To investigate the effect of flexible car body vibration on the dynamic responses of vehicle-bridge system, the dynamic analysis model of a vehicle with flexible car body moving over multi-span bridges is established, and the dynamic responses of this system is computed by Newmark-β method. In this model, the car body is regarded as an Euler beam with both ends free, and the bogie and wheel set are regarded as rigid. The multi-span bridges are regarded as a series of simple bridges and the vibration of the bridges are determined by modal superposition method, and the vehicle and bridge are linked by the wheel-rail corresponding assumption. A series of irregularities are chosen as the system excitation, and the resonance and cancellation of the flexible car body are analyzed. The calculation results show that the vibration of the flexible car body has some effect on the car body dynamic responses, which shows little feedback to the bridge vibration. The flexible resonances of the car body may result in significant amplification of the dynamic responses of the car body, and the flexible resonant speeds are determined by the bogie spacing and the car body flexible natural frequencies. Due to the wheelbase filtering effect, that is when the cancellation of the flexible car body vibration occur, the dynamic responses of the car body can be effectively suppressed.

A method based on the minimum amplitude of LTE and axis force and vibration were proposed to reduce the vibration of double helical gears. Firstly, the modified tooth surfaces were represented by a sum of two vector functions that determined the theoretical tooth surface and the deviations surface. Secondly, a 10-DOF vibration model was established considering time-varying meshing stiffness and corner meshing impact and axial motion excitations based on TCA、LTCA. Finally, a improved algorithm was applied to optimize the parameters of modified pinion to get the best performance. The results show that the loads then tend to be uniform totally when considering both modification and axial motion, besides, torsional vibration mainly result from corner meshing impact and meshing stiffness excitation which have little effect on axial vibration , and is more sensitive to the impact than other excitations, meanwhile, the axial motions excitation contribute to both axial and swing vibration. In brief, the vibration decrease greatly because of smaller excitations with modified double helical gears.

An approach of parameter identification for predicting uncertainties in honeycomb sandwich composite is conducted in this paper. The initial finite element model of honeycomb plate is constructed by application of an appropriate sandwich theory, in which the equivalent parameters are predicted by homogenization method. According to analysis of the internal honeycomb structure and the relative sensitivity of eigenvalues respect to system parameters, the sensitive parameters which also contain uncertainties (Gcxz, Gcyz and thickness of the face sheet) are selected to be identified. Through modal experiments of six different honeycomb plates with free-free boundary condition, the mean value and deviation of the modal frequencies are obtained, using which the uncertain parameter identification of honeycomb sandwich plate is conducted. Results show that when considering the uncertainty in honeycomb sandwich composite, the proposed identification method can be used for accurately identifying the mean value and deviation of the uncertain parameters, the dynamical finite element model with statistical significance can be constructed at the same time.

In seismic design of steel beams, it is necessary to set lateral supports in order to diminish lateral slenderness ratio which can prevent lateral instability and can maintain sufficient rotation capacity to dissipate input energy of earthquake. The behavior of steel beams under cyclic loading is quite different from that under monotonic loading. However, the formula for critical lateral slenderness ratio recommended in the current Chinese code GB50011-2010 for seismic design of buildings is resulted from research findings for monotonic loading. At the same time, the effect of different seismic grades is not considered in the formula. So it is necessary to improve the formula. In this paper, nonlinear finite element analysis of steel beams subjected to cyclic loading is carried out based on the concept that a seismic grade should match a suitable rotation capacity. The modeling developed takes into account the influence of initial geometric imperfection and residual stresses and is validated by other researcher’s experimental results. By means of the numerical analysis for five parameters such as end-moment ratio, web height-thickness ratio, flange width-thickness ratio, residual stress distribution pattern, out-of-plane boundary condition, the formula for critical lateral slenderness ratio for the steel beam under cyclic loading is proposed, which has higher accuracy and simpler form.

