Volker Knoblauch

Reliability aspects of microsensors and micromechatronic actuators for automotive applications

Abstract In modern cars microsensors and micromechatronic actuators play an essential and still increasingly important role as the interface between the vehicle with its complex functions of motor management, chassis systems, safety as well as comfort and convenience on the one hand and the respective electronic control units on the other hand. They have to fulfill their task in a harsh environment over the entire lifetime of an automobile. Therefore reliability aspects have moved more and more into the focus of engineering and research activities in microsystem technology. A methodical procedure is described that allows reliability issues to be approached efficiently. The implementation of the methodology is illustrated with real-life examples of reliability aspects of hot film mass air flow sensors, inertial sensors as well as piezoelectric actuators.

Combined isotropic and kinematic hardening in phenomenological switching models for ferroelectric ceramics

A phenomenological model for ferroelectric switching is presented in this paper. The model is based on ideas of plasticity. A switching surface is used as the criterion for non-linear response of the material. Hardening models are used to control the size and position of the switching surface in electric field space. The distinctions between kinematic, isotropic and combined hardening models are discussed. The predicted response to electric loading is computed using combinations of isotropic and kinematic hardening. The calculated hysteresis loop and poling curve are in good agreement with experimental data.