28 September 2018, Volume 37 Issue 20
    

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  • GAO Feng1,2, SUN Wei1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 1-7.
    Abstract ( 435 ) Download PDF ( 234 )   Knowledge map   Save
    To solve the difficulty of dry friction damper implementation in vibration reduction of a blisk (integral bladed disk), a novel damping improvement method by depositing hard coating on blades was proposed and then verified in this study.Firstly, a continuous parameter model (CPM) of the composite structure of the hard-coating bladed disk was established.Then, equivalent parameters of the hard-coating blades were derived based on the Oberst beam and the complex modulus theories.Further, natural characteristics of the hard-coating blisk were obtained by using of the Ritz method.Finally, a blisk with depositing NiCoCrAlY+YSZ hard coating on single side of blades was taken to conduct numerical calculation.The results were compared with those obtained by experiment tests.Moreover, the influence of hard coating on natural characteristics of the hard-coating blisk was discussed, respectively.The influence of coating thickness and area on damping capacity were studied emphatically.Results reveal that the NiCoCrAlY+YSZ hard coating has a significant effect on modal loss factors (improve six times approximately), with slightly altering the natural frequencies (around 3%).The resonant response of the blisk can be suppressed remarkably. 
  • HUANG Tao1,ZHANG Tao2,DONG Zhanfa1,WU Hao3,FANG Qin2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 8-14.
    Abstract ( 394 ) Download PDF ( 185 )   Knowledge map   Save
    The dynamic response of a nuclear containment structure under the impact of a large commercial aircraft is a focus in the field of nuclear safety.By using the LS-DYNA program, the entire impact process of a large commercial aircraft impacting on the containment was numerically simulated.Based on a large commercial aircraft A380 and enveloping the basic features of a current typical commercial aircraft, the fine FE model of a full-scale aircraft was established and modified by comparing its simulated impact force with the specified objective curve.Meanwhile, the FE models of containment and its surrounding houses were established, which were verified based on a aircraft engine impact test.Exerting on the relatively weaker position, the normal impact was reproduced with the missile-target interaction method, and the impact phenomena, impact force, concrete damage and the impact displacement were obtained.The related work and conclusions can provide references for the engineering safety evaluation and structural design. 
  • WANG Linkai1,2,LIU Zhiwen2,CHEN Zhengqing2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 15-23.
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    For accurate and efficient identification of flutter derivatives of bridge sections, a new step-by-step forced vibration with multi-frequency method was established using the computational fluid dynamics method.The flutter derivatives of a thin plate and the girder section of the Great Belt East Bridge were identified by this new method and the traditional coupled forced vibration in bending and torsion method.The results calculated agree well with relevant existing literature and the experimental research.The results show that the new method can achieve the same level of accuracy as the coupled forced vibration method while improves the identification efficiency significantly.
     
     
  • LIU Jingliang1,ZHENG Jinyang1,LIN Youqin2,QIU Renhui1,LUO Yongpeng1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 24-31.
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    A combined method based on variational mode decomposition (VMD) and synchrosqueezing wavelet transform (SWT) was proposed to identify instantaneous frequencies from multi-component response signals of civil engineering structures.The wavelet scalogram was first introduced to estimate the number of the components contained in a response signal.Then, the VMD was used to decompose the response signal into several mono-components self-adaptively and the SWT was performed on the decomposed component signals to extract their instantaneous frequencies.A multi-component simulation, an aluminum cantilever beam test with abrupt mass reduction and a steel cable test with time-varying tension forces were used to verify the effectiveness and accuracy of the proposed method.The results demonstrated that the proposed method performs better than the traditional Hilbert-Huang transform and the continuous wavelet transform.
  • WAN Shuting1,DOU Longjiang1,LI Cong1,LIU Ronghai2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 32-38.
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    A new method for fault feature extraction of high voltage circuit breakers was proposed based on variation mode decomposition (VMD) and sample entropy, and the support vector machine (SVM) was utilized to recognize the fault types.Firstly, after the vibration signal of the circuit breakers s preprocessed, the signal was decomposed by VMD.The decomposed IMFs were used to characterize various vibration events of the circuit breakers.Then the feature vector was acquired by calculating the sample entropy of IMFs.Finally, SVM was used to classify different operating states of circuit breakers.Simulation signals show that VMD has superior decomposition characteristics to deal with transient aperiodic vibration signals.Four types of fault states were extracted and recognized using the above method.The comparison results show that this method can extract fault characteristics effectively and classify fault types of high voltage circuit breaker accurately.

