15 January 2018, Volume 37 Issue 3
    

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  • YAN Weiming1, WANG Jin1, XU Weibing2, PENG Lingyun1, ZHANG Kui1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 1-7.
    Abstract ( 512 ) Download PDF ( 231 )   Knowledge map   Save
    In order to clarify influences of connected rigidity on damping effects of tuned particle dampers (TPDs) and determine the available optimal range of the connected rigidity between TPD and a structure, a 1/30-scale RC frame model was designed and manufactured, TPDs with various connected rigidities were designed to reduce vibrations of the test model, influences of connected rigidity on TPD’s vibration control effect was analyzed through a series of shaking table tests. The results showed that the TPDs properly designed can reduce structural displacement responses effectively; the connected rigidity between TPD and the controlled structure has obvious influences on the TPD vibration control effect; when the ratio of the TPD’s natural frequency to the structure’s fundamental frequency in the controlled direction is within a range of 0.90 to 1.10, the TPD’s vibration control effect is better.

     
  • YANG Na, HU Hao-ran, DAI Lu
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 8-13.
    Abstract ( 494 ) Download PDF ( 87 )   Knowledge map   Save
    Here, a new parameter based on RMS values of human-induced floor vibration acceleration was proposed to determine whether the collected human-induced floor vibration signal data are abnormal quickly. This parameter was the ratio of RMS and weighted RMS of the collected human-induced floor vibration acceleration response signal. The specific expression of the parameter was derived with the theory of the human-induced floor vibration response. The parameter was verified using a finite element floor model with human-induced loads under different operation conditions and a site test of floor vibration with human-induced loads under different operation conditions. It was shown that human-induced loads’ parameter has little effect on this proposed parameter, it is greatly related to basic properties of the floor structure; when dealing with large amounts of data signals, this parameter can be used to screen quickly these data.
  • LI Zhuqiang1 LIAO Changrong1 FU Benyuan1 ZHANG Peng1 JIAN Xiaochun2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 14-21.
    Abstract ( 269 ) Download PDF ( )   Knowledge map   Save
    A basic problem is energy absorption degradation of conventional automotive crash-boxes due to Euler instability. Here, a novel crash-box based on the combined action of elastic cement’s multi-stage radial flow and crushable cylindrical-corrugated components was proposed. Oswald-deWaele fluid constitutive model was employed to characterize the rheological properties of elastic cement, the model parameters were determined through tests. Through dropping-hammer impact tests, impact force transfer characteristics of crushable cylindrical-corrugated components were studied. The continuity equation and governing differential equation of elastic cement in multi-stage radial flow were established. With Oswald-deWaele model, the expressions for elastic cement’s radial velocity distribution at different radial positions and pressure gradient were deduced. The influence of inertia effect on pressure gradient was analyzed based on the average inertia method. Further, the calculation method of buffer force during elastic cement unsteadily flowing in the crash-box was obtained. In order to verify the rationality of the theoretical calculation, the crash-box prototype was designed, fabricated and assembled, and a dropping-hammer test system was constructed for impact tests under two different heights. The impact forces obtained with tests and those calculated with the theoretical method were compared, and the caused errors were analyzed.

  • SHU Chang, ZHANG Jian-tao, ZHANG Jia, FANG Zhou
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 22-26.
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    In order to improve energy conversion efficiency of wind energy harvester, a piezoelectric wind energy harvester with resonant cavity was proposed. A mathematical model for the piezoelectric wind energy harvester was established considering the relationship among wind fluid, structural vibration and output power. The simulation analysis was performed based on the model to study the effects of structural parameters of the energy harvester and wind speed on its generating capacity. The piezoelectric wind energy harvester prototypes were fabricated and used to conduct tests. The test results showed that the output power of the piezoelectric wind energy harvester with resonant cavity is larger than that of the harvester without resonant cavity within a lower wind speed range of 2m/s - 12m/s.
     
  • LIANG Yunpei1, WANG Xiang1,2,WANG Qingfeng2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 27-33.
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    Effects of cut depth and cut spacing on tool forces acting on a conical pick were investigated based on rock cutting tests conducted on a sandstone using a linear rock cutting machine. Single factor regression showed that linear fitting and power function one can all be used to statistically describe the relation among cutting force, normal force and cut depth; cutting force and normal one increase with increase in cut depth, the ratio of normal force to cutting one linearly decreases with increase in cut depth; cutting force and normal one linearly increase with increase in cut spacing, the ratio of normal force to cutting one deceases with a power function form; load fluctuation coefficients linearly decrease with increase in the ratio of cut spacing to cut depth. Multi-factor linear regression showed that there are extremely strong statistical relationships among cutting force, normal force and cut depth, cut spacing; there are significant statistical relationships among load fluctuation coefficients and cut depth, cut spacing; meanwhile, load fluctuation coefficients are   proportional to cut depth, and inversely proportional to cut spacing. Performance comparison indicated that the theoretical model of Evans has a better performance to predict cutting force values than the model of Roxborough and Liu, and the model of Goktan do.

