15 December 2017, Volume 37 Issue 1
    

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  • CHEN Peng,LIU Jinyang, HONG Jiazhen
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 1-7.
    Abstract ( 147 ) Download PDF ( 101 )   Knowledge map   Save
    A dynamic formulation based on the component mode synthesis method was proposed for solving the oblique contact-impact problems in multibody systems. The contact bodies were divided into the contact zone part and un-contact zone part. The degrees of freedom of the un-contact zone part were reduced by the modal reduction, which improves the computational efficiency on condition that the accuracy is guaranteed. Impacts in the normal direction and tangential direction were modeled using the penalty method and the modified Coulumb friction model respectively. A contact system consisting a steel rod and a PVC plate was considered. An eccentric collision considering the friction effects was investigated experimentally, and the strain and velocity response of the plate were measured by the strain gauges and the 3D-DIC measuring technique. The comparison between the numerical results and experimental results proves the accuracy of the formulation proposed. Meanwhile, the influence of the relative velocity on the friction coefficient was investigated. 

  • Haijun Zhou 1 Caichun He 1 Qibin Jiang 1 Wanyou Li 2 Changrong Zhou 1 Haishu Mo 1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 8-13.
    Abstract ( 197 ) Download PDF ( 38 )   Knowledge map   Save
    A receptance synthesis approach was formulated to investigate the dynamic characteristics of a coupled beam-cylindrical shell system. The system was divided into a beam substructure and a shell substructure. The receptance functions for the beam and cylindrical shell substructures were determined using the improved Fourier series method and the wave propagation approach respectively. Based on the kinematic compatibility and force equilibrium conditions at the coupling interfaces of the substructures, the responses of the coupled system were directly predicted though the load applied to the substructures. The receptance synthesis approach was then used to determine the responses of a beam-shell system which serves to validate the correctness of the method, comparing with a FEA model. The vibration responses of a coupled lumped mass-shaft-cylindrical shell system were then used to study the effects of modifying some model parameters.
     
  • Huang Qiang1,2 Huang Hong-wei1,2 Zhang Dong-mei1,2 Huang Xu3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 14-20.
    Abstract ( 154 ) Download PDF ( )   Knowledge map   Save
    By double Fourier transform and contour integration technique, a closed-form solution to the steady-state response of a uniform beam placed on Kerr foundation and subjected to a moving harmonic load was obtained. The beam was described as a Euler-Bernoulli beam, and the cut-on frequency and critical velocity of the foundation beam were determined based on the dispersive curve of Kerr foundation beam. The influences of the train speed, load frequency, coefficient of subgrade reaction and foundation shear coefficient on the deflection of foundation beam were investigated and the influence of foundation damping on the critical velocity and resonant frequency was also studied. Moreover, a two-dimensional beam-soil model was established to calculate the deflection of foundation beam under non-moving constant load and simple harmonic load. The numerical results were compared with the analytical solutions of Kerr foundation, Pasternak foundation, and the Winkler foundation. It is concluded that the Kerr foundation model can give best agreement with the FEM results, while the Winkler foundation model presents greatest discrepancy in static calculations. As for dynamic calculation, the time history responses base on different types of foundation beam models are only close to the numerical results at the places near the applied load.
  • SONG Zhenghua1, JIANG Dong2, CAO Zhifu1,HAN Xiaolin1, FEI Qingguo1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 21-26.
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    An approach for the model updating of the nonlinear stiffness of a truss with joints using the pattern-search method was proposed. The modeling of the nonlinear truss was conducted based on the describing function method. The dynamic responses of the truss were analysed supposing the joints were of cubic nonlinearity. Based on this, an objective function was constructed with the minimum error between the experimental and simulated FRFs and was used to update the stiffness of structure by the pattern-search method. A cantilever beam with one joint and a one-bay truss were taken as the objectives of simulation. The initial errors of nonlinear stiffness are 15% and 50% respectively in these two cases without noises and a reasonable step size and convergence criteria were chosen to improve the accuracy of the updated stiffness. When the FRF data are contaminated by noise of 0.5%, 1%, 2%, the errors of updated stiffness are 0.2%, 2.2%, 2.2%, respectively. When multiple parameters are needed to be updated, the errors of the results are only 1.9% and 0.7%, respectively. These results demonstrate that the pattern search method is an effective method for nonlinear structural model updating.
     