     
  • GAO Yingjie1,FAN Hualin2,ZHANG Bei1,JIN Fengnian1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 39-44.
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    Local resonant acoustic material can filter some specific frequencies of sound waves.Based on the wave absorption theory, the article combines local resonant structure with the concrete material, a super-material wave absorption concrete (SMWAC) slab was designed.Its wave absorbing effect was then analyzed.Through numerical simulation using LS-dyna software, the wave absorbing effect was contrasted between a common concrete slab and the SMWAC slab.It was analyzed that how the coating material, aggregation size and the aggregation arrangement influence wave absorbing effect.The simulation result reveals that the SMWAC slab has strongly obvious wave absorbing effect contrasted with common concrete.The SMWAC slab has optional wave absorbing capability due to the difference of coating material.A bigger size of aggregation in the SMWAC slab makes the wave absorbing effect more obvious in the case that each component has the same ratio.The wave absorbing effect is almost the same between a rectangular SMWAC slab and an interlaced SMWAC slab.
     
  • XIA Junzhong,WANG Zhian,CHEN Chengfa,YU Mingqi,L Qipeng
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 45-49.
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    In variable speed condition, complicated frequency, amplitude and phase modulation would appear in the vibration signals of fault bearings.And the fault feature can be effectively extracted based on the order-frequency correlation of the angle/time cyclostationary (AT-CS), but the method has limitation due to its large computation.In this paper, a method of bearing fault feature extraction was proposed based on the combination of slice spectrum by applying the ideal of combined slices to estimate the order-frequency correlation.According to the structural parameters of rolling bearings, the theoretical fault characteristic orders were calculated, and the combined slice center was obtained from the characteristic orders.The combined slice intervals were obtained after a proper choice of the slice width.And then combined slice of order-frequency of the signal was calculated.The fault feature of the rolling bearing was extracted through the energy distribution between the slices.The validity of the method was verified by the simulation signal and the experimental data,and it was concluded that compared with the order-frequency correlation, the combined slice of order-frequency spectral correlation can indicate the bearing failure characteristics more clearly and accurately and have a higher computational efficiency.
  • WU Shaobo,ZHANG Shilian,YU Haiyang,LI Cong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 50-55.
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    The ultimate bearing capacity of a ship structure subjected to inner explosion is important both in theory and in practice.In this paper, the ultimate bearing capacities of a general structure ship and a box girder structure ship were calculated, with weight increment due to the box girders taken into consideration.Then the effect of the box girder structure in improving structural ultimate bearing capacity was analyzed based on comparison.Simulations of structural responses of the ship subjected to cabin inner explosion were conducted in MSC-DYTRAN, while the calculation of the ultimate bearing capacities was performed through ABUQUS, using  the quasi static loading method.The results indicate that the box girder structure can significantly improve the ultimate bearing capacity of ships under inner explosion, and the effects may vary with the explosion position.
  • LIU Linya1, QIN Jialiang1, LEI Xiaoyan1, LIU Quan1, SONG Rui1,2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 56-60.
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    The low frequency noise radiated by a trough girder under the dynamic load of trains is very harmful to human health.Taking a 30-m simply-supported trough girder for rail transit as the research object, based on the vehicle-bridge coupling analysis model, the sound power of rail transit trough girder was calculated by using the finite element method and the boundary element method.Then the response surface methodology and the calculation of sound power were combined, acoustic optimization model was established which takes total sound power in the range of analyzing frequency of the trough girder as the target and the quality of the trough girder as the constraint.Finally, the sequential quadratic programming was used to obtain the optimum section size of the trough girder.The thickness of the deck is 0.34m and the thickness of the web is 0.22m after acoustic optimization of trough girder.The results show that the response surface methodology can effectively optimize the structure-borne noise from a trough girder, and the effect of noise reduction is still significant after the optimization.
  • ZHENG Jinde,LIU Tao,MENG Rui,LIU Qingyun
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 61-66.
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    Multiscale permutation entropy (MPE) can effectively extract the nonlinear dynamic fault feature from vibration signals of rolling bearings.Aiming at the problem of coarse-graining in MPE, a new nonlinear dynamic method called generalized composite multiscale permutation entropy (GCMPE) was proposed.GCMPE was compared with the MPE by analyzing simulation data and also the influence of parameters on GCMPE calculation was studied.Then GCMPE was applied to the extraction of nonlinear fault feature from vibration signal of rolling bearings and a new rolling bearing fault diagnosis method based on GCMPE, principal component analysis and support vector machine was presented.Finally, the proposed method was applied to analyze experimental data of rolling bearing and the results show that the proposed method can effectively realize the fault diagnosis of rolling bearings and has a higher fault recognition rate.