  • WANG Tong-yin, LIU Yang, LI Gang, LU Xiao-feng, ZHU Xiao-lei
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 34-39.
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    To improve lattice sandwich panels’ anti-explosion performance, a functionally graded lattice sandwich panel structure was proposed, its upper facesheet was thinner than lower one, its upper core layer was fine and lower one was coarse (namely positive gradient distribution). The FE software ANSYS/LS-DYNA was used to study the anti-explosion performance of the new sandwich structure. Effects of facesheet gradient and core layer one on the anti-blast performance of sandwich panels were investigated, respectively. Single factor analyses were performed for size parameters of functionally graded lattice sandwich structures. The results indicated that energy absorption of lattice sandwich panels can be greatly improved by simultaneously considering positive gradient distribution of facesheet and core layer; the contribution of facesheet positive gradient distribution to energy absorption is more significant than that of core layer positive gradient distribution; moreover, the thicknesses of upper panel, lower one and core layer, and the angle between core bar and lower facesheet have a larger effect on the new structure’s anti-blast performance, while the effect of sizes of core bar’s top and bottom sections is smaller.
  • LU Zhenyong HOU Lei HOU shengliang CHEN Yushu SUN Chuanzong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 40-46.
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    Here, nonlinear dynamic characteristics of an aero-engine high-pressure rotor system with a breathing crack on a hollow shaft were investigated. Using the finite element method, the equations of motion for the rotor system were established considering the weight and unbalanced excitation. The cracked rotor system’s stiffness matrix was derived considering its time-varying features. Using the harmonic balance method, the equations were solved approximately. 3-D amplitude-frequency charts were obtained under different crack depths. It was shown that lateral vibration response peaks occur at critical speeds and subcritical ones; a deep crack located at the middle of the shaft has the most significant influence on the system’s vibration responses; 3-D amplitude-frequency charts calculated during the rotor rotating speed rising have obvious super-harmonic resonant components of 2X, 3X and 4X. Finally, the correctness of numerical computation was verified with the results obtained using Newmark-β method. The proposed modeling method for the rotor system with a breathing crack on its hollow shaft provided a theoretical guidance for the nonlinear dynamic analysis of aero-engine rotor systems with crack faults. 

     
  • YI Jiang1, SUN Ping-kuan2, LI Jian-zhong1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 47-53.
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    based on a single-tower cable-stayed bridge, a 1:20 large scale full bridge model for shaking table tests was designed to study the effectiveness of elastic-plastic damper to reduce transverse seismic responses of the cable-stayed bridge. Both a far-field ground motion wave and a near-field one were taken as seismic inputs for the bridge model’s shaking table tests. Test results showed that comparing to a rigid connection of tower-deck and pier-deck, tower-deck connected to pier-deck with elastic-plastic dampers effectively reduces transverse seismic responses of the tower; under the action of a far-field ground motion wave and a near field one, the reinforcing bar strain of the tower bottom section can be reduced by 40% and 10%, respectively; however, under the action of a near-field ground motion wave, the elastic-plastic damper’s deformation is 3.6~4.6 times of that under the action of a far-field one, it produces obvious residual deformation after loading is completed. Comparing the test results with those of numerical analysis, both of them agreed well.
  • ZHANG Shuqiang,WANG Liang,CHEN Jie,ZHAO Weigang
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 54-60.
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    In actual operation of a gas face seal, its stator ring’s ability to track its rotating seal ring’s axial endplay and angle swing (i. e. , its tracking property) is crucial, its excellent tracking property can reduce the influence of external disturbances on the seal stability. Here, a gas face seal assembly was simplified into a spring-damper-mass system. Using the perturbation method based on the linearization, the gas film dynamic stiffness and damping coefficients were solved. Then, the effect laws of stiffness and damping of spring and secondary seal on the tracking property of gas face seal were investigated. Gas face seals had three different end face structures including dynamic pressure one, hydrostatic pressure one and dynamic-hydrostatic pressure hybrid one. Results showed that the three types of seal possess perfect axial and angular tracking properties when stiffness and damping are less than a certain order of magnitude; with increase in stiffness and damping, the tracking property of gas face seal becomes poorer; under the same conditions, the dynamic pressure gas face seal has the best tracking property, followed by the dynamic-hydrostatic pressure hybrid one, and the last is the hydrostatic pressure one.

