Reliability investigation of adaptive systems for noise reduction on system and material level

The reliability of adaptronic systems for active noise reduction is regarded as one of the key issues for entering mass markets. The paper gives an overview on the results obtained within the European Integrated Project (IP) InMar (Intelligent Materials for Active Noise Reduction). On materials level, newly developed high temperature piezoelectric patch actuators as well as piezoelectric stack actuators were investigated. New test methods for accelerated testing as well as test stands for simulation of harsh environment like oil, salty water, moisture and extreme temperatures were developed. Microstructural investigations were performed in order to analyse the physics of failure. The objective of this work was to set up a condition monitoring system for piezoelectric stack actuators. The monitoring system should detect a forthcoming catastrophic failure of the stack at a much earlier stage, allowing for repair or other maintenance measures. On system level, an automotive oil pan equipped with an active system for noise reduction, which became one of the central demonstration structures in the project, was investigated. In order to set up a demonstration structure and a reliability test stand, the boundary conditions and the hardware was defined. The partners were supplied with requirements, CAD - data and test specimens concerning the aluminum cast oil pan. In a test rig able to simulate the vibration excitation of the engine, the oil temperature and the oil level inside the pan, several test scenarios were executed in order to characterize the robustness of the active system as well as its long term reliability. The overview paper presents results as well as the capability of the newly developed test hardware and -methods obtained on the various length scales of an active system from materials level up to system level. Entnommen aus TEMA