A multi-function material is a

composite material A composite or composite material (also composition material) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a ...

. The traditional approach to the development of structures is to address the load-carrying function and other functional requirements separately. Recently, however, there has been increased interest in the development of load-bearing materials and structures which have integral non-load-bearing functions, guided by recent discoveries about how multifunctional

biological system A biological system is a complex Biological network inference, network which connects several biologically relevant entities. Biological organization spans several scales and are determined based different structures depending on what the system is ...

s work.

Introduction

With conventional structural materials, it has been difficult to achieve simultaneous improvement in multiple structural functions, but the increasing use of

s has been driven in part by the potential for such improvements. The multi-functions can vary from mechanical to electrical and thermal functions. The most widely used composites have polymer matrix materials, which are typically poor conductors. Enhanced conductivity could be achieved with reinforcing the composite with

carbon nanotubes A carbon nanotube (CNT) is a tube made of carbon with a diameter in the nanometre range (nanoscale). They are one of the allotropes of carbon. Two broad classes of carbon nanotubes are recognized: * ''Single-walled carbon nanotubes'' (''SWC ...

for instance.

Functions

Among the many functions that can be attained are power transmission,

electrical Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by Maxwel ...

thermal conductivity The thermal conductivity of a material is a measure of its ability to heat conduction, conduct heat. It is commonly denoted by k, \lambda, or \kappa and is measured in W·m−1·K−1. Heat transfer occurs at a lower rate in materials of low ...

, sensing and actuation, energy harvesting/storage, self-healing capability, electromagnetic interference (EMI) shielding and recyclability and

biodegradability Biodegradation is the breakdown of organic matter by microorganisms, such as bacteria and fungi. It is generally assumed to be a natural process, which differentiates it from composting. Composting is a human-driven process in which biodegrada ...

. See also functionally graded materials which are

composite materials A composite or composite material (also composition material) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or physical properties and are merged to create a ...

where the composition or the microstructure are locally varied so that a certain variation of the local material properties is achieved.O. Kolednik, Functionally Graded Materials, 2008
However, functionally graded materials can be designed for specific function and applications. Many applications such as re-configurable aircraft wings, shape-changing aerodynamic panels for flow control, variable geometry engine exhausts, turbine blade, wind turbine configuration at different wind speed, microelectromechanical systems (micro-switches), mechanical memory cells, valves, micropumps, flexible direction panel position in solar cells, innovative architecture (adaptive shape panels for roofs and windows), flexible and foldable electronic devices and optics (shape changing mirrors for active focusing in adaptive optical systems).

References

{{emerging technologies, topics=yes, robotics=yes, manufacture=yes, materials=yes Composite materials Structural engineering Mechanics Mechanical engineering