Smart Materials in Active Vibration Control

Abstract

The mechanical behavior of classical materials can be described by their elastic constant, which relates stress to strain. In advanced engineering materials that are often referred to as smart or intelligent materials, the mechanical behavior is also influenced by other fields; such as magnetic, electric charge, temperature, light and chemical composition. This is also reflected in the underlying constitutive equations, which couple two or more of these fields to describe the physical behavior of the material. These aforementioned materials have desirable properties when it comes to their use in active vibration control (AVC), since they may be readily integrated within the controlled structure and do not alter the mass of the mechanical system significantly. The aim of this chapter is thus to give a review of advanced engineering materials used in active and semi-active vibration control. The chapter covers the shape memory and superelastic property of shape memory alloys (SMA) and their current use in vibration control. Magnetostrictive and electrostrictive (MS, ES) materials are less commonly utilized in vibration control, however due to their engineering potential we will give a concise account of these materials and the underlying physical principles. The advantages of magnetorheological (MR) fluid based dampers with adjustable properties have become increasingly recognized in the engineering community, thus the discussion of magnetorheological and the related electrorheological (ER) fluids is provided here as well. Piezoelectric materials such as piezoceramics are probably the most commonly used smart materials in AVC. Here, we introduce the direct and converse piezoelectric effect, a short review on the application of transducers in vibration damping and some notes on the mathematical modeling of their dynamics. The chapter is finished by the emerging electrochemical materials or electroactive polymers (EAP).