  • Zitao Guo1, Guo Zhao1, Wei Zhang2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 27-31.
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    Oblique perforation experiments on single A3 steel sheets with the thickness of 2 mm impacted by flat and ogival projectiles at 5 impact angles were conducted using a light-gas gun. The initial-residual velocity curves and ballistic limits for projectiles perforating single targets at different angles were obtained, meanwhile, the effects of different projectile nose shapes and obliquities on the ballistic resistance and failure patterns of targets were compared and analyzed. The results show that the target perforation by flat projectiles is easier than that by ogive nosed projectiles at each oblique angle, while the ricochet phenomenon occurs more easily for ogive projectiles at large impact angles. The ballistic resistance of targets is found to be closely related to the target damages induced by projectile impact. As the impact angle increases, the local perforation damage model of the target plate due to flat projectile impact turns gradually from the shear plugging to the dominant tensile tearing failure and the bending and film deformation of the entire structure decrease. In contrast, the oblique petal-cracking is found to be the main failure model in thin plates perforated obliquely by ogive projectiles.

  • ZHANG Guan-jun LI Tian-yun ZHU Xiang
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 32-39.
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    According to the geometry characteristics of the cross section of an eccentric cylindrical shell, the eccentric problem was converted into a circumferentially varying thickness problem. The displacements were expanded in double Fourier series in view of the concept of wave propagation and the circumferential thickness was represented as a trigonometric function. Through a series of transformation, the partial differential equations with variable coefficients were converted into a set of linear equations with the circumferential modal parameters coupled with each others. The forced vibration responses of the eccentric cylindrical shell were obtained by solving the coupled equations and then the input power flow was achieved. By comparing with the literature and FEM results, the accuracy the vibration model established and calculation method for the eccentric cylindrical shell was verified. The influences of the parameters, such as the exciting force position, eccentricity, shell thickness and material damping factor on the input power flow of the eccentric cylindrical shell were discussed in detail.

     
  • WANG Feng1, FANG Zong-de2, XU Xing1, CHEN long1, SUN Xiaoqiang1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 40-46.
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    In order to accurately calculating the time varying meshing stiffness of a herringbone gear pair, a herringbone gear teeth contact model was established considering the axial floating of driving gear. On this basis, the meshing stiffness considering installation errors was deduced, and the variation characteristics of meshing stiffness under different loads were analyzed. A three dimensional tooth profile optimization design considering the fluctuating magnitude of meshing stiffness as a target was carried out by using a genetic algorithm. Taking a ship herringbone gear transmission system as an example, the results consistently indicate that the herringbone gear meshing stiffness experiences a process of first increasing and then gradually tending to constant with the increase of external load. A herringbone gear transmission experiment testing system with closed power flow was set up to verify the theoretical analysis, and the meshing stiffness was measured through high precision Heidenhain angle encoders. The results of numerical simulations and the experimental data are in good agreement, the maximum deviation is 8.8%, and the amplitude variation trend of the meshing stiffnesses before and after teeth modification is also consistent.

  • WANG Guo-yuan 1 XU Yang 1 HU Xiao-nan 2 SHENG Xiao-wei 1 JIANG Qing-fei1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 47-52.
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    Based on the Ensemble Empirical Mode Decomposition (EEMD), a new method about the shock response analysis of an unlocking device of satellite and rocket was proposed. The shock response signals of the unlocking device of satellite and rocket were resolved into different Intrinsic Mode Functions(IMF)by EEMD. The analyses show that the IMFs during the first two phases are high-frequency vibrations caused by impacting, while the phases after IMF3 are different modes of vibration and local vibrations. The correctness of the analyses were verified by the experimental modal analysis.
  • YUAN Yu-chao1,2, XUE Hong-xiang1,2, TANG Wen-yong1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 53-59.
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    A new time domain Vortex-Induced Vibration (VIV) prediction method for a marine riser was proposed, and a special added mass element was introduced, which can take into consideration the variation effect of added mass coefficient on the modal analysis and VIV prediction. Based on a recommended prediction model, the VIV response of riser models under uniform flow and sheared flow were simulated and the predicted results were compared with the test results about the root mean square amplitude as well as the time histories and amplitude spectra of the curvature, stain and displacement responses. It is found that the new time domain model can predict VIV responses of marine risers effectively and the predicted results are much more consistent with the observed test data than that of traditional numerical models. The variation effect of added mass coefficient on VIV response can affect the predicted results evidently.

  • DING Sheng-peng,OU Yi,KE Nan,FENG Hu-tian
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 60-65.
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The relationship between the oil viscosity grade and mechanical vibration of a damping carriage for linear rolling guides was examined based on the sweep excitation method. A dynamic vibration model was proposed to analyze the correlation between the oil viscosity grade and the damping characteristics. Meanwhile, a sweep excitation experimental platform was constructed. The experimental tests were performed on the DS45EA damping carriage, lubricated with the mineral oil of four different viscosity grades (ISO 22, 46, 68 and 150). The response signals of the damping carriage, collected by the PROSIG P8020, were processed through spectrum analyses in three resonant frequency bands. It is proved that the vibration of damping carriage decreases as the oil viscosity increases. Furthermore, the rate of the vibration descent turns to be slow with the oil viscosity increasing, and the vibration magnitude of the damping carriage approaches a constant when the viscosity grade exceeds ISO 70. The results provide a guide to choose the proper oil viscosity for the damping carriage, which is significant for the better performance of linear rolling guides as well as CNC machine tools. The using of sweep excitation method provides a new idea for the study of the damping performance of the damping carriage for linear rolling guides.
     