  • LI Jun,ZHANG Guandong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 67-74.
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    For the identification of strongly coupled, nonlinear robotic systems, a modeling method multioutput support vector machine (MSVM) which based on feature vectors selection (FVS) was proposed.This method maps the input data to a high-dimensional feature space through kernel trick, considering the geometric features, selecting the relevant data subset to form the base vector of the subspace, which is called feature vector selection (FVS).Secondly, the input data was projected onto the feature subspace, and the final regression model was established by using the MSVM method.MSVM reserves the advantages of compact and sparse under the ε insensitive loss function.In order to verify the effectiveness of the FVS modeling method, it was applied to the oil pressure identification of the hydraulic drive robot, the inverse kinematics identification of the PUMA 560 industrial robot, and the inverse kinetic modeling of the SARCOS humanoid robot.Under the same conditions, the FVS-MSVM method was compared with the SVM, the KPCA-MSVM and the FVS-linear regression (LR) method etc.The experimental results show that the FVS-MSVM method can not only reduce the computational complexity, but also has good identification accuracy and good model promotion.Among them, the FVS-MSVM method has higher accuracy.
  • HU Haoran1,2,YANG Na1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 75-80.
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    In this paper, a new method was investigated for operational modal parameter identification to deal with signals in low SNR level.In order to analyze the performance of the new method, numerical simulation data signals of different SNR levels were identified by the new method and the normal HHT method.The results were analyzed.The comparison shows that the method has a better recognition effect on low SNR signal processing, and can be used in the timber structural parameters identification.

     
  • REN Chenhui,YANG Deqing
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 81-87.
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    A novel high-performance ship equipment impact-resistance device was proposed based on the NS (negative stiffness) properties of the cosine-shaped curved beams with fixed ends when they were pushed at the center.The formulas of the dimensional relationship between the force and displacement were given.According to the theoretical formulas, the optimization model of beam geometric parameters was established, and the finite element analysis was carried out, then solutions were compared between the FEA and the formulas.The finite element mesh of the multilayer NS structure and the deck grillage was modelled and the response of the system under dual-sinusoid impact load was analyzed within an explicit transient analysis step.The influence of the layer number and the installation method on shock isolation was studied.The results show that the acceleration, velocity and displacement are obviously reduced after the transmission of the shock isolation system.With the layer number increasing, the impact resistance is enhanced.With same layer numbers, the model which is separated in the length into two parts is of better shock isolation performance.The results of this study can guide the design of the NS shock isolation structure, which is of practical significance.
  • WANG Yujing1,GUO Weiwei1,2,XIA He1,2,ZHANG Nan1,2,ZHANG Tian3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 88-94.
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    With wind tunnel test of a sectional model, the tri-component coefficients of a train when it runs on the flat ground, a 32m span simply-supported box girder and a 16m span simply-supported T-shaped beam were tested, respectively.Aerodynamic characteristics of the train and the bridge were comprehensively analyzed under different running cases, different railway forms, and different wind barrier conditions (installed on single side or both sides).The results show that it is safer for the train to run on the flat ground than on the box girder and the T-shaped beam.Aerodynamic coefficients of the train and bridge were very close when the wind barriers were installed on the windward side and both sides, demonstrating that the existence of leeward barrier cannot improve the aerodynamic performance efficiently.When there are simultaneously two trains, the leeward train has little aerodynamic interference on the windward one, while the windward train decreases the aerodynamic coefficients of the leeward train even to make the side force coefficient a negative value.The existence of wind barrier obviously changes the wind flow around the train-bridge system.Rolling moment coefficient to the right track is always greater than that to the left track.
  • XU Kun,ZENG Jing,HUANG Caihong,QI Yayun
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 95-100.
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    In order to study the influence of the motor suspension parameters on the dynamic performance of the bogie, the two-degree-of-freedom lateral simplified model and eight-degree-of-freedom lateral bogie model were established, and change of lateral displacement of the frame and the motor relative to the frame and its law were analyzed.Finally, the influence of suspension parameters of the motor on the stability of the bogie was studied.The calculation results show that when the lateral frequency of the motor was close to and slightly smaller than the hunting frequency of the bogie, the lateral displacement of the frame was the smallest, but that of motor relative to the frame is very large. Under this case, the motor is equivalent to a power absorber, the vibration of the frame is transferred to the motor.The smaller the lateral damping ratio of the motor, the smaller the lateral displacement of the frame, the higher the linear critical velocity, the larger the lateral displacement of the motor relative to the frame.In order to take into account both, an appropriate bigger lateral damping ratio is a good choice.
