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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Advanced monitoring system for bolted connections in vehicle construction

Buchmann, Macro January 2010 (has links)
Bolted connections where used from the beginning of vehicle construction for joining two or more parts. The reliability of bolted connections is still a major problem. The objective of this research thesis is focused on an advanced monitoring system for bolted connections in vehicle construction. A mechanical “vibrating test bench”, which was developed by the aeronautical engineer Mr. Junkers, is being adapted, to suite the requirements of the automotive industry. It is designed according to DIN 65151 standards. The bolted connection is tightened to a specific torque to achieve the required preload forces and then exposed to an oscillating elastic shear force. The preload force and their loss are measured in relation to the number of load cycles. The ideal locking mechanism would be, if no settling occurs. Realistic in practice is the remaining of a sufficient preload force which doesn’t decry with time. The aim of this thesis is, to gain knowledge that will assist in the future control of the bolt locking procedure. The test bench can be used to verify the clamping capability of a bolted connection. With the dynamic computer-aided test system it will also be possible to test critical bolted joints and their safety, which reduces the probability of costly product recalls, or even severe cases of failure.
2

The independent steering and driving vehicle: design, energy efficiency and parking analysis. / CUHK electronic theses & dissertations collection

January 2010 (has links)
After describing the development of the ISDV, this thesis studies the energy management which can improve the energy efficiency. It is shown that the traditional electric vehicle (EV) is not capable of managing the energy required for one driving cycle because it has only a single traction motor. This thesis proposes and examines a new way to manage electrical energy in which torque is distributed among different in-wheel motors to achieve a higher level of overall energy efficiency, which has been enhanced and demonstrated in various driving cycles. / Thereafter, the thesis studies two aspects of benefits the ISDV can bring to parking. One is in space efficiency, defined as the ratio of the total space occupied by the vehicle in its final parked state over the whole area covered by the parking lot. Comparison of the ISDV and traditional vehicles in parking proves that the ISDV afford a higher level of space efficiency. The other aspect is the parking time. It is tested experimentally in the hardware-in-loop (HIL) system, and the motions of traditional vehicles, the zero radius turning motion, and the free motion of the ISDV are compared. The less time for parking demonstrates the easiness to steer the ISDV. / Throughout the history of human civilization, vehicles have played a significant role by connecting people in various locations. They have thus boosted the progress of civilization and made our lives more convenient. However, as the number of vehicles on the road has increased, the convenience, which vehicles provide, has gradually turned into inconvenience in three respects: 1) the energy consumed by vehicles accounts for a large proportion of total energy consumption, which is in an ever-increasing trend; 2) more parking space is needed, a significant proportion of which is not for parking itself but for enabling the vehicle to be navigated to its final parking slot; 3) the effort required to park a car is also troublesome, causing the driver to spend much more time in a crowded parking lot. / To alleviate these three problems, I develop a methodology to design an independent steering and driving vehicle (ISDV). It brings together the robotic technologies of steer-by-wire, drive-by-wire, four-wheel-independent-steering, and four-wheel-independent-driving. All four wheels of the ISDV can be steered independently, so that vehicle rotation and translation can be decoupled from each other. Omni-directional motions such as zero radius turning (ZRT) and lateral parking (LP) are realized, thereby enhancing the agility of the vehicle. In contrast with omni-directional wheeled mobile robots, this vehicle is targeted at serving as a human carrier or even as a vehicle carrier in the future. / Qian, Huihuan. / Adviser: Yangsheng Xu. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 149-159). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
3

An investigation into the effectiveness of dynamic section control (inspection and rework) on the quality of the 3-series from the assembly plant at BMW (South Africa) (PTY.) Ltd.

Chantler, Jonathan January 1996 (has links)
A project report submitted to the Faculty of Engineering, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 1996. / This research project is an investigation into the effectiveness of an inspect and rework system called dynamic section control which has the purpose of improving the assembly quality of the BMW-3 series manufacturing in the Rosslyn Plant just outside Pretoria in South Africa, The system was introduced into the assembly plant in February 1995 to improve the assembly quality of the vehicles as quickly as possible. The main motivation behind the need for this system was to bring the quality onto the same level as the German plants in order to become recognised in the international network of BMW's manufacturing plants along with the new manufacturing plant in the USA The origins of the dynamic section control system come from the Munich 3-series plant as well as being based on the principles of poka yoke, a quality philosophy devised by the quality expert from Toyota in Japan, Shigeo Shingo, Defects found on the assembly plant's line, identified by the quality auditor and information from the marketing department regarding warranty claims are entered onto a checklist which is used by reworkers in the plant to inspect and make good the defects that have been found. The checklist is updated on a weekly basis, hence its name: dynamic section control. Seven rework stations, in which the dynamic section control reworkers work, have been strategically positioned in the assembly plant which trims the painted bodies it receives from the paint shop, The effectiveness of the system has been measured by analysing the information from the daily audits as well as investigating the trend of vehicles If rving the assembly plant still requiring rework and repairs off-line. The analyses were divided into three distinct periods. The first being approximately 4 months before the introduction of :he dynamic section control system, and the second and third periods after the introduction of the system. The results show that the dynamic section control system have a positive influence in improving the assembly quality of the vehicles, especially reducing the number of recurring defects. The number of defects that have only occurred once in each of the periods has remained reasonably constant indicating that the system has no impact in reducing the random occurrence of "one-off" defects. Another significant finding was. the increase in the number of vehicles requiring Department of Mechanical Engineering, University of the Witwatersrand repair off-line, attributable to the assembly plant, after the vehicle has left the assembly line. This increase is probably the result of an increased quality awareness within the assembly plant, resulting in reworkers identifying an increasing number of defects for repair off-line. Other factors such as clearer identification of production goals, training and development of a proportion of the assembly plant's workers in the German plants lor three weeks, reorganizing of support. staff by installing "the right people in the right place" and reducing the number of model derivatives in the plant have also contributed to the enormous quality improvement achieved. Further development of the. dynamic section control system is recommended by installing a rework station within each team area, and including the actions of dynamic section control in the work content of that team. Currently, the system uses external workers which are not part of individual teams as the current sections overlap team areas. Finally, it is recommended that the work of the dynandc section control reworker be incorporated as a noma! function within the team and be rotated amongst the team members. / AC2017

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