Simulation and analysis of all terrain vehicle ride comfort

A multi rigid body dynamic model of an all terrain vehicle (ATV) is established in MSC.ADAMS. The model takes into consideration the body, suspension, frame and the steering system. According to the method of superposition of harmonic wave, a Grade B road file is created in ADAMS for the riding comfort test. The engine excitation is analyzed. The infliction for engine excitation to ADAMS is achieved. The ATV ride comfort simulation is carried out with the excitation of the engine, and the seat vibration is evaluated using an evaluation method programmed via MATLAB. It has laid a good foundation for further analysis.     

simulation and improvement of an all terrain vehicle muffler

Aiming at a muffler of a 400 all terrain vehicle(ATV), a vibration model and an acoustics model of the muffler were built by finite element method(FEM). The vibration and acoustics characteristic analysis of the muffler are carried out according these models, it shows the 3D model is exact and it is possible to generate regeneration noise. Acoustics model can help to know further about the characteristic of each chamber and intention of the designer. According the demand of factory, some projects of improvement are offered. The final result of road test proves that he improved muffler is feasible.     

Objective Evaluation Methods for ATV Ride

To make up the vacancy of the evaluation methods for ATV ride in the world, the pratical feature of ride comfort of ATV are studied and analyzed. Based on the ISO2631 and ISO5349, the objective methods of ride com-fort of ATV are proposed. This method uses the total root mean square of weighed of three axles to evaluate the vibration of the handle and seat. Road tests and experiments on rolling drum experiment table with the test system on ride comfort of some typical ATVs are conducted, the result of the two tests are matched each other, so the evaluation method can well reflect the effects of the vibration on human body.     

Application of frequency shifting in truncating substructure low order normal modes

A method to cutoff substructure low order normal modes in component mode synthesis is proposed. Frequency shifting technique is introduced in substructure free vibration differential equation. Quasi-static constraint mode is taken into coordinate transformation and the contribution of substructure low order normal modes to system middle frequency modes is reduced,thus substructure low order normal modes truncation is achieved. This technique is used to compute dynamic characteristics of a body-in-white FEM mode in the frequency band of 160~190 Hz. The results show that compared with traditional component mode synthesis,which keeps 1 836 normal modes,this method only needs 297 normal modes and saves 27.7% calculation time. It means frequency shifting technique can improve the computational efficiency for middle frequency band dynamic characteristics of complex structure.     

Analysis of Vibration Experiment for Pedal-motor

Based on the analysis of experimental model, the vibrating experiment was made for the frame and engine of motorcycle in order to find the resonance frequency of the frame. Then the effect of engine exciting on the body vibration was analyzed, so that the mode frequency avoids the range of engine rotation speed. The experiment results show that the vibration of the saddle in vertical direction and the handlebar are caused by the resonance, while the vibrations of the other two directions of saddle and the pedal are the result of the transmission of engine energy. In order to decrease the transmission of the engine energy to pedals, we can change the stiff welding between the pedals and the frame of the motorcycle into the elastic link. Furthermore, to avoid the resonance of the frame in vertical direction, besides increase the stiffness of the frame, we can reduce the stiffness of the frame under the condition of having sufficient intensity, so that the nature frequency of the frame is reduced below the operating speed of the motorcycle engine.     

Dynamic Finite Element Model Updating of Prestressed Concrete Continuous Girder Bridge Based on Real-Coded Accelerating Genetic Algorithm

The dynamic finite element model (FEM) of a prestressed concrete continuous girder bridge (PCCGB), named Zhangjiagang river main bridge, was established and updated based on the results of field ambient modal testing using real-coded accelerating genetic algorithm (RAGA), which objective function was defined based on frequency index and correlation coefficient index for evaluating the updated FEM. The dynamic FEM of the bridge was updated based on seven experimental modal parameters. The prediction ability of the updated FEM were evaluated based on three experimental modal parameters. The updated results and prediction ability of updated FEMs indicated that they can reflect adequately the dynamic characteristics of actual PCCGB by using the above objective function and RAGA.     

Quantitative evaluation of all terrain vehicle mobile platform vibration

对3种气调保鲜箱贮藏环境的气体成分变化及对杨梅保鲜效果进行了研究.试验结果表明,在0℃冷藏条件下,使用气调保鲜箱杨梅适宜贮藏时间为20天,保鲜效果明显好于对照;气调箱-2效果最好.气调箱-2在贮藏6天时O2、CO2含量达到平衡;在贮藏12～15天时CO2含量达到峰值20.65%,O2含量接近2%,该环境条件有利于杨梅贮藏保鲜.     

