Author(s)

W. Szyszkowski & D. Hill

Abstract

Multi-cell cascaded Electro-Thermal Micro-Actuators (ETMA) made of nickel alloys are analyzed by the finite element (FE) method. The computer simulation runs over the electrical, thermal, and mechanical phases of the ETMA operations. The main challenges of modeling are discussed. Some of the material’s parameters such as the electrical resistivity, thermal expansion coefficient and emission are strongly temperature dependent. Furthermore, any measurements of such dependences are complicated by a magnetic phase transition occurring in nickel within the operating range of temperature. All the properties are sensitive to a particular composition of the material. The surface convection is additionally shape-dependent and, mainly due to small dimensions of the actuators, cannot be determined experimentally with sufficient accuracy. For the above reasons the use of the material data estimated from the available literature usually does not render reliable simulations. In the approach proposed the material characteristics of the ETMA considered are determined by utilizing the fact that for a given applied voltage the total current and displacement in the real actuators (performance parameters) are measured with a relatively high precision. Similar performance parameters, i.e. the total current and displacement can be obtained as output from the FE simulation in which some important material properties of the actuator’s model are assumed in a parametric form (material’s parameters). The FE simulation procedure is integrated with these real measurements in such a way that the

Keywords

micro-actuators, finite elements, electro-thermal-mechanical fields, uncertain material characteristics