<title>Are biological structures smart?</title>

Abstract

There is widespread agreement among engineering scientists that the next major step in the design, development and manufacture of structural components will most likely be a focus on building smart structures. Therefore the question posed above will be examined in the context of design of engineering structures and structural components. We begin by defining the key words here: smart and structures. By structure we mean an assembly or its components which serves an engineering function. Therefore, in addition to familiar examples such as airplanes, helicopters, bridges, buildings, roads, railways, ships, etc., a wide variety of objects such as microchips, semiconductors, accelerometers, strain gages, tennis rackets, musical instruments, cooking utensils, etc. quaIif' to be described as structures or structural components. These components may be subjected to wind, ice, heat, loads, noise, radiation, etc. Extending the context a little further, we are mainly concerned with these structures or structural components maintaining their structural integrity in performing their design function throughout the period of their estimated life. The dictionary deñnition of the word '1smatt" is not very complimentary. However, the engineering community has adapted the word and in its usage over nearly a decade now, the word has come to define a certain extraordinary ability of a structural component in performing its function. Thus a structure or structural component may be defined as "smart" if it can sense a variable such as strain, pressure, temperature, etc. and process the same to initiate any action needed, in order to continue to perform the functions for which it was designed. Some prefer the word intelligence to describe the above characteristics but that word implies features fr and above those intended here, such as, for example, cognitive abilities. For the present we interpret smartness, in realistic terms, to mean the inherent ability of structural members to sense, diagnose and actuate in order to retain their integrity. Within the scope ofthese definitions, we study some specific examples and examine the extent oftheir smartness and relevance to engineering design