This MEng (Master of Engineering) research thesis evaluates the capabilities and limitations of line-scan thermography for the non-destructive evaluation of composite structures containing hidden defects. In simple terms, line-scan thermography is a state-of-the-art technique in which a focused line of thermal energy is transmitted into a material. Line-scan thermography has great potential for the rapid and low cost non-destructive inspection of composite structures for aircraft, automobiles and ships. In this project, theoretical research exploring the heat transfer physics was undertaken in conjunction with experimental studies to develop an optimum inspection regime for line-scan thermography. The capability of line-scan thermography to detect impact damage in carbon/epoxy laminates was experimentally investigated in Chapter 3. From the impact side, in all materials, line-scan thermography overestimated the size of the impact damage whereas flash thermography underestimated the size. There was a close relationship between the ultrasonic profile and the line-scan thermographic thermal response curve. New experimental data has been produced and analysed for the ability of line-scan thermography to determine the defect as well as the defect size. It was found that line-scan thermography was able to distinguish back drilled holes, but it was not possible to determine accurate defect sizing due to the depth of the holes from the inspected surface and the limitations associated with the line-scan thermographic apparatus itself. There was excellent correlation between the C-scan ultrasonics intensity curves and the line-scan thermographs as well as excellent correlation with the theoretical results. The relationship between line-scan thermography and foreign body objects were experimentally investigated for carbon/epoxy composites. A major limitation found with line-scan thermography is its limited depth penetration, which is highlighted in the foreign object study using 6 mm and 13 mm diameter Teflon® discs and 13 mm Teflon® strips embedded in carbon/epoxy laminates. Depth penetration allowed only 2 mm resolution for the 13 mm diameter discs and 1.5 mm resolution for the 6 mm discs in a composite panel. The results of the investigation of stainless steel shim objects in carbon/epoxy laminates reveal that line-scan thermography is capable of determining their presence and size close to the surface. There was also excellent correlation between the ultrasonic response curve and the line-scan thermographic intensity curve. The results of the investigation of thermoplastic film foreign body objects in carbon/epoxy laminates show that at present line-scan thermography does not have the capability to determin e such defects. Experimental results show that line-scan thermography is capable of detecting large voids, back drilled holes, some foreign body objects, and impact damage. However, the ability of line-scan thermography to measure the defect dimensions is dependent on the size and type of damage, the distance from the line source, the depth of the defect, and the type of composite material.

Little is known about the spatial distribution and abundance of tree holes in New Zealand’s native forests, or the invertebrate communities that they support. I found that tree holes were common on five endemic tree species, belonging to the families Fagaceae and Podocarpaceae in the mixed broadleaf-podocarp rainforest of Orikaka Ecological Area, Buller District, New Zealand. However, tree holes were not uniformly distributed throughout the forest, with more holes found on the three podocarp species, Prumnopitys ferruginea, P. taxifolia and Dacrycarpus dacrydioides, than on Nothofagus fusca or N. menziesii. Nevertheless, Nothofagus fusca had the largest holes of any of the tree species sampled and larger trees generally had larger holes. Large, hole-bearing Nothofagus fusca trees support a specialist hole-dwelling vertebrate fauna in New Zealand and worldwide, tree holes provide habitat for a range of invertebrate species. Using specially-designed emergence traps, I collected invertebrates emerging from naturally-occurring dry tree holes and compared this assemblage with invertebrates inhabiting leaf litter on the forest floor and those dispersing aerially throughout the study area. At the higher taxonomic resolution (i.e., Order or Class), community composition within the tree holes was highly variable, and there was no strong distinction between invertebrates from tree holes, leaf litter or Malaise traps. Moreover, although some beetle species emerging from tree holes were found exclusively in tree holes, most of these were represented by a single individual. Consequently, only minor differences in species composition were detected between beetle assemblages from tree holes, leaf-litter and those aerially dispersing throughout the forest. In contrast, the aquatic invertebrate assemblage within water-filled tree holes was highly distinctive from that in ground-based freshwater ecosystems, with only six aquatic taxa in common between all freshwater habitats. Using experimental water-filled tree-hole microcosms, I found that species richness and community composition within these microcosms were primarily driven by resource concentration, although habitat quality (i.e., water chemistry parameters) was also an important determinant of the identity and composition of colonising species. Overall, my study has shown that tree holes are common in the study area, and are likely to be more abundant in New Zealand’s indigenous forests than previously thought. Moreover, these generally small, discrete forest ecosystems support a diverse array of terrestrial invertebrates as well as a distinctive aquatic invertebrate community that is primarily structured by organic matter resource availability. These findings not only represent an important advance in our knowledge of New Zealand’s freshwater invertebrate biodiversity, but also highlight the need for further investigation into these unique forest canopy habitats which may well be at risk from deforestation and land use change.

Thesis (Ph.D.)--University of Melbourne, School of Physics, 2001. / Typescript (photocopy). Includes bibliographical references (leaves 124-135).

Thesis (Ph.D.) - University of St Andrews, January 2008.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [108]-114).

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1997. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisor: Richard Matzner. Vita. Includes bibliographical references. Available also from UMI company.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (p. 90-94).

Thesis (Ph.D.)--Victoria University of Wellington, 2009. / Includes bibliographical references.