Mechanical Engineering Commons^™

Peridynamic Modeling Of Crack Propagation In Brittle Materials With Electromechanical Coupling, Semsi Coskun

Dissertations

The bond-based peridynamics (BB-PD) is a widely used peridynamic model in the literature. Despite Poisson's ratio restriction, it still serves as a powerful tool to solve challenging engineering problems with a relatively cheap computational cost. Consider the Poisson ratio of the material does not deviate from the ones that BB-PD can model. In that case, it becomes advantageous to use the BB-PD compared to other PD models in terms of computational cost and simplicity. However, the BB-PD suffers from the so-called surface or skin effect where the material response at boundaries becomes softer than the bulk material points. As a …

A Data-Driven Approach For The Investigation Of Microstructural Effects On The Effective Piezoelectric Responses Of Additively Manufactured Triply Periodic Bi-Continuous Piezocomposite, Wenhua Yang

Theses and Dissertations

A two-scale model consisting of ceramic grain scale and composite scale are developed to systematically evaluate the effects of microstructures (e.g., residual pores, grain size, texture) and geometry on the piezoelectric responses of the polarized triply periodic bi-continuous (TPC) piezocomposites. These TPC piezocomposites were fabricated by a recently developed additive manufacturing (AM) process named suspension-enclosing projection-stereolithography (SEPS) under different process conditions. In the model, the Fourier spectral iterative perturbation method (FSIPM) and the finite element method will be adopted for the calculation at the grain and composite scale, respectively. On the grain scale, a DL approach based on stacked generative …

Fabrication And Characterization Of Polyvinylidene Fluoride Nanofibers For Energy Harvesting Applications, Jui Vitthal Kharade

Theses and Dissertations

Miniaturization of portable devices demand a power source that does not require recharging or replacement. Piezoelectric energy harvesters are devices that harvest mechanical energy from environment and convert it into electrical energy thus being an ideal candidate for replacing batteries in small devices. Objective of this thesis is to fabricate an energy harvester with efficient energy conversion. In this thesis, the effect of fabricating mechanisms, solvents, and composites on polyvinylidene nanofibers are analysed in order to improve the piezoelectric response of the nanofibers. These nanofibers are then used for fabricating an energy harvester. The energy harvester is implemented in a …

Multidirectional Cylindrical Piezoelectric Force Sensor: Design And Experimental Validation, Ye Rim Lee, Justin Neubauer, Kwang Jin Kim, Youngsu Cha

Mechanical Engineering Faculty Research

A common design concept of the piezoelectric force sensor, which is to assemble a bump structure from a flat or fine columnar piezoelectric structure or to use a specific type of electrode, is quite limited. In this paper, we propose a new design of cylindrical piezoelectric sensors that can detect multidirectional forces. The proposed sensor consists of four row and four column sensors. The design of the sensor was investigated by the finite element method. The response of the sensor to various force directions was observed, and it was demonstrated that the direction of the force applied to the sensor …

Lead Free Piezoelectric And Triboelectric Energy Film For Energy Harvesting And Sensory Applications, Abu Musa Abdullah

Theses and Dissertations

In recent times, Triboelectricity and Piezoelectricity has been widely used for utilizing mechanical energy from ambient environment. Scientists are focusing towards developing advanced material composites for utilizing piezoelectricity and triboelectricity for energy harvesting and sensory applications. This work includes two projects regarding the application of lead free piezoelectric and triboelectric energy for energy harvesting and sensory applications. Human motion has been attributed as a source of mechanical energy to drive electronic devices and sensors through Triboelectric Nanogenerator (TENG). Based on the principles of single electrode TENG, we have developed a Triboelectricity based Stepping and Tapping Energy Case (TESTEC) which magnifies …

Phase Transitions In Monochalcogenide Monolayers, Mehrshad Mehboudi

Graduate Theses and Dissertations

Since discovery of graphene in 2004 as a truly one-atom-thick material with extraordinary mechanical and electronic properties, researchers successfully predicted and synthesized many other two-dimensional materials such as transition metal dichalcogenides (TMDCs) and monochalcogenide monolayers (MMs). Graphene has a non-degenerate structural ground state that is key to its stability at room temperature. However, group IV monochalcogenides such as monolayers of SnSe, and GeSe have a fourfold degenerate ground state. This degeneracy in ground state can lead to structural instability, disorder, and phase transition in finite temperature. The energy that is required to overcome from one degenerate ground state to another …

Predictive Modeling On The Piezoelectric Properties Of 3d Printed Functional Nanocomposites Using The Data Analytics Approach, Md Didarul Islam

Open Access Theses & Dissertations

This paper presents research done on prediction modeling using a data analytics approach to determine various factors affecting the piezoelectric properties of the 3D printed pressure sensors. Previously, the material extrusion 3D printing technique was used to fabricate pressure sensors composed of multiwall carbon nanotubes (CNT), barium titanate (BT), and polyvinylidene fluoride (PVDF) using simple fabrication and low-cost methods. This sensor produced a voltage output of 725 mV (0.13 pC/N) which is enough for pressure sensing applications. However, a holistic study to determine impacts of all factors was not carried out in the previous model. In this study, the design …

Designing And Testing 3-D Printed Wafer-Box With Embedded Pzt Sensors To Identify The Shape Effect On Energy Harvesting, Ahmad Jami Safayet

