A purely bending model considering the clearance, stiffness, damping of joints and nonlinear cables, is derived to show the nonlinear dynamic characteristics of jointed deployable structures. The Taylor series expansion of nonlinear differential equation and harmonic expansion of variables are used to convert the nonlinear dynamic equation to nonlinear algebraic one. The response of the deployable structures can be analyzed by iteration method. The numerical analysis by Runge-Kutta method for deployable structures is employed to validate the incremental harmonic balance (IHB) method. IHB method is used to analyze the stability of response for deployable structures when the exciting frequency changes, which is based on the nonlinear dynamic model. The stability of deployable structure response are presented in a frequency range when the clearance and stiffness of joint, exciting force and cable change. The IHB method can be used for multi-degree deployable structures to obtain the steady response and nonlinear dynamic characteristics, which provides a method for further research of the dynamics of jointed deployable structures.

A multibody dynamic model for helical planetary gear train (HPGT) is proposed and the dynamic performance of the HPGT system is analyzed. The free vibration characteristics, steady-state dynamic responses and effects of design parameters on system dynamics are investigated through numerical simulations. The free vibration of the HGPT is classified into 3 categories according to modal properties such as eigenvalue multiplies, modal coordinates of central components and coordinates ratios of planets. The classified vibration modes are demonstrated as axial translational and torsional mode (AT mode), radial translational and rotational mode (RR mode) and planet mode (P mode) followed by the characteristics of each category. The simulation results agree well with those of previous discrete model when neglecting the component flexibilities, which validates the correctness of the present multibody dynamic model. The steady-state dynamic responses indicate that the dynamic meshing forces fluctuate about the average static values and the time-varying meshing stiffness is one of the major excitations of the system. The parametric sensitivity analysis shows that floating sun gear and reducing circumferential error of planets are two effective solutions for vibration control of the HGPT.

As the tool of Hybrid Simulation(HS), Hybrid Testing System(HTS) is developing toward distributed and complex direction. It is difficulty for the beginners to understand the process of HS and for the researchers to focus on a particular field. Herein a basic HTS is studied. Firstly, Simulink simulation environment is introduced. Then, the basic principle of HS and the framework of HTS is elaborated, A HTS based on Simulink simulation environment is proposed, and some key problems in HS are discussed. Finally, HTS simulation and validation are carried out using a simplified loading system model and a real loading system respectively. The results indicate that the modules of the HTS can work together and it can easily implement hardware in the loop simulation.

Based on the finite element analysis program ANSYS, the three-dimension integral finite element model of pile-soil-LNG storage tank interaction system was established, the effect of considering the pile-soil interaction on the seismic performance of LNG storage tank was analyzed in the soft site of class IV. Analysis results show that the peak shear force, peak overturning moment and the maximal Von Mises equivalent stress for the inner steel wall of the LNG storage tank were reduced by different degrees, but the maximum sloshing wave height of the liquid was increased. In addition, the effect of different insulation layer stiffness on the seismic response of LNG storage tank was also analyzed, by contrast, the variation of insulation layer stiffness had important influence on the seismic response of LNG storage tank. With the increase of insulation layer stiffness in a certain range, the peak shear force, peak overturning moment and the maximum sloshing wave height have minor changes, but the maximal Von Mises equivalent stress for the inner steel wall was reduced significantly.

Based on wind tunnel tests of two square tall buildings, the characteristics of wind pressure spectra on the isolated and interfered building were investigated. Firstly experiments on a single square tall building in C terrain were carried out, then tests on the same building with 16 different locations and 3 different height ratios of an interfering building were conducted and wind pressures on the interfered building were obtained. In these foundations, the interference effects on wind pressure spectra of the typical taps of the interfered building were analyzed in frequency–domain with different spacing ratio and height ratio in tandem configurations. The results show that wind pressure spectra energy on the center line of the windward face of the isolated building is distributed over a wide frequency range; however, that near the edges on the face has sharp peaks. Energy at high reduced frequency near the trailing edges on the side face of the isolated building is significantly greater than that near the leading edges. The sharp peak amplitudes were dampened dramatically when the spacing ratio is small in tandem arrangements. The lower interfering building leads to larger energy at low reduced frequency, while the taller interfering building mainly affects the energy at high reduced frequency.