  • BAI Jin1 LI Sheng1,2 XIA Maolong1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 66-71.
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    The left eigenvectors of a closed loop system were controlled to be orthogonal with the excitation force vector for the active structural acoustic control by use of the dependent modal space control (DMSC) method. The relationship between the left eigenvectors and the mode shapes of the vibration system was derived. The conclusion was drawn that the left eigenvectors of the closed loop system are also a linear combination of the left eigenvectors of its corresponding open loop system when the mode shapes of the closed loop system are a linear combination of the mode shapes of the open loop system. The left eigenvectors orthogonal with excitation force vector were constructed and the mode shapes corresponding to the constructed left eigenvectors were considered as the control target, then the control of the left eigenvectors of the closed loop system was realized by the DMSC method indirectly, and finally the active structural acoustic control was achieved. The active structural acoustic control method proposed has the characteristics of clear physical meaning, simple implementation and good sound radiation control performance. The active structural acoustic control of a rectangular simply supported plate was numerically evaluated, and the first and fourth left eigenvectors of the closed loop system were assigned to be orthogonal with the excitation force vector by the DMSC method. The results show that the control scheme proposed here is very efficient in reducing sound radiation.
     
  • Maziyuan Yuxiaoli Huangyuqi LIU Zhentao Huangrui
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 72-76.
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    The engine lubricating fluid transient oscillation process is a complex fluid solid coupled problem. A fluid solid couple model for the crankshaft, oil sump and lubricating oil of a vehicle was established and the transient sloshing responses of the lubricant by using the coupled Euler Lagrange (CEL) algorithm during the starting, acceleration, braking and steering working conditions were analysed. The finite element modeling and the volume fraction treatment of the CEL method were discussed. On the basis of the case analysis of a liquid shock, the dynamic responses of the oil sump shell were investigated. The results show that under the liquid sloshing conditions, the sharp peak phenomenon will appear on the oil pan wall stress curve, which has a great impact on the NVH performance. The results are of practical significance to realize the visualization of transient liquid oscillation processes and to implement the noise reduction in engine design.
  • CAO Hai-ying,Liu Yun-fei, LI Yu-nong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 77-84.
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    Aiming at inspecting the size effect of scale models in tests, and considering a two-layered subgrade with upper dry crust and lower weak subsoil under vehicle load as a study abject, the soil's energy absorption coefficient was selected as a characterization parameter for analysing the size effect from the view of revealing dynamic stress attenuation behaviors. On the basis of numerical simulation results of different scale calculation models, the attenuation  expression for the dynamic stress's representative value along depth was obtained, and the response equation for describing the size effect was built in hard and soft soil layers according to the fitted relationship between the model scale and homogeneous soil's energy absorption coefficient. The response equation for describing the size effect at the transition section was derived base on establishing the functional relation between the dynamic stress's interface transfer coefficient and model scale, and introducing the dimensionless energy absorption coefficient at soil interface. The reliability of the response equations was validated by the field monitoring data and indoor model tests. The results show that the working condition of the prototype experiment can be inferred by applying the test results of scale models and the evolution of size effect, under the premise of vibration frequency being 1Hz to 5Hz. The relevant results have some guiding meaning for actual projects.
     
  • Wang Ya-nan1, Du Yong-feng2, Hu Gao-xing1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 85-89.
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    An isolation bearing would experience large deformation under pulse-like ground motions, and this may cause isolation bearing’s cracking or instability. Using constant-strength displacement demand spectra to evaluate the maximum inelastic deformation of the isolation bearing is a very simple and effective method. The constant-strength displacement demand spectra of base-isolated structures were studied taking near-fault pulse-like ground motions as inputs. The nonlinear mechanical characteristics of the isolation bearing were represented by the Bouc-Wen model, and the relevant motion equations with respect to the constant-strength displacement demand spectra of base-isolated structures were established. The software MATLAB was used to solve these motion equations, and the constant-strength displacement demand spectra of base-isolated structures were obtained. At last, the constant-strength displacement demand spectra's mathematical expression was established by numerical fitting. This expression can be used to evaluate the isolation bearing's maximum inelastic deformation quickly, and is easy to be applied in engineering practice.

