Influence of central buckle on suspension bridge dynamic characteristics and driving comfort

The central buckle, which is often used in a suspension bridge, can improve bridges' performance in the actual operation condition. The influence of the central buckle on natural vibration characteristics and bridge-deck driving comfort of a long-span suspension bridge is studied by using a case study of Siduhe Suspension Bridge in China. Based on the finite element software ANSYS and independently complied program, the influence of the central buckle on the structure force-applied characteristics of a long-span suspension bridge has been explored. The results show that the huge increases of natural frequencies can result in the presence of central buckles because of the increases of bending and torsional rigidities. The central buckle basically makes the stiffening girders and cables within the triangular area covered as a relatively approximate rigid area. Hence, the central buckle can reduce the torsional displacement of the main girder. However, the increases of bending and torsional rigidities have little influence on the impact factor, which is obtained by using vehicle-bridge coupled vibration analysis. This means that the central buckle has little effect on the comfort indices. In addition, it is found that the central buckle can enhance the bridge deck's driving stability due to the decrease of the torsional displacements of the main girder.

Comparable study on typhoon and strong northern wind characteristics of the Runyang Suspension Bridge based on field tests

The strong wind characteristics of the Runyang Suspension Bridge（ RSB） including the wind speed and direction, the turbulence intensity, the turbulence integral length and power spectrum are analyzed based on measurement data from the wind environment monitoring subsystem of the structural health monitoring system （SHMS）of the RSB and field tests during strong winds. The differences between the typhoon and the strong northern wind are especially studied. It is found that the mean wind speed of the strong northern wind is a little smaller and the mean wind direction is more stable than that of the typhoon. The turbulence intensity of both the typhoon and the strong northern wind is greater than the values suggested in Chinese code, and the turbulence integral length difference between the typhoon and a strong northern wind is not clear. As for the along-wind turbulence power spectrum, the spectrum of the strong northern wind can fit the Kaimal spectrum better than that of the typhoon. The obtained results can provide measurement data for founding a strong wind characteristic database and determining the strong wind characteristic parameter values of the RSB.

Kinematic characterization and optimization of vehicle front-suspension design based on ADAMS

To improve the suspension performance and steering stability of light vehicles, we built a kinematic simulation model of a whole independent double-wishbone suspension system by using ADAMS software, created random excitations of the test platforms of respectively the left and the right wheels according to actual running conditions of a vehicle, and explored the changing patterns of the kinematic characteristic parameters in the process of suspension motion. The irrationality of the suspension guiding mechanism design was pointed out through simulation and analysis, and the existent problems of the guiding mechanism were optimized and calculated. The results show that all the front-wheel alignment parameters, including the camber, the toe, the caster and the inclination, only slightly change within corresponding allowable ranges in design before and after optimization. The optimization reduces the variation of the wheel-center distance from 47.01 mm to a change of 8.28 mm within the allowable range of ?10 mm to 10 mm, promising an improvement of the vehicle steering stability. The optimization also confines the front-wheel sideways slippage to a much smaller change of 2.23 mm; this helps to greatly reduce the wear of tires and assure the straight running stability of the vehicle.

悬架KC特性对车辆极限工况稳定性的影响研究

汽车在极限工况下的稳定性是衡量汽车性能的重要指标之一。尽管现代电子控制系统在提升车辆极限工况稳定性方面发挥着重要作用,但悬架运动学及动力学(KC)特性作为车辆机械结构的基础性能,对于确保车辆在各种极限条件下的稳定性依然至关重要。文章研究了悬架KC特性对车辆极限工况稳定性的影响。首先,进行了极限工况稳定性评价方法的研究;其次,以某乘用车为例,通过建立车辆动力学模型,并运用灵敏度分析方法,分析了不同悬架KC特性对车辆极限工况稳定性不同指标的影响;最后,对该车型的极限工况稳定性进行了优化,并取得了较好的效果。文章的研究成果可以提升车辆开发效率,为汽车极限工况稳定性的开发、评价等提供支撑,并为汽车底盘设计和调校提供重要的理论依据和实践指导。

