Towards the validation of thermoacoustic modelling in aerospace structures

Sebastian, Christopher Towards the validation of thermoacoustic modelling in aerospace structures. PhD thesis, University of Liverpool.

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Abstract

The research presented in this thesis has been performed over the course of three years under funding from the European Office of the United States Air Force (EAORD) as a part of a long-term project to collect high quality data for the validation of computational mechanics models of thermoacoustic loading. The focus is on the adaptation of stereoscopic (3D) Digital Image Correlation for use in a combined thermal and high temperature measurements. To that end, a background is provided which highlights the current state of the art in high temperature, vibration experiments and data acquisition. A system is described in which a pulsed laser of duration 4 nanoseconds is used to capture high-quality displacement and strain data from vibrating components (PL- DIC). Based on this a novel method of capturing data from a component subjected to random excitation was developed. A laser vibrometer was used along with a custom LabVIEW program to trigger the pulsed laser relative to points of maximum velocity in the components vibration cycle. A dynamic calibration procedure was performed of both a high speed DIC system and the Pulsed-Laser DIC system to assess and compare the measurement uncertainty from the respective systems. It is crucial to know the uncertainty in experimental data when using it for the validation of computational models. A new way to validate computational models of vibration behavior using full-field DIC data and image decomposition is described. This is a phasic approach in which data from the entire cycle of vibration is used. The validation assessment is performed using the expanded uncertainty calculated and a concordance correlation coefficient. An example is provided using an aerospace component to validate four different simulation conditions of a modal frequency response model. An apparatus was designed and built which uses a 10 kW array of quartz lamps to reproduce some aspects of the heating provided by the Air Force test chambers. Experiments were performed in collaboration with the University of Illinois using induction heating and a small Hastelloy plate. A thermal buckling phenomena was observed using the PL-DIC system, the first full-field results of such.

Item Type:	Thesis (PhD)
Additional Information:	Date: 2015-05 (completed)
Subjects:	?? TA ?? ?? TJ ??
Depositing User:	Symplectic Admin
Date Deposited:	06 Aug 2015 12:00
Last Modified:	17 Dec 2022 01:26
DOI:	10.17638/02012079
URI:	https://livrepository.liverpool.ac.uk/id/eprint/2012079