  • TIAN Zhenghong1, JIANG Guilin1, SU Weihao1,Ni Jun2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 90-97.
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    The split Hopkinson pressure bar impact test was used to systematically study the dynamic compressive properties of fiber mortar doped with ultra-high molecular weight polyethylene (UHMWPE) and polyvinyl alcohol (PVA). The effects of strain rate and fiber type on mortar’s strength and toughness were analyzed according to the stress-strain curves during the specimen’s failure process. The results show that the comprehensive performance of UHMWPE fiber mortar is the best, that of the Japanese PVA fiber mortar is the second, and that of the domestic PVA fiber mortar is slightly poor. A simplified constitutive model with four parameters of the fiber mortar was proposed based on the theory of traditional viscoelastic damage. Comparing with the test results, it is shown that the model can well simulate the dynamic compressive stress-strain relationship of the fiber mortar subjected to impact load..

  • XIE Weiping1,CAO Xiaoyu1, Xiao Boqiang2, Liu Haiqing2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 98-105.
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    An accurate finite element model for wide steel box-girder bridges is very important for the evaluation of structural dynamic performance and the structural design. A sophisticated finite element model was presented for a certain wide steel box-girder bridge. Modal tests in various stages of construction were carried out based on the field ambient vibration excitation. The stochastic subspace identification and peak picking of the average normalized power spectral densities were used to identify the bridge’s dynamic characteristics. The response surface method based on the dynamic characteristics identification was adopted to update the FEM. And the influences of the paving, equivalent masses of adjacent bridges on the bridge’s natural frequencies were discussed. The results show that the FEM established is quite accurate, the paving will lead to the huge decrease of natural frequency, and equivalent masses of adjacent bridges have significant effect on the lateral and torsional frequencies.

  • LI Ying1,2,WU Weiguo1, ZHANG Lei2, DU Zhipeng2, ZHU Haiqing1,ZHANG Wei
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 106-110.
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    An experiment device was set up to investigate the dynamic responses of water- spacing aluminum plates, and a super-speed camera was used to record the whole process with complex phenomena in different stages. The projectile velocity and the deformation during its motion in water were studied and the failure modes for water-back plate and air-back pates were analysed. It is gained that: the process can be divided into three stages, and the kinetic energy of the projectile transforms to the kinetic energy and potential energy of water; the projectile resistance when moving in water is a constant, about 0.38; the failure modes of the plates is mainly the radial-shrinkage and the successive petal breaking, and the local deformation and petal number of water-back plates are much less than those of air-back plates.

     
  • LI Xiaorun1, 2, Song Bo1, Bian Xiaofang2,Wang Pin2, Wu Changdong 2,Chen Shuirong2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 111-116.
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    Low-cyclic loading experiments on a new type vertical outside connection between H-section beam and rectangular tube column were conducted. The damage phenomena and failure mechanism, the hysteretic performance and ultimate bearing capacity were presented. The software ABAQUS was adopted to establish the models in tests and the numerical results are almost consistent with the experiment ones. At the same time, the effects of the flange and web thicknesses of the beam, and the thickness of the rectangular tube column on the mechanical behaviors of the steel connection were analyzed. The results show that the connection has a good capacity of energy dissipation and is of enough ductility. The plastic hinges mainly occur in the beam. The initial stiffness, yielding load and ultimate load are obviously affected by the flange and web thicknesses of the beam. The thickness of the column has negligible effect on the behavior of the connection.

  • Ren Yongsheng, Shi Yuyan, Zhang Yuhuan
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 117-127.
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    The nonlinear free vibration and stability of an internally damped rotating composite shaft were investigated. The shaft was assumed as an inextensional rotating beam with nonlinear curvature and inertia. The internal damping was described by the dissipative behavior of composite. Based on the constitutive relations and the strain-displacement relations of composite, the strain energy, virtual dissipative work and kinetic energy of the shaft were obtained. The equations of motion governing the nonlinear bending-bending vibration of the rotating composite shaft were derived using the extended Hamilton principle. The partial differential equations of motion were reduced into ordinary differential equations by the Galerkin’s method. In order to find the boundaries of stability, the corresponding linearized model of the composite shaft was used in eigenvalue analysis. The critical rotating speeds and instability thresholds of composite shaft were provided. The fourth-order Runge-Kutta method was used to integrate numerically the differential equations of motion. The displacement-time responses, phase plane curves and power spectra of the shaft were presented. The effects of the ply angle, ratio of length to outer radius and stacking sequence on the nonlinear bending vibration responses of the composite shaft were evaluated.
     