Cantilever plate is a common kind of structure in aerospace field. Due to its large deflection, low-frequency vibration problem is relatively serious. Active vibration of a kind of cantilever Kagome sandwich plate is studied here. First, the finite element models of the cantilever structure and piezoelectric actuator are established. Then the active control strategy of cantilever Kagome sandwich plate is proposed by combining independent modal space control with modal observer. And, aiming at one kind of gust load, the independent modal space control of Kagome sandwich plate is simulated, while focus is on the influence of observer poles on the control effect. The results show that this control method can significantly improve the damping properties, while greater attenuation factor of the observer can get better control effect. Therefore, Kagome sandwich panels has obvious advantages over traditional board structure in vibration control aspect.

Improvement of mutual information algorithm is good for gaining time delay in phase space reconstrution of time series rapidly and reliably. Firstly, fault of Cellucci’s mutual information algorithm is analyzed based on respectively partitioning plane, which constructed by a pair of Lorenz series with the same size, into four and sixteen grids with equal distribution probability in elements on each axis. Then improved mutual information algorithms is promoted based on the original probability matrix that shows the distribution of points corresponding to data pairs of Lorenz series on the plane by sorting two series respectively, replacing each numerical value with its order number in its own series so as to judge the element in which data sets are located and revising the last column and row of the matrix. Finally, after reconstructing phase space with the optimal time delay, comparison between the maximal Lyapunov exponent calculated by Rosenstein’s algorithm from time series and that gained by Jaccobi matrix from Lorenz equation is used to confirm the validity of the new mutual information algorithms. The results show that Cellucci’s mutual information algorithm will lead to wrong optimal time delay when series size is not a multiple of elements. The new algorithm, whose result is steadier when large numbers of data pairs are used, can not only eliminate the default of Cellucci’s algorithm but also is faster than Fraser’s algorithm. Besides, the lesser error of the maximal Lyapunov exponents from the comparison shows that the new mutual information algorithm is available and feasible.

Wall function is preferred to model the low Reynolds-number flow near wall based on the Reynolds-averaged Navier-Stokes turbulent models. Wall function problem in simulating the atmospheric boundary layer based on the standard turbulent model was investigated in this paper. An extra term which considers the extra effects induced by non-uniform and irregular distribution of roughness elements such as various structures on the land surface was proposed and appended to the widely accepted standard wall function. The effectiveness and application situation of the proposed term was firstly demonstrated by simulating a neutral wind field with the scale of 1:300 featured by larger aerodynamic roughness length. The flow around the TTU model in a neutral wind field with the scale of 1:50 was then simulated. The extra term is shown to be necessary to solve the wall function problem by preserving the inlet flow boundary conditions in both cases.

In order to increase the range of vibration frequencies, a novel combination of the hydraulic vibration table and the electrodynamic shaker is proposed. The joint test system has been used in sine on random vibration test. The sine signals and random signals are provided by the hydraulic and electrodynamic shaker respectively, and the control algorithms are spectrum equalization and power spectral density (PSD) equalization. The variable spring-damp elements are set to simulate the transfer properties from the table to the electrodynamic shaker. Based on the simulation results by the MSC (Nastran) software, it is indicates that the dynamic characteristics of electrodynamic vibration shaker is closely related to the low frequency part of test article. The random and sine signals separated can use the control algorithm to continuously update the drive signals, and the control accuracy of the reproduced PSD at the control point is quite satisfactory.

The problem of the mobility of the off-road vehicle over the roughness roads is studied. The vehicle model parameters is gain by the frequency offset tests. The road roughness is tested by testing the suspension displacement. The driver’s vertical acceleration sequence signal on the roughness roads is acquired. The absorbed power is calculated based on human tolerance limit. The ‘human-vehicle body-wheel’, three-degrees-of-freedom vibration model is built. And road roughness sequence signals by the inverse Fourier transform is worked out, which is the input of the simulation. Then the driver’s vertical acceleration sequence signal on the roughness roads is simulated utilizing the Simulink software. The speed at six-watts of absorbed power shows the mobility of the off-road vehicle passing through the roughness roads.

