Active materials and adaptive structures

This paper gives a brief discussion of the ONR program on active materials and adaptive structures, and addresses its objectives and issues as they relate to naval applications. The main focus is on the mechanics tools necessary for the design of this new class of structures. A review of the research in the mechanics of high-strain active materials and engineering active materials, hybrid active materials, constitutive modeling, failure of ferroelectric ceramics, and active material interaction with host material is given. The majority of the effort is devoted to understanding failure mechanisms in active materials, which were recognized early in the program to be of great importance to reliable design of high-performance actuators and their acceptance by the design community. Some new concepts of engineering active materials, and developments of hybrid active materials, are introduced as a means to achieve high-performance actuation. The paper also covers various design approaches for high-strain - high-frequency actuators in addition to some new actuator concepts. The reliability issue of the host materials and the mechanics of embedding of actuators in composite structures are addressed.