  • WANG Ruochen1 QIAN Yuchen1 DING Renkai1 MENG Xiangpeng1 XIE Jian1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 61-65.
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    A hybrid electromagnetic suspension with three modes was proposed here. Three modes focused on ride comfort, tire grounding ability and comprehensive performance of a suspension, respectively. The contradiction between ride comfort and tire grounding ability was coordinated. The dynamic model of the hybrid electromagnetic suspension was established. Weight coefficients of LQG control strategy under the three modes were determined. The effects of the suspension’s stiffness and damping on its dynamic performance and energy consumption characteristic were analyzed under different modes, the suspension’s stiffness and damping values under different modes were determined. Simulation analysis was performed. The results showed that compared with a traditional passive suspension, the hybrid electromagnetic suspension can improve a suspension’s dynamic performance effectively; it can significantly reduce a suspension’s energy consumption compared with an active suspension. Finally, the tests were conducted. It was shown that the test results agree well with those of simulation, the correctness of the simulation results is verified.
  • DANG Xuan-ju 1 MIAO Mao-yu 1 JIANG Hui 1 WU Xi-ru 1 LI Shan 2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 66-71.
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    A switched reluctance motor (SRM) has strong nonlinear characteristics due to its double-salient structure, nonlinear magnetic circuit and pulse power supply mode. In traditional control, the SRM linear torque model is used to calculate reference current to lead to large torque ripple when operating. Here, the SRM control strategy combining the self-adaptive PID control based on torque deviation’s double-weight neural network (DWNN) and the feed-forward compensation control based on finite-difference extended Kalman filtering (FDEKF) to predict current was proposed. The pretreatment of deviation was used to nonlinearly process torque deviation to realize the control with "small error, large gain, large error, small gain". Then, the self-adaptive PID control based on DWNN was used to control current. The current prediction was adopted to form the reference current’s feed-forward compensation control to improve the one-step predictive ability of the control system. The current was predicted based on FDEKF, the difference between the predicted current and the reference one was used to compensate the reference current in real time. After optimization, the effective controlled current was obtained under constant torque to realize indirectly the effective control of the total torque. Simulation results showed that the proposed control strategy can effectively suppress torque ripple of SRMs.          
  • CHEN Jian, DENG Zhi-qiang, ZENG Wei-jun, SHU Hong-chao, LI Shi-ai, RONG Fang-ming
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 72-78.
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    The basic theory of OPAX method was presented, and transfer path analysis (TPA) for a medium-sized truck cab vibration was done. A two-level TPA model including a powertrain-cab 1st level TP model and a frame-cab 2nd level TP model based on OPAX method was proposed according to structural design features of the truck. The dynamic stiffness, operating load and path contribution of various mount components were obtained with tests and calculations. They were used to correctly judge causes of the cab’s higher vibration level and propose an improved scheme to effectively reduce the cab’s vibration level. The results showed that the improved two-level TPA model can more fit the structure design of the study object and reflect the structure path characteristics in detail; the new model enriches and extends the existing TPA model and provides a reference for the application of OPAX method.
  • ZHANG Ju-hui1 WANG Wei1 JIANG Da-wei1 GUAN Zhong-guo2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 79-84.
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    To explore a reasonable joint connection between casing and cap, quasi-static tests were conducted on three specimens constructed with different pile-to-pile cap joint forms including a shallow embedment form, a shallow embedment one strengthened with anchor bars and a deep embedment one. Test results were evaluated with aseismic indexes including failure feature, hysteretic behavior, load-bearing, stiffness, ductility, and energy dissipation to study the effects of joint connection form between casing and cap on aseismic performance of joint. The results showed that the deep embedment form has the best aseismic performance, it can significantly improve the joint’s load-bearing capacity, and accumulate hysteretic dissipated energy and stiffness; cracking and spalling of cap concrete cover near joint zone are the main failure modes for other two forms; the shallow embedment form’ failure effect is the most obvious, and its load-bearing capacity is the poorest; although the shallow embedment strengthened with anchor bars form has a 20% higher load-bearing capacity than the shallow embedment one does, it is a weak joint connection form.
  • WANG Wei, CHEN Zhangwei, LUAN Qiangli
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 85-90.
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    Through analyzing a three-axis vibration test system, the multi-input multi-output (MIMO) power spectrum emersion control algorithm was studied.  frequency response function (FRF) estimation method was used to identify the system. Aiming at that the system’s frequency response matrix was rectangular and had singular points, the singular value truncation method was adopted to ensure the stability of the algorithm, the iterative control algorithm was adopted to modify drive spectrum and improve the accuracy of vibration control. Three-axis vibration tests were conducted with a three-axis vibration table and a MIMO vibration controller integrating the above algorithm. Results showed that the modified iterative control algorithm based on  FRF estimation method has a good accuracy and an engineering practicability for the repetition of power spectrum. 
  • WANG Cai-feng, GAO Shi-qiao, NIU Shao-hua, LIU Hai-peng
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 91-97.
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    Model parameters’ change characteristics of a pedestrian single-DOF spring-mass-damper (SMD) system were investigated. The coupled free vibration equation of a walking crowd-structure system was established. The structure natural frequencies and damping ratios were derived with the complex mode method. The influences of pedestrian model’s natural frequency, damping ratio and elastic mass on change rates of the structure fundamental frequency and damping ratio were studied, respectively. Using Monte-Carlo simulation, a series of meaningful results were obtained under different mass ratios of crowd to structure. The results indicated that change rates of the structure’s fundamental frequency and damping ratio are the maximum when the ratio of the structure fundamental frequency (no crowd) to pedestrian one is about 1.1; when the structure fundamental frequency (no crowd) is close to the allowed range of pedestrian model’s natural frequency, the increase in mass ratio of crowd to structure causes the random distribution of the structure’s fundamental frequency and damping ratio to expand.

