This thesis investigates the principle of integration of vehicle dynamics control systems by proposing a novel control architecture to integrate the brake-based electronic stability control (ESC), active front steering (AFS), normal suspension force control (NFC) and variable torque distribution (VTD). A nonlinear 14 degree of freedom passive vehicle dynamics model was developed in Matlab/Simulink and validated against commercially available vehicle dynamics software CarSim. Dynamics of the four active vehicle control systems were developed. Fuzzy logic and PID control strategies were employed considering their robustness and effectiveness in controlling nonlinear systems. Effectiveness of active systems in extending the vehicle operating range against the passive ones was investigated. From the research, it was observed that AFS is effective in improving the stability at lower lateral acceleration (latac) region with less interference to the longitudinal vehicle dynamics. But its ability diminishes at higher latac regions due to tyre lateral force saturation. Both ESC and VTD are found to be effective in stabilising the vehicle over the entire operating region. But the intrusive nature of ESC promotes VTD as a preferred stability control mechanism at the medium latac range. But ESC stands out in improving stability at limits where safety is of paramount importance. NFC is observed to improve the ability to generate the tyre forces across the entire operating range. Based on this analysis, a novel rule based integrated chassis control (ICC) strategy is proposed. It uses a latac based stability criterion to assign the authority to control the stability and ensures the smooth transition of the control authority amongst the three systems, AFS, VTD and ESC respectively. The ICC also optimises the utilisation of NFC to improve the vehicle handling performance further, across the entire operating regions. The results of the simulation are found to prove that the integrated control strategy improves vehicle stability across the entire vehicle operating region.

In a research study, which focused on a strategy to link informal and formal motor mechanic artisan training, a number of constraints leading to the shortage of artisans in general were identified in the literature. Disparities between big businesses and the informal sector were highlighted. Emphasis was placed on the need for a growth initiative, which would include the informal practising motor mechanic, to address the key constraints and obstacles encountered in the development and implementation of artisan training for South Africa. The study was explorative and a qualitative research design followed. The researcher used semi-structured interviews to collect data from 16 (n = 16) experts in the field of training automotive artisans. A purposive snowball sampling method was applied to select participants from educational sectors (public and private FET colleges), automotive organisations and organised labour with the common characteristic of involvement in the training of motor mechanic artisans. The key themes identified in the different participants’ responses formed the data for the study, which was analysed by means of the ATLAS.ti 7.0 version data analysis program. The research confirmed that a strategy could be developed to successfully link the informal and formal motor mechanic artisan communities.

The accuracy and precision of catalytic converter analysis using conventional analytical methodology such as fire assay, x-ray fluorescence, atomic absorption and ICP-AES are typically in the range of ±7-10% RSD. Due to the high cost of noble metals, methods of analysis with increased accuracy and precision are desired to evaluate the loading of noble metals onto converter bricks. The investigations described in this work have resulted in a better understanding of many of the inherent problems and have contributed new approaches for sample dissolution and analysis using array detector based Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). These methods are shown to be accurate and precise for the analysis of Pt, Pd, and Rh in catalytic converters. Catalytic converters are difficult to dissolve by conventional acid methodology. While carius, tubes have previously been employed to dissolve small weights of sample, complete dissolution of increased amounts of sample, as needed for high precision ICP-AES analysis, has been hindered by the insufficient oxidation potential of the acids in the carius tube. In this work, the addition of ferric chloride is shown to increase the dissolving power of the carius tube method and specifically targets Pt, Pd and Rh for dissolution. Simultaneous collection of analyte wavelengths and simultaneous background correction, as performed with multichannel array detector ICP-AES instrumentation, have enhanced sensitivity and precision in catalytic converter analysis when compared to single channel instrumentation. The studies described within this dissertation demonstrate that flicker noise has been effectively eliminated through the use of multichannel array based ICP-AES instrumentation. With proper line selection and the use of the high-resolution system, Pt, Pd and Rh in catalytic converters can be analyzed with precision of 1-1.5%. ICP-AES accuracy has been confirmed through isotope dilution ICP-MS employing new methodology to avoid Zr isobaric interferences.

This study presents a comprehensive analytical tire model for both vehicle dynamic simulation and tire design. The model is composed of two parts--modeling of the contact mechanism and determination of the tire forces/moments. A static circular beam model is introduced for the contact mechanism, in which a tire is modeled with three compliance components--6-DOF spring/damper elements for the sidewall and the internal pressure, a flexible circular beam for the belt layers, and a series of radial springs for the tread. This contact model can estimate the 2-D contact shape and the contact pressure distributions for even or uneven road surfaces. The tire forces and moments are represented with the deformation of the tread elements. Two different methods are introduced to estimate deformations of tread elements---direct measuring method and integrating deformation rate method. In the former, the deformations of tread elements are directly measured by monitoring their displacements. In the latter, a tread deformation is obtained by integrating the slip velocity over the contacting time. By employing a rigid ring concept, the transient characteristics of the tire can also be examined in low frequency ranges. The ideas that are presented in this study are verified with a set of measurement data. For example, the tire forces/moments for various driving conditions such as combined slip conditions as well as pure lateral and longitudinal slip conditions. Also, the simulation results of 2-D contact pressure distributions are given for straight running and severe slip angle conditions.