The influence of charge characteristics of suspension droplets on the ion flow field in different temperatures and humidity

In order to clarify the charging characteristics of suspension droplets in ion flow field under different temperatures and humidity,the effective charging factor used to characterize the charging characteristics of suspension droplets is introduced in this paper,and a calculation method of charging factor is proposed based on the upstream finite element method(FEM).Then,the charging factor under different temperatures and humidity is calculated,and the analytic expression of the charging factor considering the influence of temperature and humidity is obtained by fitting the calculation results.The influence of suspension droplets on the ion flow field is analyzed.The results show that the charging factor is small and increases little with the relative humidity when the relative humidity is less than 60%,and the charging factor is large and increases rapidly with the relative humidity when the relative humidity is more than 60%.At the same relative humidity,the charging factor increases linearly with the temperature.The influence of charged suspension droplets on the ion flow field can be ignored when the relative humidity is less than 60%and must be considered under high temperature and humidity.The calculation method and analytic expression of the charging factor proposed in this paper can be used to model of ion flow field considering the influence of temperature and humidity and provide technical support for the construction of HVDC transmission lines across high temperature and humidity.

Dynamic Characteristics of Long -Span Steel -Concrete CompositeBeam Bridge Based on Vehicle -Bridge Coupling Effect

In order to investigate the effect of vehicle-bridge coupling on the dynamic characteristics of the bridge,a steel-concrete composite beam suspension bridge is taken as the research object,and a three-dimensional spatial model of the bridge and a biaxial vehicle model of the vehicle are established,and then a vehicle-bridge coupling vibration system is constructed on the basis of the Nemak-βmethod,and the impact coefficients of each part of the bridge are obtained under different bridge deck unevenness and vehicle speed.The simulation results show that the bridge deck unevenness has the greatest influence on the vibration response of the bridge,and the bridge impact coefficient increases along with the increase in the level of bridge deck unevenness,and the impact coefficient of the main longitudinal girder and the secondary longitudinal girder achieves the maximum value when the level 4 unevenness is 0.328 and 0.314,respectively;when the vehicle speed is increased,the vibration response of the bridge increases and then decreases,and the impact coefficient of the bridge in the middle of the bridge at a speed of 60 km/h achieves the maximum value of 0.192.

Basic Problems in Design and Inverse Engineering Solution for Outer Characteristic of Vehicle Suspension Shock Absorbers

Based on the theory and the practical experiences of linearity design of feasible design area and inverse solution of non linear outer characteristic of suspension shock absorber, in accordance with non linearity outer characteristic formed by open up damping coefficient, full open damping coefficient and smoothness to safety ratio of suspension shock absorber, a method and a research conclusion of the feasible design and inverse solution for the basic problems of designing and inverse solution of non linear outer characteristic of suspension damping components are provided.

Research on dynamic characteristics model test scheme for middle pylon of multi-pylon multi-span suspension bridges

Multi-pylon multi-span suspension bridge is a new type super flexible structure system, and the rigidity design of middle pylon is one of the main difficult technical issues. Due to the requirements of longitudinal rigidity, the structural form and the corresponding foundation type of middle pylon are different from those of the ordinary steel pylon, and the complicated dynamic characteristics make the calculation quite difficult. In this article, exploration has been made in selection of similarity ratio and model materials, section simulation, restriction conditions simulation, fixing of mass blocks, fabrication scheme and testing method by taking into account different construction and working conditions such as restriction conditions and working environment of a three-pylon suspension bridge, to conduct the test experimental design of the dynamic behavior of the middle pylon, with the purpose to reveal its dynamic characteristics and make comparison and analysis with theoretical assumptions, to provide basis for anti-wind and anti-seismic design and reference for the design and research of three-pylon two-span suspension bridges in the future.