In order to study dynamic response characteristics and swing-arm fatigue strength of heavy hydraulic modular trailer, a rigid-flexible coupling multi-body dynamic model of trailer was established based on finite element analysis method and rigid-flexible multi-body dynamics theory. The model was simulated with excitation signal by road roughness and verified by vibration experiment results. Dynamic response simulation analysis of trailer was carried out with different operational conditions, as the road roughness and trailer speed. The stress time histories of swing-arm, which are necessary for fatigue analysis, were calculated by using finite element analysis method with dynamic load, as the results of multi-body dynamics simulation. Fatigue life of swing-arm were predicted based on local stress-strain analysis method. The calculation results show that, stress concentration positions of swing-arm appears at cross section of fracture failure location and stress level has entered into plastic state. With operational conditions of trailer on B grade, C grade and D grade roads, the fatigue life of risk points are greater than the service life of trailer. However, on sinusoidal uneven roads, the fatigue life of risk points decreases obviously with the augmentation of sinusoidal amplitude and trailer speed. Reasonable operating conditions, which could enhance trailer’s operation security and transportation efficiency, are proposed from swing-arm fatigue life simulation results.

According to the measurement of wheel profile by line test for high speed train, the contact geometry of new and worn wheel profiles S1002GCN with different wear mileages are studied .The relationship between contact angle difference and equivalent conicity of wheel/rail contact is analyzed, which provide a basis for stability study when wear profiles are difficulty to obtain. A high speed dynamic model is established and the stability of vehicle is analyzed with the new and the worn wheel profiles respectively. The results showed that: the relationship between the equivalent conicity and contact angle tend to a constant with wheel wear. Equivalent conicity, the longitudinal stiffness of the primary suspension affect the amplitude and the form of bifurcation. From the simulation results we can see that rail cant, track gauge and rail grinding have nonlinear relationship with the contact geometry between the worn wheel profile and rail.

An generalized inverse subsructuring method was develped for multi-component coupled system, the back-caculating formula for four-component coupled system was obtained as an example. Then, the mothod was verified by a lumped parameter model, the FRFs of the components and coupling stiffness were predicted by the system-level FRFs applying the developed method and compared with the given value, showing perfect agreement. The results indicated that the propsed method is effective to model the multi-component coupled system.

An approach based on the minimum amplitude of loaded transmission error, meshing impact force and acceleration of vibration with drive diagonal modified helical gears was proposed to reduce vibration and noise. Firstly, the modified tooth surfaces was represented by a sum of two vector functions that determined the theoretical tooth surface and the deviations surface, which was fitted by 3 B Spline based on tooth surface grid data established by the deviation curve. Secondly, with the tooth bearing deformation ascertained by TCA and LTCA, the meshing force and meshing stiffness were established according to the meshing impact theory. Finally, a dynamic model with a pair of helical gear was built, and used genetic algorithm to optimize the parameter of curve to get the best deviation surface. The results shows that the diagonal modified helical gears can greatly reduce the vibration and noise due to the positions changing and small loads under approaching meshing, as well as higher coincidence degree than other type modified gears.

There have periodic impulses in vibration signals of bearing, so a new method, so called time-wavelet energy spectrum entropy, is proposed for rolling element bearing fault diagnosis. Firstly, the impulse response wavelet is constructed to extract wavelet energy spectrum in time domain by using continuous wavelet transform, then energy spectrum entropy which represents vibration signals quantitatively change with time is calculated along the time axis, bearings with different faults have different variation complexity, and the entropy is different. To identify the fault pattern and condition of bearing, entropy of different fault signal could as input vectors of support vector machine. Practical examples showed the method can diagnose efficiently faults of rolling element bearings.

For the data-processing reliability problems in risk-assessment group decision-making, the importance of the expert weights for the data processing was proposed. From the industry characteristics of automotive crash safety research, based on expert social factors indicators, by using two analysis methods of system clustering and K-means clustering, clustered the experts according to expert-authority-weight; Based on the data consistency and the consistency degree of individual and group from expert opinions, by using the method based on information entropy, clustered the experts according to expert-opinion-weight; Two clustering results were compositely clustered to get the final weight of the experts. The results show that the expert weights got by the composite clustering have good proportionality and reliability, based on compositing expert-authority-weight and expert-opinion-weight, it lays a foundation for the study of systems projects.

Impact assessment test for large-medium sized shipboard equipment should be carried out through the floating shock platform, and the structure form of the floating shock platform can make the difference between a successful or unsuccessful test. But the IFSP (intermediate floating shock platform) has not been started the construction in China. So the structural design of IFSP is analyzed. The response of the IFSP is calculated through nonlinear doubly-asymptotic approximation. Several structure forms of the floating shock platform are put forward and their strength and shock environment are analyzed. The results show that the main response of the IFSP is the rigid body motion and the structure form of IFSP with box girder and outer plate dissection has the best strength. The spectrum displacement and spectrum velocity of shock environment provided from the inner bottom are consistent with the specification. The spectrum acceleration requires the filtering of deck simulator to meet with the specification. Analysis results are expected to be useful for the construction of IFSP for the impact assessment of large-medium sized shipboard equipment.

