good damping effect on cable vibration.
2022 Vol. 41 (8): 93-101 [Abstract] ( 421 ) HTML (1 KB)  PDF (1796 KB)  ( 315 )
102 An excitation test and dynamic simulation of wheel polygon wear based on a rolling test rig of single wheelset
LIU Pengfei1，YANG Shaopu1，LIU Yongqiang2，GU Xiaohui1，LIU Zechao1，LIU Hongjun2
By grinding the rail wheel to simulate the short-wave irregularities, the high-speed train rolling test rig of single wheelset was used to carry out the excitating test of wheel polygon wear. A dynamic model of test rig was established. For speed below 300 km/h, the effects of high-order wheel polygon and single harmonic wave excitations on the vibration of wheelset system were studied. The test and calculated results were compared in time-frequency domains. It was found that, the high frequency vibration of thousands of Hertz in wheel-rail system can be excited by grinding polygons on rail wheels. In the axle box vibration, the basic frequency and its frequency multiplications induced by the side length of polygon wear became dominant. The vertical natural vibrations of wheelset and axle box also contributed large vibration energy. The calculated results could reflect the vibrations of basic frequency and frequency multiplication below 2500Hz excited by the wheel polygon. The time-domain amplitude characteristics and the main frequency distributions also agreed well with the test results. By setting a single harmonic on the rail wheel, the wheel-rail medium-high frequency vibration from hundreds to thousands of Hertz could be excited. As the running speed increased, the vibration signal in the harmonic excitation area was strengthened. For speed rising to 200km/h and 300km/h, the simulation model could reflect the wheelset vibration below 1000Hz and 250Hz respectively, but it was difficult to capture the higher frequency vibrations. The results showed that, the single wheelset rolling test rig could be used to carry out high-frequency vibration test with short-wave irregularities. For this test rig, the corresponding dynamic model had certain applicability in the simulation analysis of medium-high frequency vibrations.
2022 Vol. 41 (8): 102-109 [Abstract] ( 380 ) HTML (1 KB)  PDF (2692 KB)  ( 223 )
110 A new testing method for low frequency impact environment of ships
JI Chen1，GUO Jun2，FENG Linhan1，HAO Ning2
When the accelerometer is used to test the low-frequency impact environment of ships, it is easy to produce "zero drift" effect, which leads to large error and unreliability of the results. Therefore, through the analysis of the formation mechanism of low frequency impact environment, this paper proposes an indirect test method based on the total vibration strain of ship shock trail. The validity of the proposed method is verified based on the test data of a real ship. Results show that the average error of the new method is 12.6% compared with the data measured by the low frequency oscillator. Compared with the traditional method, this technology has the advantages of simple sensor installation, low number of measurement points and large effective coverage of the ship length, which has important reference value for the low-frequency impact environment test of ship shock trail.
2022 Vol. 41 (8): 110-115 [Abstract] ( 326 ) HTML (1 KB)  PDF (1603 KB)  ( 231 )
116 Seismic analysis of eccentric single-rigid-body considering the influence of colliding-to-wall
JIA Chuanguo1,2，PAN Jiafu2，LI Jianguang2，MA Li2
During an earthquake, rocking and overturning of high objects in buildings, such as cupboard, refrigerator etc., perhaps cause certain casualties and economic losses. Most of high objects are located near walls. However, the influence of colliding-to-wall is not considered in existing dynamic analysis of single-rigid-body. Colliding-to-wall would change motion pattern of single-rigid-body, which increase the overturning probability. Therefore, it’s particularly important to consider the influence of colliding-to-wall into simulating the dynamic response of single-rigid-body. With this in mind, this paper firstly adopted Lagrange's theorem to establish equations of motion. Then a dynamic analysis method of single-rigid-body is proposed based on Rosenbrock integration method. Subsequently, a multi-step-two-step method is developed to realize state transition before and after colliding to floor and wall. Finally, the reliability of the proposed dynamic analysis method is validated via comparing its results with those of shaking table tests.