     
  • GUO Fang, FANG Zongde, ZHANG Yongzhen
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 98-104.
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    Using the lumped-parameter method, a generalized dynamic model for a star gear transmission system  was established considering gear manufacturing eccentric errors and gear pair time-varying mesh stiffness and clearance floating mechanism. The system’s dynamic differential equations were solved with the numerical method to get its forced vibration responses. The system’s dynamic characteristics were analyzed with time histories, phase plane plots, Poincare maps and Fourier spectral analysis. The effects of star gears’ eccentric errors and clearance floating mechanism on dynamic characteristics of the system were studied. The results showed that star gears eccentric errors enhance the system’s vibration; different positions and different numbers of star gears eccentric errors cause different dynamic responses of the system; the clearance floating mechanism affects the stability of the system, it is harmful to vibration and noise control.


  • QIAO Hong 1 XIA He 1 DU Xian-ting 1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 105-111.
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    The influence of soil-pile interaction on the dynamic response of a train-bridge coupled system was studied. Based on the substructure method, the whole train-bridge-pile foundation-soil system was divided into the train-bridge interaction subsystem and the pile-soil interaction subsystem, the motion equations of them were established, respectively. When establishing the latter’s motion equation, in order to consider the system’s frequency correlation, its impedance function in frequency domain was converted approximately into that of a high-order spring-damping-mass model in time domain. The dynamic responses of the two subsystems were obtained with the iteratively solving method, respectively. A train with 8 cars passing through a 5-span simply-supported beam bridge was taken as a case study, influences of soil-pile interaction on the dynamic response of the train-bridge coupled system were studied. The results showed that after considering soil-pile interaction, dynamic responses of the train-bridge coupled system increase; so, the effects of soil-pile interaction should be considered fully in future computations to get the results on safe side.
  • LIANG Yan1, LI Jie1, LUO Xiaoyong2, CHEN Huai1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 112-118.
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    Applying the performance-based aseismic design method, considering influences of typical durability environment and time-varying earthquake action, the performance-based time-varying aseismic design method for durability damaged RC members was explored. Through quantified processing of panels’ deformation ability, under the typical durability environment within the design working life, the quantified relation expressions among panels’ damage indexes, relative height of compression zone, stirrup characteristic value and curvature ductility were established. In RC member aseismic durability design, the design demands were adjusted to meet performance objective requirements according to the durability environment and design working life. So, the aseismic design indexes, such as, stirrup characteristic value, minimum reinforcement ratio and relative height of compression zone were adjusted. Their adjusting coefficients for different design working lifes under the common atmosphere environment were given.
  • WANG Di1, ZHU Xiang1.2,LI Tianyun1.2,HE Xing1,GAO Shuang1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 119-124.
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    Functionally graded materials (FGMs) are more and more widely used in engineering because of their excellent structural properties and important application value. Here, bending vibration characteristics of FGM beams and coupled beams were analyzed based on the energy finite element method. In order to get the energy density and energy flow, FGM beam energy density control equation and energy finite element matrix equation as well as coupled beam energy finite element matrix equation were deduced, respectively. Taking a simply supported FGM beam as an example, its energy density was computed with the energy finite element method and the traditional finite element method, respectively. The two energy densities were compared to verify the correctness of the proposed energy FE method. Then the energy density and energy flow of the coupled FGM beam were solved. Finally, the energy distribution features of the beam were obtained. This study provided a theoretical basis for the vibration characteristics analysis of complex FGM structures based on the energy finite element method.