适应H9亚型禽流感病毒增殖的MDCK悬浮细胞株的驯化及其生物学特性

本研究通过筛选驯化的MDCK细胞获得无血清悬浮生长MDCK细胞(命名为MDCK-sus),测定该细胞的比生长速率、细胞活力及细胞最大生长密度等生长特性,采用间接免疫荧光法和流式细胞仪检测法比较母本MDCK细胞与MDCK-sus细胞流感病毒受体[唾液酸-α-2,3-半乳糖糖链受体(SAα2,3Gal)和唾液酸-α-2,6-半乳糖糖链受体(SAα2,6Gal)]的丰度,用荧光定量PCR检测比较细胞中α-2,3唾液酸转移酶(ST3Gals)基因与α-2,6唾液酸转移酶(ST6Gals)基因表达水平的差异,通过测定流感病毒血凝HA效价比较母本MDCK细胞与MDCK-sus细胞对流感病毒的增殖能力。结果表明,经驯化获得的适合无血清悬浮培养的MDCK-sus细胞,细胞密度最高可达1ml 3.6×106个细胞,最大比生长速率可达1 d 0.56。MDCK-sus细胞表面流感病毒受体SAα2,3Gal的丰度明显高于母体MDCK细胞,ST3Gal转移酶基因表达水平也明显高于母本MDCK细胞。MDCK细胞驯化后增殖禽流感病毒的能力增强,其中H9亚型禽流感病毒AH1102株在MDCK-sus细胞中HA效价达到9lg2(25μl)。MDCK-sus细胞各种生长特性表明,其适于H9亚型禽流感的繁殖,可以为采用悬浮细胞培养禽流感疫苗的大规模工业化生产提供技术支持。

悬架K&C特性在底盘性能分析中的研究

归纳出影响车辆转向特性的各种因素,并用悬架K&C参数定量化;提出车辆在常用车速直线行驶时期其前束角和外倾角应尽量为零,以保证轮胎磨损尽量小,并建立了行驶时前束角及外倾角的表达式;将各向力作用下的变形统一为悬架及轮胎刚度,并分析了各种刚度的意义;通过悬架K&C特性计算出动力学参数,建立了研究操纵稳定性及底盘电控的虚拟车辆,并在Carsim和ADAMS软件中实现。

基于CarSim与Isight的悬架K特性优化设计方法研究

汽车前悬架对汽车操纵稳定性至关重要,因此前悬架应具有良好的运动学特性(K特性)。针对悬架系统K特性优化设计问题,以某轿车前悬架为例研究了基于Car Sim与Isight的悬架K特性优化设计方法。论文给出了优化设计原理,选取K特性优化曲线并进行了合理拟合处理。根据所确定的优化目标对优化参数进行了灵敏度分析,采用多岛遗传算法对参数进行了优化,并通过蛇形工况仿真试验对优化设计方法进行了验证。结果表明:基于Car Sim与Isight的悬架K特性优化设计方法提高了汽车的操纵稳定性。

客车空气悬架的建模与K&C特性分析

根据某新型大客车的设计要求,运用刚柔耦合的建模方法对客车关键部件进行了柔性处理,建立了前悬架的刚柔耦合的Adams多体动力学模型,并对悬架系统进行了动力学仿真分析。结合理论分析得出该悬架的K&C(Kinematics&Compliance)特性相关数据,以及悬架在运动过程中的参数变化范围,为后期的调校和生产提供了可靠的理论数据。

基于ADAMS的双横臂式前悬架K&C特性的仿真分析

悬架的K&C特性直接影响操纵稳定性等汽车使用性能,文章利用软件ADAMS/CAR模块建立某开发车型的双横臂式前悬架多体动力学模型,通过对车轮分别施加位移和力约束进行悬架运动学分析和弹性运动学分析,从而获得车轮定位参数在2种特性下的变化,为该车前悬架及整车性能的改进提供指导依据。

