Using carbon nanotubes for structural health assessment

If engineers can better understand the impact of hurricanes and earthquakes on structures, they could avoid lots of undesired consequences. Erik Thostenson and Thomas Schumacher, faculty members in the University of Delaware's Center for Composite Materials, explore the efficiency of carbon nanotubes, a material which can be used to reinforce structures.

Carbon nanotubes (CNTs) are long hollow cylinders of graphene, with great strength in axial direction. Young Modulus value is estimated from 270 to 990 GPa and the tensile strength from 11 to 63 GPa. 

A new technique- called electrical impedance tomography (EIT)-, is based on surface electrode measurements and estimates the conductivity of materials or structures. Moreover, EIT is applied to a carbon-nanotube-based sensor. This sensor can be adhered to any shape and evaluate the damage of the material or structure. In addition, its electrical properties are isotropic and as a consequence of this, it is mechanically strong.

The aim is to collect a number of one-dimensional measurements from a two-dimensional sensing space which can constitute the data of EIT maps. EIT maps are compared with thermographs developed using an infrared camera.

Also, the new technique is inexpensive, while it doesn't need a large quantity of CNTs. The new method's results are of course different from usual metrics used for damage assessment, nevertheless structural engineers, and notably Thostenson and Schumacher are trying to improve the accuracy of the technique.