Open Access. Powered by Scholars. Published by Universities.®
- Discipline
- Institution
Articles 1 - 4 of 4
Full-Text Articles in Engineering
Near-Field Pressure Distributions To Enhance Sound Transmission Into Multi-Layer Materials, Andrew Martin Jessop
Near-Field Pressure Distributions To Enhance Sound Transmission Into Multi-Layer Materials, Andrew Martin Jessop
Open Access Dissertations
The large impedance difference between air and most solids prevents significant energy transfer from incident acoustic waves across the air-material interface. Refraction also plays a role in preventing acoustic transmission, as the wave speed difference between air and solid materials results in an increase of the resulting propagation angles, creating near-field pressure distributions in the solid material. By utilizing evanescent pressure distributions, which decay normal to the usual direction of propagation and are represented as plane waves propagating with complex angles, energy propagation through the interface can be increased in the subsonic region of wave propagation: i.e., where waves typically …
Miniature, High Efficiency Transducers For Use In Ultrasonic Flow Meters, Meghna Saikia
Miniature, High Efficiency Transducers For Use In Ultrasonic Flow Meters, Meghna Saikia
Master's Theses (2009 -)
This thesis is concerned with the development of a new type of miniature, high efficiency transducer for use in ultrasonic flow meters. The proposed transducer consists of a thin plate of a suitable piezoelectric material on which an inter-digital transducer is fabricated for the generation and detection of plate acoustic waves. When immersed in a fluid medium, this device can convert energy from plate acoustic waves (PAWs) into bulk acoustic waves (BAWs) and vice versa. It is shown that this mode coupling principle can be used to realize efficient transducers for use in ultrasonic flow meters. This transducer can be …
Analyzing The Acoustical Properties Of Alternative Materials In Guitar Soundboards To Reduce Deforestation, Chris Dunn
Analyzing The Acoustical Properties Of Alternative Materials In Guitar Soundboards To Reduce Deforestation, Chris Dunn
Materials Engineering
To mitigate the effects of deforestation, man-made alternative materials were analyzed and tested for potential use in the soundboards of acoustic guitars. The materials evaluated included 0.06 in. foamed polycarbonate, 0.12 in. single-ply honeycomb fiberglass, and 0.04 in. epoxy fiberglass. The properties of Sitka spruce, the most common tonewood, were used as a benchmark. The Young’s modulus to density ratio found in Sitka spruce is relatively high, making its properties ideal for soundboard applications. Both Young’s modulus and density were necessary to calculate the acoustic constant of each material that was tested. The samples were subject to the impact of …
Vibration And Acoustic Properties Of Honeycomb Sandwich Structures Subject To Variable Incident Plane-Wave Angle Pressure Loads, Jiaxue Yan
All Theses
Honeycomb structures are widely used in many areas for their material characteristics such as high strength-to-weight ratio, stiffness-to-weight, sound transmission, and other properties. Honeycomb structures are generally constructed from periodically spaced tessellations of unit cells. It can be shown that the effective stiffness and mass properties of honeycomb are controlled by the local geometry and wall thickness of the particular unit cells used. Of particular interest are regular hexagonal (6-sided) honeycomb unit cell geometries which exhibit positive effective Poisson's ratio, and modified 6-sided auxetic honeycomb unit cells with Poisson's ratio which is effectively negative; a property not found in natural …