  • CAI Ganwei1,HUANG Yuanxing2,HUANG Yizhe1,LI Junming3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 101-108.
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    The paper deals with the dynamic characteristics and stability of vibratory stress relief for shaft part using coupled lateral and torsional vibrations.The dynamic equation of rotor-bearing system was established by the finite element method.The appropriate modal was obtained by the modal analysis.According to the resonance condition, the lateral response, torsional response and dynamic stress response of the rotating shaft subjected to torsional excitation were obtained by the Newmark method.The resonant characteristics of coupled vibration were analyzed.Based on the transient analysis, the periodic stability of the parametric system was analyzed by the Floquet stability theory and the Poincaré method during the rotational speed raised from zero to the coupling resonant speed.The results show that the coupled dynamic characteristics of the vibratory stress relief process using coupled lateral and torsional vibrations are obvious, and the vibration is stable, which have reference value for the application of vibratory stress relief.
     
  • LIU Cuiwei1,JING Huafei1,FANG Liping2,XU Minghai1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 109-114.
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    Studies on the propagation model for natural gas pipelines have not been considered thoroughly.When the propagation characteristics are studied, the influences of gas flow on the attenuation model were not consideration.Therefore, the propagation equation was deduced in the gas pipelines.The amplitude attenuation models were established in theory and in experiments.Firstly, the theoretical attenuation model was established in the viscous flow with uniform velocity considering gas flow, turbulent effect and viscothermal effect.Then the attenuation factors were calculated in experiments and in theory in 10 mm gas pipelines.When the original signals were processed, the upstream errors calculated in theory were less than 6.0%.When the wavelet transform (WT) signals were processed, the upstream errors calculated in theory were less than 7.0% while the downstream ones were less than 12.0%.And the reasons for the errors were analyzed.The results show that the established attenuation model can be verified by the experiments.
     
  • QIAN Ji1, CHEN Xin1 JIANG Yong2, YAO Guowen1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 115-121.
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    Through carrying out ultrasonic guided wave experiments in steel strands with different level corrosion, corrosion indicators were established by calculating the eigenvectors of wavelet packet energy spectrum from the measured guide wave.The results indicated that the wavelet packet energy spectrum changed obviously and the corrosion indicators increased linearly with the increasing of corrosion degree.The sensibility of corrosion indicators was superior when the excitation source located at the lateral of steel strands, and the K-value from end section was 51.35% of strands side and the determination coefficient reduced 6.4% meanwhile.Corrosion indicators possessed good performance in anti-noise capability, which reduced 5.97% when the signal-noise ratio reached 10 dB and still reached 0.51 as the signal-noise down to 0 dB.Corrosion indicators were affected by guide wave propagation distance and their sensibility brought down slightly and appeared great fluctuation in low corrosion degree with the increasing of propagation distance.
  • YANG Renshu1,2,CHEN Cheng1,ZHAO Yong1,DING Chenxi1,SU Hong1,ZHENG Changda1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 122-128.
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    In order to study the influence of the void-crack offset method on the impact-fracture behavior of materials, PMMA was used as the experimental material.The dynamic caustic experiment method was used to study the three-point bending of impact loading.The results show that: under the impact load, the relative offset position of the hole and the prefabricated crack affects the crack initiation direction and the crack and void penetration.In the case of prefabricated crack offsetting, at the time of crack initiation, KdⅡ<0 and the direction of the fracture points to the empty hole; the hole has an attractive effect on the running crack, crack propagation path is parabolic, crack and hole coalesce, the crack will be initial again at the top of the hole.Under the condition of hole offsetting, KdⅡ>0 and crack initiation direction away from the hole; the role of hole on the propagating crack is attractive firstly, then repulsive and attractive finally, crack propagation path is S-type, crack and hole are not through.When the running crack and the empty hole penetrate, crack arrest will delay the destruction of the specimen on a time scale.But after the second crack initiation at the upper boundary of the hole, crack propagation velocity and dynamic stress intensity factor are increased accordingly, which will exacerbate the destruction of the specimen.
  • LIU Canchang,GONG Qingmei,MA Chicheng, ZHOU Jilei, JIANG Ruirui,ZHOU Changcheng
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 129-134.