  • ZHANG Longwen1, LU Zhaohui1,2, ZHAO Yangang1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 128-135.
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    An analytical procedure was developed for estimating the first passage probability of stationary non-Gaussian structural responses. In the procedure, based on the beforehand obtained first four moments of the stationary non-Gaussian structural responses, a stationary non-Gaussian response was mapped into stationary standard Gaussian processes by using the equivalent Gaussian fractile of translation model and the critical level. The equivalent Gaussian fractile of Winterstein’s polynomial (1994) and Ding and Chen model were used for softening and hardening non-Gaussian responses, respectively. Then, the Poisson model based on stationary non-Gaussian structural responses was established considering the effects of clumping and initial conditions on the up-crossing rate. The accuracy and efficiency of the modified method were demonstrated through the comparison study of numerical examples. The results show that the computational efficiency is greatly improved compared with the Monte-Carlo simulation, which provides an efficient and rational tool for the first passage probability assessment of stationary non-Gaussian structural responses.

  • ZHANG Qiang1,2,3,SUO Jiang-wei1,WANG Hai-jiang1,SUN Guo-qing1,SUNHe-wei1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 136-141.
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    In order to improve the rock breaking speed and efficiency, a dynamics simulation analysis was done by using the ABAQUS analysis software to study the process of continuously crushing hard rock under the rotary-impact load from a hydraulic drill. The effects of the impact frequency, rotary speed and initial crustal stress on the rock breaking efficiency were discussed. The numerical simulation analysis results show that: the rock breaking speed increase with the increase of rotary speed. When the rotary speed is up to 300r/min, the rock breaking speed is almost no longer changed and the rock breaking efficiency reaches the maximum. As the impact frequency increases, the rock breaking speed increases obviously, and at 70 Hz achieves the highest rock breaking efficiency. Different initial crustal stress conditions have little influence on the rock breaking speed, but it has a great impact on the efficiency of rock breaking. The results provide an important theoretical reference and numerical basis for improving the rock breaking effect of rock drills in practical engineering.
     

     
  • YI Yuan-yuan,QIN Da-tong,LIU Chang-zhao,JIA Han-jie
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 142-149.
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    To investigate the dynamic behavior of the transmission system of a coal shearer under different working conditions, a cutting-haulage coupled model was established by using MATLAB/Simulink, in which the electromagnetic characteristics of the driving motors, variation of the cutting resistance of the coal seam, torsional vibration of the transmission system, time-varying meshing stiffness and tooth backlash were considered. Then, the electromechanical dynamic behaviors of the system were simulated in the regimes of run-up, drum load sudden-change and locked-rotor. Finally, a coal-cutting experiment was conducted on a realistic shearer to verify the simulation results. The results show that in the regimes of run-up and locked-rotor, strong interactions occur between the motor and the transmission system, which causes nonlinear impact phenomena including the gear contact lose and clonk. In the design of the transmission system of a coal shearer, a higher application factor should be adopted for the cutting unit than the haulage unit and a higher safety factor should be adopted for the high-speed stage gears than the low-speed stage gears.
     
  • FU Bin1,LUO Shi-hui1,XU Zi-Qiang2,TANG Yang1,3,MA Wei-hua1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 150-155.
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    Aiming at analysing the bad ride comfort caused by the nine-order polygon wheel of a domestic subway vehicle, numerical simulations and field tests were carried out. The reason of polygon wheel was analyzed theoretically. A dynamic model for the subway vehicle was established and the natural frequencies of bogie components were calculated. The simulations show that the vehicle ride comfort is irregularly bad at 40km/h. The transfer function from the track irregularity to the motor displacement was established and the results show that nine-order polygon wheels produce external excitation of 43Hz at 40km/h which is close to the vertical vibration natural frequency of the linear motor, causing the resonance of motor and the development of polygon wheel. The field tests show that the ride comfort tested on the car body is also irregularly bad at 40km/h and it tends to deterioration with the growth of polygon wave depth. The methods for simulations and field tests for studying polygon wheel effect, featured with the irregular vibration velocity as a key factor, were summarized. Finally, the parameters of motor suspension were optimized to eliminate the severe vibration and to improve the ride comfort.  