The establishment of scientific finite element mode for soil plays a pivotal role in simulating and analyzing the landing impact of space capsule. The LS-DYNA was used to simulate the landing process of space capsule, and the effect of main parameters in soil mode on impact characteristic was analyzed through orthogonal test. The results demonstrate that bulk modulus and parameter A2 significantly influence the maximum impact acceleration and pulse width, parameter A0 A1 and their interaction are not significant. These conclusions can provide some references to both the study on ground test in the landing process and the structural optimization of space capsule.

Particle jets driven by the central explosion determine the dispersal of particles in the blast flow. We tracked the dynamic fragmentation of sand shells with different saturation subject to the central explosion, and obtained the onset of jet formation and the characteristics of jets. The stretch and dissolution of particle jets can be studied by virtue of the analysis of the vibration acceleration of targets generated by the impact of jets. We found the interstitial fluid plays an important role in both formation and evolvement of particle jets.

A test rig is performed to measure power flow and estimate vibrational energy in this paper. Both force signal and acceleration signal of the same location and direction of one point could be simultaneously captured by inserting an impedance head. Subsequently, the power flowing into the foundation is calculated by the time average method, the fundamental frequency method and the second harmonic frequency method respectively. Experimental investigation shows that the harmonic vibration should be controlled, if the operating frequency of vibration source is the fractional frequency of natural frequency. However, due to the negative value which is inevitable during the measurement process of power flow, this study attempts to interpret the cause of the negative power flow from multi-degree of freedoms vibration. Due to the difficulty of measurement, the vibrational energy of the foundation is estimated via the driving impedance and mobility. Finally, the relationship between power flow and vibrational energy is examined by the loss factor.

Blades of turbomachine are important components to produce power like turbines or pressure compressors working in a complicated condition with high pressure, high temperature and three dimensional air flows as well. The aeroelastic problem like flutter may occur during different working states. Flow-induced vibration of the blade with the coupling of bending and torsion is investigated to reveal the mechanism of flutters. Averaging method and power flow approach are used to demonstrate the flutter behaviours of interaction between an isolated blade and the quasi-steady flow. The relation between amplitudes and the frequency of blades vibration is given to predict flutters, which is beneficial to aeroelastic designs of the turbomachine.

Due to the fact that the existing isolation theories and technologies have many defects to isolate multi-dimensional vibrations, they are unable to meet the needs of the isolation in practice engineering, in which the excitation and the environment maybe change frequently. A novel metamorphic parallel mechanism is presented as the main body of the multi-dimensional vibration isolation system, in which some springs and dampers are installed on the active joints. The presented mechanism has two configurations, or can change to 3-CRR mechanism or CRU-2CRR parallel one, just by adjusting the configurations of the rT joint. The kinematics and dynamics equations of the presented isolation system are deduced, and then the modes, dynamics characteristics and vibration isolation of the isolation platform are studied. The simulations show that the system has good vibration effect in both two configurations, and it can isolate two sets of multi-dimensional vibrations.

Based on finite rotation hypothesis, a rigid-flexible rotor dynamic model is developed. Comparing with classical finite element model, this model introduces three rigid degrees of freedom for hinge rotations coupled with blade elastic deformations and thus has potential advantages over the small rotation beam model. Generalized aerodynamic forces are tightly coupled with structural rigid rotations and elastic deformations. Structural loads are computed using three load calculation methods (force integration method, reaction force method, and curvature method) while equations of motions are solved on each step. The loads are examined by analysis results of BO105 model blade and flight test data of SA349/2 Gazelle helicopter. All load methods can handle the structural load calculation without aerodynamic forces applied. Force summation method loses some power at sections near the blade root especially when transient aerodynamic forces are taken into account. Results from curvature method and reaction force method are nearly the same at the nodes of finite element method. Accuracy of reaction force method depends on the response solutions and only shows efficient to predict loads at the nodes. Since curvature method simplify considers the bending and torsion deflections, it requires higher order shape functions to satisfy the continuity of second derivatives. To speed up convergence and decrease accumulated errors, extrapolation technique is introduced to implement numerical integration algorithm.