Electronic Theses and Dissertations

Piezoelectric energy has been recently paid attention in the field of alternative energy. Day by day the traditional energy sources including Coal tar and oils are becoming scarce. People are heading to an alternative energy source to meet the future energy demand. Piezoelectric energy is one of the competitive energy sources compared to the conventional renewable energy sources including solar, wind, and geothermal power and so on. This energy production method bears enormous research potential because it can be used as the roadway for a new method of power generation. This research project aimed to identify which shaped wafer-box produced …

Novel Transducer Calibration And Simulation Verification Of Polydimethylsiloxane (Pdms) Channels On Acoustic Microfluidic Devices, Scott T. Padilla

USF Tampa Graduate Theses and Dissertations

The work and results presented in this dissertation concern two complimentary studies that are rooted in surface acoustic waves and transducer study.

Surface acoustic wave devices are utilized in a variety of fields that span biomedical applications to radio wave transmitters and receivers. Of interest in this dissertation is the study of surface acoustic wave interaction with polydimethylsiloxane. This material, commonly known as PDMS, is widely used in the microfluidic field applications in order to create channels for fluid flow on the surface of a piezoelectric substrate. The size, and type of PDMS that is created and ultimately etched on …

Detecting Laminate Damage Using Embedded Electrically Active Plies – An Analytical Approach, Amany Micheal, Yehia Bahei-El-Din

Centre for Advanced Materials

Assessment of damage initiation and progression in composite laminates with embedded electrically active plies is modeled. Utilizing electrically active layers embedded in composite laminates as damage sensors is proposed by several researchers and is mainly assessed experimentally. Sensing damage using embedded electrically active plies is generally preferred over the use of surface mounted PZT wafers since the range of the latter is limited to a very narrow area underneath the surface, while multiple damage mechanisms can generally be found in several plies of the laminate. The solution presented invokes two levels of analysis. Firstly, on the laminate level, applied membrane …

Smart Nanocoated Structure For Energy Harvesting At Low Frequency Vibration, Sudhanshu Sharma

Electronic Theses and Dissertations

Increasing demands of energy which is cleaner and has an unlimited supply has led development in the field of energy harvesting. Piezoelectric materials can be used as a means of transforming ambient vibrations into electrical energy that can be stored and used to power other devices. With the recent surge of micro scale devices, piezoelectric power generation can provide a convenient alternative to traditional power sources. In this research, a piezoelectric power generator composite prototype was developed to maximize the power output of the system. A lead zirconate titanate (PZT) composite structure was formed and mounted on a cantilever bar …

Thermo-Mechanical Reliability Of Micro-Interconnects In Three-Dimensional Integrated Circuits: Modeling And Simulation, Omar Rodriguez

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Three-dimensional integrated circuits (3D ICs) have been designed with the purpose of achieving higher communication speed by reducing the interconnect length between integrated circuits, and integrating heterogeneous functions into one single package, among other advantages. As a growing, new technology, researchers are still studying the different parameters that impact the overall lifetime of such packages in order to ensure the customer receives reliable end products. This study focused on the effect of four design parameters on the lifetime of the interconnects and, in particular, solder balls and through-silicon vias (TSVs). These parameters included TSV pitch, TSV diameter, underfill stiffness and …

Connected Vibrating Piezoelectric Bimorph Beams As A Wide-Band Piezoelectric Power Harvester, Zengtao Yang, Jiashi Yang

Department of Engineering Mechanics: Faculty Publications

We analyze coupled flexural vibration of two elastically and electrically connected piezoelectric beams near resonance for converting mechanical vibration energy to electrical energy. Each beam is a so-called piezoelectric bimorph with two layers of piezoelectrics. The 1D equations for bending of piezoelectric beams are used for a theoretical analysis. An exact analytical solution to the beam equations is obtained. Numerical results based on the solution show that the two resonances of individual beams can be tuned as close as desired by design when they are connected to yield a wide-band electrical output. Therefore, the structure can be used as a …

Multiplexed Control Of Smart Structure Using Piezoelectric Actuators, Kumar S. Nale

ETD Archive

Active control of smart structures containing a large number of actuators and sensors presents a tradeoff between increased system performance and the cost and bulk of the required hardware and computational resources. A technique called multiplexed control offers advantages when software and hardware resources are scarce and performance specifications call for a large number of actuators and sensors. In structural control applications, in particular those using smart materials, it is often desirable to increase the number of actuators to enhance controllability.The focus of this research is to demonstrate real-time multiplexing on the hardware side of the actively controlled structure. Multiplexing …

Characterization And Modeling Of Local Electromechanical Response In Stress-Biased Piezoelectric Actuators, N. Navapan-Traiphol, Robert W. Schwartz, Daniel S. Stutts, J. Wood

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Numerous investigators have explored the factors that contribute to the high electromechanical performance of stress-biased actuators with particular attention being given to the importance of the extrinsic (domain wall translation) response mechanism. Based on the variation in lateral stress through the thickness of the piezoelectric layer within these devices, it has been suggested that the piezoelectric coefficient varies as a function of position within the layer, though no direct evidence has been previously presented. In this study, the results of Moire interferometry investigations of local strains within these devices are reviewed. The technique permits effective depth-profiling of local deformations at …