There are many mechanical elements in the vehicle suspension system which employing the three types elements, namely, the inerter, the spring and the damper, and it cannot be easily applied to the automotive engineering. Due to this problem, a parameter optimization design method of the vehicle mechatronic suspension is proposed in this paper based on the electromechanical similarity theory. On the basis of the dynamic model of a half car model with four freedom degrees of vehicle mechatronic suspension considering the vertical motion and the pitch motion during the driving process of the vehicle, this paper explores the improvements of the new vehicle mechatronic suspension employing mechatronic inerter on the dynamic performance of the vehicle. In terms of the multi parameters and multi constraints optimization problem, the improved particle swarm optimization algorithm is used to optimize the main parameters of three different modes of vehicle mechatronic suspension by considering the positive real of transfer function and the dynamic performance constraints of the suspension, and the mechatronic inerter and the external electric network are used to realize the network passively. Numerical simulations showed that, under the single objective optimized condition, the RMS of vehicle body acceleration and pitch angular acceleration of the new vehicle mechatronic suspension are reduced by 26.5% and 18.3% respectively, and they can decrease by 15.5% and 11.4% simultaneously when taken the two objectives into consideration. The dynamic vibration isolation performance of the proposed vehicle mechatronic suspension is significantly improved compared with the traditional passive suspension, which provides a new idea for the suspension design method.

The experimental modal analysis, dynamic modeling and structural parameter identification were employed to research the inplane vibration modes of heavyloaded radial tires with larger flat ratio. The coupled characteristics of flexible tread, distributed sidewall element and rim were investigated by means of the experimental modal analysis. Taking the bending and inflation features of the flexible tread and the inertial force and sectional spring of the sidewall into consideration, the coupled kinematics of flexible tread, distributed sidewall element and rim was modeled. The inplane coupled analytical modal frequency was derived. The structural parameters identification was implemented and the higher order modal frequenies were predicted with the analytic method. The results show that: the flexible tread vibrates in the same/opposite direction with the distributed sidewall within 0-180 Hz and 180-300 Hz respectively ; the modal analysis and kinetics modeling in consideration of the coupled features of flexible tread, distributed sidewall element and rim can accurately characterize the inplane vibration features of heavy loaded tires within the frequency band of 300 Hz. 

In order to study the efficiency and mechanism of the vibration control of particle dampers in longperiod bridge structures, a 1/20scale bridge model was designed according to a typical asymmetric selfanchored suspension bridge with a singletower, and a multilayer compartmentalparticle damper applied to the scaled test model was proposed. Corresponding shaking table tests of the scaled model with and without particle dampers were conducted. The experimental results show that the multilayer particle damper proposed does not show the phenomenon of particle accumulation in the experiments, and it has a good damping effect on the longitudinal seismic responses of the main beam of the scaled model bridge. It can dramatically reduce the displacement responses and acceleration root mean square responses of the main beam. This type of damper can significantly increase the equivalent damping ratio to reduce the longitudinal vibration of the main beam (in the low frequency vibration direction), and its has a significant tuning effect on the fundamental longitudinal vibration frequency of the main beam; The multilayer compartmental particle damper can effectively control the lowfrequency dynamic responses of longperiod bridges and can be applied to the seismic control of longperiod engineering structures.

The surface topography of the rolling interface can change the interface dynamics,and influences the dynamic response of a rolling mill system.Considering the roughness of the rolling interface,the nonlinear dynamic model of the rolling mill system was established.The nonlinear stiffness and natural frequency characteristics of the rolling system with different rough surface topography were calculated and compared with the traditional rolling mill model using Duffing oscillator to describe the interface stiffness.The main resonance amplitude-frequency characteristics of the rolling mill system were solved by using the method of multiple scales,and the expression of the jump frequency and the corresponding amplitude of the forced vibration response were derived.The influence of the rolling surface roughness,excitation load,nonlinear stiffness ratio and damping on the dynamic response characteristics of the rolling mill was analyzed.The results provide theoretical reference for suppressing rolling mill vibration.

Here, 528 m high Nanning Wuxiang ASEAN Tower was taken as an engineering example, a new turbulent inflow generator named the narrowband synthetic random flow generator (NSRFG) was used to do the large eddy simulation (LES) for its wind-induced vibration response.Its base loads and displacement responses were calculated.The numerical wind tunnel’s simulation results were compared with those of the HFFB wind tunnel tests, and the effectiveness and correctness of NSRFG were verified.The results showed that the base bending moment power spectra simulation results in downwind and crosswind directions agree well with those of the wind tunnel tests, but the simulation results in torsional direction have a certain gap compared with the wind tunnel test ones; for the tower’s wind-induced vibration responses, the numerical simulation results in downwind direction agree well with the wind tunnel test ones, but the simulation results in crosswind and torsional directions are a little smaller; in across-wind direction, the predicted value for the vortex shedding frequency of the tower model with NSRFG was close to the wind tunnel test one.The study results provided a valuable reference for structural design.

