Christoph Häusler

3-D Modeling of Pyroelectric Sensor Arrays Part II: Modulation Transfer Function

The modulation transfer function (MTF) for a pyroelectric infrared sensor array is determined from a finite-element simulation. Consideration of the full thermoelectromechanical coupling and use of a 3-D sensor model result in a good agreement between calculated and measured data.

Full Form of the Near Tip Field for the Interface Crack between a Piezoelectric Material and a Thin Electrode

The Hilbert problems and their solutions of the near tip field for the permeable and the impermeable electrode-ceramic interfacial cracks are derived with the aid of the modified Stroh formalism. In addition, a linear extrapolation method for numerical calculation of field intensity factors is given. This extrapolation method is based on a special combination of the field quantities.

3-D Modeling of Pyroelectric Sensor Arrays Part I: Multiphysics Finite-Element Simulation

When modeling pyroelectric sensors, not all relevant and coupled physical phenomena could be considered contemporaneously up to now. We describe a method to examine problems with coupled thermal, electrical, and mechanical fields using finite-element software. Modeling the complex interaction between the physical fields is realized by implementing a two-step approach that takes advantage of the internal computational routines of finite-element programs. The method will be exemplified on a standard pyroelectric sensor array, whose efficient 3-D modeling and simulation is demonstrated using a public accessible commercial finite element software.

Modulation transfer function of pyroelectric infrared sensor arrays

Pyroelectric infrared sensor arrays are imaging devices for infrared radiation that utilise the temperature dependency of the remanent polarisation in pyroelectric materials. We use the finite element method (FEM) for the calculation of the coupled thermo-electro-mechanical fields for a 3D sensor model. From the simulation data we derive the modulation transfer function.

Fracture in Piezoelectric Ceramics and PZT/Electrode Interfaces

The fracture behavior of piezoelectric ceramic (PZT) as well as metal/PZT interfaces under mechanical and electric loading is examined in four and three point bending under conditions of controlled crack growth (see Fig. 1). The experiments are performed in a custom made very stiff testing machine. A special modulation technique, i.e. a small signal compliance method, allows in situ determination of the mechanical compliance Cm, the capacitance Ce, and the piezoelectric compliance Cp as a function of the crack length. By calculating the derivatives of these generalized compliances with respect to the crack surface area we get the total linear energy release rate.