【作者】 闫振华；

【导师】 王国强；

【作者基本信息】 吉林大学 ， 机械设计及理论， 2014， 博士

【摘要】 非公路车辆由于工作环境复杂、路面条件差及车辆动力传动系统振动等原因导致驾驶员承受严重的全身低频振动，这种振动导致多种职业病，对驾驶员身心造成伤害，不仅影响矿山和工程施工的生产效率，针对相关职业病的治疗也增加了社会成本。非公路车辆座椅是振动向驾驶员传递路径中的关键一环，与驾驶员直接大面积接触，座椅悬架对座椅的隔振性能起决定作用。本文结合国家自然科学基金项目（51175216），系统研究了非公路车辆座椅非线性悬架静态特性、位移传递率及次谐波响应特性、非公路车辆座椅-人系统动态特性，并创新设计了基于球面滚子机构的座椅非线性悬架，通过试验验证了该悬架的隔振性能。论文完成的主要工作如下：(1)座椅非线性悬架静态特性研究。基于能量守恒原理建立了非公路车辆座椅非线性悬架静态特性数学模型，并应用ADAMS软件进行了仿真验证，在此基础上分析了各主要设计参数对座椅非线性悬架静态特性的影响。同时，给出了非线性悬架静态特性简化数学公式。另外，通过分析典型线性隔振运动传递曲线及公式，提出刚度、阻尼之间相互匹配的依据。结果表明可通过合理匹配关键设计参数来实现悬架具有理想的零刚度、任意线性刚度、最小刚度为正值或零的非线性刚度特性，且可通过调整主弹簧预压缩量进而实现悬架隔振性能随驾驶员体重变化的调整。这对非公路车辆座椅悬架低频隔振性能改进具有十分重要的现实意义。(2)座椅非线性悬架位移传递率特性研究。基于谐波平衡法分别推导了最小刚度为正值和零的两种静态特性情况座椅非线性悬架位移传递率数学模型，并基于四阶龙格库塔法进行了数值求解验证，分析了各关键参数对座椅非线性悬架位移传递率特性的影响，同时，还将线性与非线性座椅悬架特性做了对比分析。结果表明通过合理的参数匹配可增宽非线性悬架的隔振频带甚至使整个位移传递率低于1；稳态振动位置偏离了静态平衡位置。这对设计出具有宽频带隔振特性非公路车辆座椅非线性悬架提供了参考。(3)座椅非线性悬架次谐波响应特性研究。基于多尺度法推导了非公路车辆座椅非线性悬架参数可工程实现条件下，单自由度振动模型时间域位移响应的二阶近似解析解，基于该近似解分析了次谐波响应的频率成分。此外，应用Matlab软件针对该单自由度振动模型进行了数值求解，获得了时间域位移响应曲线，并针对该曲线进行了FFT变换，研究其频率成分。结果表明，在座椅非线性悬架参数可工程实现条件下，响应中主要成分为主谐波响应，次谐波响应成分几乎为零。(4)非公路车辆座椅-人系统动态特性研究。基于拉格朗日方程建立了8自由度非公路车辆座椅-人系统动力学模型，同时，建立了简谐激励、多频率组合激励、随机激励和冲击激励4种激励模型，进而将各激励模型分别与座椅-人系统动力学模型耦合，并应用四阶龙格库塔法进行数值求解，基于此研究了非公路车辆座椅-人系统动态特性。结果表明悬架刚度、阻尼特性相比座椅其他参数而言，对座椅-人系统动态特性的影响最显著。这对非公路车辆座椅-人系统参数匹配设计奠定了基础。(5)基于球面滚子机构的座椅非线性悬架、非线性隔振器的创新设计及试验。创新设计了两种非公路车辆座椅非线性悬架和座椅悬架用非线性隔振器，并制造、装配了物理样机，以及进行了准静态试验和振动试验。试验结果验证了本文理论的正确性。论文提出的非线性座椅悬架设计理论及基于球面滚子机构的新型隔振悬架，对减少振动向驾驶员的传递，提高非公路车辆振动舒适性具有重要意义。更多还原