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    In recent years, with the development of nano manufacturing, one-dimensional materials are widely used in all kinds of electric thermal nano device for their excellent physical properties.The lateral vibration control of the monatomic chains considering atomic longitudinal displacement was studied with the theory of the vibration of strings.The lateral vibration modes of the monatomic chain were assumed as the modes of string vibration.The vibration equation of string of the monatomic chains was established based on the assumptions.A method was proposed to calculate natural angular frequency of the transverse vibration of monatomic chains.The tension of the quantum limitation was given which can distinguish the NEMS and QEMS by the thermal occupation number.The coordinates of the position of the vibration atoms can be calculated by utilizing the boundary conditions and the symmetry conditions of the monatomic chain.The natural angular frequency and resonant frequency of the monatomic chain string are associated with the axial tension acted on the string and the length of monatomic chain, and they can be altered by changing the length of the string and the tension acted on the string.
  • DENG Youxian,ZHUANG Zhipeng,KIM Sonjoo,YANG Xiaoguang
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 135-140.
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    Using a test car and their tires, the influence of tire pressure on the internal noise was studied by changing the tire pressure, the trend of the typical frequency band noise level of interior noise can be characterized by RMS value through frequency domain calculation.The test results show that with the increase of tire pressure, tire low frequency booming noise shows a decreasing trend on the rough road.The tire cavity noise shows an increasing trend.Pattern noise also shows an increasing trend on the smooth road. The relevant results were analyzed using relevant theories.
     
  • LI Qiang1,ZHANG Shuo1,XU Weiwei2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 141-147.
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    The result of the nonlinear oil film force analysis of journal bearings directly determines the accuracy and efficiency of the nonlinear dynamic analysis of the rotor bearing system.According to the transient analysis of nonlinear oil film force of journal bearings under large disturbance, this paper proposes a dynamic mesh method of structure grids suitable for 3D transient flow field calculation.The linear and nonlinear oil film forces under different disturbance were compared.Under the influence of oil film nonlinearity, the radial and tangential components of transient oil film force were analyzed.It was observed that the disturbance impact was necessary to be taken into consideration in the analysis of nonlinear oil film force; the oil inlet and the oil tank will significantly reduce the radial oil film force, causing the support stiffness reduction.The decrease of the tangential component of transient oil film force causes the reduction of journal bearing damping, thereby causing oil film instability.

  • XUE Jianyang, QI Liangjie
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 148-154.
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  • GUO Zhongjin1,2,ZHANG Wei2,3,XIA Lili2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 154-158.
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    Based on the harmonic balance method, a solution procedure of residue harmonic was developed for studying the system in which the motion of a particle is a rotating parabola.Firstly, the higher-order analytical vibration frequency and steady state response were obtained.Secondly, we study the change trend of vibration frequency as nonlinear coefficient, initial amplitude, linear stiffness coefficient of the system in steady state, the effects of initial amplitude, nonlinear coefficient on vibration frequency response were presented.The results show that the presented second-order residue harmonic balance approximations to vibration frequency and steady response are more accurate than some existing results, and that the relative error of the solution is greatly reduced, which are in good agreement with the exact ones.The vibration frequency is decreased with the increase of the nonlinear coefficient and the initial amplitude, but it increased with the increase of the linear stiffness coefficient.            
  • LIU Zhihui 1,2,3 YAN Hongzhi 1,3, CAO Yuming 1,3
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 159-165.
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    In order to ensure the sprag one-way clutch two shafts assembly have good dynamic performance, a four-degree of freedom lateral-torsional coupling dynamic model was established by the lumped parameter method.The method of Runge Kutta was used to solve the nonlinear dynamic system equations.The effect of the sprag one-way clutch torsional stiffness and torsional damping on the dynamic transmission error and dynamic load of the gear pair was studied.And the effect of the contact ratio of the gear pair on the dynamic windup angle, the maximum impact force and the steady contact force of the sprag one-way clutch was studied also.The results show that: ① The dynamic transmission error and the meshing force of the gear pair decreases with the sprag one-way clutch torsional stiffness at the lower range of excitation frequencies, and it is vice verse at the higher range of excitation frequencies.② The dynamic transmission error and the meshing force of the gear pair decreases with the sprag one-way clutch torsional damping.③ The dynamic windup angle, the maximum contact force, the steady contact force of the sprag one-way clutch increases the contact ratio of the gear pair.