Aiming at the phenomenon of mode mixing in the extraction of fault information from the vibration signal of a high speed elevator rolling guide shoe,by the method of singular value decomposition (SVD) optimizing local mean decomposition (LMD), a feature extraction method based on self-adaptive sharpening wavelet decomposition (SSWD) optimizing LMD was proposed.First of all, the low pass filter, high pass filter, wavelet basis function and scale function were constructed.The original signal was decomposed into a high-frequency detailed feature signal and a low-frequency approximate signal by the multi-resolution filtering characteristics of wavelet decomposition (WD).Then, signal enhancement was done on the high frequency detailed feature components, and the enhanced high frequency detailed characteristic signal and the low frequency approximate signal were reconstructed.Finally, the LMD method was used to extract the fault features’ PF component of the rolling guide shoe from the reconstructed signals.The instantaneous Teager energy waveform of the PF component was obtained for comparative analysis.Through the actual working condition signal processing and analysing, the experimental results show that, compared with the SVD optimizing LMD method, the method completely extracts the fault characteristic components of the vibration signal of the rolling guide shoe, and avoids the phenomenon of modal confusion.

A finite element model of half steel plate-concrete composite slabs (Half-SC slabs) under impact action was established using LS-DYNA. The accuracy of the model was verified based on the available test results. The effects of the impactor mass, the impact velocity, and the steel plate thickness on the displacement response of Half-SC slabs were further analyzed. On this basis, the resistance and stiffness equations of the Half-SC slabs were derived. The resistance function of the Half-SC slabs was proposed. Thus, an equivalent single-degree-of-freedom model for calculating the displacement response of the Half-SC slabs was established. The results show that the damage process of Half-SC slabs under impact can be divided into three stages such as the elastic stage, the concrete cracking stage, and the horizontal reinforcement fracture stage. The impact velocity has the greatest influence on the displacement response of the Half-SC slabs, followed by the impactor mass and the steel plate thickness. The proposed equivalent single degree of freedom model can accurately predict the displacement time histories of Half-SC slabs.

The collapse vibration performance laws of city viaduct to metro tunnel were obtained by using ANSYS/LS-DYNA software. The calculation model of collapse bridge impact to the underground tunnel of the city was established. Dynamic response of metro tunnel including three-direction vibration velocity and stress process of typical units was also obtained by comparison different conditions. The results show that as a main form of composite protective structure consists of Steel Plate-Rubber Tires system can make maximum of metro tunnel vibration velocity, compressive stress and tensile stress were decreased by 98.7%、95.6% and 94.4% compared with the absence of protective measures. It has shown excellent agreement between measured data and simulation results. Metro tunnel borne vibration speed is lower than the administration proposed safety threshold requirement and the design of comprehensive protection system achieved the expected result.

A large number of signals collected by mechanical equipment monitoring system are usually nonlinear signals with multiple natural oscillation modes, so the single-scale feature extraction can’t characterize these nonlinear signals. For high dimensional feature matrix, its main lower dimensional features need to be further extracted. Here, to solve these two problems, a nonlinear feature extraction method combining multiscale permutation entropy and linear local tangent space alignment (MPE-LLTSA) was proposed. Firstly, signals were calculated using MPE to obtain multi-scale features with high dimensions. Then, LLTSA was used to excavate the embedded intrinsic structure, and realize low dimensional feature extraction. Finally, least squares support vector machine (LSSVM) was introduced to train and recognize low dimensional features. The test results showed that the proposed method has application potential in fields of mechanical pattern classification and fault recognition.

In the field of fault diagnosis, acoustic emission signals are often exposed to strong background noise because of the environment and the detection system, which leads to aliased distortion of AE signals. A review of the research states of the extraction and processing for acoustic emission signals under strong background noise is presented, including the characteristics of AE signals in fault diagnosis, the processing flow of AE signals, the denoising of AE signals including wavelet, ICA and EMD, the feature extraction and fault recognition. Then a summary of insufficiency and methods in the research of denoising, feature extraction and fault recognition of AE signals is also presented. At the end, the future development of AE technology and signal processing methods is forecasted.

In this paper a new method of fault feature extraction based on sample entropy and fractional Fourier transform is presented. The core of this new method is to map the original data with poor separability into the appropriate fractional space firstly. Then the sample entropies of the transformed data after fractional Fourier transformation with appropriate order are computed and compared, so that fault feature extraction is fulfilled. The results show this new method could enhance the separability of different failure modes, and discriminate the normal, inner ring fault, outer ring fault and roller fault signals distinctly.