Based on the structural topology optimization idea, a structural material optimization method with varying frequency interval constraints was proposed to solve the problem of structural material optimization with frequency constraints. By use of homogenization and ICM (Independent Continuous and Mapping) method, the effective mass matrix and its derivatives were established through taking the reciprocal topological variables of micro structural elements as design variables, and the one order approximate explicit functions of frequency interval constraints were constructed. Integrated with the idea of varying frequency interval constraints, a topological optimization model of micro structures was formed by taking the structural mass as objective function and the frequency as constraint functions. Then, a dual solving method was adopted. Two example results show that the proposed method is feasible and effective, and the optimal result obtained by the proposed method in which the change quantities of the mass matrix is considered, are more reasonable.

To meet the demands of rotating machine for self-powered monitoring system, a novel piezodisc generator excited by the coupling effect between rotating magnets and those fixed on the piezodisc was presented. The influence of system factors on the maximal voltage and total energy generated from the piezodisc at one excitation was investigated mainly. The research results show that both the output voltage and effective speed-band can be enhanced with increasing magnet size or decreasing the distance between the magnets. In this way, output voltage beyond 12 V was obtained at rotating speed range of 100-2850 r/min. Besides, the thickness of the piezodisc exerts also great influence on the generated voltage and electric energy. Both the maximal voltage and total electric energy can be enhanced with using a thin piezodisc at low speed or a thick piezodisc at high speed. The optimal speeds for the piezodiscs of 0.2/0.4/0.6 mm in thickness to obtain maximal energy are 707.5 r/min，1301.8 r/min，2490.4 r/min respectively. At the optimal speed and one excitation, the obtained energy/power from the 0.2mm-thickness piezodisc are 3.1/1.7 and 6.4/2.0 times those from the 0.4mm and 0.6mm thickness piezodiscs. Taking 5V output voltage for example, the usable energy generated from the 0.4mm-thickness piezodisc is 5 times that from the 0.6mm thickness piezodisc at 912 r/min. While, the usable energy from the 0.6 mm-thickness piezodisc is 1.7 times that from the 0.4mm thickness piezodisc at 1710 r/min.

The periodic viaduct is assumed to be composed of an infinite number of spans, and each span is supposed to consist of a pier, two longitudinal beams and three linking springs. Based on the Bernoulli–Euler beam vibration theories and Bloch theorem, a transfer matrix for the junction linking the beams and the pier is obtained. The polynomial eigenvalue equation for the energy bands of the periodic viaduct undergoing in-plane motion is also derived. Based on the obtained eigenvalue equation, the energy bands of the periodic viaduct were presented. With the proposed model, the influences of the ratio of Young’s module of the beams to that of the piers and the stiffness of the spring on the energy bands of the periodic viaduct is investigated. Numerical results in this paper demonstrate that when the periodic viaduct with beam-beam and beam-pier spring junction is undergoing in-plane motion, there exist three lattice waves: the first kind of wave is a highly decaying wave and cannot propagate a long distance along the viaduct; the second kind of lattice wave can propagate only at some frequency ranges; and the third kind of lattice wave can propagate at most frequencies. However, within a low frequency range, the lattice wave does not propagate. As a result, to guarantee the dominant frequency of the base for the periodic viaduct not to be located within the low frequency range is crucial for the periodic viaduct design. Otherwise, the wave components carrying most energy of seismic waves will be localized, which is dangerous for the viaduct。Moreover, with increasing the ratio of Young’s modulus of the beams to that of the piers and the stiffness of the beam-beam spring, the attenuation of the lattice waves decreases significantly, implying that the wave can propagate a longer distance along the structures.

In order to solve the problem that rotating machinery vibration is too large around the critical speed, a two-span rotors system bench was established to simulate the starting process. Without changing original supports of the rotors system, two self-designed magneto-rheological dampers were installed at each shaft. Different working conditions was set to study the influences in different mounting position and operating current of dampers. The results show that the damper can reduce the vibration of the shaft where the damper was installed near the critical speed vibrations. According to test results, an on-off control method was proposed to control the two-span rotors’ vibration. The results show that the on-off control method can reduce the vibration when the rotors went through the critical speed of first and second order without stopping the machine.

