INTELLIGENT MATERIALS, COMPOSITES AND SYS TEMS

The terms ''smart'' or ''intelligent'' are used for materials whose pr operties surpass modern high performance materials (f. e. superalloys) in the following respects: the ability to increase either the strengt h stimulated by an external load, or another structural or functional property by a corresponding stimulus: the ability to perform controlle d motions or exert forces; the ability to obtain a feedback signal abo ut changes in geometry of properties (Or damage). Hadfield steels and bi-metals are used to show historic stages of the development of adapt ive monolithic materials and composites. Modern intelligent systems or e often based on ferroelectric (piezo-electric), ferromagnetic or shap e memory materials. A similar feature of these materials in the domain structure, which forms in connection with the transformation to the l ow temperature phase. The different materials show shape changes which increase in the following sequence: FE < FM < SM. This determines the ir function in intelligent systems. As examples are used shape and vib ration control of airplane wings and helicopter blades, the developmen t of a micron-sized gripper and a robot hand. The fingers of the robot hand are made of thermo-mechanically treated shape memory alloy wires acting like muscles, embedded in a silicone robber, which in turns co ntains sensors for control of forces and motion.