  • JIANG Xingxing1,WU Nan1,SHI Juanjuan1,SHEN Changqing1,LI Chuan2,ZHU Zhongkui1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 166-172.
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    One of the key steps for rotating equipment fault diagnosis under variable speed condition is to acquire the accurate shaft instantaneous frequency (IF).The most effective way to realize it is based upon the Time-frequency distribution (TFR) analysis.However, its effectiveness is often undermined by the TFR’s poor energy concentration and weak shaft IF-related signal segmentations caused by strong background noise and interferences.A speed estimation method based on the ridge enhancement and feature fusion was, therefore, proposed in this paper.The TF ridge candidates were enhanced firstly by the amplitude sum-square method, and then the TF ridge candidates in lower band and the resonance band were searched, respectively.The fusion criterion based on probability distribution and local fluctuation was, finally, established to acquire the accurate estimation of shaft IF ridge.Compared with conventional methods, the proposed method yields more accurate IF approximation results and is less sensitive to noise.The experiment results validate the effectiveness of the proposed method for shaft IF estimation.
  • LI Junming1,3, CAI Ganwei2, HUANG Yuanxing4, LI Yanzhou2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 173-178.
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    Ultraharmonic resonance of Vibratory Stress Relief (VSR) is an effective way to solve the resonance problem of high-frequency structures.However, the application of the process has hitherto been limited by complex manufactured process, nonlinear parameters, difficulty in controlling the nonlinear springs, and so on.To solve these problems, a VSR equipment combined linear springs was designed, which was marked by the use of linear springs to achieve ultraharmonic resonance.The nonlinear elastic properties were given based on the analysis of the mode and the vibration mechanism of the third ultraharmonic resonance was obtained by using the multi-scale method.The response of the high-frequency structure excited by the above third ultraharmonic resonance was analyzed based on simulation results of the finite element model.It was shown that the linear spring combination system can produce the third ultraharmonic resonance in the vertical direction and the high-frequency structure can be achieved primary resonance, which generalizes the known results of VSR.
  • ZHAO Xiaodan1,HAN Junyang1,SUN Liming1,2,WANG Xifu1,
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 179-184.
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    Closely spaced modes exist in vibration response signals widely.The damping ratio of closely spaced modes can not be identified accurately.It has been a difficult problem to improve identification accuracy of the damping ratio of closely spaced modes.A new method to estimate the damping ratio was presented.A set of basis functions were constructed nearby the closely spaced modes and processed with the Schmidt orthogonalization.The projection of vibration response signals on standard orthogonal basis functions was calculated with the inner product algorithm.The maximum of the projection was searched using a genetic algorithm and quasi-Newton methods.According to Bessel Inequality, the natural frequency and attenuation coefficient of each modal were obtained when the projection achieved the maximum value.The damping ratios could be estimated with the natural frequency and attenuation coefficient of each modal.This method is not restricted by modal density.Digital simulations and experiment show that the damping ratio of closely spaced modes can be identified accurately.This method is valuable practically.
  • REN Xiaosong1,ZHONG Yuan1,GUO Xuefeng2,ZONG Gang1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 185-192.
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    Dynamic acceleration responses of steel stairs under pedestrian loads are important indicators of structural comfort evaluation.It is necessary to establish a practical method to realize rapid estimation in engineering.This paper explored the calculation and fitting process of acceleration design response spectrum for steel stairs by taking an internal steel staircase in a public building as background.Pedestrian pace frequencies were measured on eight steel stairs in different kinds of public buildings.The Monte Carlo simulation method was used to fit and establish practical design response spectrum on the basis of dynamic equation in a standard incentive system.An internal steel staircase was tested under different conditions.The measured results were used to compare with estimation results gained by using the response spectrum method.The comparison results demonstrate that the proposed method can be applied to vibration estimation of common steel stairs.
  • CHENG Hongjie,CHEN Li,ZHAO Yuan,LIU Zhun
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 193-199.
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    For double pressure peaks impact of gas-ejection, RNG k-ε turbulence model, Finite-Rate/Eddy- Dissipation model and layering dynamic mesh technique were adopted to establish an initial cavity secondary combustion numerical model with missile movement.Experimental data were used to verify the reliability of model.The effectiveness of smoothing pressure impact through increasing annular baffle was studied.The influence mechanism of main structural parameters of annular baffle on smoothing effect was analyzed by decoupling.A set of ideal structural parameters was obtained.The results show that as the number of annular partitions increases, the pressure peak is gradually reduced and smoothing effect of the four baffles is optimal.As the number of the height of bottom baffle increases, the pressure peak is decreased at first and then increases.When the height is 200mm, the pressure peak reaches the smallest.After baffles are arranged reasonably, the peak value of missile acceleration is reduced by 10.5%, and the velocity out of tube is decreased by 0.55% and the time out of tube is delayed by 2.6%.