  • ZHOU Feng-xi1,2, GAO Xiao-li1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 125-128.
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    Plate structures are widely used in acoustical insulation design, their critical frequency and coincidence frequencies are closely related to sound radiation and sound insulation performance of plate structures. From the mechanism of coincidence effect and conditions to cause coincidence effect, based on the vibration control equation of thin plates made of saturated porous materials, the calculation formulas for critical frequency and coincidence frequency of thin plates made of saturated porous materials were deduced through theoretical analysis. Using numerical examples, the parametric analysis for coincidence frequency and critical frequency of thin plates made of saturated porous materials were performed. The variation laws of coincidence frequency with changes of plate thickness, porosity, incident angle, and permeability coefficient were analyzed. The coincidence frequencies of thin plates made of saturated porous materials under different porosities were compared with those of elastic solid plate with changes of plate thickness and incident angle. Results showed that coincidence frequencies of single-phase elastic solid plates are much larger than those of thin plates made of saturated porous materials, their coincidence frequencies decrease with increase in plate thickness and incident angle, and increase with increase in porosity, while permeability coefficients almost have no effect on their coincidence frequencies.
  • ZHANG Yun-qiang1, ZHANG Pei-lin1, WANG Huai-guang1, YANG Yu-dong2, WU Ding-hai1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 129-135.
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    Aiming at nonlinear and non-stationary characteristics of rolling bearing vibration signals, a feature extraction method for rolling bearing vibration signals based on variational mode decomposition(VMD) and Volterra prediction model was proposed. VMD with a good ability of non-stationary signal decomposition was utilized to decompose a rolling bearing vibration signal into finite stationary intrinsic mode functions (IMFs). Then phase space reconstruction was conducted for these IMFs. Volterra prediction model was established in the reconstructed phase space. With the class distance within class criterion, the model’s parameters were optimized to describe the bearing vibration signal. Four different states of rolling bearing vibration signals were analyzed, the optimized feature parameters had a better classification performance. Test results indicated that the proposed method can effectively be used to extract nonlinear and non-stationary features of vibration signals, and improve the fault diagnosis accuracy of rolling bearings.
     

  • MEI Zhen, HOU Wei, GUO Zixiong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 136-142.
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    Shaking table tests were conducted on an aseismic structure model with and without viscous dampers. In tests, random ground motion samples generated by a physical stochastic ground motion model were taken as table inputs. Then reliability assessments were performed, respectively for test structure model with control and that without control using the probability density evolution method and the principle of the equivalent extreme value events. Test results revealed that both mean value and standard deviation of inter-story drift responses of the test structure model with dampers are significantly smaller than those in the uncontrolled cases; generally, RMS values of story shear forces in the controlled cases are obviously smaller than those in the uncontrolled cases; the variability of dynamic responses of the test structure model with dampers subjected to random earthquake ground motions is significant, the vibration control effects of viscous dampers are different when the test structure model is under inputs of various ground motion samples. Dynamic reliability analysis of the controlled structure model indicated that the aseismic reliability of its each story and that of the whole system are obviously enhanced compared with those in uncontrolled cases.
  • WANG Zhi-wei1 QIN Jun-qi1 YANG Gong-liu2 SHI Zhi-yong1 DI Chang-chun1 WANG Feng-jie3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 143-146.
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    Aiming at that the traditional analytical method for coarse alignment is not applicable for moving base, a new analytical method for moving base initial alignment based on gravity measurement was proposed. Firstly, a mid- frame was built in an inertial coordinate frame at the middle point of navigation time. Then gravity vectors in carrier frame and navigation frame were projected into the mid-frame, Sum and cross-product operations were done for projections at both sides of the mid-frame. Two 3-D spaces obtained were corresponding to the initial navigation frame and the initial carrier frame. Finally, several alignment processes were simulated and compared under different operation conditions. Results showed that the proposed method can be applied in moving base alignment, it is easy to realize in engineering, and it provides a certain guidance for alignment in motion of vehicle navigation systems.
     