Recently the application of neural networks to the online model updating of hybrid testings is an important research direction.How to improve the adaptability, stability and anti-noise ability of online model updating algorithm of neural network is a key problem.An on-line model updating method for hybrid testings based on the forgetting factor and LMBP neural network was proposed, namely in each time step the historical experimental data of the test substructure were used to form a dynamic window sample with a forgetting factor.Then the LMBP neural network was trained with the sample set by the incremental training method, and the restoring force of the numerical element with the same constitutive model was predicted synchronously.The model updating hybrid testing on a 2-DOF nonlinear system was simulated and the RMSD of the predicted restoring force of numerical substructure was found to be 0.023 0 finally.The results show that the online model updating method of hybrid testings based on the forgetting factor and LMBP neural network has good adaptability, stability and anti-noise ability.

Theoretical research and the most rent advances of discrete intensive frequency spectrum zooming analyze and correction methodology was reviewed. According to the numbers of frequency component including in the spectrum, the existing methods are classified into two kinds. One kind of methods deal with spectrum including only two frequency components, the other relate to spectrum including more than three frequency components. The detailed analyses and expatiation are made to account for the basic theory, algorithm, principle, characteristic and application scope. The deficiency of current spectrum zooming methods are discussed, and some possible directions in discrete intensive frequency spectrum zooming analyze and correction domain are tipped.

Based on the two-way fluid structure coupling theory, the numerical model of tuned liquid damper (TLD) and multi-layer multi-modal platform structure was established in this paper. The effects of TLD damping frequency and installation height on the first two resonant modes of multi-layer structure were systematically studied. The damping force has been quantified by numerical method. Combined with the phase delay relationship of sloshing wave and platform motion, the damping characteristics of TLD on multi-layer multi-modal platform structure were analyzed. The results show that the control effect of different installation positions of TLD is related to the maximum vibration mode of the corresponding mode of the structure. The damping frequency band of TLD can be widened by the frequency doubling excitation generated in the sloshing process. In addition, keeping the mass ratio of 2% unchanged, the multi-TLD system has a more stable vibration reduction effect on the multi-layer structure without local negative excitation. The average vibration reduction ratio at the two resonance points is better than that of other schemes.

To prevent torsional resonance of multi-gears of multi-speed planetary transmission system which because of improper choose of the parameters, dynamic optimization and modification for the parameters of the system was conducted by using the multi-step genetic algorithm which adopt relative sensitivity of natural frequencies to parameters of the system to be the constraint conditions, and to minimize the change rate of parameters relative to its initial value was taken as the dynamic objective function and dynamic constraint boundary. Comparative study of taking the change rate of parameters relative to its initial value to be optimal and taking every step to be optimal when different step size was taken into consideration had been done. And the characteristic of natural frequencies to parameters of planetary transmission system apply to multi-gears and single-gear was analyzed. The result indicate that better optimization result can be got in the multi-step genetic algorithm when using the change rate of parameters relative to its initial value to be optimal compare with using every step to be optimal; The natural frequencies to parameters of single-gear of planetary transmission system can not be used for guidance of multi-gears system directly. Resonance will not produce at the range of working speed of the system after optimization and modification of parameters, and a guidance for the design of the planetary transmission can be provided by this paper.

Under multi-axis complex vibration environment, an electrical connector structure may be loose to affect electrical contact performance of its electrical appliances and cause failure of equipment function.Here, in order to explore mechanical characteristics of electrical connector in loosening process under multi-axis random vibration environment, a model of electrical connector in missile electronic cabin was established.The change time history of contact pressure in pin’s withdrawing process during it being loose relative to pinhole was simulated under random vibration environment, and the stress evolution mechanism in loosening process of electrical connector was revealed.Through comparing stress varying trend under triaxial random vibration and that under uniaxial random vibration, according to differences of three intervals, looseness characteristics of electrical connector under triaxial vibration were compared with those under uniaxial vibration, and a triaxial vibration stress screening method for connector looseness was provided.The mapping relationship between stress and resistance of electrical connector was derived by using R.Holm expression for relation between contact resistance and contact pressure, and the monitoring of contact stress between pin and pinhole was converted into monitoring of contact resistance to solve the technical problem of dynamic stress inside pinhole being difficult to measure.