  • WANG Xing-hua1, PENG Yong1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 156-162.
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    To investigate the differences between the head and leg dynamic responses of a bicyclist and a motorcyclist under different impact conditions, 60 groups of simulation experiments were designed considering the variables of vehicle speed (30km/h, 35km/h, 40km/h, 45km/h and 50km/h), vehicle type (large family car and sport utility vehicle) and impact location (front, middle and rear parts of two-wheeler). Then, the vehicle-bicycle/motorcycle side collision accidents were simulated under different conditions based on PC-Crash software, and the dynamic response parameters (such as head resultant acceleration, head resultant speed, head impact speed, struck leg impact force, etc) of the bicyclist and motorcyclist in side traffic accidents were analysed. The results show the bicyclist the firstly slides on the bonnet, and then rotates around the contact position of hip and bonnet towards the windscreen, while the motorcyclist directly rotates around the contact position of thigh and bonnet leading edge towards the bonnet rear or windscreen when impacting with a large family car. Furthermore, the bicyclist suffers severer head injury and the struck leg of the motorcyclist sustains greater impact force under the same impact conditions. These findings can contribute to generate suitable protecting strategies for bicyclists and motorcyclists.

  • Li Jingru 1 and Li Sheng1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 163-171.
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    A new periodic metamaterial plate was proposed based on the concept of the phononic crystal and local resonance mechanism. The proposed structure consists of negative modulus acoustic metamaterial microstructures acting as local resonators. The structure not only exhibits low frequency stop band characteristics, but also provides multi-flexural band gaps, and leads to the transformation of partially flexural waves. Since no wave energy propagation is allowable in the multi-frequency domain, the frequency domain for vibration transmission mitigation in the structure is broadened. The dispersion relation was acquired by using the plane wave expansion method. A comparison between the results obtained by the plane wave expansion and finite element method was presented and a good correspondence between the results of both methods was found. The vibration transmission loss of a finite metamaterial plate was calculated to validate the band gap, demonstrating the efficiency of the vibration isolation. Moreover, a parametric study was implemented to investigate the effects of parameters of the local resonators and unit cell on the band gap property, which makes it possible to satisfy the specific requirements (low frequency, wide band gap, etc) of metamaterial plates for vibration isolation.

  • HUANG Yun-sheng1, DENG Si-er1,2,3, ZHANG Wen-hu3, HU Jie1,3, SUN Li-ming4,MA Zikui5
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 172-180.
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    Besides supporting the direct heavy load above the primary suspension, railway axle box bearings also bear the impact loads passed from the wheel and rail interaction due to track irregularity. The cage bridge fracture because of impact loads is one of the main factors leading to the early invalid ity of bearings. The influence of the impact from wheel flat on the vehicle system was analyzed and taken as the boundary condition in bearing dynamics analysis. The discrete element approach was used to model the elastic cage. The influences of impact loads on the axle bearing cage dynamic characteristics, the contact force between the roller and cage and the stress distribution in the cage were researched. The results show that the contact force and contact frequency between the roller and cage increase significantly with the increase of the impact acceleration, which will speed up the fatigue failure of the cage. It can be judged from the cage strength analysis that the external heavy impact acceleration from the wheel and rail interaction will lead to the instant fracture of cage bridges.

  • Yang Fengli
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 181-186.
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    The finite element analysis model of a 220kV cat-head transmission tower was established by using the general FEA software ANSYS. The axial forces of tower members under different load cases were analyzed by the static method and dynamic method respectively. Three typical load cases were taken into account, including the non-uniform settlement, inclination and horizontal slip of the tower foundation. The dynamic impact factors of the axial forces of tower members with a sudden foundation deformation were calculated. It is shown that the stress in the diagonal member located at the tower leg varies greatestly and fails earlistly in the process of foundation deformation. The peak values of tower member forces occur near the initial time of the foundation settlement, while the effect of damping ratios on the peak values is not significant. When the damping ratio is valued as 0.01 and 0.05, the difference between the peak axial forces of the leg main member different is only about 3.5%. For the transmission lines in the mining subsidence areas with dramatic surface deformations, the dynamic impact effect of sudden foundation deformations on transmission tower structures is significant. By considering the dynamic impact effect, the stress ratio of the diagonal member located at the tower leg under non-uniform settlement is increased by more than 50%. The increasing extents even exceed 100% in the single side inclination case and the horizontal slip case.
     
     
  • JIA Qingxuan, HONG Xunchao, CHEN Gang, ZHANG Long
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 187-195.
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    Aiming at the capture task performed by a free-floating flexible space manipulator, a method for analyzing the system responses causes by the contact between the end-effector of the space manipulator and the target was proposed. Based on the cantilever beam model and the assumed mode method, a kinematics model of the space manipulator considering its flexible links was established. The Hertz damping model was adopted to simulate the soft contact process and according to the Lagrange equation, a contact dynamics model of the space manipulator was also established. On this basis, the response equations of the system due to the external excitation were deduced with its joints free or completely controlled. Finally, the responses of the space manipulator were analyzed by using the numerical simulation with its joints in special state and its end-effector contacting with the target. The numerical simulation results show that when the manipulator performs the capture task, the impact force may be huge, and the forces suffered by its joints may even exceed its limit. Meanwhile, due to the deformations in the motion plane and perpendicular plane caused by the impact are in the same order of magnitude, the impact responses in both planes should be considered simultaneously.
  • Fu chuan
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 196-202.
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    The tuned liquid column damper, TLCD, is a cost-effective passive device to increase the structural damping. The design method for TLCD was evaluated. The most efficient placement for the absorber was determined in accordance with the dynamic characteristics of the structure. The optimum geometric parameters were analysed based on the equation of motion. The optimal frequency and damping with respect to a selected mode of the structure were simplifiedly achieved by comparing with the TMD tuning with the properly transformed Den Hartog’s optimal parameters. Finally, the design procedure was gained. The numerical simulation of a 30-storey plane-asymmetric structure illustrates the effectiveness of TLCDs to mitigate the earthquake induced vibrations of plane-asymmetric buildings, and also the feasibility of the proposed method.
     