Calculation on Natural Frequency and Main Vibration Mode of Double-lined Type Mounting System

The vibration characteristic of engine mounting system is analyzed, the vibration model of engine mounting system is established, and calculation method of natural frequency and main vibration mode of mounting system is put forward. Then an engine mounting system with double - lined type isolator is presented. Isolation performance of engine mounting system is improved greatly by selecting elastic coefficient of isolator reasonably.     

Structual Dynamic Characteristics Analysis and Improvement for Two-way Branch Exhaust Pipe Shield

The two-way branch exhaust pipe shield is the main source of surface radiate noise of a vehicle's engine.(Using) the finite element analysis software ANSYS,a finite element model of the shield is established,and then the(modal) analysis is done theoretically with this model,the result is consistent with the experiment.The result shows that this finite element model can be used for the next structual dynamic characteristics analysis.With this model,the relationship of structural parameter,structural style of the shield and the corresponding vibrative modal is analyzed.The(optimal) improved measures are adopted which is based on the practical structure of the shield.The analysis of the(improved) structure shows that the increase of natural vibration frequency is visible,the vibration noise of the shield is suppressed distinctly.     

机体弹性变形对主轴承润滑特性的影响

为揭示机体弹性变形对曲轴主轴承润滑特性的影响，在考虑整机体和曲轴弹性的条件下，建立发动机曲柄连杆机构多柔体动力学模型，耦合基于质量守恒边界条件的广义雷诺方程和Greenwood/Tripp接触模型，分析机体弹性变形对曲轴主轴承润滑特性的影响。结果表明：与刚性机体相比，计入机体弹性变形后，各主轴承的润滑特性随曲轴转角的变化趋势与将缸体处理为刚性时基本一致；润滑油平均端泄量和总摩擦功耗在一个工作循环内均变化较小；润滑油最小油膜厚度、最大油膜压力和轴承的最大粗糙接触压力在一个工作循环内的某些时刻变化明显。     

Testing and modal analysis on multi stage planetarygearbox housing of shield tunnelling machine

The finite element model is developed for the multi stage planetary gearbox housing in shield tunnelling machine (STM), and the the eigenvalue problem is solved by using block Lanczos method, and then the low order natural frequencies and corresponding modes are extracted. Based on the theory of experimental modal analysis, the modal testing is made for the gearbox housing by pulse excitation method. The least squares complex frequency domain (LSCF) estimation method is used to analyze the modal data, and the natural characteristics of housing is obtained. According to the modal assurance criterion (MAC), the experimental modal parameters are validated. Modal analysis shows that the experimental data is coincided with analytical results, which indicates the accuracy of the theoretical model and testing method. The coupling sympathetic vibration is disappearing between the gears train and housing, the local vibration is large at the high speed side of gearbox housing, and the torsional mode is outstanding under operating condition. The research results provide theoretical basis and experimental support for the structural optimization of the gearbox of STM.     

Multi-object Optimization Design of Engine Mounting System Parameters

A multi-object optimization model is proposed with respect to the completed vehicle in ergonomics,which takes the root-mean-square value of body in multiple work condition and the decoupled energy of engine mounting system as a general object. The optimization values is given. An example shows that the vibration of an automobile can be reduced effectively by choosing proper parameters of mounting system.Moreover, comfort of automobile can be improved.     

THE APPLICATION OF MULTIBODY DISCRETE METHOD IN RING''S VIBRATION ANALYSIS

A ring's muJtibody discrete model is discussed in this paper. The ring's plane geometric nonlinear vibration equations are derived. Compared with the finite element and lump mass methods, this method is better. In the last pa it of the paper, the eigenvalues, the first 9 modes of the ring, the geometric nonlinear dynamic responses of the ring are calculated.     

Junction stiffness analysis and vibration noise prediction of wind power speed-increase gearbox

In order to study the vibration characteristics and radiation noise of wind power speed-increase gearbox, a torsional vibration model of wind power speed-increase gearbox is established based on the analysis of supporting stiffness of bearing and contact stiffness of gear pairs. By solving the vibration differential equation with the help of Matlab, the frequency and corresponding vibration mode are obtained. With taking stiffness excitation, error exaction and meshing impact exaction into account, the dynamic finite element model of speed-increase gearbox is set up, and the dynamic response simulation is carried out. Regarding vibration displacement of the nodes on gearbox surface as boundary condition, an acoustic boundary element model of speed-increase gearbox is built. The surface acoustic pressure of gearbox and the radiation noise of field points are solved by the direct boundary element method. The results show that there is a great difference between torsion frequency and excitation frequency of wind power speed-increase gearbox, and so the resonance doesn't occur. The maximum structural noise and radiation noise mainly appear near the double octave of the gears meshing frequency of high-speed grade.     