  • Lü Yong, SHI Wei, YI Can-can
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 147-152.
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    In order to deal with mass centroid selection of phase points in neighbor zones for the local projective noise reduction algorithm, the influences of neighbor zone mass centroid selection on noise reduction effects were analyzed. Higher-order polynomials were used to estimate neighbor zone mass centroid more accurately and better adapt to geometric shape of the attractor. In this way, the noise was further suppressed, noise reduction effects of the local projective method was improved. Numerical simulation signals were used to verify its effectiveness. The superiority of the higher-order local projective algorithm was revealed by comparing it with other nonlinear time series noise reduction methods based on phase space reconstruction. Finally, the proposed method was adopted in fault diagnosis of industrial fans’ bearings, fault features of rolling bearings were extracted successfully in frequency domain.
  • LIU Run-dong1, MAO Jun1, XI Yan-hong1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 153-159.
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    The sliding mesh method was used to simulate the process of high speed trains passing through a windbreak region under cross wind. The single layer type and chamber type porous and corrugated plate windbreaks were used. The characteristics of flow field around train and windbreaks, time domain characteristics of windbreaks’ aerodynamic load and frequency domain characteristics of fluctuating pressure caused by coupling between cross wind and high speed train wind were analyzed. The results showed that when there is no cross-wind, the train head car’s impacting action is stronger than that of the tripper car be; when there is a cross wind, the head car’s aerodynamic impacting action offsets cross-wind to dissipate its energy, while the tripper car’s aerodynamic impacting action is coupled with cross-wind to amplify cross wind’s aerodynamic impacting action against windbreaks; the single layer windbreak weakens cross-wind’s action through changing its direction, while the chamber windbreak produces a large number of small vortexes inside chamber and wake flow to dissipate cross-wind’s energy and it obviously reduces aerodynamic load of a single windbreak plate.

  • LIU Yu1 WANG zhenyu1 YANG Huigang2 ZHANG Yimin1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 160-166.
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    Chatter problems in milling severely affect productivity and quality of machining. Tool wear causes cutting force coefficient, process damping coefficient, and other parameters to change with cutting time. These variations significantly reduce the accuracy of chatter prediction using conventional methods. To solve this problem, the time-varying reliability theory was introduced, and Gamma process was used to describe the relationship between tool edge radius and cutting time. The models for a micro milling system’s cutting force coefficients, time-varying stability and time-varying reliability were established. The changes of the system’s chatter stability and chatter reliability with cutting time under the given conditions were analyzed. The system’s chatter time-varying stability and chatter time-varying reliability were investigated under given cutting depths and spindle speeds. The results of case study showed that with increase in cutting time, the system’s chatter stability drops gradually; the proposed method can be used to predict the system’s chatter stability more accurately within different cutting time intervals.
  • LI Yan1,2, TANG Yougang1,2,WANG Bin1,2,QU Xiaoqi1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 167-173.
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    Freak waves can cause destructive effects on offshore structures. In order to study the dynamic response of a tension leg platform (TLP) under freak waves, nonlinear equations for its coupled motions were established based on the platform’s 6-DOF motions and the leg’s nonlinear restoring stiffness. Time histories of freak wave surface were generated using the random frequency phase angle modulation method. The 1st order, 2nd order difference frequency and sum frequency wave loads exerted on the platform were calculated under freak waves. The platform’s 6-DOF motions were solved with numerical method. The results showed that freak waves affect both the 1st order and the 2nd order wave loads, increases in amplitude of different wave loads are different in different DOFs; the lower frequency motion, such as, surge of TLP, is mainly affected by the 2nd order difference frequency wave load; the higher frequency motions, such as, heave and pitch of TLP, are mainly affected by the 2nd order sum frequency wave load; under the action of the 2nd order difference frequency wave load, the negative motion caused by motions in horizontal plane of TLP increases significantly to cause an obvious increase in heave motion; therefore, heave motion under freak waves is affected by both the 2nd order difference frequency wave load and the 2nd order sum frequency wave load; besides, due to the impact characteristic of freak waves, the amplitude of each DOF motion appears at different time instants.
     
  • LI Qing, YANG Deqing, YU Yang
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 174-179.
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    Aiming at ship underwater sound radiation calculation problems in low frequency domain, adopting the vibro-acoustic FEM/AML and the vibro-acoustic IBEM is the strategy with higher calculation accuracy based on vibro-acoustic coupling dynamic equations strictly. Taking a small waterplane area twin hull (SWATH) as a computational example, the influences of size selection for sound field surrounding the hull in vibro-acoustic coupling computing model were studied. Taking sound power as an evaluation index, the difference in computing properties between aforementioned vibro-acoustic coupling method and the conventional fluid-structure interaction method was discussed. The study showed that the acoustic response computing results in vibro-acoustic coupling mode are smaller compared with those in fluid-structure interaction mode, the former is more accurate; the deviation between SWATH ship’s synthetic whole sound power levels obtained in the two modes reaches 1-3 dB; the vibro-acoustic IBEM based on vibro-acoustic coupling mode is the preferred method for ship underwater sound radiation prediction.
  • WU chunzhi1, JIA Jide1, JIA Xiangyu1, ZHANG Shuai 1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 180-185.
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    Aiming at that diesel engine crankshaft bearing wear fault signals’ characteristics are very weak, they are easy to be buried by noise and signals of different fault levels are hard to be distinguished, a new information entropy enhancement method based on the synchro-squeezed wavelet transform and locally preserving projection was proposed. Firstly, a signal was reconstructed in multi-scale mode with the synchro-squeezed wavelet transform. Then the dimensions of the multi-scale signal were reduced with the locally preserving projection to eliminate its redundant information and enhance its impact characteristic. Finally, three information entropies in time domain, frequency domain and time-frequency domain were used to characterize the signal features. Simulated and actual signals showed that the proposed method can enhance the fault signals’ features obviously, and realize classification recognition of crankshaft wear states according to information entropy values.



