On the Design and Development of a Magneto-Rheological Mount

This paper evaluates the performance of a Magneto-Rheological (MR) mount. The mount incorporates MR fluid in a conventional fluid mount to open and close an inertia track between the fluid chambers of the mount. It is shown that such switching of the inertia track improves the mount's isolation effect by eliminating the large transmissibility peak that commonly exists at frequencies larger than the notch frequency for conventional fluid mounts. The switching frequencies of the MR mount are evaluated based on the parameters of the mount. A simple control scheme for switching the mount between the open and closed states is proposed, and the performance of the controlled mount is compared with conventional mounts. A sensitivity analysis is conducted to evaluate the effect of parameter errors in estimating the switching frequencies and mount performance. The results show that the switching frequencies can be accurately determined from mount parameters that are easily measured or estimated.     

Application of Sensitivity Analysis to the Development of High Performance Adaptive Hydraulic Engine Mounts

Summary In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a global optimization technique is used to find the magnitude of the adjusting parameters to minimize objective functions in low and high frequency excitations. The results indicate significant improvement over conventional hydraulic mounts. It is further shown that when the upper compliance is used as the adjusting parameter, a simple on-off control which is triggered by the engine revolution and vehicle speed is sufficient for tuning the adaptive mount.     

Application of Sensitivity Analysis to the Development of High Performance Adaptive Hydraulic Engine Mounts

Summary In this paper, the sensitivity analysis is applied to the development of high performance adaptive hydraulic mounts. The analysis allows us to select the most effective design parameters for tuning an adaptive mount to different road and engine conditions. It is shown that in the low frequency road excitation, the upper chamber compliance and inertia of the fluid column in the inertia track are the most influential properties in changing the dynamic stiffness of the hydraulic mount. These properties for the high frequency engine excitations are the upper compliance and the inertia of the fluid column of the decoupler. For tuning the adaptive mount to different road and engine excitation, a global optimization technique is used to find the magnitude of the adjusting parameters to minimize objective functions in low and high frequency excitations. The results indicate significant improvement over conventional hydraulic mounts. It is further shown that when the upper compliance is used as the adjusting parameter, a simple on-off control which is triggered by the engine revolution and vehicle speed is sufficient for tuning the adaptive mount.     

液压悬置动特性实验分析及模型修正方法研究

在综合分析现有悬置非线性数学模型的基础上,重点分析了惯性通道弯管损失系数对悬置动态性能的影响,建立了包含惯性通道弯管损失系数的更精确的数学模型,并探讨了悬置及橡胶主簧动态、静态特性的试验测试方法,建立了相应的测试平台,对相同工况下液压悬置和橡胶主簧动、静态特性进行了测试及对比分析。将橡胶主簧的实验数据应用于所建的模型中,仿真结果和实验分析表明本模型具有更高的精度。     

Semi-active engine mount design using auxiliary magneto-rheological fluid compliance chamber

Engine mounts are used in the automotive industry to isolate engine and chassis by reducing the noise and vibration imposed from one to the other. This paper describes modelling, simulation and design of a semi-active engine mount that is designed specifically to address the complicated vibration pattern of variable displacement engines (VDE). The ideal isolation for VDE requires the stiffness to be switchable upon cylinder activation/deactivation operating modes. In order to have a modular design, the same hydraulic engine mount components are maintained and a novel auxiliary magneto-rheological (MR) fluid chamber is developed and retrofitted inside the pumping chamber. The new compliance chamber is a controllable pressure regulator, which can effectively alter the dynamic performance of the mount. Switching between different modes happens by turning the electrical current to the MR chamber magnetic coil on and off. A model has been developed for the passive hydraulic mount and then it is extended to include the MR auxiliary chamber as well. A proof-of-concept prototype of the design has been fabricated which validates the mathematical model. The results demonstrate unique capability of the developed semi-active mount to be used for VDE application.     