2022 Vol. 41 (8): 116-123 [Abstract] ( 251 ) HTML (1 KB)  PDF (2167 KB)  ( 190 )
124 An experimental study on bending behavior of damaged beams reinforced with high ductile concrete
KOU Jialiang1,2，CAI Pengyang1，WANG Dong1，ZHOU Heng3
Using high ductile concrete (HDC) good adhesion properties and crack control ability, 19 reinforced concrete beams with ultimate bearing capacity are strengthened.The four-point bending performance test was carried out to study the effects of HDC-reinforced broken concrete beams on the development of cracks, failure modes, bearing capacity, deflection changes and stress changes.The effects of different HDC thickness and reinforcement ratio on the reinforcement performance of HDC reinforced concrete beams were analyzed. The results showed that: The load-carrying capacity of the damaged concrete beam strengthened by HDC has been significantly improved, and the peak load is increased by up to 89%; The fracture after the failure is more than the original beam and the development is complete; the reinforcement effect of increasing the thickness of the reinforcement layer is obviously better than the improvement of the hoop ratio; The ultimate deflection at cracking load and failure was increased by 250% and 189%, respectively, and the ductility was significantly improved. The largest crack did not occur at the interface, the bonding between the old and new concrete was very good, and the cooperative work performance was good. According to the test results, the simplified calculation formula of the flexural capacity of the damaged concrete beams with high ductility is obtained. The calculated values agree well with the experimental results.
2022 Vol. 41 (8): 124-133 [Abstract] ( 305 ) HTML (1 KB)  PDF (2687 KB)  ( 392 )
134 A study on wind vibration response of a tower heliostat based on comparison of a rigid model and an aeroelastic model wind tunnel test
LIU Zhenhua1，NIU Huawei1，LI Hongxing2，HE Shaohua2
The tower heliostat is an important concentrating device in the solar power tower plant, and the control load is wind load. A finite element model of the tower heliostat structure was established by ANSYS. The modal analysis shows that the frequency distribution of structure is dense, and the change of the wind attack angle has little effect on the low-order mode of the heliostat structure. Based on the pressure measurement wind tunnel test of the rigid model, the wind-induced vibration response of the tower heliostat was analyzed by ANSYS, and the aeroelastic model vibration test was carried out. The errors between the two are within 10%. The results show that the modes that affect the wind-induced vibration of the structure are mainly the first 3 orders, and the displacement response at the end of the main purlin is the largest. The wind vibration coefficient is recommended to be 1.57.
2022 Vol. 41 (8): 134-140 [Abstract] ( 310 ) HTML (1 KB)  PDF (2625 KB)  ( 124 )
141 Analysis of the influence of outer ring raceway peeling fault on the dynamic response of a rolling bearing
DING Dongsheng1,2，LIU Yongqiang1,2，YANG Shaopu1,2
In order to explore the dynamic response law of the internal components of the axle box bearing of the high-speed train after the peeling fault occurred in the outer ring raceway, the bearing dynamic model was established by using three-dimensional modeling software Solidworks and multi-body dynamics analysis software ADAMS. The model takes into account the factors such as material properties, constraints, load and contact relationship, and simulates the peeling fault at multiple positions of the outer ring raceway. The dynamic experiment of axle box bearing is carried out on the bearing comprehensive test-bed of high-speed train, and the validity of the model is verified by comparing with the simulation results. By analyzing the dynamic simulation results of bearings with different fault positions, the dynamic response rules of rollers and cages are studied. It is found that the radial motion trajectory of the roller centroid shows a "sinusoidal" shape, which does not change with the damage position of the outer ring raceway, and when the outer ring raceway damage is at 3 o'clock and 9 o'clock, the radial motion trajectory of the cage centroid is irregular. When the damage of the outer ring raceway is located at 6 o'clock, the radial motion track of the center of mass of the cage is approximately "sinusoidal", the fluctuation of the center of mass of the roller and the cage is the smallest, and the contact force between the roller and the inner ring and the outer ring is the largest. When the outer ring raceway damage is located at 12 o'clock, the radial motion trajectory of the cage centroid is approximately "sinusoidal", the fluctuation of the roller and the cage centroid is the largest, and the contact force between the roller, the inner ring and the outer ring is the minimum. the research results provide a certain reference significance for understanding the motion law of the internal components, bearing operation and maintenance and vibration data collection when the bearing has outer ring failure.
