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Ultrasonic Non-Destructive  Testing of Fibre Reinforced  Composites

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thesis
posted on 12.11.2021, 14:02 by Thomson, Matthew

This thesis focuses on the application of high frequency ultrasound as a tool for performing non-destructive testing for pultruded fibre reinforced composite (FRC) rods. These composite rods are popular in the manufacturing, construction and electrical industries due to their chemical, electrical and strength properties. Such FRCs are manufactured on automated production lines that operate day and night. Non-destructive testing techniques are desired to quickly and accurately detectmanufacturing flaws such as coating thickness irregularities and surface cracks. Layers and cracks can present as large changes in acoustic impedance and will strongly reflect ultrasonic waves. Combined with their low cost, east of use and absense of potentially harmful radiation, ultrasound has proven popular worldwide for Non-Destructive Testing. Finite Element Analysis (FEA) was employed to investigate the propagation of ultrasonic waves through layers of material to simulate a thickness measurement and the ability of ultrasound to measure thicknesses was proven. Experimental work was conducted on two fibre reinforced composite samples with varying thickness coatings of plastic and paint. The thickness was measured accurately using immersion transducers at 50MHz and a resolution of 20μm was attained through the use of matched filtering techniques. Surface acoustic waves, particularly Rayleigh waves were investigated using FEA techniques so that the generation, scattering and detection of such waves was understood. This lead to the development of methods for detecting surface cracks in glass using Rayleigh waves and these methods were successfully used in experimental work. Wave propagation in fibre reinforced composites was modelled and experimentally investigated with the results confirming theoretical expectations. Finally a Rayleigh wave was launched onto a fibre reinforced composite sample however the amount of energy leakage into the water was so great, due to the acoustic impedance of water, the detection of the wave was prevented. The conclusion reached was that an immersion setup was not appropriate for launching a travelling Rayleigh wave.

History

Copyright Date

01/01/2012

Date of Award

01/01/2012

Publisher

Te Herenga Waka—Victoria University of Wellington

Rights License

Author Retains Copyright

Degree Discipline

Physics

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level

Masters

Degree Name

Master of Science

Victoria University of Wellington Item Type

Awarded Research Masters Thesis

Language

en_NZ

Victoria University of Wellington School

School of Chemical and Physical Sciences

Advisors

Gouws, Gideon; Harris, Paul