Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 99-101). Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2003. / Typescript. Includes bibliographical references (leaves 99-101). Also available on the Internet.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1968.

Thesis (Ph. D.)--Institute of Paper Chemistry, 1959. / Bibliography: leaves 87-92.

Scientists are constantly seeking new and convenient non-destructive damage assessment techniques. In fact, a global market has developed for structural health monitoring products. Many of the currently available techniques are expensive and difficult to implement. An inexpensive alternative is technology based on strain memory alloys. These materials encompass a vast array of alloys, from austenitic stainless steels through to the extremely high strength TRIP steels. All, however, have in common the transformation from paramagnetic austenite to ferromagnetic martensite upon application of strain. The degree of ferromagnetism can be directly correlated to the peak strain undergone by the material. Strain memory alloys are not as expensive to manufacture as some smart materials, and in addition are capable of bearing significant load, and it is therefore possible to manufacture entire components from these alloys, thereby producing what is known as a smart component, i.e. one that is capable of doing the job of an ordinary component while at the same time assessing its own peak damage levels. A possible application of this technology is that of wing bolts for the Hercules e130 aircraft. The material usually used to manufacture the aircraft wing bolts is HSLA steel (AISI 4340). A strain memory alloy was therefore developed to match the mechanical properties of 4340 steel, while also having the requisite properties to perform the self damage-assessment. Ultra high strength TRIP steels were identified as possible candidates, and four alloys selected for investigation. These alloys were melted and then thermo-mechanically processed using a rolling operation. All alloys were tensile tested and magnetic susceptibility monitored. The final material selected possesses an ultimate tensile strength (UTS) of between 1270 and 1500 MPa with 10 to 12% elongation. The stress / strain induced transformation begins to occur before the yield point, which is important because bolts must be replaced before they fail. Compression tests were also performed, and yielded similar results to those of the tensile tests, with martensitic transformation again beginning before plastic yield. The strain induced phase transformation was confirmed not only by magnetic susceptibility measurements, but also by metallographic inspection before and after testing. A subscale Smart bolt was designed, manufactured and tested for magnetic sensitivity using a smart washer. / Thesis (Ph.D.)-University of KwaZulu-Natal, 2005.

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A survey is made of analytic, experimental and numerical techniques in the field of the dynamic initiation, and early propagation, of cracks. As no closed form analytic solutions exist for finite geometries, even in the elastic case, numerical and experimental techniques have to be developed. In instrumented impact tests plasticity often occurs. The specific problem of the Instrumented Charpy Test is discussed in detail by virtue of its technological significance and the extensive literature available for the test. Although a standard for the test has been proposed there are still outstanding questions to be answered, for which the techniques described above can be used. The problem of the dynamic calibration of various notched geometries is addressed in the original work of the thesis. The Charpy, Izod, Slender Cantilever and Double Notched Bar geometries are studied using dynamic photoelasticity and 8000 fps photography. It is shown that the response of the DNB is more straightforward than the Charpy geometry. Further photoelastic study of the latter two geometries, using epoxy model material and 10⁶ fps photography, gives a quantitative measure of the growth of stress intensity factor at the notch tips and hence a dynamic calibration is deduced. An explicit finite difference code is used to supplement photoelastic data. Having achieved progress in the derivation of the dynamic calibration of the two selected geometries, corresponding instrumented impact tests are then undertaken. The Hopkinson Pressure Bar method of loading is used. It is concluded that the proposed standard for the Instrumented Charpy Test is valid within limits but that there is a requirement for a dynamic calibration. Such a calibration is complex in the case of the Charpy geometry whereas a simpler geometry, viz. DNB, could prove to be more amenable to analysis and hence be more practical from the technological point of view.

Recent application of using spheres as carriers of LNG on ships has highlighted a lack of guidance given to the inclusion of imperfections and to the operating con- ditions imposed as a result of the motion of the ship. Spheres with a radius to thickness ratio of between 450 and 1700 were made by electrodeposition of copper on a wax former. Imperfections of three types were introduced: <ul><li>a) A local flat.</li><li>b) A zone of reduced curvature.</li><li>c) A bulge.</li></ul> These shells were tested under partial vacuum and the deformation at selected points monitored by proximity gauges. Buckling pressures were found to range between ⅕ and one-fifteenth of the theoretical value for a perfect shell. The experimental results were analysed on the basis of Koiter's imperfection theory and by a numerical computer solution. The former showed good agreement with types a) and b) and no agreement with type c); the latter showed little agreement with the experimental results. The ASME design code was found to be adequate for all imperfection sizes considered, BS 5500 only partly. Cast epoxy models with a radius to thickness ratio of 900, supported on an equatorial ring and partially filled with water, were subjected to vertical accelerations both normal and inclined to their equatorial rings. Buck- ling was detected by proximity gauges, and occurred as a result of tensile meridional and compressive circumferential stresses. The sphere was found to be imperfection insen- sitive and to be more susceptible to buckling at approximately ⅓ and ⅔ full for respectively the normal and inclined loading cases. Both a numerical com- puter solution and an analytical analysis were found to be in good agreement with the experimental results. Both the ASME and BS5500 design codes were however, found for this mode of failure to be too conservative for design purposes.

No description available.