2022 Vol. 41 (8): 141-148 [Abstract] ( 327 ) HTML (1 KB)  PDF (2295 KB)  ( 165 )
149 Shock wave evolution of cylindrical charge with different slender ratios
MA Teng,WANG Jinxiang,LIU Liangtao,HUANG Ruiyuan,TANG Kui,LIN Shangjian,GU Yangchen
In order to analyze the influence of charge shape on the evolution of underwater explosion shock wave, the calculation method of initial shock wave pressure and its propagation direction on the interface between explosive and water was established in theory for the problem of center initiation of two-dimensional cylindrical charge. With the aid of AUTODYN finite element program, the tests are conducted with constant-mass cylindrical explosives with slender ratio ranging from 1:2 to 10:1. Experiments on underwater explosion of cylindrical TNT with slender ratio of 1:1 and 2.6:1 are carried out. By comparing with the result of the theoretical, simulation and experimental, the effects of the slender ratio on the propagation of the shock wave，the initial shock wave pressure and the pressure distribution in the infinite water were analyzed. The results show that the shock wave front gradually changes from cylindrical shape to ellipsoid shape and then to spherical shape for cylindrical charge exploding underwater. When the shock wave propagates to 10 times of dimensionless detonation distance, the transfer of high-pressure zone ends. When the slender ratio is greater than 1:1, the decay rate of the shock wave approach the axial (End surface) is greater than that of the radial (Cylindrical surface), and the peak pressure of shock wave changes with the direction angle. In the range of 1:1-5:1 slender ratio and 20 times dimensionless detonation distance, the radial shock wave pressure of explosive can be enhanced directionally by increasing the slender ratio of explosive, and the influence of the shape charge on shock wave pressure distribution decreases with the increase of detonation distance.
2022 Vol. 41 (8): 149-157 [Abstract] ( 285 ) HTML (1 KB)  PDF (2194 KB)  ( 243 )
158 Wind induced vibration response analysis and vibration reduction optimization design of a frame lightning rod based on bidirectional fluid structure coupling
ZHAO Guifeng,CAO Pengyi,SHI Yuhao,ZHANG Meng,LIU Ran
Taking the lightning rod structure of a 500 kV high-voltage substation as an example, the finite element model is established to do the lightning rod wind-induced vibration response analysis. The wind-induced vibration response of the lightning rod is simulated and analyzed by the two-way fluid structure coupling method, and the vibration reduction optimization design of the lightning rod is carried out by using the method of attaching spiral guide plate. The results show that: due to the thin and flexible superstructure characteristics, the wind-induced vibration response of the lightning rod with round steel tube frame is more prominent in the along-wind direction and across-wind direction, especially the across-wind direction vibration response even occupies the dominant position in some conditions. For the frame lightning rod analyzed in this paper, when the wind speed is 12.64m/s ~ 25.30m/s, the across-wind direction vortex induced vibration "lock-in" phenomenon will occur, and its maximum resonance response (wind speed of 18.97m/s) even exceeds the along-wind direction response value of the structure under the design basic wind speed (23.83m/s). In the actual design, the spiral guide plate with pitch of 8D and coverage rate of 30% can be attached to the top of the frame lightning rod to control its across-wind direction vortex induced vibration effectively.
2022 Vol. 41 (8): 158-170 [Abstract] ( 311 ) HTML (1 KB)  PDF (7536 KB)  ( 225 )
171 Fault diagnosis of rotating machinery based on time-series correlation analysis
TAN Shuai1,MA Yao1,SHI Hongbo1,CHANG Yuqing2,GUO Lei1
With the application of large-scale rotating machinery, more and more attention has been paid to fault diagnosis of high-speed rotating machinery. Due to the periodic rotation characteristics of rotating machinery, there is a strong temporal correlation between signals. Fault features will gradually transfer during the week of rotation. In this paper, different types of faults and different level of damages of rotating machinery were analysed, which refer to temporal association characteristics of vibration signal. Then Periodization long short-term memory (Periodization – LSTM,P-LSTM) fault diagnosis method was proposed. The method extract features from periodization data and use memory factors to forget some information that of insignificance. Finally, the performance analysis and test of the proposed method were carried out based on the multi-fault data of rolling bearings, which verified the effectiveness of p-lstm method in learning the time-series correlation characteristics of rotating machinery during the cycle, as well as the accuracy of fault diagnosis.
2022 Vol. 41 (8): 171-178 [Abstract] ( 461 ) HTML (1 KB)  PDF (1436 KB)  ( 279 )
179 An early composite fault feature extraction method of bearing based  on square envelope spectrum negentropy criterion
CHEN Peng1,ZHAO Xiaoqiang1,2,3
In view of the problem that it is difficult to extract the early composite fault feature in fault diagnosis of bearing. An optimized Swarm decomposition (OSWD) method based on the criterion of square envelope spectrum negentropy is proposed. Firstly, an optimization criterion based on square envelope spectrum negentropy is constructed and the improved grasshopper optimization algorithm (IGOA) is used to optimize the threshold parameters of the Swarm decomposition (SWD) to obtain optimal threshold. Then the adaptive decomposition of the composite fault vibration signals is realized by using OSWD. The decomposed components are analyzed by using envelope spectrum analysis to extract the fault feature frequencies. So the early composite fault diagnosis of bearing is accurately realized. Finally, the effectiveness of the proposed method is verified by the simulation analysis case and the fact engineering case.
