Technical Sessions

Mr. Tommy Luft, Otto-von-Guericke University of Magdeburg / Faculty of Mechanical Engineering, Germany
Mr. Stefan Ringwelski, Otto-von-Guericke University of Magdeburg / Faculty of Mechanical Engineering, Germany
Prof. Ulrich Gabbert, Otto-von-Guericke University of Magdeburg / Faculty of Mechanical Engineering, Germany
Dr. Wilfried Henze, Otto-von-Guericke University of Magdeburg / Faculty of Mechanical Engineering, Germany
Prof. Helmut Tschöke, Otto-von-Guericke University of Magdeburg / Faculty of Mechanical Engineering, Germany

Subject group: A4, C1

Key words: Active Noise Reduction, Adaptive Controllers, Piezoelectric Actuators, FEM, BEM

Abstract: Recently, active control techniques have received an increasing attention, since they provide an effective way for vibration suppression and noise reduction of thin-walled structures. In active noise reduction smart materials are attached to the structure as actuators and sensors connected by a control unit, which enable the system to reduce the structural vibrations with the objective to reduce simultaneously also the sound radiation caused by structural vibrations. Piezoelectric materials are widely used as actuators and sensors, because they provide large forces, operate in high frequency regimes and can easily be bonded on or imbedded into conventional structures. Active control methods are usually employed in applications where the frequency range of interest is between 50 Hz and 1500 Hz. This is also an important frequency region in engine acoustics.

Considering passenger cars, the power train represents one of the main noise sources, where the engine oil pan significantly contributes to the noise emission.

The aim of the present paper is to design a smart car oil pan with surface-attached piezoelectric actuators for active vibration and noise reduction of a stripped engine.

At first, numerical FEM-BEM simulations of the stripped engine are performed in order to investigate the general noise reduction potential of the piezoelectric patch actuators as well as to calculate optimal actuator locations. Based on these results a demonstrator of a stripped engine is developed, built and experimentally investigated. The demonstrator is excited by a shaker with a white noise excitation, and in addition also a real engine spectra resulting from combustion engine measurements is applied. The developed experimental setup enables measurements of the controlled and the uncontrolled structural vibrations as well as the radiated sound field. The vibrations can be recognized by surface attached acceleration sensors. The sound field is measured with help of microphone-array techniques.

The focus of the paper is the design and the verification of different control strategies. Different adaptive controllers are proposed and applied to reduce the noise radiation of the stripped engine. Adaptive control formulations are analyzed with respect to random variations of real engine parameters, where also neuro-fuzzy networks are included for the controller design.

The paper presents the main results of the investigations and concludes with an outlook to ongoing research activities.

This abstract is supplemented by a PDF, which can be viewed here.

Session: Noise and Vibration Reduction