In this thesis a parameter recovery method for use in ultrasound elasticity imaging is developed. Elasticity imaging is a method for using a series of ultrasound images (and the displacement field between them) to estimate the spatial variation of the stiffness of the tissue being imaged. Currently iterative methods are used to do this: a model of tissue mechanics is assumed and a large number of simulations using varying parameters are compared to the actual displacement field. The aim of this work is to develop a solution method that works back from the known displacement field to determine the tissue properties, reducing the number of simulations that must be performed to one. The parameter recovery method is based on the formulation and direct solution of the 2-d linear elasticity inverse problem using finite element methods. The inverse problem is analyzed mathematically and the existence and uniqueness of solutions is described for varying numbers of displacement fields and appropriate boundary conditions. It is shown to be hyperbolic (and so difficult to solve numerically) and then reformulated as a minimization problem with hyperbolic Euler-Lagrange equations. A finite element solution of the minimization problem is developed and implemented. The results of the finite element implementation are shown to work well in recovering the parameters used in numerical simulations of the linear elasticity forward problem so long as these are continuous. The method is shown to be robust in dealing with small errors in displacement estimation and larger errors in the boundary values of the parameters. The method is also tested on displacement fields calculated from series of real ultrasound images. The validity of modelling the ultrasound elasticity imaging process as a 2-d problem is discussed. The assumption of plane strain is shown not to be valid and methods for extending the parameter recovery method to 3 dimensions once 3-d ultrasound becomes more widely used are described (but not implemented).

A small gas gun, capable of accelerating a projectile 1m long by 25.4mm diameter to about 50 m/s, and an extended split Hopklnson bar apparatus have been designed and constructed for the tensile impact testing of fibre reinforced composite specimens at strain rates of the order of 1000/s. Elastic strain measurements derived from the Hopkinson bar analysis are checked, using strain gauges attached directly to the specimen and the validity of the elastic moduli determined under tensile impact is confirmed. Epoxy specimens reinforced with plain-weave fabrics of either carbon or glass or with several hybrid combinations of the two in various lay-ups, giving five different weight fractions of reinforcement from all-carbon to all-glass, have been tested in tension at three strain rates, nominally, ~10^-3/s, ~10/s and ~10³/s. The effect of both hybrid composition (volume fraction of carbon reinforced plies) and applied strain rate on the tensile modulus, the tensile strength and the strain to fracture is determined and a limited hybrid effect is observed in specimens with a carbon volume fraction in the approximate range 0.6 to 0.7 where, at all three strain rates there is an enhancement of the failure strain over that for the all-carbon plies and an increased failure strength, most marked in the impact tests, over that predicted by the rule of mixtures. The fracture surfaces of specimens are examined by optical and scanning electron microscopy and the failure process in the hybrid composites is related to that found in the all-carbon and the all-glass specimens. The classical laminated plate theory and the Tsai-Wu strength criterion are used to predict the stiffness and strength of the hybrid composites from the elastic and strength properties of the constituent plies. Analytical predictions are in good agreement with experimental measurements.

Bibliography: leaves 91-95. / x, 155 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / This thesis contains methods of solution for a number of different problems within the area of the elasticity of anisotropic materials. The first problem concerns the calculation of stresses and strains within a concentric arrangement of cylindrical shells, where each shell has a differing set of anisotropic properties. This has immediate application to the design of yacht masts, and the particular example of the "Moth" yacht mast is considered. The second problem considered is the uncoupled thermo-elastic problem, where a boundary element method is derived for solving the class of boundary value problems governing plane thermo-elastic deformations of isotropic and anisotropic materials. The final class of problems deals with mixed boundary value problems in which the stresses become singular at some points, for instance in elastic problems containing cracks. / Thesis (Ph.D.)--University of Adelaide, Dept. of Applied Mathematics, 1998

Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.D.S.)--University of Adelaide, 1983. / Some ill. mounted. Includes bibliographical references (leaves 97-107).

Diss. Karlstad : Karlstads universitet, 2007.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (M.S.)--University of Texas at El Paso, 2008. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (Ph. D.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 106-113). Also available on the World Wide Web.

Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Jianmin Qu; Committee Member: David McDowell; Committee Member: Elisa Riedo; Committee Member: Min Zhou; Committee Member: Mo Li.