2022 Vol. 41 (8): 179-187 [Abstract] ( 433 ) HTML (1 KB)  PDF (3720 KB)  ( 235 )
188 An nonlinear parametric identification and test method for minimal ratio of width to depth liquid sloshing based on analytical modal decomposition
LI Haidong1,LI Long1,HOU Kaiyu2,SHI Xiaoming1,XIA Peng1,GAO Yang1
To solve the problem in the notch filter design of unmanned air vehicle caused by fuel tank sloshing frequency closed to rigid body frequency and time-varying as fuel dissipates, minimal ratio of liquid width to depth baffles with "#" profile were designed to suppress sloshing. Transverse step excitation on the fuel tank was exerted by vibration table with sliding table. Free decaying vibration response of the fuel was acquired by laser Doppler vibrometer. Sloshing frequency and damping were identified by Analytical Mode Decomposition and FREEVIB method based on Hilbert Transform. The sloshing fundamental frequency of the fuel tank with minimal ratio of liquid width to depth "#" baffles was much higher than that with sparse baffles, and wasn't varied with the depth of the fuel. The sloshing damping with "#" baffles was also much higher, resulted in the sloshing response decayed very quickly.
2022 Vol. 41 (8): 188-192 [Abstract] ( 229 ) HTML (1 KB)  PDF (1295 KB)  ( 119 )
193 A study on structural instantaneous frequency identification based on an improved multi-synchrosqueezing generalized S-transform
YUAN Pingping1,2,3,CHENG Xueli4,WANG Hanghang3,SHEN Zhongxiang3,REN Weixin5,ZHANG Jian4
To improve the accuracy of structural instantaneous frequency identification, this paper proposed a new form of improved generalized S-transform（IGST）. The parameters selection method of window function in IGST was derived by concentration measure（CM）principle, and the improved multi-synchrosqueezing generalized S-transform（IMSSGST）was proposed combined with squeeze algorithm. The core idea of this algorithm is to perform multi-synchrosqueezing on the time-frequency distribution of IGST to the time-frequency ridge in a certain range. In terms of numerical simulation, the accuracy of the method was verified by using a time-varying structure of two-story shear frame. In the aspect of experiment, instantaneous frequency identification of a seven-story Reinforced Concrete（RC）shear wall structure was carried out, which verified the practicability of the method in practical engineering. Numerical simulation and experimental results show that this method can effectively improve energy aggregation of time-frequency analysis and accuracy of instantaneous frequency identification.
 
2022 Vol. 41 (8): 193-198 [Abstract] ( 265 ) HTML (1 KB)  PDF (2000 KB)  ( 189 )
199 A rolling bearing fault diagnosis method based on multi-sensor two-stage feature fusion
LIU Cang,TONG Jinyu,BAO Jiahan,ZHENG Jinde,PAN Haiyang
To address the problem of insufficient diagnostic accuracy due to the limited information obtained by a single sensor, a two-stage feature fusion fault diagnosis method based on multi-sensor is proposed and applied to the fault diagnosis of rolling bearing under different working conditions. First, the intrinsic mode function (IMF) of each sensor vibration signal is calculated by variational mode decomposition to eliminate redundant information such as noise. Then the time domain, frequency domain and multi-scale entropy features are extracted according to the IMF and fused into a multi-dimensional feature set at the one-dimensional feature level, which is the first stage of feature fusion. Second, an improved deep auto-encoder network based on the Swish activation function and log(cosh) loss function is firstly constructed, then the multi-domain feature set is further fused and fault classification is performed based on the improved deep auto-encoder network, which is the second stage of feature fusion. The proposed model is applied to the rolling bearing fault diagnosis data set under different working conditions. The experimental results show that the proposed method has higher classification accuracy and robustness compared with the existing methods.
