Civil Engineering ETDs

Publication Date

8-30-2011

Abstract

This research presents a novel, mechanically tunable sensor that utilizes the acoustic response of a polymer based acoustic bandgap (ABG) material to identify and quantify damage in material substrates. Acoustic bandgap (ABG) sensors are the mechanical analogues of semi-conductors by which a periodic array of differing acoustic impedances causes an acoustic bandgap. This is comparable to the periodic array of electronic potentials that cause an electronic bandgap in semi-conductors. An ABG sensor is composed of a host matrix material with a periodic array of inclusions/scatterers made of a material with dissimilar acoustic impedance. ABG sensors offer advantages to structural health monitoring (SHM) applications. Such advantages include sensor scalability which enables macro to sub-micron damage detection and the non-intrusive attachment of the sensor to substrates. The specific use of ABG sensors is proposed for areas of known damage already initiated (hot-spots) in critical components of a structure. This thesis examines the proposed use of ABG materials as sensors by showing experimentally and analytically how ABG can be used to detect and quantify change in the strain field of the substrate underneath. A parametric experimental study examines specimens composed of two host materials of low and medium elasticity, one viscoelastic and one elastic respectively. Four volume fractions are also considered for both host material types. A finite element simulation is employed to verify the experimental observations of the acoustic bandgap sensors and to demonstrate the functionality of the sensor.

Keywords

Structural health monitoring, Detectors.

Sponsors

Sandia National Laboratories

Document Type

Thesis

Language

English

Degree Name

Civil Engineering

Level of Degree

Masters

Department Name

Civil Engineering

First Advisor

Taha, Mahmoud

First Committee Member (Chair)

Walter, Gerstle

Second Committee Member

Timothy, Ross

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