SMART COMPOSITES

PROCESS OF MAKING SMART COMPOSITES

Intelligent materials are those that exhibit coupling between their electromagnetic response and their thermomechanical response. This coupling allows smart materials to react mechanically e.g., an induced displacement to applied electrical or magnetic fields for instance. These materials find many important applications in sensors, actuators, and transducers.
The key to the process is the placing of mixtures of heat shrinkable synthetic and natural fibers in precise positions in the cross-section of pultruded profiles – notably rods and sheet. When subsequently cut to size, the rods or sheet elements are passed on belts through a series of heating zones for prescribed times which cause them to curl or twist into the shapes required. The process is economical since both the pultrusion stage and the thermal forming stage are continuous, not requiring manual intervention. It can be able to make shapes from straight rods and flat sheet feedstock which are either impossible to mould or very expensive to do so by conventional processes.

Fabrication And Characterization Of Thermomechanical Properties Of Smart Composite Materials

Smart materials have the ability to perform both sensing and actuating functions which sense a change in the environment and responds by altering one or more of its property coefficients. In this way, it can tune its sensing and actuating capabilities in time or space to optimize behavior. With the help of a feedback system, a very smart material becomes smarter with age. Typical smart materials are piezoelectric, magnetostrictive, shape memory, thermoelectric, electrorheological fluid. Smart composite materials can be obtained by mixing the metal and polymer matrix with smart material and used for health monitoring, active control and self-restoration of structural and functional materials. Compared to smart materials, smart composite materials have many technical issues such as uniform mixing, interfacial adhesion, and property characterization.




MAC/GMC Code Enhanced For Coupled Electromagnetothermoelastic Analysis Of Smart Composites

Interest has arisen in the development of smart composites that are formed via the combination of two or more phases, one or more of which is a smart material. To design with and utilize smart composites, designers need theories that predict the coupled smart behavior of these materials from the electromagnetothermoelastic properties of the individual phases. The micromechanics model known as the generalized method of cells (GMC) has recently been extended to provide this important capability. This coupled electromagnetothermoelastic theory has recently been incorporated within NASA Glenn Research Center's Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC). This software package is user friendly and has many additional features that render it useful as a design and analysis tool for composite materials in general, and with its new capabilities, for smart composites as well.
The initial sensing of a smart composite material can be achieved with optical fibers which can act as both sensor and data transmitter. There are a variety of fiber optic sensors which can measure such external forces as pressure, temperature, strain, and vibration. A key advantage with embedded optical fibers is that their small size does not greatly affect the mechanical properties of the composite reinforcement.
The study includes:
•    the manufacturing technology for the smart composite reinforcements, from hand lay-up fabrication to more automated processes such as pultrusion, filament winding, or tape laying;
•    the choice of appropriate fiber optic sensors;
•    interconnection of components;
•    application for the non-destructive testing and monitoring of structures; and
•    comparison with the traditional testing techniques.