惯性通道—解耦膜式液压悬置动特性分析

本文以Ａｕｄｉ１００轿车总成液压悬罩为例，建立了惯性通道－解耦膜式液压悬的非线；力的非线性力学模型和数学模型，对其原点动特性和跨点动特性进行仿真计算，经与试验结果相比较，二者吻合良好。     

Optimal design of an engine mount using an enhanced genetic algorithm with simplex method

This study provides an analysis of the applications of optimization routines for designing fluid mounts. After summarizing the concept of fluid mounts and their dynamic characteristics, we review the importance of the notch and resonance peak that occur in dynamic stiffness of fluid mounts. Fluid mounts are tuned for specific application so that their notch frequency coincides with the disturbance frequency, by selecting the proper parameters for the mount. Additionally, the mount parameters are selected such that the notch remains as deep (close to zero) as possible and the resonance peak is kept as short as possible. The notch depth and resonance peak present opposing requirements for the selection of mount parameters in the sense that lowering one will result in increasing the other. Using a bond graph model, this study will evaluate the effect of various parameters on the mount notch depth and resonance peak height characteristics. The results show that different parameters can have a varying effect on the notch frequency and depth, as well as the resonance frequency and peak height. The results of the study are extended by examining the effectiveness of two different optimization methods—namely, the Enhanced Genetic Algorithm (EGA) and Sequential Quadratic Programming (SQP)—for selecting the combination of parameters that can yield the deepest notch and shortest resonance peak. Using two different design cases, the study shows that SQP exhibits much more sensitivity to the initial conditions that are selected for the mount parameters than EGA. Both methods, however, are able to converge to an optimal solution within the constraints that are selected for the parameters. For both cases, EGA is able to converge to the set of parameters that provide a deep notch and a short resonance peak.     

Dynamic and Vibration Analysis of a Vehicle Rear Axle System

A detailed finite element model for the rear axle system of a sport utility vehicle is developed in this investigation. The axle system is treated as a multibody system that consists of nine bodies that include the input shaft, two output shafts, the carrier and tube system, four control arms and a track bar. The rotating input and output shafts are mounted on the carrier and tube system using six bearings. The four control arms and the track bar are connected to the carrier system and the frame of the vehicle using rubber bushings. In the model developed in this investigation, three dimensional beam elements are used to develop the finite element model for the input and output axle shafts, the control arms, and the track bar. A non-conventional finite element formulation is used to develop the equations of motion of the rotating input and output shafts in order to account for the effect of their angular velocities. These equations are expressed in terms of inertia shape integrals that depend on the assumed displacement field. The inertia shape integrals are first evaluated for each finite element. The inertia shape integrals of the rotating shafts are obtained by assembling the inertia shape integrals of its finite elements using a standard finite element assembly procedure. A conventional finite element formulation is used for the control arms and the track bar. The model developed in this investigation includes the effect of the bearing stiffness, the effect of the stiffness of the helical springs of the suspension system, and the effect of the stiffness of the tires. Using the Lagrangian dynamics and the finite element method, the equations of motion of the axle system are developed and expressed in terms of the nodal coordinates of the shafts, the control arms and the track bar as well as the degrees of freedom of the carrier. This finite dimensional model is used to determine the mode shapes and the natural frequencies of the axle system. The discrepancies between several of the natural frequencies predicted using the dynamic model developed in this investigation and natural frequencies determined experimentally are found to be less than 2%. A parametric study is performed in order to investigate the effect of the axle system parameters on the natural frequencies and mode shapes. Using the modal transformation, a set of differential equations of motion of the axle system is developed and used to examine the system dynamics under given loading conditions. The solutions of the resulting equations of motion are obtained using numerical methods.     

