Adaptative structures for improvement of mission success

Abstract

In this paper, the research status on intelligent adaptive structures especially in space engineering is presented by focusing various adaptive attempts to improve the possibility of mission success. Recently there appear many structures which could have various functions to change their configurations and physical properties, and to detect their conditions. These new concepts of structures are called intelligent adaptive structures. Important functions of intelligent adaptive structures are shape control, vibration control, aid of construction, health monitoring, and so on. Various researches related to this new technology are arranged, and some new directions to improve the possibility of mission success such as increase of design feasibility and addition of autonomous ability are discussed.A structure is a hardware constructed in order to keep some spatial extension. It is composed of interrelated elements which are rigid elements and flexible ones, such as wires, beams, plates, shells, etc. After getting some shapes through these elements, it has representative indexes such as stiffness and strength. Conventionally “structure” means a permanent structure, but especially a recent technology development requests a relatively short life structure or a temporary structure. A permanent structure is usually a passive structure, but in a temporary structure various structural controls might be necessary and possible to realize a more adaptive or efficient structure. One of such examples is a deployable structure in which some mechanisms are installed as parts of structural elements. Structural elements are usually flexible ones, and the effects of flexibility are requested to be included in the rigid body mechanics. Thus adaptive structures technology is naturally requested and appeared in the interdisciplinary research field among “structure”, “mechanism” and “control”.Recent technology development especially in the field of large space structures requests the intelligent adaptive structures technology. Large space structures are “closed”, “free-free”, “flexible”, “low-damping” and “autonomous” structural systems. The intelligent adaptive structures technology naturally covers or is requested to cover these characteristics. For closed and free-free systems grovel optimization based on not only structural mechanics but also broad considerations including, for example, operational efficiencies which usually are not the elements of structural mechanics. For flexible and low damping systems active or semi-active functions are necessary, and for autonomous systems various analogies to existing biological systems are helpful, which is not the case for conventional structural mechanics. The intelligent adaptive structures technology covers necessary shape and vibration control functions for space structures, and some adjustable functions to compensate the uncertainty of ground testing for large space structures. It also directly leads to a new construction scheme for relatively large space structural systems. Health monitoring functions are also requested to general structures.