The high-rise structure with multi-skirt building is used widely so as to satisfy the increasing requirement of use function. In high intensity area, the structure adopts the isolation technology to promote its seismic safety and protect equipment. But, the structure is complex, the horizontal and vertical stiffness are not uniform, so the relationship of parameters between main tower, skirt building and isolated layer will seriously influence its seismic behavior and isolation effect. The paper analyzes influence of different parameters on isolation effect, the results show that: when the stiffness ratio of isolated layer to main tower is N≤1/14, the ratio of number of floor of skirt building to main tower is 1/3~1/1.5, the stiffness ratio of skirt building to main tower is 0.42~1.1, and the mass ratio of skirt building to main tower is P≥1.1, the main tower can obtain better isolation effect; it is possible to overstate the isolation effect of the upper structure according to the rigid floor assumption, so the large podium must be supposed to be elastic. Above suggestion may provide some references to design the base isolated high-rise structure with multi-skirt building.

This paper presents the results of a integration algorithm developed to reduce the trend of error that usually appears in the process of acceleration integrating for displacement in engineering test. The integration of acceleration was conducted directly in frequency domain and the integral accuracy is governed by a controlling equation. Experiments were conducted to compare the integration algorithm with previous methods and the result indicates that it is privileged to better control the trend of error. Vibration experiments with impact of limit position were introduced to investigate the characteristics of the integration algorithm. It’s to be noted that the integral trend of error was reduced effectively by the integration algorithm, and it is decreasing with increasing acceleration baseband. The amplitude of integral error is less than 10% while the baseband of the acceleration signal exceeds 3.8Hz and less than 5% corresponds to exceeding 4.35Hz, which could satisfy the engineering requirements more effectively.

To study the vortex-induced vibration (VIV) and its control measures for a Π shaped deck, the aerodynamic performance of a cross-sea cable-stayed bridge was investigated through section-model wind tunnel tests. The research results show that the Π shaped deck concerned suffers remarkable VIV at low wind velocity, which exists under the structural damping ratios of 1%. Crash barrier and maintenance way railings with cylinder shape are conducive to decrease VIV amplitude, both vertical and torsional. The VIV can be mitigated via sharpening wind fairings and the vibration mitigation effect is more significant with the smaller wind fairing angle. The horizontal flow-isolating plate (HFIP), jutting out of the inner edge of the girder bottom plates, can mitigate and even eliminate the VIV effectively. Generally, within certain limits, the wider the HFIP is, the better the mitigation effect.

Teflon slide rubber bearing is often used on bridge. The ideal expansion bearing element is usually adopted to simulate this rubber bearing in analysis. This ideal expansion bearing model will ignore friction between Teflon layer and steel surface. This paper takes one curved continuous girder bridge as an example, and employs bilinear sliding bearing element and friction isolator elements to simulate Teflon slide bearings on this bridge. Nonlinear dynamic analysis results show that seismic responses of bridge in which the slide rubber bearings are modeled as ideal expansion bearing elements are overestimated. Seismic responses of bridge adopting bilinear sliding bearing model is similar to that of bridge adopting friction isolator model. Friction isolator can consider the varying friction force of bearing, so using this model to simulate Teflon slide rubber bearing is accordance with the actual case.

For a vehicle suspension shock absorber abnormal noise problem, the vehicle road test and rig test has been carried on, which result in the consistency rule: shock absorber piston rod acceleration signal within the specific frequency band has similarity. So the part of road test can be replaced by a series of rig tests for shock absorber abnormal noise identification. Then research on the rig test for identifying abnormal noise of shock absorber puts forward The Time Difference Method, The Subsection Auto-power RMS Value Method and The Characteristic Energy of Wavelet Analysis Method and compare their advantages and disadvantages. Depends on that, the Clustering Analysis Method Based On Weight Coefficient has been proposed and adopted, which transfer rigid rectangular single index into a more flexible circular determine areas and reduce the final misjudgment probability caused by single index. This method can provide the reference for the mass, different types of absorber abnormal noise identification and improve the judgment accuracy.