2022 Vol. 41 (8): 199-207 [Abstract] ( 398 ) HTML (1 KB)  PDF (3301 KB)  ( 260 )
208 Dynamic characteristics and fracture energy dissipation of fiber reinforced concrete beams under low-velocity impact
MA Gang1,GAO Songtao1,WANG Zhuoran2,MA Zhihong2
With the reduction of the production cost of various types of chopped fiber, fiber reinforced concrete has been developed on a large scale and its application fields are expanding. In order to ensure the service safety of fiber reinforced concrete in complex environment, this paper analyzes the concrete beam and carbon fiber (CF) with the fiber length of 6-8 mm and the volume content of 0.30% The low velocity impact tests of glass fiber (GF) and basalt fiber (BF) concrete beams were carried out to study the bending failure mechanism and fracture energy consumption of ordinary concrete beams and fiber reinforced concrete beams. The fracture process of each beam was recorded by high-speed camera, and the vertical displacement time history curve, acceleration time history curve and tension compression strain time history curve were extracted and analyzed. The impact force and inertia force of hammerhead were analyzed in detail, and the equivalent deformation force displacement curve was obtained, and the fracture energy consumption of each fiber reinforced concrete beam was calculated. The results show that the failure mode of each specimen is typical bending failure, and a vertical main crack is formed. The energy consumption of GFRC beam is the most, which is 88% higher than that of （plain concrete）PC beam. The energy consumption of CFRC beam and BFRC beam is 43% and 18% higher than that of PC beam, respectively. In this paper, the quantitative research results of mechanical properties and energy consumption of different types of fiber reinforced concrete flexural members under low velocity impact condition can provide reference for the engineering application of fiber reinforced concrete.
2022 Vol. 41 (8): 208-216 [Abstract] ( 339 ) HTML (1 KB)  PDF (2321 KB)  ( 195 )
217 Development of eight-beam phased array transducer
ZHOU Bowen,TONG Hui,ZHANG Bin,XU Weijie
Doppler Velocity Log (DVL) is one of the important devices which can provide positioning and navigation information for surface or underwater vehicle. The traditional DVL usually uses Janus configuration method to launch four beams along the front, rear, left, and right directions of the vehicle to the seabed, and uses Doppler frequency shift to calculate the speed of the carrier. For traditional phased array DVL, the distance between array elements is usually half of the wavelength, and the angle between two beams in the same direction is 60 degrees. Based on the traditional phased array DVL, an eight-beam phased array DVL was proposed, which forms four beams in two mutually perpendicular directions, so is namely double Janus configuration mode. According to the simulation, it was determined that the distance between the array elements is 0.35 of wavelength, and the angles corresponding to the four beams in the same direction are    and   respectively. In this way, in two mutually perpendicular directions, the four beams with a smaller angle with the horizontal plane can provide a larger horizontal component, which is more conducive to the calculation of Doppler shift; the four beams with larger angles to the horizontal plane have larger vertical components, so that the received echo signals have larger signal strength, and the advantages of the two types of beams are complementary. At the same time, an eight-beam transducer was made and tested in a pool. The angles of the directional beams are   and  , which are in good agreement with the simulation results. The corresponding transmitting voltage response is 170.2dB and 170.6dB respectively.
2022 Vol. 41 (8): 217-222 [Abstract] ( 203 ) HTML (1 KB)  PDF (1465 KB)  ( 125 )
223 A study on the deformation mechanism of U-type corrugated cores sandwich panels subjected to quasi-static compression load
LI Yao,LIU Kun,SHEN Chaoming,WANG Jiaxia
The corrugated cores sandwich panel has excellent mechanical properties and can meet many requirements of ship design. It has been applied in the design and manufacture of high-end ships. Therefore, this paper takes the U-type corrugated cores sandwich panels as the research object. The analytical prediction methods of U-type corrugated cores sandwich panels under in-plane quasi-static compression load are studied though experiment, simulation and theoretical analysis. By designing and carrying out quasi-static stamping test and corresponding simulation, the deformation characteristics of the U-type corrugated cores sandwich panels were analyzed and the deformation process were summarized and classified. On the basis, the deformation mode of the U-type corrugated cores sandwich panels are proposed, the geometric mathematical models of the plastic deformation of the U-type corrugated cores sandwich panels are established, and the analytical calculation formulas of the deformation resistance of the U-type corrugated cores sandwich panels are deduced. Finally, the calculated results are compared with the test results for verification. The results show that the analytical results are in good agreement with the experimental and simulation results. The analytical method presented in this paper has guiding significance for the design and evaluation of crushing performance of corrugated cores sandwich panels.
