A. Keresztes

Dynamic Modelling Of Commercial Road Vehicle Structures From Test Data

The paper discusses the identification of multivariable models for air suspension bus structures using the measured stress response arising from stochastic road profile excitation. The vehicle and noise transfer matrices are identified from the time history of measured data. Applying a special parametrization of the transfer matrices, the modal characteristics can also be directly computed. Models were identified at various selected road categories, road profile variances and speed levels, thus the random vibration analysis of the vehicle can be performed for the whole range of operation. The identified models can be used to determine the global dynamic characteristics of the vehicle for arbitrary road profile excitations and speed levels within the examined range.

Multivariable Identification for Commercial Vehicle Stress Analysis

This paper presents the application of multivariable identification methods to obtain models for commercial road vehicles from measured stress responses arising in certain structural elements due to stochastic road excitation. The elementary subystem representation of the system transfer matrix allowing an effective structure and parameter estimation is used to model the vehicle and noise dynamics. Measurements were carried out on a laminated spring suspension bus, and models were indentified atvarious road profile variances and speed levels of the vehicle.

Identification of Bus Dynamics from Test Data

Abstract The paper discusses the identification of multivariable models for vehicle structures excited by stochastic road profiles. A time domain approach is used to the identification of the transfer matrix and the modal characteristics /natural frequencies and eigenvaluesl from accelerations and stress measurements. It will be shown that the application of ESS-representation arise naturally in modelling vibrating structures. The methods are u6ed to identify models of an air suspension bus for various speed levels and road profile variances

Determination of mass, damping and stiffness matrices using structural and parametric identification of linear vehicle frame models

SUMMARY The paper deals with some important problems of determination of mass, damping and stiffness matrices using identification of linear vehicle dynamic models. The body of the vehicle is considered as distributed parameter system wich can be described by partial differential equations and the parameters represent mass, stiffness and damping distributions. Using finite elements method the body dynamics can be modelled as concentrated parameter system given by second order vector differential equations. For this case the directly identified parameters of discrete models are sophisticated functions of physical parameters of continuous models. Therefore, it is very important to choose the suitable discrete model class for an effective and reliable solution of the above problem. In the paper special time-domain maximum likelihood method is applied to estimate the coefficients in the transfer matrix of the body and to ensure a direct relationship between the transfer matrix, the modal and physical paramete...

NONLINEARITY ANALYSIS FOR IDENTIFICATION OF COMMERCIAL ROAD VEHICLE STRUCTURE DYNAMICS

SUMMARY The modelling problem for dynamic analysis of commercial or public service road vehicles due to excitation of stochastic road surface roughness is considered. It is shown that under reasonable assumptions, the body dynamic can be described by linear models, and the axle dynamics can be described by nonlinear Volterra or Zadeh functional series models. Statistical structure detection methods are suggested to explore the nonlinear characteristics from measured acceleration and road profile excitation data.

IDENTIFICATION OF MULTIVARIABLE MODEL FOR COMMERCIAL VEHICLES

Abstract This paper discusses the identification of multivariable model for commertial road vehicles from the measured stress reponse arising in given structural elements due to stochastic road profile exitation. A special reprezentation of the system transfer matrix is used as model which makes possible the direct identification of the poles and the estimation of the number of natural frequencies. The parameters in the system and output noise model are estimated by the maximum likelihood method. The measurement were carried out on a laminated spring suspension bus. Models of the vehicle were identified for various speed levels and variances of road profile exitation process.

Statistical Identification of Nonlinear Vehicle Vibrating Stuctures

Abstract This paper considers the nonlinear modelling and identification problem for the ride quality and stability analysis of road vehicles due to excitation of stochastic road surface roughness. The basic nonlinear phenomena in dynamic behavior of ground vehicles are related to the progressive damping and stiffness characteristics of the axle/body dynamics and the nonlinear response of the pneumatics of the wheels excited by the road surface. To model the above system, the parameters in the nonlinear differential equations of vibrating phenomena of road vehicle dynamics have to be estimated by using nonlinear parametric identification methods. In certain experimental situations it is possible to separate the nonlinear analysis of axle subsystem from the dynamic analysis of the linear models based on measurements data carried out on an air suspension vehicle. The determination of the eigenfrequencies appearing in the axle vibrations and of the physical parameters (mass, stiffness and damping one) from the identified model parameters can also be investigated.

Mathetical model of the load and stress statistics of vehicle structures

Abstract Factors which must be kept in mind when designing utility vehicles such as buses and trucks are discussed. Attention is focused on the input to the process, i.e. modelling of the road surface, simulation of operational modes, loading conditions and stress statistics.