Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 144-147).

Thesis (Ph.D.) -- McMaster University, 2002. / Includes bibliographical references (leaves 168-178). Also available via World Wide Web.

published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

The structural behaviour of single shear bolted connections, double shear bolted connections and single shear screwed connections of thin sheet steels at elevated temperatures has been investigated in this study. The current design rules on bolted and screwed connections of thin sheet steels for cold-formed steel structures are applicable for ambient temperature condition only. These design rules may not be applicable for elevated temperature conditions. Therefore, design guidelines should be prepared for bolted and screwed connections of cold-formed steel structures at elevated temperatures. A total of 30 tensile coupon tests were conducted to investigate the material deterioration of the thin sheet steels at elevated temperatures, and also to determine the critical temperatures for connection tests. A total of 510 tests on single shear bolted connections, double shear bolted connections and single shear screwed connections of thin sheet steels at elevated temperatures was performed in the temperature ranged from 22 to 900?C using both steady state and transient state test methods. The test results were compared with the predicted values calculated from the North American, Australian/New Zealand and European specifications for coldformed steel structures. In calculating the nominal strengths of the connections, the reduced material properties of the thin sheet steels were used due to the deterioration of material at elevated temperatures. It is shown that the design strengths predicted by these specifications are generally conservative at elevated temperatures. Finite element models for single shear bolted connections, double shear bolted connections and single shear screwed connections were developed and verified against the experimental results. Explicit dynamic analysis technique was used in the numerical analyses. Extensive parametric studies that included 490 finite element specimens were carried out using the verified finite element models to evaluate the bearing strengths of bolted connections as well as the tilting and bearing strengths of screwed connections of thin sheet steels at elevated temperatures. Design equations for bearing strengths of bolted connections as well as design equations for tilting and bearing strengths of screwed connections were proposed based on both the experimental and the numerical results in the temperature ranged from 22 to 900?C. The bearing strengths of bolted connections as well as the tilting and bearing strengths of screwed connections obtained from the test specimens and the finite element analyses were compared with the predicted strengths calculated using the proposed design equations and also compared with the design strengths calculated using the current North American, Australian/New Zealand and European specifications with consideration of the reduced material properties at elevated temperatures. It is shown that the proposed design equations are generally more accurate and reliable in predicting the bearing strengths of bolted connections as well as the tilting and bearing strengths of screwed connections of thin sheet steels at elevated temperatures than the current design rules. The reliability of the current and proposed design rules was evaluated using reliability analysis. The proposed design equations are suitable for bolted and screwed connections assembled using thin sheet steels of thickness ranged from 0.35 to 3.20mm. / published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

No description available.

Thesis (Ph. D.)--University of Sydney, 2008. / Includes graphs and tables. Includes list of publications co-authored with others. Title from title screen (viewed November 28, 2008) Submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the School of Civil Engineering. Includes bibliographical references. Also available in print form.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xi, 106 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 101-106).

Thesis (M.S.)--Brigham Young University. School of Technology, 2007. / Includes bibliographical references (p. 57-59).

