Thesis (M.S.)--Oregon State University, 1977. / Includes bibliographical references (p. 47-49). Also available on the World Wide Web.

Thesis (M.S.)--West Virginia University, 2006. / Title from document title page. Document formatted into pages; contains x, 111 p. : ill. (some col.), map (part col.). Includes abstract. Includes bibliographical references (p. 93-94).

M.Sc. (Mechanical Engineering) / Please refer to full text to view abstract

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The rail dynamics modeling package NUCARS has been used extensively to model freight cars. We have found that it can also be used effectively to model freight locomotives. This thesis discusses the development of a NUCARS model to represent a six-axle freight locomotive equipped with steerable trucks. This includes separating it into a set of individual bodies, representing the suspension components as inter-body connections, and validation of the computer model. This model is then used to conduct a study of the impact on tangent track stability and curving performance of varying suspension parameters. It is found that the presence of damping in the system improves hunting stability, while increasing wheel conicity is harmful to stability and varying the flexicoiling stiffness has little effect. In curving, the clearances between the axles and truck frame are very important. Limiting these clearances in the steerable truck causes it to curve similar to a conventional straight locomotive truck and increases both the track force ratios and angles of attack. Increasing the wheel conicity increases an axle's tendency to align with the track and improves the locomotive's curving performance. The lateral stiffness of the inter-axle links and inter-motor links has little effect on the curving of the locomotive. / Master of Science

Traffic signal violations by drivers are a leading contributor to crashes at signalized intersections. The yellow indication is used to inform drivers of an upcoming change in the status of the traffic signal. Yellow-interval durations are currently calculated to provide dilemma zone protection for passenger cars. Due to differences in vehicle characteristics and driver characteristics, heavy trucks such as tractor-trailers behave differently at the onset of a yellow-indication. The research presented in this thesis characterizes the difference in driver behavior between truck and light-duty vehicle driver behavior at the onset of yellow-indication and then revises the yellow timing procedures to address the truck requirements. A dataset of 910 stop-go records was collected using a truck driving simulator located at the Virginia Tech Transportation Institute (VTTI). Participant drivers were placed in a simulated urban environment with a speed limit of 45 MPH and instructed to drive as they would regularly drive in such a situation. Participant drivers were recruited using the VTTI participant database. Using the data collected as part of this research effort, statistical models were created to model driver perception-reaction times (PRTs) and deceleration levels considering driver attributes (age) and the time to the intersection at the onset of yellow. The data collected, along with the statistical models developed were compared to data collected and statistical models created by the same research organization in 2008 in a similar study of passenger car driver behavior. Lastly, a Monte-Carlo simulation was conducted to develop appropriate yellow indication timings to provide adequate dilemma zone protection for trucks. / Master of Science

M.S.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005. / In this document the reduced order simulation and optimisation of the passive suspension systems of a locally produced forty ton articulated dump truck is discussed. The linearization of the suspension parameters were validated using two and three dimensional MATLAB models. A 24 degree-of-freedom, three dimensional ADAMS/VIEW model with linear parameters was developed and compared to measured data as well as with simulation results from a more complex 50 degree-of-freedom non-linear ADAMS/CAR model. The ADAMS/VIEW model correlated in some aspects better with the experimental data than an existing higher order ADAMS/CAR model and was used in the suspension system optimisation study. The road profile over which the vehicle was to prove its comfort was generated, from a spatial PSD (Power Spectral Density), to be representative of a typical haul road. The weighted RMS (Root Mean Squared) and VDV (Vibration Dose Value) values are used in the objective function for the optimisation study. The optimisation was performed by four different algorithms and an improvement of 30% in ride comfort for the worst axis was achieved on the haul road. The improvement was realised by softening the struts and tires and hardening the cab mounts. The results were verified by simulating the optimised truck on different road surfaces and comparing the relative improvements with the original truck’s performance.

South African heavy vehicles are currently designed according to prescriptive standards designed and enforced by the National Department of Transport (DoT); these standards are regulated in terms of mass, dimensions and vehicle configuration. However, the current prescriptive standards leave little room for innovation in terms of heavy vehicle design. Performance Based Standards, or PBS, is a new Australian based innovative alternative to the current heavy vehicle prescriptive standards, mass, dimensions and vehicle configuration. PBS seeks to align actual vehicle performance efficiencies, productivity and safety objectives as well as road and bridge infrastructure to the current road network. Vehicle performance measures are based on engineering and science, supporting superior safety and known road and bridge wear performance criteria. PBS produces “a result orientated approach” to improved heavy vehicle operations and safety rather than a „one size fits all approach‟ utilised by the current prescriptive legislation. Currently, dynamic vehicle simulations are not carried out on South African manufactured vehicle combinations. Evidence exists that this has, in some cases, resulted in safety compromises. The computer dynamic vehicle simulation technology developed and validated could be employed for the credible assessments of the vehicle design concepts/prototypes for compliance with PBS. This service, which includes vehicle performance simulation and testing, development of high productivity vehicle concepts, assessment and development of risk management strategies, advice on safety and productivity issues, would have a substantial commercialisation potential for the implementation in the larger transport industry in South Africa. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2009.