Monolith reactors are studied with models and simulations, with particular attention given to the catalytic converter. It is found that previously noted differences between one- and two-dimensional monolith reactor models are largely due to artifacts introduced into the two-dimensional models through the boundary conditions at the reactor entrance. These artifacts can be avoided by modeling a pre-entrance region. Difficulties have been encountered in previous studies which attempt to match two-dimensional catalytic combuster models to data from experimental systems, which are essentially three-dimensional in character. These difficulties can be resolved with a new approach to choosing parameters for two-dimensional models. Considering that the procedure for choosing parameters for one-dimensional model approximations to either two- or three-dimensional systems is well understood, it is recommended that parameters be chosen for two-dimensional models such that one-dimensional model approximations are preserved. In a related development, it is recommended that the merits of various passage shapes be evaluated by comparing reactors with identical one-dimensional approximation. Using this basis for comparison the inherent merits of various geometries are found to be far less than had previously been judged. An elementary analysis of a monolith reactor indicated that there is an optimal heat transfer coefficient at each point in the reactor. If a reactor is designed with an optimal heat transfer coefficient profile, the required amount of catalyst could be only one fourth of the minimum for any uniform transport rate profile. This result is not altered when detailed models and complex kinetics are considered. A simple way to approach this optimum is to use a graded cell monolith. Additional improvements may be achieved with complex geometries such as reactor passages with lips at the front. Finally, the usual conception that with increasing temperature, density, residence time, and conversion go down, is inaccurate. While density is decreasing, diffusivity is increasing at twice the rate. Higher temperatures lead to higher transport rates which usually means greater conversion. Incidental to this study it is found that the there is little radial convective transport in the neighborhood of a reaction zone.

Part assembly is an important goal of part manipulation. Among other techniques, programmable force fields have been introduced for part manipulation. Many different force fields have been proposed to manipulate a part, such as the squeeze and the elliptical fields. For part assembly, more than one part needs to be manipulated. This can create problems since there can be interactions between the parts such as impact and friction. With technology developing, certain fields can be implemented in the micro-scale with MEMS actuator arrays and in the macro-scale with arrays of directed air jets or small motors. Modern technology is beginning to provide the means to control the magnitude and frequency of each actuator of the implemented force field. Thus dynamic and localized force fields can be used for part manipulation. This thesis presents a novel strategy for assembling two parts with a sequence of static and dynamic programmable force fields. The strategy involves some initial sensing. The choices of the force fields are discussed extensively. Uncertainties occurring in the motion of the parts are taken into account to make the proposed strategy more robust. This process does not make any assumption about the shape of the assembled parts, thus any pair of parts can be assembled by our strategy. We have implemented two simulators: one mimics the motion of a part under a static force field and the other mimics the part assembly process using static and dynamic force fields.

A novel multi-scale model is developed to describe in detail the reaction and diffusion processes taking place in the catalytic layers of three-way automobile converters. This comprehensive model considers the simultaneous oxidation of carbon monoxide, hydrogen and one hydrocarbon species, as well as the reduction of nitrogen oxide. The resulting problem of coupled and nonlinear ordinary differential equations is solved using an adaptive spline collocation technique. Our computations reveal significant diffusional limitations in the catalytic layers and important interactions among the various gaseous reactants. A systematic study is carried out to determine the relative importance of various operating and system parameters, and several possible ways are suggested to improve the operating efficiency of the catalytic converters.

In order to increase vehicle fuel efficiency while improving safety and performance and maintaining affordability, the global steel industry has initiated the use of advanced high strength steels that ultimately result in the design of stronger, lighter and more energy efficient vehicles. Tubular steel columns are extensively used in the automotive body structure due to their inherent capacity to absorb energy on impact. Hence, the objective of this research work is to study the crashworthiness performance of columns made from advanced high strength steels. / To conduct this study, computational simulations are developed to accurately assess the influence exerted in the crush response of the columns by different types of materials as well as geometrical characteristics of the thin-walled structural sections. / Furthermore, it is well known that spot-welding is the primary method of joining in the ground vehicle industry. Therefore, the strength of the spot weld under impact is extremely important to the safety design and durability of automobiles. Thus, in this project such an essential factor is addressed by developing a reliable and practical finite element model to predict the dynamic failure of spot-welds in the sheet metal structures. / It is shown that numerical results of the developed robust finite element model give fairly good agreement with experimental data in terms of collapse profile, deformed column shape, final crush length, and impact peak force. / Throughout the investigation, the finite element model permits the study of several structural and material variables that can be validated by a moderate set of destructive tests. Moreover, the current finite element crash model and the findings in this work can eventually be used to improve the crashworthiness efficiency of steel column specimens and to help meet society's demands for affordable, fuel efficient, environmentally responsible, and safe vehicles.

No description available.

<p>This thesis describes a custom algorithm developed to optimize a simple planetary gear set. The optimization minimizes volume for one simple planetary gear set using American Gear Manufacturers Association stress equations, custom design constraints, and material constraints. Through predetermined reactions to adjustments, component features and planetary variables are modified systematically to obtain the target solution. This thesis demonstrates that the defined approach is an effective means of balancing all three components of a simple planetary gear set, thus resulting in a solution that has been optimized for volume. </p>