Theses and Dissertations

Issuing Body

Mississippi State University


Shamsaei, Nima

Committee Member

Schneider, Judith A.

Committee Member

Jha, Ratneshwar

Committee Member

Novotny, Mark A.

Date of Degree


Original embargo terms


Document Type

Dissertation - Open Access


Mechanical Engineering

Degree Name

Doctor of Philosophy


James Worth Bagley College of Engineering


Department of Mechanical Engineering


Since their development in the early 1930’s, strain gauges have become an integral part of our lives. The amount of strain measured using strain gauges are the basis for calculating the corresponding: car engine torque, train rail forces, detection of traffic flow and vehicle type, and monitoring bridge safety. As the design of structural parts become more complex in geometry, the need for highly sensitive strain sensors are becoming more essential to ensure the vitality of structural parts. This is especially true when it comes to additive manufactured (AM) parts made from metals, polymers and composites. If sensors can be miniaturized, or even in some cases, be incorporated as part of the host structure, this will provide a non-intrusive monitoring method during the manufacturing process and subsequent service life of the part. However prior to the actual use of embedded sensors, more information is needed regarding the sensitivity of the geometry to the fidelity of the signal. The objective of this research was to explore the feasibility of signal outputs from carbon nanotube (CNT)/epoxy strain sensors and their ability to sense strains on structural components. This research evaluated (1) how percolation within the sensors was affected based on sensor array geometry, (2) various weight percent (w/w%) loading of CNTs required for signal output, (3) how the various w/w% loading affected the mechanical and electrical resistance and conductivity of the sensors and (4) the ability of the sensors to give the same signal output under repeatable cyclic loading.