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Bbt Acoustic Alternative Top Bracing Cadd Data Set-Norev-2022jun28, Bill Hemphill

STEM Guitar Project’s BBT Acoustic Kit

This electronic document file set consists of an overview presentation (PDF-formatted) file and companion video (MP4) and CADD files (DWG & DXF) for laser cutting the ETSU-developed alternate top bracing designs and marking templates for the STEM Guitar Project’s BBT (OM-sized) standard acoustic guitar kit. The three (3) alternative BBT top bracing designs in this release are
(a) a one-piece base for the standard kit's (Martin-style) bracing,
(b) 277 Ladder-style bracing, and
(c) an X-braced fan-style bracing similar to traditional European or so-called 'classical' acoustic guitars.

The CADD data set for each of the three (3) top bracing designs includes …

Development And Validation Of A Vibration-Based Sound Power Measurement Method, Cameron Bennion Jones

Theses and Dissertations

The International Organization for Standardization (ISO) provides no vibration-based sound power measurement standard that provides Precision (Grade 1) results. Current standards that provide Precision (Grade 1) results require known acoustic environments or complex setups. This thesis details the Vibration Based Radiation Mode (VBRM) method as one approach that could potentially be used to develop a Precision (Grade 1) standard. The VBRM method uses measured surface velocities of a structure and combines them with the radiation resistance matrix to calculate sound power. In this thesis the VBRM method is used to measure the sound power of a single-plate and multiple plate …

Distributed Sensing And System Identification Of Cantilever Beams And Plates In The Presence Of Weak Nonlinearities, Patrick Sean Heaney

Mechanical & Aerospace Engineering Theses & Dissertations

While the mathematical foundation for modal analysis of continuous systems has long been established, flexible structures have become increasingly widespread and developing tools for understanding their mechanics has become increasingly important. Cantilever beams and plates, in particular, have been extensively studied due to their practical importance as approximations of more complex structures. The focus of this thesis is on understanding the dynamics of vibrating cantilever beams and plates through analytical and experimental investigation. Various models for the mechanics of these structures, of varying physical fidelity, are described and compared. A fiber optic sensing system is utilized to experimentally acquire distributed …

Hole Size, Location Optimization In A Plate And Cylindrical Shell For Minimum Stress Points Interfacing Ansys And Matlab, Soundararaj Thangavel

Mechanical and Aerospace Engineering Theses

Discontinuities in Structures are inevitable. One such discontinuity in a plate and cylindrical shell is presence of a hole / holes. In Plates they are used for mounting bolts where as in Cylinder / Pressure Vessel, they provide provision for mounting Nozzles / Instruments. Location of these holes plays a primary role in minimizing the stress acting with out any external reinforcement. In this Thesis work, Location Parameters are optimized for the presence of one or more holes in a plate and cylindrical shell interfacing ANSYS and MATLAB with boundary constraints based on the geometry. Contour plots are generated for …

Analysis Of Transient Natural Convection Flow Past An Accelerated Infinite Vertical Plate, Innovative Research Publications Irp India, Kaprawi S.

Innovative Research Publications IRP India

This work describes a vertical hot plate moves with acceleration and with variation wall temperature. The temperatures of the plate decrease with the increase of velocity of the plate. The temperature and velocity are given by the governing equations. The dimensionless equations of the problem have been solved numerically by the finite difference method. The temperature and the velocity profiles against several parameters like Prandtl Number, Grashoft number and time are presented. The results show that the temperature and velocity profiles are significantly influenced by Prandtl and Grashoft number.

Biomechanical Performance Of Variable And Fixed Angle Locked Volar Plates For The Dorsally Comminuted Distal Radius, Patrick Atkinson, D. Martineau, J. Shorez, C. Beran, A. G. Dass

Mechanical Engineering Publications

Background

The ideal treatment strategy for the dorsally comminuted distal radius fracture continues to evolve. Newer plate designs allow for variable axis screw placement while maintaining the advantages of locked technology. The purpose of this study is to compare the biomechanical properties of one variable axis plate with two traditional locked constructs.

Methods

Simulated fractures were created via a distal 1 cm dorsal wedge osteotomy in radius bone analogs. The analogs were of low stiffness and rigidity to create a worst-case strength condition for the subject radius plates. This fracture-gap model was fixated using one of three different locked volar …

Analysis Of Degenerative Cervical Spondylolisthesis And Corrective Orthopaedic Implants, Tyler Heck

Honors Theses

Back pain is often due to the degeneration of intervertebral discs, which can lead to a condition known as spondylolisthesis, whereby a vertebra slips out of position in the anteroposterior direction. There are numerous orthopaedic implants which are used by surgeons to correct this condition; however, there has been no conclusive research conducted in comparing the efficacies of these implants. In the cervical spine, this condition most commonly occurs over two levels. For the purposes of this study, an implant’s efficacy depends on its ability to return the slipped vertebra back into natural position immediately after surgery. To test these …

Thickness-Shear And Thickness-Twist Vibrations Of Circular At-Cut Quartz Resonators, Huijing He, Jiashi Yang, Qing Jiang

Department of Mechanical and Materials Engineering: Faculty Publications

Exact solutions for free vibration frequencies and modes are obtained for thickness-shear and thickness-twist vibrations of unelectroded circular AT-cut quartz plates governed by the two-dimensional scalar differential equation derived by Tiersten and Smythe. Comparisons are made with experimental results and the widely-used perturbation solution by Tiersten and Smythe under the assumption of weak in-plane anisotropy. Our solution is found to be much closer to the experimental results than the perturbation solution . For the frequency of the fundamental thickness- shear mode, the error of the perturbation method is 0.4549%, significant in resonator applications.