Adhesives have presently reached a stage where they have become part of everyday life both in a professional sense as well as for household applications. They offer advantages that in many respects surpass other joining processes such as bonding of large areas, joining a wide range and dissimilar materials; and without the need for special tooling or operator training, that is often required by many other joining processes. They are of course not a panacea to all fastening applications, but they can easily be described as the most versatile and most widely used joining method at present. Engineering applications have also benefited from the advantages offered by adhesives, but they are not as liberally used due to the severe consequences that may result from bond failure. Although adhesives can demonstrate their ability to fulfil the joining strength requirements under laboratory conditions, their application in industry proved to be not as reliable as expected. A number of parameters that can easily be controlled under laboratory conditions such as temperature, humidity, surface preparation and uniform adhesive application are not as easily observed in industry. Quality assurance during manufacturing can achieve excellent results; however even in these cases the probability of having adhesive bond defects is still present. Therefore, there is a need for post process inspection of adhesive bonds where risk levels require higher reliability than what is offered though process quality control. Adhesive bond inspection is a well researched area with respectable outcomes. Non destructive inspection techniques such as x-ray, thermal, and ultrasonic are well utilised in the inspection of adhesive bonds. However, despite all the effort in this area for more than forty years, there is still no singular technique that can achieve the confidence level required in some engineering applications. Therefore, the need for continuing research in the area of non-destructive evaluation of adhesive bonds is as necessary today as it�s ever been. The research presented in this thesis, continues in the same endeavour as many other researchers; that of achieving the ultimate technique in adhesive bond inspection, capable of reaching the confidence level required for all engineering applications. The research in the thesis commenced with coverage of adhesives used for engineering applications and a study of the adhesion science that was considered necessary to enable an informed approach to the problem. Adhesive bond failure is also analysed through a literature survey as well as experimental tests on standard specimens. At the completion of the literature survey and preliminary tests, a decision was taken to follow the ultrasonic path of non-destructive testing of adhesive bonds. The reasons for this, are clearly outlined in the main body of this thesis but in summary, the literature has shown that ultrasonic evaluation is the most widely used technique by industry. Therefore, improvements on data analysis using existing techniques that exploit ultrasonic inspection have the potential to reach the widest spectrum of industrial applications. Ultrasonic inspection equipment was sourced that was capable of achieving experimental results to the accuracy level required in this research. A precision test rig was designed and constructed that was subsequently calibrated using computer based statistical techniques to ensure the validity of all results. Other ancillary equipment, such as a portable tensile testing device were also designed and constructed during the research as it became necessary. Research concentrated on techniques found to be inadequately researched in this domain. The first technique evaluated was to measure bond quality through the stress distribution in adherent and adhesive. Computer based Finite Element Analysis showed that the ability to detect variation in stress distribution at the adhesion interface is capable of revealing the local bond strength. Having found that there is no technique available at present that can measure the stress distribution at the interface, a different direction was taken that showed potential in achieving excellent quantitative results in the analysis of ultrasonic signals from adhesive bonds. This technique was rigorously evaluated and the results are systematically reported in this work.

This thesis explores the elastic behaviour of the mechanical double action press and draw die system commonly used to draw sheet metal components in the automotive industry. High process variability in production and excessive time spent in die try-out are significant problems in automotive stamping. It has previously been suggested that the elastic behaviour of the system may contribute to these problems. However, the mechanical principles that cause the press system to affect the forming process have not been documented in detail. Due to a poor understanding of these problems in industry, the elasticity of the press and tools is currently not considered during the die design. The aim of this work was to explore the physical principles of press system elasticity and determine the extent to which it contributes to problems in try-out and production. On the basis of this analysis methods were developed for controlling or accounting for problems during the design process. The application of frictional restraining force to the edges of the blank during forming depends on the distribution and magnitude of the clamping force between the binders surfaces of the draw die. This is an important control parameter for the deep drawing process. It has been demonstrated in this work that the elasticity of the press and draw die can affect clamping force in two ways. The response of the press system, to the forces produced in the press during forming, causes the magnitude of clamping force to change during the stroke. This was demonstrated using measured data from a production press. A simple linear elastic model of the press system was developed to illustrate a definite link between the measured force variation and the elasticity of the press and tools. The simple model was extended into a finite element model of the complete press system, which was used to control a forming simulation. It was demonstrated that stiffness variation within the system could influence the final strains in a drawn part. At the conclusion of this investigation a method is proposed for assessing the sensitivity of a part to clamping force variation in the press during die design. A means of reducing variation in the press through the addition of a simple linear spring element is also discussed. The second part of the work assessed the influence of tool structure on the distribution of frictional restraining forces to the blank. A forming simulation showed that tool stiffness affects the distribution of clamping pressure between the binders. This was also shown to affect the final strains in a drawn part. However, the most significant influence on restraining force was the tendency of the blank to increase in thickness between the binders during forming. Using a finite element approximation of the try-out process it was shown that the structure of the tool would also contribute to the problems currently experienced in try-out where uneven contact pressure distributions are addressed by manually adjusting the tool surfaces. Finally a generalised approach to designing draw die structures was developed. Simple analysis methods were combined with finite element based topology optimisation techniques to develop a set of basic design guidelines. The aim of the guidelines was to produce a structure with uniform stiffness response to a pressure applied at the binder surface. The work concludes with a recommendation for introducing the methods developed in this thesis into the standard production process.