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Showing 1 to 20 of 64 for “"piezoelectricity"”.
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Piezoelectric response of bone and tendon subjected to inhomogeneous stress
… they obey the classical or standard theory of piezoelectricity. However, this thesis shows that when bone and tendon are subjected to in-homogeneous stress, as in cantilever bending, they do not obey the classical piezoelectric theory, although the piezoelectric minerals quartz and tourmaline …
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Electrostatic effects of inhomogeneous strain in monolayer transition metal dichalcogenides
… behavior. In this work, inhomogeneous strain and piezoelectricity in transition metal dichalcogenides are studied. We first examine the luminescence behavior of monolayer MoS₂ and WSe₂ in the presence of strain and strain gradients generated via nanoindentation. The strain distribution and …
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Analytical Modeling and Equivalent Electromechanical Loading Techniques for Adaptive Laminated Piezoelectric Structures
… lamination theory, and the linear theory of piezoelectricity. Finite element approximations are used with the principle of minimum potential energy to derive the static equilibrium equations for piezoelectric laminated structures. Equivalent loading techniques are derived based on the …
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Size-dependent Electroelastic Properties of Piezoelectric Nanoplates
… to fulfill the design and application of those piezoelectricity-based nanodevices. Due to large surface to volume ratio and manifest strain gradients typically present in nanostructures, surface effects and flexoelectricity are commonly believed to be responsible for the size-dependent …
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Theory of piezoelectric materials and their applications in civil engineering
… moment that an actuator, whose energy comes from piezoelectricity, can develop when attached to a beam. As a piezoelectric material cannot generate much energy, and often requires amplification, the goal is to optimize the circuit linked to the piezoelectric material to obtain as much power as …
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Preparation and investigation of polymer-foam films and polymer-layer systems for ferroelectrets
… and internal quasi-permanent dipole moments. The piezoelectricity of ferroelectrets stems from linear changes of the dipole moments in response to external mechanical or electrical stress. Over the past two decades, polypropylene (PP) foams have been investigated with the aim of ferroelectret …
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Understanding new regimes for light-matter interactions
… nanostructured materials. We will show that bone piezoelectricity may be a source of intense blast-induced electric fields in the brain, with magnitudes and timescales comparable to fields with known neurological effects, and may play a role in blast-induced traumatic brain injury. We will also …
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Interplay of Electrical, Mechanical and Thermal Fields in III-N Nanostructures for LED Applications
… on the optical transition rates; (3) to model piezoelectricity in the wurtzite lattice, we have considered four different polarization models (based on the experimental /bulk and ab initio coefficients) in increased order of accuracy; (4) to study the origin and effects of these four competing …
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Using Macro-Fiber Composite Actuators for Aquatic Locomotion
… incorporates Euler-Bernoulli beam theory, linear piezoelectricity, and fluid mechanics is developed to predict the thrust generated by the beam vibration. Experimental testing is performed to verify aspects of, as well as recommend corrections to, the analytical model. A prototype carangiform …
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Electro-mechanically interfacing with biology using piezoelectric polymer nanostructures
… and that the nanowires displayed shear piezoelectricity with an estimated piezoelectric coefficient $d_{14} = 8$ pC/N. This was the first observation and quantification of shear piezoelectricity in PLLA at the nanoscale. FEA was used to show that hollow nanotube structures would more …
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Multiphysics Modeling And Simulation Process To Develop Thin Piezoelectric Film Sensors To Measure The Vibration Of Structures With Complex Shapes And Boundary Conditions.
<p>Piezoelectricity was discovered in 1880 by Jacques and Pierre Curie. Its application has since been extended to actuators and sensors, widely used in industry, automotive, and aerospace applications. The last two decades have seen intensive research in piezoelectric theory in an effort to …
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Characterization of Nanoporous Polyvinylidene Fluoride (PVDF) Sensors under Tensile Loading
… process. To improve the material’s piezoelectricity, a Polyvinylidene Fluoride (PVDF) sensor with integrating nanoporous structures was developed and fabricated. Several sets of samples with different porosities from 0% to 42.0% were made. The porosity effect on the sensor samples …
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Physics of electrical degradation in GaN high electron mobility transistors
… tensile stress in the AlGaN layer due to piezoelectricity of the material.
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CRYSTAL STRUCTURE ENGINEERING FOR IMPROVED PERFORMANCE OF EMERGING NANOSCALE DEVICES
… based model to gauge the importance of nonlinear piezoelectricity on the single-particle electronic states and interband optical transitions in emerging In(Ga)N/GaN disk-in-wire LED structures having c-plane and m-plane wurtzite crystal symmetry. (3) Coupling the NEMO 3-D software toolkit with a …
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Surface functionalization of graphene devices
… chemical properties, such as bandgap opening and piezoelectricity engineering, etc. Hydrogenation and fluorination have been experimentally demonstrated to be effective in changing the hybridization state of carbon atoms and opening a bandgap from 2.9 eV to 5.4 eV. However, both of these methods …
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Investigation of Zinc Oxide Nanowires for Impedance Based Structural Health Monitoring
The goal of this work is to investigate the piezoelectricity of composite laminates embedded with layers of zinc oxide (ZnO) nanowires. ZnO nanowire embedded composites have the potential to sense and actuate giving the potential for these smart composites to serve the function of being load …
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Optimization of a Plate Beam System for Energy Harvesting Using a Piezoelectric Material
… The study begins with an in depth explanation of piezoelectricity, its fundamental concepts, operational mechanisms, and various applications. Next, the phenomenon of flutter is explained in detail as it is essential for identifying conditions where vibrations can be harnessed for energy …
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A tight-binding analysis of the electronic properties of III-nitride semiconductors
… origins of spontaneous polarisation and piezoelectricity as well as attempting to accurately calculate the values and coefficients associated with these phenomena. We first develop an analytic model for the polarisation of a one-dimensional linear chain of atoms. We compare the zincblende …
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Interfacial Properties of Graphene and 2D Materials Heterostructures Investigated by Scanning Probe Microscopy
… with PFM, which revealed a new source of piezoelectricity in graphene layers that arises from the presence of interfacial dipole moments induced by the polarization in the substrate. The last part of the dissertation discusses the interfacial mechanical properties of graphene deposited …
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Model reference control for ultra-high precision positioning systems
… of ultra-high precision positioning using piezoelectricity has become an important area because of its high displacement resolution, wide bandwidth, low power consumption, and potential low cost. However, the relatively small displacement range limits its application. This work proposed a …
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