I. Granular Fiber Sensor for Distributed Large-Strain Measurements

In this research, we aim to develop a new type of rugged strain sensor based on one-dimensional granular crystals, enabling monitoring and sensing of distributed strains within a single granular fiber. This granular fiber sensor leverages the formation of acoustic solitons – a highly nonlinear mechanical wave – to achieve enhanced sensitivity and reliability. These acoustic solitons carry information about distributed strain fields along the fiber. The proposed granular fiber sensor can be employed as a novel instrument to test and measure the real-time, high-strain deformation of structures caused by blast, shock, and impact. With the view of future engineering applications, the granular fiber sensor can contribute to the creation of an intelligent, self-sensing structure that can assess its structural integrity with minimal human intervention to enhance the mission readiness and reduce the maintenance costs. 

II. Nonlinear Diagnostic Techniques for Inspecting Complex Structures

(Collaborators: Dr. Chiara Daraio, Caltech, Dr. Piervincenzo Rizzo, Univ. of Pittsburgh)

We propose to develop a novel method for airplane hot spot inspection by using acoustic solitons. Acoustic solitons are compactly-supported nonlinear waves with extremely high acoustic energy and remarkable robustness, fundamentally different from conventional linear elastic waves. In this study, we aim to construct a prototype of soliton-based sensor/actuator by assembling a one-dimensional chain of tightly packed granular particles, called granular crystals. To inspect a structural hot spot, we generate a single pulse of solitons and inject it into the inspection area to excite the local structure via direct mechanical contact. We obtain diagnostic information about the structural damage by analyzing the reflected solitons. In this novel NDE scheme, the granular crystal functions as a combined sensor and actuator by both exciting the host structure and recording the reflected solitons via an instrumented particle embedded in the granular chain.

III. Identification of Impurities in Granular Architectures Using Acoustic Solitons

(Collaborator: Dr. Lucy Yu, Univ. of South Carolina)

We experimentally investigate the transmission and reflection behavior of solitons in the region of the impurity embedded in granular architectures by using a laser Doppler vibrometer. We aim to establish a foundation to use highly nonlinear solitons as an efficient, nondestructive probing tool to identify impurities in granular media.

Previous Projects

Nonlinear Diagnostic Techniques for Inspecting Complex Structures

(@ Caltech)

In-vivo Characterization of Bone Mechanical Properties Using Granular Crystals

(@ Caltech, Collaborators: Dr. Edward Ebramzadeh and Dr. Sophia Sangiorgio, Los Angeles Orthopaedic Hospital)

Construction of Granular Crystal-based Acoustic Lens

(@ Caltech sponsored by DURIP)

Visualization of CAI (Compression after impact) for Composite Structures

(@ Think Composites)

Structural Health Monitoring of Thermal Protection Panels for Space Operation Vehicles

(@ Stanford University sponsored by the U.S. Air Force Research Laboratory and the Lockheed Martin Space Systems)

© University of South Carolina