  • XIE Jiang, MA Congyao,HUO YuJia, ZHOU Jian, Mou HaoLei, Feng ZhenYu
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 200-206.
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    Aiming at revealing effect of ply orientations on energy-absorbing characteristics of T700/3234 composite thin-walled circular tubes under axial compression, the material properties were measured and quasi-static axial crush tests of thin-walled circular tubes were performed.The finite element model and analysis method of the composite tube were validated by comparing the experimental results of peak load and specific energy absorption of composite thin-walled circular tubes under axial compression.Based on the validated finite element model and analysis method, effect of ply orientations on energy-absorbing characteristics of composite thin-walled circular tubes under axial compression was discussed.The results show that the SEA increase almost linearly first, and then decreases to a certain extent with the ply orientations increase for composite thin-walled circular tubes under quasi-static axial compression.The initial peak load is the lowest and load efficiency is the highest when ply orientation is relatively ±45°, and it is easier to achieve progressive failure energy absorption stage.The research results can be used as a reference for the design of composite fiber plies and the finite element modeling of thin-walled composite structures.
  • GUAN Yu1, SHI Yu2, GAO Li1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 207-215.
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    Two full scale models of cold-formed thin-walled steel-gypsum based self-leveling mortar composite floor were carried out for vibration test under four dynamic loadings which included walking along and transverse to the floor joist, walking along the diagonal direction of floor and hammer impact.The effects to the natural frequency of composite floors were studied when steel mesh was installed.The study showed that the natural frequency of composite floor did not change greatly with the change of external excitation.It did not significantly increase the natural frequency of composite floor via installing steel mesh into the gypsum based self-leveling mortar.The ABAQUS finite element software was used to conduct modal analysis of test models as well as variable parameter analysis based on the calibrated model.The research shows that fundamental frequency of cold-formed thin-walled steel composite floor can be improved by increasing plate thickness of floor joist and reducing floor span.The change of floor slab thickness and floor width along with strengthening flat strap and blocking brings little effect to the fundamental frequency of cold-formed thin-walled steel composite floor.Based on parameter analysis, composite floor can be equivalent to a simply supported beam with uniform quality and stiffness for computing the fundamental frequency of cold-formed thin-walled steel composite floor.
  • YANG Fan DENG Bin
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 216-221.
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    A compliant urethane lining was used in an expansion chamber hydraulic suppressor to reduce the propagation velocity of pulse wave, which made compact pulsation attenuation possible.An expansion chamber hydraulic muffler with a compressible urethane liner was put forward in this paper.Besides, a lumped parameter method was used to build the equivalent circuit model and its feasibility was proved within a certain frequency range.Manifestations of large capacitance were caused by strong compressibility of urethane lining from the point of view of lumped parameter and the results of ageing lining.Unaged ling and ordinary expansion chamber hydraulic attenuators show that bandwidth can be expanded by changing liners’ material composition and there is no needed to change outline dimension of suppressors.Given the situations that other conditions remain unchanged, sapce size can be significantly reduced by using ageing lining, in comparison with ordinary expansion chamber hydrulic mufflers.For an expansion chamber hydraulic suppressor with an ageing liner, with the increase of system pressure, mufflers’ effective attenuation band decreases and attenuation characteristics are affected by system pressure.
  • GUO Huaipan1,LI Hao2,CHEN Weidong1,ZHOU Xubin2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 222-229.
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    A novel quasi-zero-stiffness (QZS) vibration isolation system based on cross-ply composite laminates was proposed in this paper.A theoretical model and a finite element model (FEM) were established to explore the bistability and negative stiffness characteristics of cross-ply composite laminates with residual thermal stress.The deformation range corresponding to the negative stiffness was narrowed as the thickness of the laminate increases.As long as the laminate thickness is slightly thicker than a critical thickness, the cross-ply laminate loses bistability and then shows the characteristics of quasi-zero-stiffness.The proposed vibration isolator takes advantage of the quasi-zero-stiffness of cross-ply laminate.The characteristics of the proposed isolator was evaluated theoretically and numerically, and compared with the corresponding linear vibration isolation system.The proposed QZS vibration isolator exhibits lower nature frequency than the linear isolator.Moreover, significant lower acceleration transmissibility and wider frequency range of vibration isolation were observed for the QZS vibration isolator.