Dynamic and Vibration Analysis of a Vehicle Rear Axle System

A detailed finite element model for the rear axle system of a sport utility vehicle is developed in this investigation. The axle system is treated as a multibody system that consists of nine bodies that include the input shaft, two output shafts, the carrier and tube system, four control arms and a track bar. The rotating input and output shafts are mounted on the carrier and tube system using six bearings. The four control arms and the track bar are connected to the carrier system and the frame of the vehicle using rubber bushings. In the model developed in this investigation, three dimensional beam elements are used to develop the finite element model for the input and output axle shafts, the control arms, and the track bar. A non-conventional finite element formulation is used to develop the equations of motion of the rotating input and output shafts in order to account for the effect of their angular velocities. These equations are expressed in terms of inertia shape integrals that depend on the assumed displacement field. The inertia shape integrals are first evaluated for each finite element. The inertia shape integrals of the rotating shafts are obtained by assembling the inertia shape integrals of its finite elements using a standard finite element assembly procedure. A conventional finite element formulation is used for the control arms and the track bar. The model developed in this investigation includes the effect of the bearing stiffness, the effect of the stiffness of the helical springs of the suspension system, and the effect of the stiffness of the tires. Using the Lagrangian dynamics and the finite element method, the equations of motion of the axle system are developed and expressed in terms of the nodal coordinates of the shafts, the control arms and the track bar as well as the degrees of freedom of the carrier. This finite dimensional model is used to determine the mode shapes and the natural frequencies of the axle system. The discrepancies between several of the natural frequencies predicted using the dynamic model developed in this investigation and natural frequencies determined experimentally are found to be less than 2%. A parametric study is performed in order to investigate the effect of the axle system parameters on the natural frequencies and mode shapes. Using the modal transformation, a set of differential equations of motion of the axle system is developed and used to examine the system dynamics under given loading conditions. The solutions of the resulting equations of motion are obtained using numerical methods.     

半主动控制惯性通道式液力悬置开发

介绍了一种惯性通道半主动控制式液力悬置的设计开发。该液力悬置不改变橡胶主簧刚度和液体黏度,随发动机转速变化,由步进电机控制旋转阀的旋转角度,改变惯性通道的工作段(各段具有不同的长度),从而改变液力悬置的动态特性,使发动机—悬置系统的振动传递率最小。装车试验表明,所设计悬置具有较好的宽频带减振隔振性能。     

汽车动力总成液阻型橡胶隔振器的研究发展

本文对被动式液阻型橡胶悬置及动力总成－液阻悬置系统的设计分析方法和研究成果进行了较系统的述评和总结。首先介绍了汽车动力总成液阻悬置的应用概况，总结，阐述了汽车动力总成悬置系统所要求的理想隔振特性，然后综述了节流孔型，惯性通道型，惯性通道－固定解耦膜型，惯性通道－活动解耦膜型等典型被动式液阻悬置元件的结构原理，集中参数模型，动态特性及其参数设计分析结果，同时综述了动力总成－液阻悬置系统隔振生能研究概况及设计分析方法，其中着重介绍了德国Freudenberg公司，美国Ohio州立大学，日本Nissan公司等主要研究者的研究工作及结果。     

Impact technique for measuring global dynamic stiffness of engine mounts

Engine mounts are used for engine vibration isolation. The dynamic performance of the mount depends on the orientation. Measurements of the dynamic properties of engine mounts are usually performed in the axial direction because of the problem related to actuator loading direction and set up costs. Impact technique is developed here to measure the dynamic driving point stiffness and driving point shear stiffness of engine mount in a single setup. The compressive and shear frequency-dependent stiffnesses are obtained in the vertical orientation. A transformation matrix is used to calculate the frequency-dependent stiffnesses and loss factors in other orientations. Three different designs of engine mounts are used to verify the accuracy of the transformation model. The correlation coefficient between calculation and measurement results show R²≥ 0.995 along the X- and Y-axes. For the Z-axis, mounts B and C showed R²≥ 0.95 and mount A 0.687 ≤ R²≤ 0.791.     

基于流固耦合有限元法的汽车发动机液力悬置动力学分析

介绍了车载发动机液力悬置流固耦合的有限元分析法,模拟了液力悬置的动态响应。通过瞬态时域响应的模拟结果,计算了液力悬置的动态性能。在计算过程中使用ALE方法进行坐标变换,有效解决了流体力学和结构动力学在坐标系上的不一致问题。计算过程无须估算或测试液力悬置的流体阻尼,无须测量橡胶主簧的体积刚度,可以得到液力悬置在时域内的动态响应,仿真结果与试验测试结果吻合较好。     

RQ11动力总成悬置系统设计分析与试验研究

在建立RQ11G动力总成悬置系统的6自由度刚体振动微分方程基础上,分析比较了RQ11G动力总成系统悬置改进前后的固有频率、能量解耦度。通过在试车场进行的整车道路试验,比较分析了RQ11G动力总成系统悬置改进前后的隔振性能、存在的问题,验证了理论分析的结果。结果表明,通过合理设计车辆动力总成悬置系统固有频率和提高能量解耦度可有效降低车辆的振动与噪声,提高乘坐舒适性。探索了建立动力总成悬置系统一整套完整的设计、开发、试验保证体系。     