2022 Vol. 41 (8): 223-230 [Abstract] ( 195 ) HTML (1 KB)  PDF (2753 KB)  ( 111 )
231 Analysis of vibration characteristics of a simulated spinal vibration isolator
LI Xiaopeng1,2, WANG Zhenghao2, WANG Bihan2
Inspired by the biological effect of human spine load-bearing and shock absorption, a bionic vibration isolator with multi-layer nodal connection is designed, the static model of the isolator is established The influence of different design parameters on the static stiffness and bearing capacity of the isolator is analyzed. The system dynamic equation is established by Lagrange dynamic formula, and the system is solved by harmonic balance method. The influence of different structural parameters on the displacement transmissibility of the system is analyzed, The validity of the harmonic balance method is verified by comparing the numerical solution obtained by the fourth-order Runge Kutta method with the analytical solution of the harmonic balance method. The results show that: The static stiffness of the isolator has obvious nonlinear characteristics. The positive stiffness, zero stiffness or negative stiffness can be obtained in the working range by adjusting the design parameters; when the positive stiffness condition is satisfied, reducing the stiffness ratio and increasing the initial angle can improve the bearing capacity of the isolator By adjusting the design parameters of the vibration isolator such as reducing the initial angle and reducing the stiffness ratio can significantly reduce the displacement transmissibility of the system, the research results have guiding significance for the engineering application of the bionic spinal vibration isolator.
2022 Vol. 41 (8): 231-237 [Abstract] ( 302 ) HTML (1 KB)  PDF (1616 KB)  ( 363 )
238 Analytical solution of band gap in an attached locally resonant phononic crystal thin plate
YANG Wen, CHEN Kailun, GUO Xu, CHEN Zeyu, LIU Changli
Phononic crystal is a kind of composite vibration-reduction material with metamaterial characteristics, and its band gap calculation has always been a hot research topic. At present, the main calculation methods are numerical methods. The band gap range depends on system parameters selection. Band gap design can only adopt parameter trial and error or optimization methods. For the above problems, the analytical solution of system vibration displacement was obtained according to the dynamic equation of locally resonance phononic crystal(LR PC) thin plate. On this basis, according to impedance concept, band gap formation mechanism was explained, system damping influence on the band gap was discussed, and band gap analytical solution under undamped conditions was obtained, which were consistent with finite element method and plane wave expansion method. Using this band gap analytical solution, designing band gap of LR PC thin plate can be convenient, which provides a new method for phononic crystal research and application.
2022 Vol. 41 (8): 238-243 [Abstract] ( 209 ) HTML (1 KB)  PDF (1223 KB)  ( 227 )
244 A study on the shock reduction method for the super-zip
SUN Jing1, CHEN Shaorui1, WENG Fei2, HU Zhenxing1, CHEN Rong3
The Super-Zip separation device will be applied to the payload connection and release structure due to its pollution-free and high load-bearing characteristics. As a direct-drive linear separation device of the pyrotechnics, it is accompanied with large impact action in the process of separation. How to reduce the detonation effect of the impact source and control the transmission of the impact during the unlocking process is an important prerequisite for the wide application of this type of separation device. In this paper, the LS-DYNA software is used to simulate and analyze the separation process of the Super-Zip separation device and the in-plane shock wave transmission law. In addition, based on the prediction results of the two simulation schemes, the test verification of one of the shock reduction schemes is carried out. The results show that the Finite Element Analysis（FEA）can effectively guide the development of the test and it is pointed out that reducing the collision area between the flat tube and the connecting frame can effectively improve the impact environment of the whole Super-Zip separation process.
2022 Vol. 41 (8): 244-249 [Abstract] ( 196 ) HTML (1 KB)  PDF (1567 KB)  ( 120 )
250 Three-dimensional rough contact collision characteristics of plow head-sliding framework with coal powder layer
ZHANG Yu1,2, WANG Qian1, CHEN Hongyue3， MAO Jun3
Three-dimensional clearance causes complex contact collision phenomenon between plow head and sliding framework.Coal powder layer aggravates the dynamic characteristics of the system. Based on the geometric characteristics of plow head and sliding framework, a method of reducing the 3D polyhedral collision detection to 2D polygonal collision detection was proposed. Considering the effects of surface roughness and coal powder layer, a three-dimensional contact collision dynamics model between plow head and sliding framework was established, rough interface contact force model and the contact force model with the coal powder layer were introduced, and the restitution coefficient were measured by experiment. A numerical analysis was conducted to obtain the dynamic characteristics of the contact and collision between plow head and sliding framework. The results show that contact collision of plow head-sliding framework has many forms, such as point, line, single-side and multi-surface.With the decrease of restitution coefficient, angle vibration and displacement vibration amplitude of plow head are reduced, contact collision vibration amplitude at the gap boundary is reduced, and collision force average of each point and the number of collisions decreases. Finally, the validity of the collision dynamics model is verified by experiments.