【Abstract】 Off-road vehicles work in mines, construction sites and other harsh environments.Due to the poor road surface, complex working conditions and the driveline vibrationof vehicle itself and so on, the drivers suffer severe whole-body low-frequencyvibration.This can lead to a variety of occupational diseases, such as cervical vertebraaches, low back pain, etc., which will harm the drivers’ physical and mental, and evencan cause the driver to lose the ability to work, and then result in the productionefficiency decline in mining and construction sites. Thus it will seriously affect theeconomic benefit both in mining and construction sites. In addition, the treatments forthe above-mentioned related diseases can also cause huge economic losses. Therefore,it is very urgent to carry out researches on the vibration comfort for off-road vehicles.Off-road vehicle’s seat is a key link on the vibration transmission path, which directlycontacts with the driver in a large area, and changing seat parameters appropriately,has little effect on vehicle’s performance. Therefore, the study on the off-roadvehicle’s seat has attracted more attentions of researchers. Suspension is the majorcomponent of off-road vehicle’s seat and plays a decisive role on the vibrationcomfort of seat. Mostly existing seat suspensions are designed based on the theory oflinear vibration isolation, while isolation effect for the theory of linear vibration isrelative poorer for the low-frequency vibration. Therefore, the nonlinear theory isintroduced to study the characteristics for the off-road vehicle’s seat suspension in thispaper. The paper is completed supported by the National Natural Science Fund Project(51175216). The static characteristics, displacement transmissibility, sub harmonicresponse characteristic of off-road vehicle’s seat and dynamic characteristic ofoff-road vehicle’s seat-man system are studied systematically in the paper. Also, theseat nonlinear suspension is innovative designed based on the theories of this paper.Then the static characteristic test and vibration isolation performance test are carriedout. The main work and conclusions of this paper are as follows:(1) Static characteristic of seat nonlinear suspension. The mathematic model ofstatic characteristic of nonlinear suspension of off-road vehicle’s seat is establishedand verified by the simulation using the ADAMS software. And then the impacts of main design parameters of the nonlinear suspension on the static characteristic arediscussed using the mathematic model. It is found that the desired zero stiffnesscharacteristic, arbitrary linear stiffness, and nonlinear stiffness characteristic with thezero or positive minimal stiffness can be achieved through reasonably matching thekey design parameters. And the suspension vibration isolation performance can makeadjustment with the driver weight by changing the pre-compression of the main spring.The simplified mathematic formula for static characteristic of the nonlinearsuspension of off-road vehicle’s seat is provided, and the basis of mutual matchingbetween stiffness and damping is proposed by analysis.(2) Displacement transmissibility characteristic of seat nonlinear suspension.Mathematic models of displacement transmissibility characteristic of the seatnonlinear suspension of off-road vehicle, which the minimum stiffness is zero andpositive, are derived based on harmonic balance method. And the numericalverification is made by fourth-order Runge-Kutta method. Then the impacts of keydesign parameters on the displacement transmissibility of seat nonlinear suspensionare analyzed. It is found that the vibration isolation frequency band of nonlinearsuspension can be widened through rational matching key parameters and even theentire displacement transmissibility can be less than1. In addition, it is found that thesteady vibration position deviate from the equilibrium position, the comparison andanalysis on the characteristics between linear and nonlinear seat suspension is carriedout.(3) Sub harmonic response characteristic analysis on seat nonlinear suspension.The second-order approximate analytical solution of time domain displacementresponse of single degree of freedom vibration model of seat nonlinear suspension ofoff-road vehicle is derived based on multi-scale method. And the frequencycomponents of sub harmonic response is analyzed based on the approximateanalytical solution. In addition, the numerical solution is conducted using MATLABsoftware and the time domain displacement response curves are obtained. Then thefrequency components are analyzed using FFT method on the time domain curve.Research results show that the displacement response mainly consists of harmonicresponse, and the proportion of sub harmonic component is nearly zero in theachievable parameters for the seat nonlinear suspension.(4) Dynamic characteristic of off-road vehicle seat-man system. In the paper,8 degrees of freedom dynamic model of off-road vehicle seat-man system is established,and the harmonic excitation, multi-frequency combination excitation, randomexcitation and impact excitation are modeled. The seat-man dynamic model and theexcitation model are coupled and solved using the fourth-order Runge-Kutta method,then the dynamic characteristics of off-road vehicle seat-man system is discussed.Analysis results show that the stiffness and damping of seat have serious impact onthe dynamic characteristics of the seat-man system compared with other seatparameters.(5) Innovative design and test of seat nonlinear suspension and nonlinearvibration isolator. Two nonlinear suspension of off-road vehicle seat and a nonlinearvibration isolator are innovative designed in the paper. Test content includequasi-static test and vibration test. Test results indicate that the theory provided in thepaper is correct.Design theory and new suspension proposed by this paper are important toreduce the transmission of vibration to the driver, and to improve off-road vehiclevibrition comfort.更多还原