共查询到20条相似文献,搜索用时 546 毫秒
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M.M. Elmadany 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1987,16(5):297-312
The purpose of this paper is to develop a procedure based on covariance analysis and nonlinear programming techniques which can be used for the parameter selection of optimum truck suspensions. The procedure is applied to explore the differences in parameter selection caused by the changes in the frequency content of the road input or by changes in the criteria for optimization. The equations of motion for a tractor-semitrailer truck are cast in state space form. The road excitations are represented by the output of a white noise excited shaping filter taking into consideration the time delays between the different vehicle axles. Shape filters to represent human perception of vibration in both the vertical and longitudinal directions in the time domain are presented and realized in terms of state variables. The suspension parameters of the road-vehicle-human body system are optimized using a direct search algorithm. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(5-6):297-312
SUMMARY The purpose of this paper is to develop a procedure based on covariance analysis and nonlinear programming techniques which can be used for the parameter selection of optimum truck suspensions. The procedure is applied to explore the differences in parameter selection caused by the changes in the frequency content of the road input or by changes in the criteria for optimization. The equations of motion for a tractor-semitrailer truck are cast in state space form. The road excitations are represented by the output of a white noise excited shaping filter taking into consideration the time delays between the different vehicle axles. Shape filters to represent human perception of vibration in both the vertical and longitudinal directions in the time domain are presented and realized in terms of state variables. The suspension parameters of the road-vehicle-human body system are optimized using a direct search algorithm. 相似文献
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S.Y. Bhave 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1992,21(1):225-245
Airsprings have been used for vehicle suspensions over the last 40 years. They are mostly used as independent suspensions. Analysis of air springs available in literature is mostly limited to a single-degree-of-freedom system or a two-degrees-of-freedom system only in the translation mode. This paper deals with a model of a vehicle where the front and the rear springs are connected by a capillary tube. A two-degrees-of-freedom model having motion in bounce and pitch mode is presented. Equations of mass flow are linearized on the assumption of small variations in volume and pressure. Expressions for the transmissibility and the phase angle in the bounce and the pitch mode are derived. Road inputs to the front and the rear axles are assumed to be identical except for a phase difference between them. The effect of the capillary flow coefficient and that of the phase angle between the front and the rear axle excitation are studied. It is shown that an optimum value of the capillary flow coefficient exists which minimizes the transmissibility of motion in both modes over the entire frequency range. It is also observed that a phase angle of 180 degrees presents ideal transmissibility characteristics. Thus, a promising application of air springs for a vehicle suspension is presented. 相似文献
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发动机-悬置系统的能量法解耦及优化设计 总被引:15,自引:0,他引:15
本文通过发动机-悬置系统的能量分布得到系统解耦的能量指标,并以该能量指标为优化设计目标。以系统的固有频率为约束条件,应用DSFD算法对系统进行优化计算。所编制的优化设计程序具有计算可靠、收敛速度快的特点。为便于程序应用,本文指出了系统能量解耦目标、频率约束及设计变量等因素对优化计算的影响。对某一轻型货车发动机-悬置系统的优化计算表明,仅通过悬置刚度参数的调整即可使系统的解耦水平明显提高。 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(1):225-245
SUMMARY Airsprings have been used for vehicle suspensions over the last 40 years. They are mostly used as independent suspensions. Analysis of air springs available in literature is mostly limited to a single-degree-of-freedom system or a two-degrees-of-freedom system only in the translation mode. This paper deals with a model of a vehicle where the front and the rear springs are connected by a capillary tube. A two-degrees-of-freedom model having motion in bounce and pitch mode is presented. Equations of mass flow are linearized on the assumption of small variations in volume and pressure. Expressions for the transmissibility and the phase angle in the bounce and the pitch mode are derived. Road inputs to the front and the rear axles are assumed to be identical except for a phase difference between them. The effect of the capillary flow coefficient and that of the phase angle between the front and the rear axle excitation are studied. It is shown that an optimum value of the capillary flow coefficient exists which minimizes the transmissibility of motion in both modes over the entire frequency range. It is also observed that a phase angle of 180 degrees presents ideal transmissibility characteristics. Thus, a promising application of air springs for a vehicle suspension is presented. 相似文献
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针对概念设计阶段的车身结构轻量化设计,提出了一种可实现车身多材料结构设计的分层迭代优化方法。该优化方法的设计变量中,除常见的板厚、材料外,还包括装配设计中的拓扑连接,以实现“将合适的材料用在合适的部位”的要求。分层迭代优化的第1层以拓扑连接为设计变量,采用图分解和NSGA-II对车身装配拓扑结构进行多目标优化,最大化车身弯扭刚度和1阶固有频率;第2层对板厚和材料进行多目标优化,最小化车身质量和材料成本。最终采用基于模糊集合的评分公式选定综合最优解,实现了考虑成本的车身结构轻量化设计。 相似文献
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J. Wu 《International Journal of Automotive Technology》2012,13(3):409-422
This paper presents a robust optimization method to decrease the variations in the performance of the designed system caused
by the unavoidable manufacturing, installation or measurement errors of the design variables. Generally, it is difficult and
costly to determine statistical information with sufficient precision for uncertain design variables; in this study, interval
numbers are used to describe the uncertain design variables, and only the bounds of these variables are required. An improved
interval truncation method is presented for estimating the variation ranges of the system performances. The robustness estimations
of the system performances are incorporated into the optimization formulation to obtain the nominal design variables, which
could make the system performances relatively robust; therefore, the design robustness is estimated and improved in the optimization
iteration process. The robust optimization method is applied to a general powertrain mounting system (PMS) to improve the
design robustness of the PMS decoupling layout and frequency allocation. The optimization results show that the robust optimization
method could effectively increase the decoupling ratios in the interested vertical and pitch directions, and the frequency
