Author: santon

Ryan Kettle successfully defended his Masters of Science degree in Mechanical Engineering entitled “Electromechanical Impedance Based Microsecond State Detection” on March 14, 2018.  Congratulations Ryan!

Abstract:

This thesis concerns the development of various technologies necessary to increase the speed of electromechanical impedance based state detection to the microsecond timescale. The eventual end goal of this research is the creation of a microsecond state detection system for structures operating in highly dynamic environments capable of monitoring the structure during dynamic events in real-time. Measurements are made using the electromechanical impedance method, which utilizes a piezoelectric transducer bonded to the surface of the structure as both an actuator and sensor. State detection is the process of continuously monitoring a structure with the goal of detecting and identifying any physical change that effects the structure and so is related to the field of structural health monitoring. Conventionally though, structural health monitoring is applied to large civil structures which undergo slow structural changes, such as crack propagation and creep; therefore both the measurements and time between measurements of the structure take place over large time scales. By decreasing the measurement time sufficiently physical changes occurring in a structure during dynamic events can be detected. This drastic decrease in measurement time will be achieved through the use of: a novel multi-tonal excitation signal, field-programmable gate arrays, and high-frequency MHz excitation signals. This work applies these methodologies to static structure and lays the foundations for further work to be done on dynamic testing.

DSSL presents one technical paper at the 2018 SPIE Smart Structures & Nondestructive Evaluation conference held March 5-8, 2018 in Denver, CO. Both Dr. Anton and Mohsen Safaei were in attendance.

• Safaei, M., Ponder, R. I., and Anton, S. R., Detection of Compartmental Forces and Location of Contact Areas with Piezoelectric Transducers in Total Knee Arthroplasty, Proc. SPIE, 2018, Vol. 10595, 105951Q (10 pp.)

DSSL presents two technical papers at the 2018 SEM IMAC conference held February 12 – 15, 2018 in Orlando, FL. Both Dr. Anton and Ekramul Ehite were in attendance.

• Ehite, E. H. and Anton, S. R., A Low-Cost Modular Impact-Based Experimental Setup for Evaluation of EMI Based Structural Health Monitoring at High Rates, Proc. SEM IMAC, 2018 (10 pp.)
• Kettle, R. A. and Anton, S. R., Multi-tonal Based Impedance Measurements for Microsecond State Detection, Proc. SEM IMAC, 2018 (7 pp.)

Edward Tefft successfully defended his Masters of Science degree in Mechanical Engineering entitled “A Coupled Electromechanical Model of Piezoelectret Foam in a Multi-layer Stack Configuration” on February 9, 2018.  Congratulations Edward!

Abstract:

Piezoelectric polymers, such as the Emfit polypropylene piezoelectret foam investigated in this study, have distinct advantages over traditional piezoceramics. Although piezopolymers have a smaller piezoelectric coupling coefficient when compared to piezoceramics, they are well suited for in vivo applications, having a lead-free composition, for applications with curved or flexible surfaces, being flexible, or where weight or large shocks are factors, being light weight and resilient. Presented here is a 20-layer flexible electret stack harvester design with no adhesive between layers, but that incorporates the Emfit foam electret material, composite graphene sheets as the electrode material, and Kapton tape as the encapsulation material. Also presented is an electromechanical, fully coupled, single degree of freedom model of the multilayer piezoelectret foam stack’s mechanical and electrical vibration responses to harmonic base excitation, including a cubic stiffness nonlinear factor. The model parameters are tuned to fit the experimental data through an iterative error minimization process, with the final model accurately representing the stack’s frequency response for a range of electrical load resistances on the stack. Finally, the energy harvesting capabilities of the electret stack are demonstrated by charging a 100 µF capacitor to 1.041 V in 15 minutes and a 1000 µF capacitor to 1.025 V in an hour.

DSSL welcomes undergraduate URECA! (Undergraduate REsearch and Creative Activity) grant winners Justin Carlson and Zach Tiberi to the lab. The title of their joint research project is “Parametric Testing of Surrogate Knee Replacement Bearings with Embedded Piezoelectric Transducers.”

DSSL PhD student Mohsen Safaei has won the Best Student Hardware Paper Competition and was runner up for the Best Student Paper Competition at the 2017 ASME Smart Materials Adaptive Structures and Intelligent Systems conference held September 18-20, 2017 in Snowbird, UT! Mohsen was awarded for his work entitled “Experimental Evaluation of Sensing and Energy Harvesting Behavior of Implanted Piezoelectric Transducers in Total Knee Replacement.” Students participating in the Best Hardware competition were judged based on their technical paper by a committee of smart materials and structures experts. Five finalists were selected and the overall winner was judged based on a poster presentation and demonstration of the developed hardware in a special session of the conference. Students participating in the Best Paper competition were judged based on their technical paper by a committee of smart materials and structures experts. Six finalists were selected and the overall winner was judged based on an oral presentation of the research in a special session of the conference. Congratulations Mohsen for this prestigious award!

DSSL presents two technical papers and one technical presentation at the 2017 ASME Smart Materials Adaptive Structures and Intelligent Systems conference held September 18-20, 2017 in Snowbird, UT. Both Dr. Anton and Mohsen Safaei were in attendance.

• Safaei, M. and Anton, S. R., Experimental Evaluation of Sensing and Energy Harvesting Behavior of Implanted Piezoelectric Transducers in Total Knee Replacement, Proc. ASME SMASIS, 2017, SMASIS2017-3881 (8 pp.)
• Ponder, R. I., Safaei, M., and Anton, S. R., Development of Surrogate Biomedical Knee Implants for Validation of Embedded Smart Sensors, Proc. ASME SMASIS, 2017, SMASIS2017-3879 (7 pp.)
• Ehite, E. H., Kettle, R. A., and Anton, S. R., Investigation of Various Excitation Signals for Real-Time Impedance Structural Health Monitoring, ASME SMASIS Conference, Snowbird, UT, September 19, 2017, SMASIS2017-3902

DSSL welcomes MS student, Robert Ponder.  Rob received the B.S. degree in Mechanical Engineering in 2017 from Tennessee Tech University. Rob previously participated as an undergraduate researcher in DSSL.  Welcome back Rob!

The DSSL lab volunteered at the innaugural “Invention Convention”, a free community STEM event held on Tennessee Tech’s campus and organized by the Cookeville Children’s Museum, on July 29, 2017. DSSL put on a 3D printing demonstration with free keychain and rocket giveaways!

DSSL PhD student Mohsen Safaei received the Best Poster Award for graduate research in Mechanical Engineering, and DSSL undergraduate researcher Robert Ponder received the Best Poster Award for undergraduate research in Mechanical Engineering at the 2017 TTU Research and Creative Inquiry Day. The awards were presented by Dr. Francis Otuonye, Associate Vice President for Research at TTU. Mohsen presented a poster entitled ““Smart Knee” – Instrumented Total Knee Replacement with Piezoelectric Transducers,” and Robert presented a poster entitled “Modeling and Prototyping of Artificial Knee Joint for Embedded Piezoelectric Transducers” Congratulations Mohsen and Robert!

TTU President Dr. Philip Oldham also stopped by to chat with DSSL researchers Ryan Kettle and Ekramul Ehite regarding their poster entitled “Investigation of Alternative Electromechanical Impedance Method for Condition Monitoring”!