Lifetime prediction and modeling the constitutive behavior of tetragonal ferroelectrics under electromechanical loading
报告人：Prof. Andreas Ricoeur and Stephan Lange
Institute of Mechanics, University of Kassel, Germany
主持人：李法新 特聘研究员
时 间：4月21日（周二）下午1：30-4:00
地 点：工学院力学楼434会议室
Abstract
Ferroelectric materials are widely used in smart structures and devices as actuators, sensors etc. In this work, a condensed model for ferroelectric solids with tetragonal unit cells is presented. The approach is microelectromechanically and physically motivated, considering discrete switching processes on the level of unit cells and quasi-continuous evolution of inelastic fields on the domain wall level. Hysteresis loops are simulated for a pure electric and an electromechanical loading to demonstrate the influence of a compression preload on the poling and stress-strain behavior. Further, residual stresses are calculated as a result of switching processes and interaction between crystallits. To study the high cycle fatigue damage and to predict lifetime of ferroelectric devices, an accumulation model is proposed based on the growth of microcracks. Here, the Paris law is applied to calculate fatigue crack growth rates. The lifetime is calculated considering different parameters, e.g. initial crack length, material parameters, loading cases etc. The simulations agree with experimental findings, where actuation efficiency and structural integrity come out to be opposing properties.
Biography
Prof. Andreas Ricoeur
10/88 - 09/94 Studies in Mechanical Engineering at the University of Stuttgart
03/95 - 03/98 Doctoral candidate at the Robert Bosch GmbH, Department of Applied Physics, and PhD student at the University of Stuttgart
04/98 - 06/2000 Postdoctoral research fellow at the Institute of Mechanics and Machine Components, Technical University Bergakademie Freiberg
07/00 - 08/09 Scientific associate at the Institute of Mechanics and Fluid Dynamics (IMFD), TU Bergakademie Freiberg
since 09/2009 Full Professor for Engineering Mechanics/Continuum Mechanics at University of Kassel
since 04/1011 Dean of Students of the Department of Mechanical Engineering
since 05/2012 Head of the Institute of Mechanics of the University of Kassel
Dipl.-Ing. Stephan Lange
Since 2012 Research assistant (Ph.D.), Institute of Mechanics, Engineering Mechanics / Continuum Mechanics, Department of Mechanical Engineering, University of Kassel
2007 – 2012 Dual studies (StiP) – Diploma in Mechanical Engineering & Vocational training to Industrial Mechanic, University of Kassel & Rheinmetall AG
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