  • LI Ying1,2, ZHANG Wei1,ZHU Haiqing2,DU Zhipeng1,WU Weiguo2,ZHANG Lei1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 186-194.
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    Based on the one-dimensional stress wave theory, two kinds of air-contain structures were presented. Their numerical simulation models were established. Based on verifying these simulation models, the dynamic change processes of cavity evolution, shock wave propagation and air-contain structure deformation for a liquid-filled structure with air-contain structures under projectile penetration were analyzed, the decay law of projectile velocity was studied. Shock wave features of different cabin structures under spherical projectile penetration and energy transfer relations among different parts of cabin were discussed. The plastic deformations of front plate and rear one under different projectile velocities were compared. The study results showed that air-contain structures added in a liquid-filled structure can effectively reduce impulse, energy and plastic deformation of both front plate and rear one of the liquid-filled structure; the cause of air-contain structures affecting deformations of front plate and rear one is impedance mismatch, expansion wave due to air-interlayer deformation and liquid cavitation; double-layer plate structure’s ability to reduce deformation of liquid-filled structures is superior to that of square sandwich plate one, but with increase in projectile velocity, their difference drops gradually. 
     
  • LI Ling ZHANG Jiang RUAN Xiaoguang CAI Anjiang
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 195-201.
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    In order to investigate the effect of asperity and substrate deformations on micro-contact characteristics of a hard-coating surface, contact stiffnesses of asperity and substrate were solved with Hertz contact theory, the deformation of asperity was determined with the fixed point iteration method, and the stiffness model for contact deformation of asperity was established, finally a new surface micro-contact model was established through parallel coupling. To verify the correctness of the new model to describe contact characteristics of rough surface with a hard coating, finite element models with different sizes and materials for asperity was established. Through comparing analysis results of the new model, Hertz model and the finite element models, it was found that when materials of substrate and asperity are different, stress distribution of asperity-substrate system is not uniform, contact force on asperity surface is smaller than that when materials of asperity and substrate are the same, the maximum stress is larger than that when materials are the same; when the deformation is very small, Hertz model solution and the new model one agree well with analysis results of finite element models; with increase in deformation, finite element model analysis results and the new model solution start to deviate Hertz model solution, but the new model solution is always close to the finite element model analysis results.
     

  • ZHAO Hexue1, ZHANG Bangji1, ZHANG Nong1,2, PENG Peng1, ZHENG Minyi1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 202-209.
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    A height adjustable hydraulically interconnected suspension was proposed for actively adapting  road condition changes. Parameters of the hydraulically interconnected suspension were optimized to make the vertical stiffness of a vehicle with this suspension keep the same as that of the original vehicle. Based on the hierarchical control theory, a switching control strategy for the height adjusting of vehicle body was adopted. based on CarSim, AMESim and Matlab/Simulink simulation platforms,a joint simulation system including a vehicle multi-body dynamic model and a control model was established. The simulation analyses for switching processes, ride comfort and handling stability were performed. The results indicated that this system is able to adjust adaptively the height of vehicle body, and improve the handling stability of vehicle, in the premise of  simultaneously keeping vehicle’s ride comfort.
     
     
  • HU Tingxun, HU Dean
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 210-216.
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    Dynamic response of a vessel with a preformed hole under inner explosion was simulated using the 3D adaptive FEM-SPH coupled algorithm considering the effect of air inside the container. Failure characteristic parameters obtained with simulation agreed well with those gained in tests. Moreover, the results obtained using the ALE algorithm in LS-DYNA software were compared with those using the adaptive FEM-SPH coupled algorithm. It was shown that the adaptive FEM-SPH coupled algorithm can effectively reproduce the process of vessel’s inner explosion bulges, the process of preformed hole failure and air movement in vessel under internal explosion load; it provides an effective study way for the numerical simulation of internal explosion problems of vessels.