  • Fang Shilin,Li Tie,Lu Mei
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 203-207.
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    For the sake of the institution of percussion test condition of missiles under the situation of insufficient measured data, the Shock Response Spectrum (SRS) model was introduced. The SRS of a missile in a specific range of rate was calculated by using the SRS model based on the actual shock excitation (acceleration of barycenter) and compared with telemetering data to improve the validity of the SRS model. Then, based on the output of the experiment equipment and the SRS of the missile in the specific range of rate, a self-adapting differential evolutionary algorithm was used to obtain the optimal experiment condition of missile to simulate the actual impulsive environment. The method can be used as a theoretical basis for ensuring the percussion experiment condition of missiles in development phase.

  • XIANG Yu1,2,SUN Run1,2,LU Jing1,2,YUAN Li-yun1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 208-215.
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    Based on the elastic theory of thin shells, and by applying the motion equations of the solid frame and fluid part and the constitutive equation for a porous media proposed by Biot, the first order differential governing equations of a thin fluid-saturated porous cylindrical shell under harmonic excitation were established. Employing the extended homogeneous capacity precision integration method and precise element method, a new semi-analytical method for analysing the vibration performance of this kind of structures was developed. Considering thoughtfully the coupling effect between the solid frame and the fluid, the present model is reasonable and adaptable, which could make up the insufficiency of the existed calculated models and the effective medium method. Based on the new method, the effect of porosity on the frequency response of a fluid-saturated porous cylindrical shell was discussed.

  • Wang Min1 Shi Shao-qing Liu Ying-feng1,2 Cui Lian-ming1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 216-222.
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    The flexible rock-shed for rockfall protection is composed of a steel vaulted structure and ring nets. The existing researches show that the stiffnesses of the rock-shed internal components are mismatched and the most serious plastic distortion occurs on the steel vaulted structure because of some weak components in the flexible rock-shed obstructing the load transfer path under the impact of rockfall. These defects would increase the maintenance cost and limit the engineering application. In order to optimize the flexible rock-shed and decrease the plastic distortion of the steel vaulted structure, a numerical model was employed to investigate the energy absorbed by each component in the flexible rock-shed based on results of the full-scale model experiments and numerical simulations, and a design method was presented to improve the connections between the components of the flexible rock-shed. The numerical simulation results show that: compared to the original flexible rock-shed, the energy absorbed by the steel vaulted structure of the improved flexible rock-shed is significantly decreased and the distortion is improved. In addition, a parametric study for the improved flexible rock-shed was implemented and an optimum design was presented.

     
  • Mi xuhui1Qin lei1 Liao qingwei 1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 223-228.
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    In this paper, Tthe vibration modes of 1-1-3 composites made from which were prepared by PZT-5H, silicone rubber and epoxy resin were analyzed. Two groups of experimental samples were prepared. 。It is found that the composites haves higher electromechanical coupling coefficient and lower acoustic impedance. The PSV-400 type laser vibrometer was used to measure the vibration shape. The measured results shows that the vibration amplitude of the piezoelectric ceramic column is much bigger than that of the silicone rubber and epoxy resin columns.And Tthe vibration mode of the piezoelectric ceramic column is the k33 mode. The composite material of the structure can fully exert the piezoelectric properties of the piezoelectric cylinder, improve the piezoelectric propertiesy of the whole element, and the vibration mode is more favorable for the composite element to be used in the underwater transducer.
  • Li Shang-ping 1,2 Zhang Biao 1 Zhou Jing-hui 1 Zhong Jia-qin3 Yang Dai-yun1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 229-235.
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    Aiming at the small sugarcane harvester cutter's vibration leading to the high broken rate of sugarcane ratoon, unbalance mass blocks were designed to build an excitation source to simulate the cutter's dynamic imbalance and to control the cutter's vibration. The feasibility of the tests was verified through mechanical calculations and simulations. To explore the effect of cutter's vibration on the cutting force and the effect of cutting force on the ratoon cutting quality, both simulations and physical tests were carried out. The simulation results show the axial cutting force accounts for about 92.6% of the total cutting force when the force reaches maximum. The test results show that the vibration has a significant influence on the cutting force and the cutting force shows a linear upward trend in the scope of the amplitude of 1.02-1.20mm. The correlation coefficient between the axial cutting force and ratoon cutting quality is from 0.91 to 0.95. When the amplitude changes, the axial cutting force is the main influential factor on the ratoon cutting quality of sugarcanes.
     