2022 Vol. 41 (8): 250-259 [Abstract] ( 193 ) HTML (1 KB)  PDF (2347 KB)  ( 213 )
260 A study of fracture range of tunnel surrounding rock under blasting
LI Fangtao1, HU Zhiping1,2, CHEN Nannan1, ZHANG Yonghui1, AN Xuexu1
The Fractures of tunnel surrounding rock under blasting load create good conditions for karst development and groundwater movement. In order to study the fracture range of surrounding rock under blasting load, considering the influence of medium principal stress and circumferential tensile stress, two kinds of calculation models of crushing area are obtained based on unified strength criterion and Mohr Coulomb strength criterion respectively. When the crushing area is filled with blasting gas, the secondary expansion range of fracture is calculated. Then, the scope of crushing area and fracture area is calculated through an engineering example, and the calculation results are compared and verified with the site experiment results. Finally, the following conclusions are obtained: (1) The calculation method of crushing area based on unified strength theory considers plastic damage, which is suitable for the calculation of tunnel crushing area. The theoretical calculation results are in good agreement with the site experiments results. This method can be used to design blasting parameters of tunnel with strict control of over excavation and under excavation; (2) The calculation method of crushing area based on Mohr Coulomb strength criterion does not consider plastic damage. Compared with the existing calculation methods based on Mohr Coulomb strength criterion, the circumferential tensile stress is considered, and the calculation unit body is more in line with the actual stress situation. The main difference between the two calculation methods of crushing area in this paper is whether the range of plastic damage is included. The two calculation methods should be selected according to different engineering requirements in practical application; (3) The site experiment results show that the calculation results of the fracture zone range based on the unified strength theory are close to the site experiments results, and this method can be used to calculate the fracture range of tunnel surrounding rock under similar blasting action.
2022 Vol. 41 (8): 260-269 [Abstract] ( 345 ) HTML (1 KB)  PDF (1283 KB)  ( 164 )
270 A numerical simulation study of a real-time hybrid test for high-speed maglev train-bridge coupling vibration
WANG Zhen1, HOU Jinyou1, WU Bin1, YANG Ge1, WANG Tao2, XU Guoshan3, DING Yong3
High-speed maglev train is a new and promising type of high-speed transportation, and has gradually become a research hotspot. When the train passes a bridge pier, owing to the pier vertical stiffness far greater than other bridge sections, there is an impact interaction between the train and the bridge. This impact is very unfavorable to the suspension control and even affects the operational safety. In order to study the coupling vibration, a real-time hybrid test for this coupling vibration between a high-speed maglev train and a bridge is proposed in this paper. This paper first describes the principle and flow diagram of this method, and then establishes a numerical simulation model of the test system, and carries out numerical simulation analysis. The studies show that the simulation results of hybrid test are fairly good as a whole, and the real-time hybrid test for high-speed maglev train-bridge coupling vibration is feasible; however, it is still difficult to accurately reproduce the impact interaction, which requires demanding dynamic performance of the loading system. The study results can provide some reference for the implementation of real-time hybrid test for train-bridge coupling vibration.
2022 Vol. 41 (8): 270-276 [Abstract] ( 374 ) HTML (1 KB)  PDF (1540 KB)  ( 210 )
277 A review on an accelerated random vibration test of transport packaging
WANG Lijun1, SONG Haiyan1, WANG Zhiwei2
The technique of accelerated random vibration test is used to evaluated the safety performance and damage of transport packaging, which can reduce test time and improve efficiency so as to reduce the optimization design period. It is composed of four parts: measurement and analysis of actual vehicle vibration signal, simulation and representation of laboratory signal, vibration fatigue damage of transport packaging and accelerated random vibration test theory and method. The research was reviewed from above four aspects. Statistical characteristics of actual vehicle vibration and influence factors were summarized. Signal simulation methods and the characteristics were concluded. Vibration fatigue theory and damage of transport packaging were described. Current research progress and disadvantage of accelerated random vibration test was analyzed. The unsolved problems were discussed and the future study direction of accelerated random vibration test was indicated.
2022 Vol. 41 (8): 277-286 [Abstract] ( 387 ) HTML (1 KB)  PDF (1063 KB)  ( 216 )
287 A study on energy absorption characteristics and multi-objective optimization of an axial variable thickness star-shaped tube
DENG Xiaolin1, HUANG Jiale2, 3
A new type of axially variable thickness star-shaped tube is proposed. Abaqus/Explicit is used to construct the finite element model of the structure, and the accuracy of the finite element model is verified. The structure’s crashworthiness such as deformation mode, force-displacement and energy absorption under axial impact was systematically studied, and its key crashworthiness indexes were analyzed. The crashworthiness of star-shaped tubes with different corners under the same mass is studied. The optimization study of the star-shaped tube was carried out. The results show that the proposed axial variable thickness star-shaped tube has great advantages in reducing the initial peak force and improving the crush force efficiency compared with the star-shaped tube of constant wall thickness. Compared with the original design, the optimal design obtained by multi-objective optimization has effectively improved the crashworthiness, the specific energy absorption is increased by 6.02%, and the initial peak force is reduced by 39.56%. This research can provide reference for the design of axially variable thickness energy absorbing structure.
