Reinhard Lerch

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Many surface acoustic wave (SAW) devices consist of quasiperiodic structures that are designed by successive repetition of a base cell. The precise numerical simulation of such devices, including all physical effects, is currently beyond the capacity of high-end computation. Therefore, we have to restrict the numerical analysis to the periodic substructure.(More)
Many sensors and actuators in technical systems consist of quasiperiodic structures which are constructed by successive repetition of a base cell. Typical examples are piezoelectric composites used as ultrasonic transducers or surface acoustic wave (SAW) devices utilized in telecommunication systems. The precise numerical simulation of such devices(More)
Todays data sets arising from computational mathematics are extremely large which poses increasing demands for performance (in the sense of graphics-performance) on interactive visu-alization systems. " Real-time " interaction interfaces have proven useful for the analysis of these data sets, but real-time performance has been difficult to achieve with such(More)
A two layer ultrasonic stack transmitter made of a ferroelectret material with a diameter of 1.5 cm was developed for emitting a chirp signal with a sound pressure level of more than 90 dB at a distance of 1 m for an artificial bat head. Compared to a single layer transmitter, the resonance frequency of a two layer stack actuator is shifted down to 100 kHz.(More)
Numerical simulations of piezoelectric stack actuators are suitable to predict the mechanical and electrical performance in actuator applications in advance. The major conditions for reliable numerical simulations are a detailed knowledge regarding internal structure of the actuators as well as precise material parameters of all involved materials. Complex(More)
In this contribution, we exploit an Inverse scheme enabling the identification of temperature dependent material parameters of piezoceramic materials as well as their electromechanical coupling factors. This information is indispensable to predict the behavior of sensors and actuators incorporating such materials. Principally, the identification procedure(More)
In order to compensate for hysteresis errors in tracking and manipulation tasks, models describing the piezoceramic actuator nonlinearities are required. These models have to meet the following two criteria: (i) Efficiency and (ii) a bidirectional description of hysteresis phenomena. Due to its flexibility and efficiency, the Preisach operator is a(More)