  • YANG Yang1 2 YUAN Ai-hui1 Li Guo-wei1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 217-222.
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    According to structural characteristics of electro-mechanical-hydraulic cutting transmission system of a coal cutter, an electro-mechanical-hydraulic coupled model was built for the transmission system including gears and pumps with flow fluctuation of piston pumps as the system’s external excitation and time-varying meshing stiffness of gear pairs as the system’s internal excitation. Then dynamic characteristics of the transmission system were analyzed under the external excitation and internal one. The results showed that the flow fluctuation of pumps affects vibrational and dynamic characteristics of the transmission system; as external excitation, the flow fluctuation is the main factor affecting the system’s dynamic characteristics; after considering the flow fluctuation, the motor output reveals torque fluctuation, the total efficiency of the cutting transmission system drops.

  • LIU Min1,YAN Zhi-tao2,1,FENG Shang-ming1,YOU Yi1,3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 223-229.
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    Icing conductors’ ice-shedding may lead to damages of end fittings, wires and towers, and even tower collapse and other machinery accidents. A three-span 1:50 scale model tests for icing conductors were conducted to obtain conductor’s ice-jump height, conductor’s tension force and axial force changes of insulators. In tests, ice-shedding loads were simulated with suddenly dropping dead-weights from conductors. Seven ice-shedding cases were studied with different magnitudes of ice-shedding, positions of ice-shedding span, ice thicknesses and wind velocities, etc. The results showed that conductor side-span ice-shedding causes larger vertical vibration than mid-span ice-shedding does, conductor’s jumping height increases by near 7% and conductor’s tension force rises obviously; when there are wind loads, conductor’s ice-shedding vibration is affected by aerodynamic damping, conductor’s jumping height and vibration period become smaller, conductor tension force and insulator axial force increase with increase in wind loads.

  • ZHONG Yukai1, JIANG Zhengrong2,3, YAO Xiaohu2, SHI Kairong2,3, LUO Bin4
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 230-236.
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    According to the principle, based on considering the strain-rate effect, the impact comparability rule for single layer reticulated shells considering geometric deviation and gravity, respectively was derived. According to the test model published in literature, the corresponding FE numerical model was built using the nonlinear FE software LS-DYNA, its computing results were compared with the test model’s results measured to verify the correctness of the FE analysis method. Then FE analysis models for single layer reticulated shells were constructed using LS-DYNA only considering geometric deviation and simultaneously considering geometric deviation and gravity to verify the derived comparability rule. The computation results were compared with those of the models unmodified (not considering geometric deviation and/or gravity). It was shown that when only considering the effect of geometric deviation or simultaneously considering geometric deviation and gravity, the FE models modified can obtain the results to satisfy the comparability rule; the FE models modified can predict dynamic responses of the prototype better with a higher precision, while prediction results of the FE models unmodified have larger errors compared to those of the prototype, and they cannot be used in practical engineering.

  • YANG Dabin1, YUN Chaoguang1, WU Jinzhi2, ZHANG Yigang2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 237-242.
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    Damage of connecting place between upper roofs and bottom substructures are one of the main earthquake damages, as is shown in many earthquakes. To reduce the probability of this kind of damage, a separated substructure design method was proposed. The substructures were divided into two parts: one part sustaining horizontal and part vertical loads of the roof and the other part only sustaining the rest of vertical loads of the roof. The former substructure was connected with the roof using steel structures with larger elastic deformation. The latter substructure was connected with the roof using horizontal sliding bearings, so horizontal shear force was released to reduce the damage probability of bearings. FE models for a typical single-layer latticed dome and its bottom substructures were built based on this design idea. Their dynamic performances were computed under smaller and stronger earthquakes based on contemporary design codes, the results showed that the dome and the part of its bottom substructures sustaining horizontal and part vertical loads of the roof can be computed independently, and the dome’s temperature stress can be released effectively; the aseismic performances of the structure are good under smaller and stronger earthquakes; it costs less steel to be used.
  • ZHANG De-bing1,XIANG Hui-yu1,ZHANG YONG2,XUE ZHEN1,WEI Jing-hui1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(3): 243-248.
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    Virtual prototype technology was adopted to establish the model of a roller coaster track and train. Then the operation simulation was done with the model to ensure the digital prototype to meet the requirements of the safety standard of entertainment equipment. But in the actual installation process of a roller coaster, it was difficult to guarantee the physical prototype and its digital model to agree well, the operation state under the actual working condition and the simulation result had a certain deviation. The physical prototype was tested to measure its accelerations. The acceleration data collected were analyzed with MATLAB to find out unqualified data points, and judge their locations. The designers were guided to improve pertinently the roller coaster track with repeatedly tests and analyses, and adjusting the track until it met the requirements of the safety standard.