2022 Vol. 41 (8): 287-296 [Abstract] ( 236 ) HTML (1 KB)  PDF (3470 KB)  ( 196 )
297 Vibration characteristics of composite I-beam with corrugated steel webs
ZHANG Zichen1, WANG Genhui1, FAN Jiang2
In order to analyze the bending vibration frequency and dynamic response characteristics of composite I-beam with corrugated steel webs, considering the influence of multi-factors such as shear deformation, moment of inertia, self balance of shear lag warping stress and accordion effect, two different longitudinal warping dynamic displacement difference functions were set up for the upper and lower flange plates of composite I-beam. The natural frequencies of composite I-beam under different boundary conditions were calculated by numerical examples. The effects of shear lag effect and warping stress self balance on the vibration characteristics of composite I-beam were analyzed in detail. It shows that the calculated results of the calculated results of the proposed closed-form solutions agree well with the ANSYS finite element values, and the calculation accuracy is significantly improved; the shear lag effect reduces the vertical stiffness of the composite I-beam, and its influence increases with the increase of frequency order, and decreases with the increase of span width ratio; Compared with the simply supported composite girder, the frequency value of the composite girderone with fixed ends is more affected by the shear lag effect; The results show that the contribution of stress self balance to the natural frequency of composite I-beam is less than 5%, and the influence on the dynamic stress amplitude of wing plate is more than 10%. The plane section assumption is no longer applicable in the dynamic analysis of this kind of structure.
2022 Vol. 41 (8): 297-303 [Abstract] ( 321 ) HTML (1 KB)  PDF (1307 KB)  ( 140 )
304 Cluster vibration and bifurcation of a fractional-order Brusselator oscillator
WANG Yanli1, LI Xianghong1, 2, 3, WANG Min2, SHEN Yongjun1,3
The Brusselator oscillator is a typical multi-scale coupling system because of catalyst, which will lead to cluster vibration behavior, characterized by spiking state coupled with quiescence state. In this paper, we consider the fractional-order Brusselator system under external periodic disturbance, and the nonlinear behaviors of the system are more complex. Based on the stability theory of fractional order system, the two-parameter bifurcation analysis is carried out, and the sufficient conditions of Hopf bifurcation are discussed. It is found that there is a singular line in the system, and its stability is verified by using the center manifold theorem and numerical simulation. The influence of different fractional orders on cluster vibration is discussed. Through the two-parameter bifurcation diagram with respect to fractional order and slowly varying parameters, it is found that the fractional order is closely related to the time of the spiking state. That is to say, reducing the fractional order of the system can shorten the time of the spiking state and increase the time of the quiescence state. It is also found that the variation of disturbance amplitude directly affects the type of attractor of the fast subsystem. When the excitation amplitude is large, two kinds of attractors are involved in the fast subsystem, the quiescence state and the spiking state coexist. When the excitation amplitude is small, the fast subsystem involves one kind of attractor, then the quiescence state disappears.
2022 Vol. 41 (8): 304-310 [Abstract] ( 317 ) HTML (1 KB)  PDF (1529 KB)  ( 142 )
311 A study on nonlinear energy sink of inertia capacity in the middle of an elastic beam
GAO Zhitong，FANG Bo，ZHANG Zhen
As a simplified model of many aerospace structures, the vibration suppression research about Euler Bernoulli beam has important engineering significance. In this paper, the inertial nonlinear energy sink was used to suppress the lateral vibration of elastic beam. With Hamilton’s principle, the dynamic governing equations of elastic beams were established. The partial differential control equations of the system were discretized by Galerkin truncation method. The steady-state response of nonlinear vibration was obtained by harmonic balance method and verified by numerical solutions. The results showed that the inertial nonlinear energy sink can effectively suppress the lateral vibration of the elastic beam. In addition, the influence of damping, inertial mass and cubic nonlinear stiffness on the vibration suppression effect was discussed. Finally, the optimal range of parameters under different excitation and bending stiffness was discussed. The results showed that the vibration suppression effect of the optimized inertial nonlinear energy sink can reach 99%.
2022 Vol. 41 (8): 311-322 [Abstract] ( 427 ) HTML (1 KB)  PDF (2426 KB)  ( 242 )
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