  • LIU Mingqian, WANG Dongwei, LI Jianxi, ZHU Zhangyang, MO Jiliang
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 236-240.
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    An experimental study was performed to investigate the effect of grooved brake disc on the tribological behaviors and friction-induced vibration and noise characteristics. The test results show that every kind of the grooved disc samples has good potential in improving the friction and wear behaviors of the interface, and cutting 45° grooves on the disc surface can significantly reduce the friction noise. Moreover, a numerical analysis was performed to simulate the experimental process by using the finite element software ABAQUS. It is found that the grooved discs can significantly disturb the contact pressure distribution on the pad surface and consequently reduce the squeal.

  • Wen-Bin Shangguan1, Dong Xiong1, Shan-Miao Yang2, Xin-Xing Xie2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 241-247.
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    The measurement and calculation methods for the sound absorption and insulation characteristics of multi-layered panel materials including double felt, ABA (absorber-barrier-absorber) and dissipative materials were proposed. The sound absorption coefficients and the insertion losses of three kinds of multi-layered panel materials were measured with the Alpha cabin equipment and in an anechoic-reverberation room, respectively. To calculate the sound absorption and insertion loss of multi-layered panel materials, the sound absorption coefficient, flow resistivity and porosity of the single-layer materials were measured. Then, the sound absorption coefficient and insertion loss of the multi-layered panel materials were estimated by using a relevant software. The comparison between the measurement and calculation results shows reasonable agreement for the insertion losses. The error between the calculation and measurement results of the sound absorption coefficient was analyzed.

  • ZOU Yu-jun1,2 YAN Peng1,2 LIU Lin3 ZHOU Tian-gang4 LU Wen-bo1,2 CHEN Ming1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 248-258.
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    The assessment and control of the blasting vibration effect on local residences have great significance to guarantee the successful engineering construction and decrease the dispute between inhabitants and construction companies. According to the inspection and classification of local residences above the right dam abutment slope in Baihetan hydropower station, monitoring schemes were determined. Based on the study on the failure mechanism of residential structures due to blasting vibration, the safety control standards of blasting vibration were recommended by combining the domestic and overseas corresponding criterions. Through longtime tracking monitoring, the influenced zone was divided by the influenced degree of blasting vibration, and the vibration responses of different types of residences were analyzed. It is concluded that for the areas from which the scaled distances to the blast center are less than 90m/kg1/3, between 90~150m/kg1/3 and greater than 150m/kg1/3, the influenced degree will be, successively severe general and slight. According to the analysis of the vibration energy, the blasting scale should be controlled in order to reduce the cracking risk of residential structures. Moreover, reasonably enlarging the linear charge density of pre-splitting holes to improve the pre-splitting blasting effect and meanwhile strictly restricting the maximum explosive charge weight of pre-splitting holes are the direct and effective measures to control the blasting vibration influences on local residences.
     
  • WANG Zhiyong,DU Weitao
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(1): 259-264.
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    In view of the technical problems of poor stability, low machining accuracy, marks on the tooth surfaces of workpieces and others, and focusing attention on a high speed dry cutting CNC spiral bevel gear milling machines the machine was thoroughly investigated. The study shows that the milling force is the important characterization of the tool running states and machining quality parameters. An indirect scheme was put forward, based on the actual working conditions of national high speed dry cutting CNC spiral bevel gear cutting machines. In the scheme, the milling force was reflected by monitoring the motor currents of the tool spindle and workpiece spindle. The spindle system of the machine tool was analyzed, aiming at building a model to express the relation between the tool spindle motor current and the milling force. The tool spindle system kinematic model was established, the motor current was monitored by using the double spindle’s torque measurement method, and then a time-frequency analysis was carried out on the current signals. Some mathematical methods were applied to process the data. All the measures were quoted to realize a final purpose, that is to calibrate the undefined parameters of the kinematic model of the cutting spindle system and accomplish the model for the tool spindle motor current and the milling force. The milling force can be monitored by this model in real-time. The results can provide data support for the optimum design of machine tool structures and the improvement of technological parameters.