Inaug.-diss.--Rostock. / Lebenslauf.

Inaug.-diss.--Rostock. / Lebenslauf.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 143-145). Also available via the Internet.

Thesis (M. Diploma (Mechanical Engineering))--Cape Technikon, 1992. / Radius hardening on journals of forged steel Diesel engine crankshafts is performed in order to increase fatigue life characteristics. This requirement may be necessary if the demands for engine power are to be increased, but where the existing crankshaft design is close to its fatigue limit, such that an increase in loading will cause it to'fail. Induction hardening of journal radii changes the make-up of the material from a coarse to a fine crystalline structure which alters the features of crack propagation. As a consequence of this higher loads can be applied onto the crankshaft without ultimately resulting in catastrophic material failure. Extending the induction hardened zone from the bearing surfaces into the radii of journals, culminates in process difficulties which are not experienced in non-radius hardened Hardening of journal radii induces crankshafts. as well as releases stresses in the crankshaft webs. This results in a deformation of the crankshaft which can be measured in the form of journal runout. Such a problem cannot be overcome by straightening the crankshafts in order to reduce runout, since this will cause Straightening hand induces the radii to crack once hardened. in the unhardened state on the other stresses which will be released again after hardening. This results in an increase in runout. High runout indicates that stresses have been induced into the crankshaft material. This is undesirable since this will make critical manufacturing processes such as grinding, governing of journal lengths, uncontrollable. It can furthermore result in creep of the crankshaft long after the manufacturing date. This results in crankshaft deformation, noticeable through an increase in runout. Since the crankshaft cannot be straightened after hardening, the consequence is that it will be unusable. The process must therefore be developed in such a manner, that all variables which can contribute towards stress induction resulting in journal 'runout, must be investigated and resolved.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2012. / Our planet is continuously being depleted of its natural resources leading to a need to conserve energy and the environment. One of the major energy consumers is the conventional internal combustion engine. Many attempts have been made to make these conventional internal combustion engines more efficient focusing mostly on the combustion side of the engine. The focus of this study is on the modification of the reciprocating and rotating components of the sub-assembly of a conventional internal combustion engine. An in-depth review was carried out on the fundamentals of spark ignition internal combustion engines and savings on fuel consumptions. A prototype single piston internal combustion engine was developed that can adjust its stroke length. Lengthening or shortening the stroke and simultaneously extending or retracting the connecting rod's travel distance, allows the internal combustion engine to function very efficiently consequently reducing the free space between the piston and cylinder head at TDC position. This allows the internal combustion engine to alter its power capability on demand whilst maintaining relatively high compression efficiency. The method of altering the stroke length is achieved by manipulating gears situated internally and externally of the engine sub-assembly. The control of these eccentric gears lowers or lifts the crankshaft in a radial motion. The eccentrics also control the automatic extension or retraction of the connecting rod's travel distance. The externally concentric gears control the mechanism that allows the internal combustion engine to change its capacity easily as adapted for automation. This study does not extend into the automation issues of the external mechanism. The prototype engine that was built could not endure vigorous testing and it failed after running for a short while. The primary focus had been on the kinematics of the engine mechanism - and to show whether the idea was feasible. The engine passed the kinematics test but failed possibly due to dynamic loads. Investigating this requires measuring instantaneous temperatures from which peak pressures can be deduced. This was not done because it was outside the scope of the project.

Progress in Industrial Engineering has consistently been closely associated with progress in measurement. The accuracy required for interchangeable parts in modern precision equipment became a reality only after years of development, refinement, and research in the field of measurement. The Standard Units for linear dimensions were at one period in history such inaccurate measures as “width of a man's hand", "the length of a man's foot", or "the normal reach of a man’s arm", When accurate standards based on the Standard Yard were comparatively recently accepted universally, there remained a serious problem in developing instruments that would measure small divisions accurately. Mass production has emphasised the paramount importance of human relations in industry. Understanding and agreement between individuals demand an accurate measure of human effort and accomplishment. Time Study with primary emphasis on Work Simplification has proven so near the answer that it has been subject to unwarranted claims and therefore unjust criticism. Instruments for measuring the accomplishment of individuals have been developed to securities beyond ordinary demand. However, the level of performance of the individual remains purely a matter of human judgement, unless supported by extensive data taken from the measurement of a large number of individuals representing a true cross section of industrial workers. Industrial Engineers have developed remarkable skill in judging the performance of individuals in relation to that which can be expected from the average worker who has been reasonably selected and reasonably trained, but similar skill might have been developed in judging the ”width of the average man's hand" or "the length of the average man's arm". An equitable measure of the time required to perform specific tasks demands a generally accepted standard that can be applied directly to the motions used in performing the task. We would then have a unit of measure with no more reason for objection than there might be today by someone who thought the yard should be somewhat longer or somewhat shorter than the accepted standard. / Master of Science

The original objectives of this thesis were two: 1.) to investigate the accuracy of standard time values for cranking motions determined by other persons and groups, and, 2.) to establish standard time values for cranking motions of diameters 11, 13, 15, 17, 19, 21, 22, 23, and 24 inches respectively. / Master of Science

Master of Science

Originally presented as the author's Thesis--Universität Karlsruhe. / Includes bibliographical references.

The detection of cracks in structural components and the evaluation of their sizes without the need of removing them from the machine in which they are placed is very important for preventing failures. The objective of this thesis is to study the effects of cracks on the dynamic behavior of shafts under acceleration or deceleration, in order to find methods or procedures capable of detecting the presence of cracks prior to failure. The equations of motion for a simply supported Bernoulli-Euler shaft are developed following Wauer's formulation. Galerkin's Method is used to obtain five-term approximate solutions. The first two natural frequencies are found for both the uncracked and cracked shaft. A computer program is written to perform the numerical integration of the equations. The shaft is subjected to several constant accelerations and decelerations. Tables and figures showing the results are presented along with discussions and comments related to the different runs made and the results obtained. The effect of the initial position angle of the eccentricity is studied to find the influence of this parameter. The effects of crack position and crack depth on the dynamic behavior of the shaft are also included in this work. Time histories and summary graphs are presented to make easier the interpretation of the results. Final conclusions and future research proposals complete the work done in this thesis. / Master of Science