Adaptronic structure

The system level - in the present example the entire motor vehicle -calls for the need to conceptualize during the creation of the adaptronic structure. For instance, the structural shape and damping characteristic of a shock absorber must harmonize with the overall design of a moving gear. Here again, the aim is to optimize the functionality of the entire system. 

The foregoing explanations show that a basis for adaptronic structures is created in numerous different disciplines of science. The range of applications covers various physical, but also chemical and biological technologies... 

The scope of the application of adaptronic structures or systems can be restricted as the spectrum of influential scientific disciplines. Almost each scientific field covers applications, whose technical benefit and business management utility can be improved by realizing adaptronic concepts. While the need for efficient multifunctional materials certainly originates in the high-technology area, the scope of application is by no means exclusively confined to this field. For example, multifunctional adjusting elements of shape memory alloys are successfully applied for the automatic control of ventilation flaps in greenhouses. 

Adaptronics as an overall concept for the development of adaptronic structures and systems is still a young discipline, which was only able to establish itself a few years ago. On the other hand, the research in the fields of multifunctional materials and multifunctional elements, which are the basic elements of adaptronics, started much earlier. The origins of adaptronics under a different name - go back to the early 1980s. Early progress came from the arms research sector, especially from various air forces. 

Fig. 2.1. The bio-inspired approach to adaptronic structures a active materials, b induced-strain actuators, c integrated active sensors d multifunctional composites, e microcontrollers...

The adaptronic approach would be one that would borrow directly from the biological world. Materials that behave more or less like muscles can be used in adaptronic structures and are called induced strain actuators. When energy is applied to the actuators, they attempt to expand/contract and work against any load that is applied to them. The actuators are typically bonded to the surface of a structure, or embedded within the material. This means that the artificial muscles must now work against the inherent structural impedance of the component, just as hmnan muscles are parallel to the skeletal structure or bone. However, whereas the arm has discrete joints about which rotation occurs, the adaptronic structure may be a continuum, thereby necessitating a distributed actuation system. For example, the tip motion of a beam will not occur by rotating the beam about a joint but by inducing its deformation by means of induced strain actuators placed on the beam. 

Adaptronic structures are complex systems displaying motion, sensing, and artificial intelligence functions synergistically to duplicate life-like functions. In line with the bio-inspired approach, we will consider in turn the actuators... 

Materials that allow an intelligent or smart structure to adapt to its environment are known as actuators. These materials have the ability to change the shape, stiffness, position, natural frequency, damping, friction, fluid flow rate, and other mechanical characteristics of adaptronic structures in response to changes in temperature, electric field, or magnetic field. The most common actuator materials are shape memory alloys, piezoelectric materials, mag-netostrictive materials, electrorheological fluids, and magnetorheological fluids [2]. Actuators with these materials will be described in detail in Sects. 6.2 to 6.6 therefore you will find only a brief overview below. 

Piezoelectric materials have found widespread use as sensors in adaptronic structures [4] (see Sect. 7.3). Piezoelectric ceramics and polymers pro-... 

Structural health monitoring (SHM), condition-based maintenance (CBM) and birth-to-retirement refer to the capability of using sensors throughout the life or an adaptronic structure to monitor its state of health and act ac-... 

Two of the three components in adaptronic structures, i. e., sensors and actuators, are made of single phase or composite functional materials. In order to design better adaptronic structures, it is necessary to know a little more about these functional materials and to understand their functional origin, which will allow us to use them more efficiently and help us design and fabricate new and better functional materials for adaptronic structures. 

These anomalies would be considered disastrous for many common materials since they signify breakdowns and instabilities. Such anomalies are, however, essential for constructing some of the adaptronic structures because they can provide clear signals to indicate the operating limits and can also respond in large amplitude to mend the damages caused by sudden environmental changes. 

Most adaptronic structures are used, or are intended to be used in macroscopic devices. In a single domain crystal system, macroscopic properties are simply the statistical average of microscopic properties of each miit cell. For most functional materials, however, such a simple average fails due to nonlocal interactions and the additional mesoscopic structures created at the intermediate length scale, such as domain patterns in single crystal systems and grain microstructures in ceramics. These nonlocal interactions and mesoscale structures often produce very strong extra enhancement to the functional proper-... 

---