Application of Magnetic Analysis in Magneto-rheological Damper Performance Estimation

As a kind of semi-active controllable devices,Magneto-rheological(MR) damper has been increasingly widely used in various occasions of vibration suppression.However,the design of MR damper greatly depends on the engineering experience of designers,it is difficult to calculate the performances relatively accurate.With the Finite Element Method,the authors carry out the magnetic analysis on the given geometry of MR damper combined with the Couette flow analysis of MR damper,the dynamic curve of MR damper is obtained.The results show that the FEM magnetic analysis effectively predicts the yield shear force and flow shear force,it is coincident with the experimental data.It is validated that the methods described is suitable for the MR damper performance estimation of the same geometry,and is an effective means for the MR damper design with the given force.     

风电齿轮箱传动误差分析及振动噪声预估

针对一级行星两级平行轴风电齿轮传动系统，综合考虑齿轮时变啮合刚度、啮合阻尼、传递误差等因素，建立31个自由度的弯扭轴耦合集中参数动力学模型，采用变步长Runge-Kutta法对系统动力学微分方程进行求解，得出齿轮传动系统各级传动误差；借助软件建立风电齿轮箱刚柔耦合动力学模型，并导入传动误差，采用模态叠加法求得齿轮箱轴承支反力，并将其作为声振耦合模型的边界条件，采用声学有限元法对风电齿轮箱进行振动噪声预估，并与试验结果对比分析，两者吻合良好。     

Numerical Prediction of Frequency of Delaminated Advanced Grid Stiffened plate

The paper aims to investigate natural frequency of delaminated advanced grid stiffened composite plates by hump resonance method.The composite laminated plate element and the rib element are adapted to simulate the laminated plate and the ribs.Based on the composite laminated plate and beam element model considering first-order shear effect,a damping model on the basis of Rayleigh damping model in conjunction with Adams' strain energy method(MSE) and a Hertz nonlinear dynamic contact model to avoid the overlap and penetration phenomenon between the upper and lower sub-laminates at the delaminated region.A numerical analysis method of dynamic response for the delaminated composite plates is carried out by precise time-integration method,and then the natural frequencies are achieved when the dynamic deflections reach the hump peak.For the frequency-domain analysis provided in the former research papers,it is a difficult problem to avoid the embedded phenomenon in the mode shapes at the delamination zone,while in the current time-domain analysis,the embedded phenomenon can be successfully overcome by using nonlinear contact model.By vibration excitation test,the specimens were excited by different excited frequency and the amplitude frequency response characteristics obtained are used to extract the frequency.The extracted frequencies of the narrow delaminated composite plates measured,which agrees well with the predicted natural frequencies.     

THE CALCULATION OF ALONGWIND RESPONSE FOR TALL BUILDINGS

This paper investigates the dynamic response of tall buildings subject toalongwind loading.According to the assumptions of the fundamental parame-ters,the function of the first vibration mode and that of the mass model,thecomputer program AWCTS is compiled.The availability of the procedure in thispaper is verified through practical calculations and comparison of results.     

Perturbation Analysis of Complex Modes for Vibration System with Viscous Damping and Its Application

The sensitivity characteristics of the undamped natural frequencies and complex mode shapes of vibration system with the non-proportional viscous damping with respect to structural mass, stiffness and damping modifications are analyzed in this paper using the matrix perturbation of complex modes. The general principles for the selectivity of the design and the most sensitive positions of the structural perturbation modifications are shown thereby. This is of importance to a great computational savings in the dynamic characteristic improvement of large or complex structures. By the dynamic characteristic sensitivity analysis of a test device type RDT-1,the optimal structural design for its especial requirement of dynamic characteristics is obtained easily and the principles presented in this paper are confirmed by the numerical results of perturbation analysis.     

Research on pitch cone design for beveloid gears with crossed axes

Based on the spatial gearing theory, the mathematical model for working pitch cone design of crossed beveloid gears is created. The formulas to determine the transition from point contact to line contact are derived. The direct and in direct methods for pitch cone design of crossed beveloid gears are proposed. The effects of gearing parameters on the angle between the first principle directions are analyzed. The loaded tooth contact analysis is performed using FEM theory. The conclusion indicates that: the angle between the first principle directions is more sensitive to cone angles than to the helix angle. The increase of the angle between the first principle directions can obtain smaller contact area, higher transmission error and lower mesh stiffness. A practical tooth bearing test is conducted to demonstrate the proposed design procedure and the experimental result compared well with the simulation. For the matching design and optimization of beveloid gears, it has both the theoretical and project practical significance.