allocation is more robust than that obtained using the traditional deterministic optimization. 相似文献
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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. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(10):867-887
In this paper a novel active compliance chamber is designed, which can be used to control the dynamic stiffness of a common hydraulic bushing. This chamber offers a simple and cost-effective solution for the variable displacement engine (VDE) isolation problem. A VDE system requires a soft bushing for the half cylinder mode and a regular one for normal engine operations. A magnetic actuator is used to produce mechanical pulses. The linearisation technique is used for simplifying the nonlinear equation of motion. Different current sources are used to feed the magnetic actuator. The pressure inside the chamber follows linearly the current input signal. The phase shift in various current inputs is used in the form of the transfer functions to create the required pressure response pattern in the frequency domain. Since the dynamic stiffness of a conventional hydraulic bushing is a direct function of the pressure inside it, the active compliance chamber can be used to alter the pressure and consequently produce the required dynamic stiffness response. As a result, it can address the engine vibration problem for VDE situation. 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(1):122-138
The efficiency of a seat in reducing vibration depends on the characteristics of the vibration, the dynamic characteristics of the seat, and the dynamic characteristics of the person sitting on the seat. However, it is not known whether seat cushions influence the dynamic response of the human body, whether the human body influences the dynamic response of seat cushions, or the relative importance of human body nonlinearity and seat nonlinearity in causing nonlinearity in measures of seat transmissibility. This study was designed to investigate the nonlinearity of the coupled seat and human body systems and to compare the apparent mass of the human body supported on rigid and foam seats. A frequency domain model was used to identify the dynamic parameters of seat foams and investigate their dependence on the subject-sitting weight and hip breadth. With 15 subjects, the force and acceleration at the seat base and acceleration at the subject interface were measured during random vertical vibration excitation (0.25–25 Hz) at each of five vibration magnitudes, (0.25–1.6 ms?2 r.m.s.) with four seating conditions (rigid flat seat and three foam cushions). The measurements are presented in terms of the subject's apparent mass on the rigid and foam seat surfaces, and the transmissibility and dynamic stiffness of each of the foam cushions. Both the human body and the foams showed nonlinear softening behaviour, which resulted in nonlinear cushion transmissibility. The apparent masses of subjects sitting on the rigid seat and on foam cushions were similar, but with an apparent increase in damping when sitting on the foams. The foam dynamic stiffness showed complex correlations with characteristics of the human body, which differed between foams. The nonlinearities in cushion transmissibilities, expressed in terms of changes in resonance frequencies and moduli, were more dependent on human body nonlinearity than on cushion nonlinearity. 相似文献
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以某型轿车为例,建立车身有限元分析模型,对模型进行了试验验证。综合考虑零件厚度对车身质量与刚度的影响,利用灵敏度分析方法确定优化设计变量。以白车身质量最小为目标函数,在保证车身刚度和模态性能的前提下,进行车身质量优化。在车身质量减轻了6.25%的同时,车身刚度和主要模态频率也获得了不同程度的提高。 相似文献
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Chang-Kook Chae Byung-Kook Bae Kwang-Joon Kim Joon-Hong Park Nam-Chan Choe 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2000,33(5):327-349
This paper presents a feasibility study on using the rubber bushing itself as a sensor for the identification of transmission forces in vehicle suspension systems. The method starts from the idea that the transmission forces can be related to the deformation of the rubber bushing by an appropriate model and the deformation of the rubber bushing can be obtained by estimation of the relative vibration across the bushing. Simple theories are presented to deal with modeling of a given geometry of rubber bushing by a concentric spring and damper, correlating of measurements of the vibration on the links to the stiffness and damping parameters, and selection of the vibration measurement positions. Importance of the measurement position selection in relation to the measurement noise is illustrated by simulation studies. Then, validity of the proposed indirect approach will be shown by applications to a rear suspension system of dual link type. 相似文献
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Application of Sensitivity Methods to Analysis and Synthesis of Vehicle Dynamic Systems 总被引:1,自引:0,他引:1
Andrzej G. NALECZ Associate Professor Research Fellow 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1989,18(1):1-44
The development and application of sensitivity methods for determining the effects of parameter changes on the response of vehicle dynamic systems is presented. The procedures shown can be used to enhance the analysis and synthesis processes of virtually any road or rail vehicle system regardless of its complexity. The parametric sensitivity of vehicle models in time domain, steady state models and vehicle models in frequency domain can be investigated using different types of sensitivity functions, both dimensional and dimensionless including first order standard, percentage, logarithmic, second order standard, and logarithmic and percentage sensitivity measures. These sensitivity functions and measures are determined as functions of partial derivatives of system variables taken with respect to system parameters. In the case of sensitivity functions in the frequency domain the variable values are computed as either the magnitude or phase angle of a complex element of the transfer function matrix. The methods presented enable to determine the influence of all system primary (constant) and secondary (non-constant) parameters on system primary and secondary variables. The primary variables are state variables or elements of the transfer function matrix and the secondary variables may be any functions of primary variables and system parameters. Typical secondary system parameters which can be examined include initial conditions, time variant coefficients, natural frequencies, loads, and typical secondary variables are forces, weight transfers, stability factors and energy components. The analysis of sensitivity results obtained for three vehicle handling models in both linear and nonlinear regimes of vehicle performance and utilizing various types of sensitivity functions is also presented. 相似文献