汽车悬架K&C特性参数相关性分析

针对大量实际产品车型的K&C实测数据进行相关性分析,利用因子分析及主成分分析方法对其进行深度解读,从而更加清晰地展示各特性参数背后的影响因子,以及在不同悬架形式时共同因子对各参数的影响程度。研究结果表明,应该根据悬架形式选择不同参数进行目标设定,并根据参数间的相关程度进行范围调整,避免由此带来的潜在优化冲突。此方法可用来指导悬架的早期参数设计。

五连杆非独立后悬架K&C特性仿真研究

利用多体动力学仿真试验技术,发现某SUV后悬架横向刚度偏低容易产生过度转向趋势的问题。针对该后悬架各硬点改变进行运动学仿真研究,将下拉杆前点降低30mm、上拉杆外移130mm及上拉杆后点提高30mm,可以弥补原车过度转向的问题,仿真结果提高了整车的操纵稳定性。通过对原车和改进后车辆进行操纵稳定性主观评价,结果是改进后车辆操纵稳定性得到很大改进,与仿真结果趋势一致,也验证了模型的正确性。该方法可以为新车悬架性能调校提供理论基础。

某微型汽车的麦弗逊前悬架K&C特性仿真分析

利用多体动力学分析软件adams/car,建立了麦弗逊前悬架虚拟样机仿真模型。采用轮跳和静载侧向力加载的方法,对汽车在弯道行驶过程中的K&C特性及其对整车稳态转向特性的影响展开分析研究。仿真结果表明,该模型具有较好的不足转向特性,为预测整车稳态转向特性提供了仿真与理论依据。

汽车悬架K&C特性优化设计

以麦弗逊悬架为载体,通过制定衬套及减振器试验方案进行台架试验,将衬套刚度及减振器阻尼特性赋予悬架模型,探究影响汽车悬架性能的悬架自身结构参数。针对悬架性能中的不足,对悬架K&C性能的影响因素(关键硬点位置和衬套刚度)进行灵敏度分析,探索有效的优化方法进行优化设计。通过对比优化前后的试验结果,验证了该优化设计方法的可靠性,初步形成一套完善的悬架系统优化设计体系,为研究整车与悬架的匹配关系,实现悬架高水平开发提供参考。

某SUV双横臂独立前悬架K&C特性研究

利用多体动力学仿真试验技术,研究了某引进车型SUV双横臂独立前悬架K&C运动学特性。从理论上验证了该悬架结构的设计合理性,为国内自主品牌双横臂独立前悬架的设计提供理论和工程指导。

引入悬架K&C特性参数的汽车操纵稳定性数学模型

基于经典操纵稳定性二自由度线性数学模型研究方法,通过力学分析建立了包含悬架K&C特性参数的汽车操纵稳定性线性数学模型,并建立其MATLAB模型。将经典操纵稳定性二自由度数学模型和引入悬架K&C特性参数的操纵稳定性数学模型对整车不足转向度及横摆角速度的影响进行对比分析,研究悬架K&C特性参数与操纵稳定性的关系。依据三种小型SUV的悬架K&C数据及整车阶跃试验数据,对两种操纵稳定性数学模型进行计算,并与试验结果进行了对比,验证了引入悬架K&C特性参数的操纵稳定性数学模型的准确性。

基于改进响应面模型的悬架K&C特性优化

悬架运动学和弹性运动学特性是影响操纵稳定性的重要因素。为提高操纵稳定性,基于ADAMS/Car建立某车型前麦弗逊悬架模型,并进行K&C特性仿真分析。在ADAMS/Insight中计算硬点坐标对K&C特性的灵敏度。利用切比雪夫多项式零点插值技术改进响应面模型,并采用该模型描述悬架K&C特性变动范围与硬点坐标之间的关系,针对该模型采用双层嵌套的改进非支配排序遗传算法和粒子群算法进行多目标优化,结果表明,优化后的悬架K&C特性的变动范围均有不同程度的减小,汽车操纵稳定性得到了提高。