The design of the electric platform in military vehicles requires the ability to determine the best combination of power system components that support the desired operational abilities, while minimizing the size, weight, cost, and impact of the overall power system. Because prototypes are both time consuming, rigid, and costly, they have become inadequate for verifying system performance. By using simulations, engineers can best plan for and observe the associations between missions (including modes of operation and system scenarios) and system performance in a dynamic, realistic environment. This thesis proposes a new tool to analyze and design military vehicle platforms: the Advanced Mobile Integrated Power System (AMPS). This tool is useful for design and design verification of military vehicles due to its unique incorporation of mission-specific functionality. It allows the user ease of design with the ability to customize the vehicle power system architecture and components, while permitting full control over source and load input parameters. Simulation of programmed mission sequences allows the user to ensure that the chosen vehicle architecture can provide all of the electrical power and energy needed to support the mission, thus providing adequate design verification. The present thesis includes an introduction to vehicle power systems and an outline of the need for simulation, a description of the AMPS project and vehicle specifications, analytical and numerical models of the simulated vehicle, explanation of the power management system, description of the graphical user interface, and a simulation performed with the AMPS tool.

The design of the electric platform in military vehicles requires the ability to determine the best combination of power system components that support the desired operational abilities, while minimizing the size, weight, cost, and impact of the overall power system. Because prototypes are both time consuming, rigid, and costly, they have become inadequate for verifying system performance. By using simulations, engineers can best plan for and observe the associations between missions (including modes of operation and system scenarios) and system performance in a dynamic, realistic environment. This thesis proposes a new tool to analyze and design military vehicle platforms: the Advanced Mobile Integrated Power System (AMPS). This tool is useful for design and design verification of military vehicles due to its unique incorporation of mission-specific functionality. It allows the user ease of design with the ability to customize the vehicle power system architecture and components, while permitting full control over source and load input parameters. Simulation of programmed mission sequences allows the user to ensure that the chosen vehicle architecture can provide all of the electrical power and energy needed to support the mission, thus providing adequate design verification. The present thesis includes an introduction to vehicle power systems and an outline of the need for simulation, a description of the AMPS project and vehicle specifications, analytical and numerical models of the simulated vehicle, explanation of the power management system, description of the graphical user interface, and a simulation performed with the AMPS tool.

Low friction lubricant development provides a worthwhile contribution to vehicle CO₂ emission reduction. Conventional low friction lubricant development focuses on empirical processes using out dated engine technology and old test methods. This strategy is inefficient and restricts the lubricant's potential. A new method proposed in the present research combines tribological simulations with rig, engine and vehicle tests. This approach provides insights undocumented until now. The contribution to CO₂ emission reduction from individual engine components on vehicle drive cycles that include warm-up is predicted using lubricants down to the new SAE 8 viscosity grade. A bearing model is used to design the lubricant's non Newtonian characteristics to achieve friction reduction. An isoviscous lubricant with a viscosity of 4.6 cSt is shown to achieve the minimum friction in the bearing. The research shows that by starting with lubricants having kinematic viscosities higher than this value, it is possible to improve lubricant performance by lowering viscosity index (VI), introducing shear thinning, or reducing the density and pressure viscosity coefficient. Conversely, for lubricants with lower starting viscosities it is shown that higher VI values, more shear-stable lubricants and higher densities and pressure viscosity coefficients are required. The model predicts that high oil film pressures occur in the bearing and cause significant local lubricant viscosity increase (300%), indicating that the lubricant's pressure viscosity behaviour is important here, despite the contact being conformal. Simulation and motored engine testing establishes lubricant behaviour in the piston-to-bore conjunction. This analysis identifies a poor correlation between measured and predicted values at low engine speeds. A rig-on-liner tribometer shows that this error is attributable to a deficiency in the simulation's characterisation of boundary regime friction. An oil pump test determines how a modern variable displacement oil pump (and its control system) responds to lowering viscosity. The hypothesis that low viscosity lubricants cause the parasitic load from this component to increase is disproven using this component-level rig test. Chassis dynamometer testing compares the CO₂ reduction performance of lubricant thermal management systems to the values achieved by reducing the viscosity grade. CO₂ reductions of between 0.4% and 1.0% are identified using a cold-start new European drive cycle (NEDC) with a 5W-30 preheated to 60°C and 90°C respectively. Reductions in CO₂ emissions between 0.4% and 1.2% are found on the NEDC by lowering the oil fill volume from 5.1 L to 2.1 L. For the unmodified case, a 3.7% reduction in CO₂ emissions is reported by reducing the viscosity grade from a 5W 30 to an SAE 8 in the NEDC. The performance of a novel external oil reservoir is simulated to understand its ability to retain oil temperature during the vehicle cool-down procedure. An oil temperature of 65°C at the end of the soak period (following a prior test where the oil was assumed to reach 90°C) is predicted by installing insulation to the reservoir and indicates that a viable method to achieve the CO₂ benefits identified through lubricant preheating tests exists. A full vehicle model combines the outputs from each of these sub-models to predict lubricant performance on the NEDC the new World-wide harmonized light duty test cycle (WLTC). This new approach provides a tool that enables next generation low friction lubricants to be developed. The model predicts that an SAE 8 lubricant can reduce CO2 emissions by 2.8% on the NEDC and 1.9% on the WLTC compared to a 5W-30. A theoretical experiment, where all lubricant related friction was deleted from the simulation, predicts that lubricant-related CO₂ emissions are 8.7% on the NEDC and reduce to 6.3% on the WLTC. These results indicate that the planned adoption of the WLTC in September 2017 reduces the potential contribution to CO₂ emission reduction from lubricants by 28%.

