Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 249-253).

Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2006. / Paul Griffin, Committee Member ; Hamid Garmestani, Committee Member ; Thomas Kurfess, Committee Member ; Steven Liang, Committee Member ; Shreyes Melkote, Committee Chair.

Thesis (Ph. D.)--University of Texas at Austin, 2004. / Supervisors: Lance Manuel and Karl H. Frank. Vita. Includes bibliographical references. Also available from UMI.

Thesis (Ph. D.)--Lehigh University, 2000. / Includes vita. Includes bibliographical references (leaves 124-128).

Thesis (M.F.A.)--Rochester Institute of Technology, 2009. / Typescript. Includes bibliographical references (leaf 48).

D.Ing. (Civil Engineering) / Please refer to full text to view abstract

The contribution of the clamping force in the technique used in this study to stretch-bend low carbon steel samples was investigated to support the subsequent changes in the microstructure and properties of the formed material with regard to parent material. Although plastic deformation by cold working is known to induce texture or preferred orientation to the grains of a formed material while decreasing its ductility and increasing the strength, as well as inducing residual stress, it is not known how the different directions (rolling, transverse and oblique/45°) of the sheet steel will respond to this stretch bending technique. The first part of the research work involved a thorough literature review on sheet metal forming processes and their effect on the formed material with interest on the above mentioned directions of the sheet. It became clear from the literature overview that cold working of a material will induce strain-hardening which varies with the magnitude of cold work, resulting in changes in the strength and ductility of the material. Besides, when plastic deformation is not uniform (e.g., tensile and compressive) throughout the entire cross section of the formed part, residual stresses remain in the material with the grains been elongated along the direction of the maximum strain. The main parameters that were considered and controlled in this study are as follows: strain experienced / stress induced into the form sample, the sample direction, the stroke length and the clamping torque, the generated radius of curvature. The chapters that follow the literature review, deal with the set-up of the different equipment used in this study, the specimen preparation as well as the recording, the calculation and interpretation of the results. It was found that the stress magnitude that generated the different radii of curvature (120 mm, 150 mm and 185 mm) was between 1 percent & 13 percent higher than the parent material’s yield strength with the lower stress been associated to the smaller radius of curvature and the higher stress to the higher radius. The stress induced into the sample during forming was not only proportional to the stroke length but also to the distance between the punch’s tip and the sample and the sample to the die’s nadir. The clamping torque adopted was restricted to the manual capacity of the operator who used a preset torque wrench to fasten the plate sample into the jig. Plate samples of low carbon steel were cut to angles of 0°, 45°, and 90° to the rolling direction of the sheet material and stretch-bent on a single-action mechanical press to 120 mm, 150 mm, and 185 mm radii of curvature. The preliminary results indicate that stretch-bent samples had increased hardness to the parent plate, in particular below the surface layers up to around 1.1 mm depth. Since there is a well established relationship between hardness, yield and tensile strengths for steel, the yield and tensile strengths of the formed material were estimated using the Nobre et al [34] incremental relation, which relates the linearity between relative increments of hardness and yield strength. Changes were not noticeable at the microstructural level of the formed samples. Meanwhile, samples from which higher plastic deformation stress values were calculated were not those absorbing higher impact energy when Charpy specimen cut from plate and stretch-bent samples were tested. The maximum relieved residual stress in the parent material was predominantly compressive and represents in magnitude approximately 12 percent (average for the three directions) of its original yield strength. In the stretch-bent samples, the relieved residual stress was compressive in the outer curved section with a magnitude about 50 percent of the parent material yield strength and tensile in the inner curved section with a magnitude approximately 25 percent of the parent material yield strength.

In Limit States Design for steel structures, single plate connections are designed to transfer beam shear to supporting member. These connections, with the connection plate shop-welded to the supporting member and field-bolted to the supported beam are becoming increasingly popular due to their economy and ease of fabrication. Single plate connections are very suitable for cases where speed of erection is a primary consideration. They are particularly superior for skewed connections. Traditional design methods which deal with connection problems generally give over-conservative solutions to this complex problem. Two series of experimental investigations of single plate connections for beam-to-girder webs were conducted. A variety of connections were tested to demonstrate their feasibility and to collect data for analytical correlation studies. The ultimate goal of these tests and studies is to devise a rational basis for the design of these connections. This work is part of a comprehensive research project and the reader is referred to other papers (References 1 and 2) for completeness. Based on experimental results and theoretical correlation studies, a modified design formula is proposed in order to predict the ultimate capacity of single plate connections. The formula tries to incorporate the influences of applied loads (shear force, torsional moment, and bending moment), resistance of the single plate connection, skew angle of the connection plate and type of holes (slotted and standard) used in the connection. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

D.Ing. (Electrical And Electronic Engineering) / Please refer to full text to view abstract

M.Tech. (Civil Engineering) / The results of an investigation on the local buckling of cold-formed stainless steel compression sections arc presented in this dissertation. The stainless steel under consideration is AISI Type 304 Austenitic, manufactured by the South African based speciality steel producing company Middelburg Steel & Alloys. All sections were manufactured by press braking process. The purpose of this investigation was to study the critical buckling stress and buckling coefficient (k), of cold-formed, partially stiffened stainless steel compression elements in order to determine the applicability of the current design specification. The mechanical properties of the stainless steel under consideration as well as the results of 28 partially stiffened double hat sections are compared with theoretical predictions. It was concluded in this study that the experimental results of the critical buckling stress compare well when using the plasticity reduction factor Es/Eo in the theoretical predictions. However the theoretical buckling coefficient (k) shows to be not representative to the experimental results obtained in this investigation.