  • XUE Fei, SUN Beibei, Chen Jiandong
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 230-236.
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    A reactive muffler is widely used to reduce the low-frequency noise generated by internal combustion engines, but it is often difficult to obtain ideal noise attenuation performance above the upper cutoff frequency range.This paper presented a case study on a novel application of U-shaped corrugated pipes in reactive muffler, which aimed to improve the noise attenuation performance above the upper cutoff frequency range.Typical performance parameters such as the insertion loss and pressure loss were experimentally evaluated.Besides, an index (improvement coefficient η) was proposed to weigh the improvement performance of corrugated pipes in noise attenuation and pressure loss.Results demonstrate that the application of U-shaped corrugated pipes in the reactive muffler significantly improves the noise attenuation performance above the upper cutoff frequency range and successfully extents the bandwidth of noise attenuation.In addition, the application of U-shaped corrugated pipes increases the pressure loss of the reactive muffler, reducing the aerodynamic performance of the muffler to a certain extent.Moreover, the overall improvement coefficient η reaches 1.12~1.13, indicating that the corrugated pipes make more contribution in noise attenuation than in pressure loss.In conclusion, this study verified that the application of U-shaped corrugated pipes in the reactive mufflers is feasible and acceptable, and it provides a novel method in the design of reactive mufflers.
  • GONG Qingshan1,2 ZHANG Hua1 ZENG Guohua2 WU Yuemin2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 237-244.
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    The pretreatment of the plate surface is important to the quality and life of production., so this paper proposes a new method of surface derusting and surface strengthening for plate based impact contact of rope. Derusting mechanisms and working process are analyzed, and kinematics equation is established; A dynamics model of the rope using 6 dimensions spring flexible connection is built based on the discretization method,and the impact contact force model between the rope and the plate is introduced .The variation rule of the velocity and contact force is obtained with dynamic simulation in Adams. Test machine is designed, the experiment show that; this derusting method is feasible and in good effect, derusting grade can reach to ST3, it has good application prospect in surface derusting and surface strengthening for small and medium size steel plate.
     
  • GAO Shaowu1, YANG Changyong1,2, XU Jiuhua1, FU Yucan1, DING Wenfeng1, SU Honghua1,SU Hao1
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 245-250.
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    An axial ultrasonic assisted grinding (AUAG) method was proposed to overcome the problems existing in milling grinding and small-hole grinding process of strong and tough materials, such as poor surface roughness caused by low grinding speed.Firstly, the ground surface generation in AUAG was investigated with a geometric analysis method.Then a series of AUAG and conventional grinding (CG) tests were carried out on 9Cr18 stainless steel.The ground surface roughness and surface topography of CG and AUAG was compared.The results showed that axial ultrasonic vibration (AUV) could improve ground surface roughness effectively and the effectiveness of AUV was influenced by the grinding parameters.The most influential factor on AUV effectiveness was grinding speed, followed by grinding depth and feed rate.The effectiveness of AUV was weakened with the increase of grinding speed and grinding depth.However, when feed rate increased, the effectiveness of AUV was slightly enhanced.
  • WEI Peng 1 WANG Yunfeng1 YANG Yong 1 YAN Lijia 1 XU Longxiang 2
    JOURNAL OF VIBRATION AND SHOCK. 2018, 37(20): 251-258.
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    The contact force between a rotor and a retainer bearing after rotor drop was studied by employing theoretical analysis and experiments in this paper.Firstly, based on the Hertz contact theory, a more accurate nonlinear contact force model between the rotor and the retainer bearing after rotor drop was established.The principle to measure the contact force was proposed.And then according to the measure principle, the measure rig was designed.The whole measure process was divided into calibration and measurement.Considering the nonlinear effects of the measure rig, the measure rig was firstly calibrated using impact force hammer under various impact forces.Then the contact forces were calculated using the acceleration responses of support ring after rotor drop.The rotor drop experiments for various initial rotational speeds were carried out.The acceleration responses of the support ring and rotor trajectories were analyzed.The experimental results show that the vibrations and impacts become larger with the increase of initial rotational speed, and then whirling motion is more likely to happen.The results also show that the maximum of vibration impact appears less than 0.1 second after rotor drop, but not appears at the first collision.The contact force was then used to recognize the equivalent mass me and equivalent stiffness ke in the established nonlinear dynamic model,and then the model was validated.