In order to study relationship between vibration characteristics of urban rail elastic vehicle body and under-vehicle equipment, a rigid-flexible coupled multi-body dynamic model for the equivalent Euler beam vehicle body with under-vehicle equipment was established using the modal superposition method.Vibration responses of the vehicle body’s middle part and the upper one on the vehicle bogie were analyzed under various different operating conditions.The sensitivity of the first-order elastic modal frequency of the vehicle body to the elastic resonance velocity was discussed.Along the whole vehicle length, the coupled vibration relationship between the vehicle body and the under-vehicle equipment was analyzed.The variation of the whole vehicle’s vibration was analyzed to evaluate the stability of the vehicle at last.The results showed that elastic suspension of under-vehicle equipment can effectively suppress vibration of the entire vehicle body; from the view point of suppressing the entire vehicle body vibration, it is necessary to symmetrically install the equipment under the middle of the vehicle body, and choose different elastic suspension devices for under-vehicle equipment with different mass; the vehicle body’s elastic vibration is greatly affected by the resonance speed, vehicle operation under non-resonant speed can effectively avoid the overall vehicle elastic resonance and improve passengers’ comfort; the study results provide a reference for reducing elastic vibration of urban rail vehicles, improving passengers’ comfort, reasonably locating under-vehicle equipment and appropriately choosing its elastic suspension devise.

Multibody system dynamics is an important branch in the field of the modern mechanics. It provides a
strong tool for dynamic performance estimation and optimizing design of many mechanical systems in a lot of important
engineering fields, such as, weapon, aeronautics, astronautics, vehicle, robot, precision machinery, and so on. The study
on dynamic modeling, design and control of complex multibody systems is the urgent demand of modern engineering
problems. The studies on the dynamic modeling methods, computational strategies, control design, software
exploitations, and experiments of multibody systems in recently years are reviewed. The future directions of this field are
indicated.

The fault diagnosis of planetary gearboxes is a challenging issue due to the complexity and variety of vibration responses generated by the relative motions of internal gears which are much different from the case of fixed-shaft gearboxes.When the damage occurs on a tooth, due to the time-varying transfer paths caused by the dynamic fault meshing behaviors, the captured fault induced information on a fixed-sensor may exhibit unique irregularity.Before properly making use of these fault induced information for fault diagnosis, the period of fault meshing behaviors should be focused and analyzed, because a certain period included in the analyzed data may involve complete fault information for fault detection.In the paper, a method was introduced to determine the period of sun gear fault-meshing positions based on the kinematics of the internal gears.Two conditions were considered: planet gears were all different; planet gears were identical.Generalized mathematical expressions for the number of rotations of the sun gear and the carrier under above two conditions were derived respectively.The proposed expressions can also be applied to ring gear fixed planetary gearboxes.Finally, experimental studies were carried out to suggest the minimal measured data length to ensure an effective fault diagnosis.

开展弧齿锥齿轮的试验研究可为理论设计、制造和装配等提供基础数据，提高弧齿锥齿轮的啮合质量和使用性能。以弧齿锥齿轮为研究对象，采用功率封闭试验系统，在准静态条件下开展试验研究。对不同转速和扭矩工况的传递误差和齿根应力开展测试，并从时域和频域角度进行了对比分析。结果表明：弧齿锥齿轮的传递误差呈正弦或余弦形式波动，并以转频对应幅值为主；随着扭矩的增加，弧齿锥齿轮传递误差峰峰值呈现递增的趋势，且传递误差转频对应幅值近似呈线性比例增加；转速对传递误差峰峰值影响较小，但对传递误差转频对应幅值影响较大。随着扭矩的增加，齿根应力峰峰值呈线性比例递增；转速对齿根应力峰峰值的影响较小；从小端到大端，齿根应力的变化很大且呈现增大的趋势；齿轮啮合过程中，轮齿进入啮合时，齿根应力为拉伸方向且应力逐渐增加达到峰值，随后轮齿逐渐退出啮合，齿根应力逐渐减小直至压缩方向并达到最小值；从频域角度齿根应力以转频及其倍频为主。

Particle slurry jet impact rock-breaking process involves large deformation, high strain and strong loads, which is characterized by complex-nonlinear-dynamic-coupled problem among steel particles, slurry and rock. Aiming at the problems of instantaneity and difficult observation of rock-breaking process, damage mechanism and failure effect of rock with particle slurry jet impact were studied. Based on smoothed particle hydrodynamics–finite element method （SPH–FEM ）coupled algorithm, modeling method of particle slurry impact rock was described. Afterwards, the rock damage constitutive model was established by combining Johnson-Holmquist-Ⅱ（JH-Ⅱ） model and Rankine tensile fracture soft model, and dynamical simulation of particle slurry jet impact rock-breaking process was carried out. The results showed that the damage of rock was mainly longitudinal propagation, with instantaneity and step property, which was a cycle process of “from damage accumulation to continuous fracture”; and the rock failure mechanism was mainly characterized by tensile crack, and shear powder. Meanwhile, the morphology of rock-breaking samples was compared and verified by experiment and numerical simulation, and influence laws of impact velocity, angle and particle size on rock-breaking effect were analyzed. This research would be of great significance for the development of particle slurry jet impact rock-breaking theory.