Thickness-Shear Vibration Of A Rectangular Quartz Plate With Partial Electrodes, Huijing He, Jiashi Yang, John A. Kosinski, Ji Wang

Department of Mechanical and Materials Engineering: Faculty Publications

We study free vibration of a thickness-shear mode crystal resonator of AT-cut quartz. The resonator is a rectangular plate partially and symmetrically electroded at the center with rectangular electrodes. A single-mode, three-dimensional equation governing the thickness-shear displacement is used. A Fourier series solution is obtained. Numerical results calculated from the series show that there exist trapped thickness-shear modes whose vibration is mainly under the electrodes and decays rapidly outside the electrodes. The effects of the electrode size and thickness on the trapped modes are examined.

Effects Of Mode Coupling On The Admittance Of An At-Cut Quartz Thickness-Shear Resonator, Huijing He, Jiashi Yang, Wei-Ping Zhang, Ji Wang

Department of Mechanical and Materials Engineering: Faculty Publications

We study the effects of couplings to flexure and face-shear modes on the admittance of an AT-cut quartz plate thickness-shear mode resonator. Mindlin’s two-dimensional equations for piezoelectric plates are employed. Electrically forced vibration solutions are obtained for three cases: pure thickness-shear mode alone; two coupled modes of thickness shear and flexure; and three coupled modes of thickness shear, flexure, and face shear. Admittance is calculated and its dependence on the driving frequency and the length/thickness ratio of the resonator is examined. Results show that near the thickness-shear resonance, admittance assumes maxima, and that for certain values of the length/thickness ratio, …

Assess The Accuracy Of The Variational Asymptotic Plate And Shell Analysis Using The Generalized Uni, Luciano Demasi, Wenbin Yu

Mechanical and Aerospace Engineering Faculty Publications

The accuracy of the Variational Asymptotic Plate and Shell Analysis (VAPAS) is assessed against several higher order, zig zag and layerwise theories generated by using the invariant axiomatic framework denoted as Generalized Unified Formulation (GUF). These theories are also compared against the elasticity solution developed for the case of a sandwich structure with high Face to Core Stiffness Ratio. GUF allows to use an infinite number of axiomatic theories (Equivalent Single Layer theories with or without zig zag effects and Layerwise theories as well) with any combination of orders of the displacements and it is an ideal tool to precisely …

Analysis Of Electrically-Forced Vibrations Of Piezoelectric Mesa Resonators, Huijing He, Guo-Quan Nie, Jin-Xi Liu, Jiashi Yang

Department of Mechanical and Materials Engineering: Faculty Publications

We study the electrically forced thickness-shear and thickness-twist vibrations of stepped thickness piezoelectric plate mesa resonators made of polarized ceramics or 6-mm class crystals. A theoretical analysis based on the theory of piezoelectricity is performed, and an analytical solution is obtained using the trigonometric series. The electrical admittance, resonant frequencies, and mode shapes are calculated, and strong energy trapping of the modes is observed. Their dependence on the geometric parameters of the resonator is also examined.

Experimental Determination Of Colburn And Friction Factors In Small Plate Heat Exchangers With High Surface Enlargement Factors, Andrew H. Pike

Masters Theses

Experiments were conducted to measure the performance of several small brazed plate heat exchangers. A test apparatus was designed and constructed that allowed for the easy switching of the plate heat exchangers, as well as having the ability to electronically monitor and record the inlet and outlet temperatures, pressures, and flow rates. The flow rates and applied electrical power were controlled electronically by the same program which recorded the data. De-ionized water was used as the heat transfer medium to reduce the uncertainty related to fluid properties.

An existing mathematical model was used to create Colburn and friction factors based …

Analysis Of A Monolithic Crystal Plate Acoustic Wave Filter, Huijing He

Department of Mechanical and Materials Engineering: Faculty Publications

We study thickness–shear and thickness–twist vibrations of a finite, monolithic, AT-cut quartz plate crystal filter with two pairs of electrodes. The equations of anisotropic elasticity are used with the omission of the small elastic constant c56 . An analytical solution is obtained using Fourier series from which the res-onant frequencies, mode shapes, and the vibration confinement due to the electrode inertia are calculated and examined.

Effects Of A Mass Layer With Gradually Varying Thickness On A Quartz Crystal Microbalance, Nan Liu, Jiashi Yang, Weiqiu Chen

Department of Mechanical and Materials Engineering: Faculty Publications

We study the effects of the nonuniform thickness of a thin mass layer on a quartz crystal microbalance. A theoretical analysis is performed on thickness-shear vibration of an AT-cut quartz plate with a nonuniform mass layer. Mindlin’s two-dimensional equation for thickness-shear vibration of a quartz plate is used. Free vibration frequencies and modes are obtained. The effects of the mass layer nonuniformity are examined. It is shown that resonant frequencies and energy trapping of thickness-shear modes are sensitive to mass layer nonuniformity.

Piezoelectromagnetic Waves In A Ceramic Plate Between Two Ceramic Half-Spaces, S. N. Jiang, Q. Jiang, X. F. Li, S. H. Guo, H. G. Zhou, J. S. Chang

Department of Mechanical and Materials Engineering: Faculty Publications

We analyze the propagation of piezoelectromagnetic waves guided by a plate of polarized ceramics between two ceramic half-spaces. An exact dispersion relation is obtained, which reduces to a few known elastic, electromagnetic, and quasistatic piezoelectric wave solutions in the literature as special cases. Numerical solutions to the equation that determines the dispersion relation show the existence of guided waves. The results are useful for acoustic wave and microwave devices.