ULTRASONIC GUIDED WAVES FOR HEALTH MONITORING OF HUMAN LONG BONES – MODELING AND EXPERIMENTS
Restricted (Penn State Only)
- Author:
- Guha, Anurup
- Graduate Program:
- Engineering Science and Mechanics (PHD)
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- February 25, 2022
- Committee Members:
- Parisa Shokouhi, Major Field Member
Clifford Lissenden, Chair, Minor Member & Dissertation Advisor
Michael Aynardi, Special Member
Daniel Cortes Correales, Outside Unit & Field Member
Gregory Lewis, Major Field Member
Albert Segall, Program Head/Chair - Keywords:
- Ultrasonic Guided Waves
Long Bones
Tibia
Frequency Domain
Wave-structure
partial-loading
omni-directional shear
tuning fork
SawBones
Stress Fracture
Eccentric Geometry
Time-domain
Bone Cement
Bone Ultrasound - Abstract:
- The current gold-standard for long bone health diagnosis include dual-energy Xray absorptiometry (DEXA) and quantitative computed tomography scans (QCT). These techniques involve subjecting patients to considerable amount of radiation, are available only at tertiary healthcare facilities, and incur very high expense. In addition, they do not provide information about the mechanical properties of the cortical bone. Ultrasonic guided waves-based health monitoring techniques are inherently sensitive to material and geometric changes of the medium in which they propagate, are ionizing radiation-free, and can be made readily portable with portable equipment. In the last couple of decades, considerable amount of work has been done in utilizing the benefits of ultrasonic guided waves towards characterizing long bone health. Although, a majority of these work rely heavily on plate and shell surrogates, they come short of realizing the true nature of the propagating ultrasonic guided wave modes in heterogeneous long bones over a long propagation range within the diaphysis. Focusing on tibia as our primary waveguide, my work characterizes the guided wave modes in tibia by utilizing the real geometry and realistic material property of tibial diaphysis. I demonstrate a sensitive transduction mechanism based on omni-directional shear transducers both using experimental setup and numerical analysis. The influence of geometric inhomogeneities pertaining to tibia is also studied in the low-phase velocity non-dispersive range, and their influence on propagating non-dispersive modes is investigated. Effect of presence of soft tissue on propagating low-phase velocity guided wave modes is also studied numerically. The natural frequency of synthetic tibia is evaluated both numerically and experimentally. Using this know-how, I give an idea of a nonlinear vibro-acoustic method as a modality to quantify stress fractures in tibial diaphysis. The average side-band peak is able to clearly distinguish between the different fracture conditions of the synthetic tibia (intact, partially fractured, completely fractured). The side-band peak is maximum for the completely fractured sample, and lowest for the intact sample. For the partially fractured samples, the presence of synthetic skin lowers the side-band peak. Throughout the dissertation, both frequency domain and time domain numerical techniques are used for numerical studies. For experiments, synthetic tibia is used in the majority of the investigation.