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.

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.

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.

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. 

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.

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.

A model of anchored rock slope with weak interlayer was established using the FLAC3D program.The influence of the weak interlayer parameters on the displacement response and the anchored interface shear action was studied.The sensitivity analysis of the weak interlayer parameters was carried out through an orthogonal experiment.The result of numerical simulation shows that the shear stress on the anchorage interface changes in steps with time, and its change is closely related to the energy of ground motion; with the increase of the thickness of the weak interlayer, the permanent displacement of slope and the peak shear stress all increase, and with the increase of cohesion and internal friction angle, they all decrease; with the increase of dip, they increase first and then decrease; the sensitivity of weak interlayer parameters to interface shear stress from great to small is the dip, cohesion, internal friction angle, thickness of weak interlayer.

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.

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.

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.

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.

Based on Euler beam theory and Hamilton’s principle, the nonlinear coupling differential equation of the packaging system with a cantilever beam type vulnerable part is derived, in order to improve the reliability of product drop impact, elastic constraints are applied between the elastic component and the rigid product. The resulting equation is discretized via the Galerkin method and the dynamic response of the packaging system are discussed with regard to different support types and support stiffness. The numerical results show that the response frequency of the elastic component decreases with the increase of end mass and increases with the increase of tip support stiffness; The elastic support has an obvious inhibitory effect on the impact response of the cantilever type component; The comparison shows that the tip support has the best suppression effect to the impact response and especially when the support stiffness in the range of 0~30.

Lattice sandwich structures are widely used in aerospace, automotive and marine fields because of their excellent mechanical properties, outstanding energy absorption capability and unique functionality. While, traditional lattice materials have problems of uneven stress distribution and joint stress concentration. In order to solve the above problems, a new cosine function cell-base (CFCB) single-cell structure is proposed based on body-centered cubic structure (BCC). To study the energy absorption characteristics of CFCB lattice sandwich structure under out-of-plane compressive load, the CFCB lattice sandwich structure was prepared, and the quasi-static crushing test was carried out, and the test results were compared with those of BCC lattice sandwich structure. The results show that the load-bearing capacity and energy absorption capacity of CFCB lattice sandwich structure under out-of-plane compressive loading are obviously better than that of BCC lattice sandwich structure. Then, based on finite element model, the effects of cell parameters such as cell diameter, amplitude, period length and single cell layer number in the thickness direction of CFCB lattice sandwich structure on capacity absorption performance under out-of-plane compressive loading were simulation analyzed. The related research results are expected to provide a reference for the design of new lattice sandwich structures.

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.

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.

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.

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.

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.

Here, considering geometric nonlinearity, damping nonlinearity and axial inextensibility of beams, the electro-mechanical coupled nonlinear dynamic equation of a cantilever beam with a tip mass piezoelectric energy harvester under parametric and direct excitations was established by using Hamilton variational principle. In fact, the piezoelectric energy harvester is a piezoelectric bimorph cantilever beam structure. Using Galerkin method, the electro-mechanical coupled nonlinear dynamic equation was reduced to an electro-mechanical coupled nonlinear Mathieu-Duffing equation. In order to study the first-order resonance response of the energy harvester, the multi-scale method was used to obtain the analytical expressions for beam deflection, output voltage and output power of the energy harvester. These analytical expressions were used to study influences of impedance, damping coefficient and tip mass under parametric and direct excitations on performances of the piezoelectric energy harvester.

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.