Introducing a new semi-active engine mount using force controlled variable stiffness

This work introduces a new concept in designing semi-active engine mounts. Engine mounts are under continuous development to provide better and more cost-effective engine vibration control. Passive engine mounts do not provide satisfactory solution. Available semi-active and active mounts provide better solutions but they are more complex and expensive. The variable stiffness engine mount (VSEM) is a semi-active engine mount with a simple ON–OFF control strategy. However, unlike available semi-active engine mounts that work based on damping change, the VSEM works based on the static stiffness change by using a new fast response force controlled variable spring. The VSEM is an improved version of the vibration mount introduced by the authors in their previous work. The results showed significant performance improvements over a passive rubber mount. The VSEM also provides better vibration control than a hydromount at idle speed. Low hysteresis and the ability to be modelled by a linear model in low-frequency are the advantages of the VSEM over the vibration isolator introduced earlier and available hydromounts. These specifications facilitate the use of VSEM in the automotive industry, however, further evaluation and developments are needed for this purpose.     

汽车发动机悬置系统动刚度模态分析

建立了基于悬置元件怠速工况下动刚度的发动机悬置系统MATLAB力学模型.同时由LMS实验模态分析系统测得了发动机实际工况下的运行模态参数,并以模态置信度对其进行了验证.与静刚度模型相比,以悬置元件动刚度建立的模型,其动态参数与运行模态参数更为接近,表明动刚度模型能更好地模拟悬置系统实际工况下的动态特性.     

Robust optimization design method for powertrain mounting systems based on six sigma quality control criteria

This paper presents a robust optimization design method based on Six Sigma quality control criteria to improve the design of a powertrain mounting system (PMS). The powertrain is modeled as a rigid body having six degrees of freedom (DOF) connected to a rigid base by four rubber mounts, and each mount is simplified as a three-dimensional spring-damper element in its local coordinate system (LCS). The calculation method based on energy decoupling is used to estimate the decoupling ratios of a PMS. The location and static stiffness of each mount and the orientations of the two anti-torsion mounts are selected as uncertain design variables, and the nominal values of these design variables are optimized to obtain a robust Six Sigma design for a PMS. The uncertain design variables are characterized by a perturbation or percent variation around their nominal values. The generalized reduced gradient (LSGRG2) optimization method is employed to solve the robust optimization problem, and a second-order Taylor series expansion is used to estimate the statistical properties of the performance constraints and objectives. The optimization results show that the robust design ensures good robustness or high reliability for the natural frequencies, decoupling ratios, and frequency separation constraints of a PMS.     

汽车动力总成磁流变悬置的磁路模拟分析与试验验证

根据磁流变液的流变特性设计了一种新型半主动磁流变悬置结构,并简述了该悬置结构和工作原理。利用ANSYS电磁场分析模块对悬置结构内部磁场进行了有限元分析,研究了相同磁流变液悬置结构下,不同隔板材料对磁流变液悬置磁场分布的影响,并分别测试了采用不同隔板材料时磁流变液悬置的动特性。结果表明,所选择的低磁导率铝合金隔板材料可改善悬置性能;在磁流变悬置的设计过程中引入ANSYS的电磁场分析方法可行并具有一定的通用性。     

发动机液压悬置低频模型参数识别方法的研究

根据悬置低频振动模型,提出了基于DE算法的发动机液压悬置模型识别方法,由简单的低频正弦激振试验直接估计模型的关键参数值,完成模型的参数识别。基于上述理论和试验相结合的模型识别方法可以代替组件试验,识别结果可直接用于复杂结构悬置元件的动特性预测和整车NVH性能研究。     

汽车磁流变悬置的动特性仿真研究

设计了一种用于某轿车的新型磁流变悬置结构,建立了其非线性动力学特性仿真分析数学模型,提出了模拟磁流变悬置动态特性的一种数值分析方法,应用MATLAB对其动态特性进行了仿真,分析了不同电流强度对该悬置动态特性的影响。