Design Principles for Linear, Axial Solid-State Actuators
A complete description of the behavior of solid-state actuators requires a multifield approach, which involves full coupling with the non-mechanical field quantities (of electrical or thermal nature, for instance). Powerful simulation tools like COMSOL® allow for such an accurate multi-field analysis for an actuator device of given geometry and material distribution. The complexity (and accurateness) of a multi-field approach depend on the number of feedback loops which are considered in the analysis. In the case of a shape memory actuator (SMA) heated by Joule effect, for instance, the activation can be modeled by prescribing the temperature in the SMA-element, the heating power, the electrical current or the electrical tension. Even in the latter case, which includes the full thermo-mechanical modeling of the SMA actuator as well as the modeling of its electrical resistance as a function of temperature and transformation state, the analysis is still incomplete since it neglects the coupling with the supply circuitry and the control system. The simplest modeling option in this sense is the direct prescription of a given induced strain. The only feedback which is considered by this option is the mechanical one, which converts the imposed induced strain into the actual strain by means of the stress-strain relationship of the active material. This option is often denoted as “thermal analogy”, since it is equivalent to the prescription of a temperature change in a material subject to thermal expansion (with anisotropic thermal expansion properties in order to allow for generating a non-hydrostatic strain state). Usually, the stress-strain relationship of the active material is linearized, which is consequent with the superposition principle implicit in the prescribed induced strain approach (actual strain = induced strain + elastic strain).
KeywordsDesign Principle Stroke Work Actuator Force Host Structure Strength Boundary
Unable to display preview. Download preview PDF.
- 1.Campanile L, Sachau D, Seelecke S (1999) Ein adaptives Windkanalmodell für einen adaptiven Tragflügel. In: (in German) Proc. ”Deutscher Luft- und Raumfahrtkongress”, Berlin, Germany, pp 19–28Google Scholar
- 3.Gandhi MV, Thomson BS (1992) Smart materials and structures. Chapman and Hall, LondonGoogle Scholar
- 4.Giurgiutiu V, Rogers CA (1996) Energy based comparision of solid state induced strain actuators. Journal of intelligent material systems and structures 7Google Scholar
- 5.Lesieutre GA, Loverich J, Koopmann G, Mockensturm E (2002) Enhancement of mechanical work output of a piezo-stack using a non-linear motion transmission mechanism. In: 13th International Conference on Adaptive Structures and Technologies (ICAST), pp 631–643Google Scholar
- 6.Letty RL, Claeyssen F, Barillot F, Lhermet N (2003) Amplified piezoelectric actuators. In: AMAS Workshop on Smart Materials and Structures, JadwisinGoogle Scholar
- 8.Uchino K (1998) Piezoelectric actuators and ultrasonic motors. Kluwer Academic Publishers, BostonGoogle Scholar