Search Results

The increasing contribution of electronic and mechatronic content to the vehicle value requires rethinking the vehicle design and engineering processes. The present paper describes an approach hereto, based on virtual and physical prototype testing of heterogeneous systems. A key element is the integration between 3D geometry-Based Models (FE, MBS) and 1D multi-physics system-theoretic models for simulating complex devices (hydraulics, actuators, specific sensors) and processes (combustion, thermal, flow). Embedding control laws paves the way to Model-ln-the-Loop (MIL) and Software-In-the-Loop (SIL) concepts. By linking the virtual models to hardware systems on a physical test-bench, the static and dynamic performance of the rest of the vehicle system (suspension, body…) can be represented, enabling “Hardware in the Loop testing” (HIL). The “Vehicle-in-the-Loop” (VIL) validation finally allows the evaluation of all system dependencies and system interconnections.

This paper reports on test-analysis correlation and model updating activities carried out in the context of the European research project “HPC-VAO” (ESPRIT Project nr 20074, High Performance Computational environment for Vibro-Acoustic Optimisation). The central aim of the project is the implementation of a state-of-the-art CAE environment to support design optimisation in the field of NVH engineering. A specific objective covers the validation of the simulation models that are used in the vibro-acoustic optimisation framework. The validity and reliability of these models can be drastically improved by application of ‘model updating’ techniques. Whilst much research has been done in this field in the last decade, the number of cases where the technique has been used on industrial applications are slowly but steadily growing.

This paper presents a model updating method based on experimental receptances. The presented method minimises the so called ‘indirect receptance difference’. First, the reduced analytical dynamic stiffness matrix is expressed as an approximate, linearised function of the updating parameters. In a numerically stable, iterative procedure, this reduced analytical dynamic stiffness matrix is changed in such a way that the analytical receptances match the experimental receptances at the updating frequencies. The updating frequencies are a set of selected frequency points in the frequency range of interest. Some considerations about an optimal selection of the updating frequencies are given. Finally, a mixed static-dynamic reduction scheme is discussed. Dynamic reduction of the analytical dynamic stiffness matrix at each updating frequency is physically exact, but it involves a great computational effort.

This paper presents two applications of the RADSER model updating technique (ref. 1). The RADSER technique updates finite element model parameters by solution of a linearised set of equations that optimise the Reduced Analytical Dynamic Stiffness matrix based on Experimental Receptances. The first application deals with the identification of the dynamice characteristics of rubber mounts. The second application validates a coarse finite element model of a subframe of a Volvo 480.

Kalman filters have been employed very successfully in control and guidance systems since the sixties, with particular application to avionics and navigation. These filters can track accurately signals of known structure among noise and other signal components with different structure. This paper investigates the application of nonstationary Kalman filters to track harmonic components. This approach enables the analysis of harmonic components in signals even when the rate of change of frequency, or slew rate, is high. A Kalman filter formulation to track harmonic components in data records sampled with constant frequency is first reviewed. Particular attention is paid to the characteristics of the filters in terms of filter resolution and harmonic separation, as well as ability to handle higher slew rates. The applicability of the method is demonstrated for analyzing driveline harshness problem.

Optimal design changes to solve vibration induced fatigue failures can only be derived by including structural dynamics considerations into the fatigue lifetime calculation process. Such an integrated design approach to resonance fatigue problems has been developed within the EC Esprit Project 2486 DYNAMO. Also an integration of crack initiation and crack growth calculations has been realised. This integrated dynamic analysis/fatigue analysis procedure is demonstrated in the paper by means of a resonance fatigue problem of a car.

The analysis of the periodic components in noise and vibration signals measured on rotating equipment, like car power trains, must more and more be done under rapid changes of an axle, or reference RPM. Normal tracking filters (analog, or digital implementations) have limited resolution in such situations; wavelet methods, even when applied after resampling the data to be proportional to an axle RPM, must compromise between time and frequency resolution. The authors propose the application of nonstationary Kalman filters for the tracking of periodic components in such noise and vibration signals. These filters are designed to track accurately signals with a known structure among noise and signal components of different, ‘unknown’, structure.

“Noise and vibration are not invented here!”. Undesirable structural dynamic behaviour is normally experienced on final assemblies, by which time the underlying cause of the problem is difficult to solve intuitively. Solving the problems classically involves the partial breakdown of assemblies and the application of various structural dynamics testing and analysis procedures. Preferably, noise and vibration problems should be avoided by designing the product right the first time, by the use of various integrated analysis and testing disciplines, from the component level to the final assembly. Such an approach is referred to, in a broader sense, by trendy themes as concurrent engineering, forward engineering, simultaneous engineering.... This paper analyzes trends in analytical and experimental structural dynamics toward better integration of the various discipline oriented techniques that are currently used.