Thesis (M.S. in mechanical engineering)--Washington State University, December 2006. / Includes bibliographical references (p. 102-107).

Thesis (M.S.M.E.)--Youngstown State University, 1998. / Includes bibliographical references (leaf 61).

Thesis (M.S.)--Ohio University, November, 1990. / Title from PDF t.p.

Thesis (M.S.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on March 19, 2008) Includes bibliographical references.

No description available.

Single Point Incremental Forming (SPIF) is a die-less sheet metal forming method. Because SPIF does not use custom tooling, this process allows for parts to be made at low cost and short lead times. In this thesis electric current is applied through the tool to alter the formability of samples formed with SPIF. The research goal of this work is to determine if formability is effected by resistive heating alone or if there is some formability change due to the current interacting with the material. An apparatus that allows electrical current to be applied through the tool during forming is designed and implemented. A method is also developed to allow the contact area between the tool and sheet to be estimated, with particular focus on developing a method that allows for experimental measurement. The effect of applied current on formability is estimated by evaluating the maximum wall angle that can be formed in a single pass, using a variety of tool sizes and current settings. Using the contact area model to estimate current density, a signicant increase in formability is found at a current density range that agrees with previously published literature on electrically assisted forming of the same material. The results show that across multiple tool sizes, a significant increase in formability is observed when applying a current density (A/mm2) larger than the current threshold density published in the literature. A study is also performed to test the performance of a set of novel tool shapes. By using parabolic tools, it was found that formability can be improved while maintaining low surface roughness. Finally, a series of case studies are presented documenting the production several parts for a variety of design groups and researchers at Queen's University. These case studies provide examples for the uses of SPIF, as well as document the methods used to produce these parts in greater detail than is present in the literature. / Thesis (Ph.D, Mechanical and Materials Engineering) -- Queen's University, 2013-11-29 16:06:51.964

Chapter 2 contains the continuum mechanical notions for the description of the plastic behavior of sheet metal under large deformations at room temperature. As such, it includes the kinematics of a continuum body, strain and stress definitions, and a general elasto-plastic constitutive model description. This last point is complemented by the definition of anisotropy, as well as the description of some yield criteria and hardening laws. Next, Chapter 3 defines the stress strain states required to be experimentally reproduced in order to describe the initial yield locus and its displacement in the stress axis representation during plastic deformation. A review of the available experimental equipment capable of reproducing the required stress strain states is presented in order to choose the best for further construction. After consideration, those deemed the highest performing are the Miyauchi device, able to perform simple shear tests and the bi-axial testing machine, able to perform plane strain and simple shear tests separately or simultaneously. This chapter presents the mechanical features of the Miyauchi device and the bi-axial test machine that were built at the M&S Laboratory, followed by a description of the optical strain gauge chosen that allows the computation of the strain field throughout the specimens deformation area. Chapter 4 focuses on the validation of the experimental equipment. First, the homogeneity of the stress and strain fields is verified. Then, the availability of performing the plane strain, simple shear, Bauschinger and orthogonal tests is checked. The repeatability (precision) of the tests is corroborated and the accuracy is validated by comparison with finite elements simulations. In Chapter 5, the identification methods are proposed and DC06 (0,8mm thick), DP1000 (1,6mm thick) and S320GD (0,69mm thick) steels are identified according to those methods. The initial yield surface for DC06 is identified by two methods (one using the strain measurements, the other using stress measurements) for two yield criteria, which are then compared with a texture-based yield criterion and the experimental points. The initial yield surface for the other two materials is described by the Hill 1948 yield criterion identified using strain measurements. The yield surface evolution (hardening) for DC06 and S320GD is described by the Teodosiu and Hu hardening law due to the observed mechanical behavior, i.e., the Bauschinger effect and strong influence of the pre-strain when strain-path changes take place. DP1000 exhibits a high Bauschinger effect and its flow stress is not influenced by the amount of pre-strain when reversing the load; hence, its behavior is described by a kinematic hardening law. Finally, in Chapter 6, conclusions about the present work are established and equipment improvement and further topics for research are proposed, namely, the study of texture evolution, the material axis rotation and the experimental validation of new yield criteria.

No description available.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2008. / Includes bibliographical references (leaves 72-75). Also available in electronic version.

Thesis (Ph. D.)--Ohio State University, 2003. / Title from first page of PDF file. Document formatted into pages; contains xvii, 155 p. : ill. (some col.). Advisors: June K. Lee, Robert H. Wagoner, and Mark E. Walter, Dept. of Mechanical Engineering. Includes bibliographical references (p. 141-147).