This thesis investigates two main aspects of air transportation system, demand and capacity. The first study aims to estimate the potential market for Zip Vehicles, an advanced commuter type of aircraft equipped with automation and electric propulsion technologies. A Multinomial Logit Model was developed to estimate the mode choice behavior of commuters between Zip vehicle, auto and transit in seven metropolitan areas in the United States. The results showed that the Out-of-Vehicle travel time plays an important role in the decision process of commuters. Zip Vehicle is predicted to achieve residual demand with the current technologies and could become more competitive if it was equipped with Vertical Take-Off Technology. The second study developed a hybrid airport runway capacity model that blends both deterministic and simulation techniques. The model includes a graphic user interface that allows high degree of freedom to modify input parameters, such as airport information, weather conditions, minimum separation distances and aircraft grouping system. The model is widely validated and it appears to be a consistent solution for estimating airport capacity at different levels and with various degree of extensibility. / Master of Science

A vehicle has several rotating components such as a traction electric motor, the driveline, and the wheels and tires. The rotating inertia of these components is important in vehicle performance analyses. However, in many studies, the rotating inertias are typically lumped into an equivalent inertial mass to simplify the analysis, making it difficult to investigate the effect of those components and losses for vehicle energy use. In this study, a backward-tracking model from the wheels and tires to the power source (battery or fuel cell) is developed to estimate the effect of rotating inertias for each component during propulsion and regenerative braking of a vehicle. This paper presents the effect of rotating inertias on the power and energy for propulsion and regenerative braking for two-wheel drive (either front or rear) and all-wheel drive (AWD) cases. On-road driving and dynamometer tests are different since only one axle (two wheels) is rotating in the latter case, instead of two axles (four wheels). The differences between an on-road test and a dynamometer test are estimated using the developed model. The results show that the rotating inertias can contribute a significant fraction (8 -13 %) of the energy recovered during deceleration due to the relatively lower losses of rotating components compared to vehicle inertia, where a large fraction is dissipated in friction braking. In a dynamometer test, the amount of energy captured from available energy in wheel/tire assemblies is slightly less than that of the AWD case in on-road test. The total regenerative brake energy capture is significantly higher (> 70 %) for a FWD vehicle on a dynamometer compared to an on-road case. The rest of inertial energy is lost by inefficiencies in components, regenerative brake fraction, and friction braking on the un-driven axle. / Master of Science

Accurate and efficient tire models for deformable terrain operations are essential for performing vehicle simulations. Assessment of the forces and moments that occur at the tire-terrain interface, and the effect of the tire motion on properties of the terrain are crucial in understanding the performance of a vehicle. In order to model the dynamic behavior of the tire on different terrains, a lumped mass discretized tire model using Kelvin-Voigt elements is developed. To optimize the computational time of the code, different techniques were used in memory allocation, parameter initialization, code sequence, and multi-processing. This has resulted in significant improvements in efficiency of the code that can now run close to real time and therefore it is suitable for use by commercially available vehicle simulation packages. Model parameters are obtained using a validated finite element tire model, modal analysis, and other experimental test procedures. Experimental tests were performed on the Terramechanics rig at Virginia Tech. The tests were performed on different terrains; tire forces and moments, soil sinkage, and tire deformation data were collected for various case studies based on a design of experiment matrix. This data, in addition to modal analysis data were used to validate the tire model. Furthermore, to study the validity of the tire model, simulations at conditions similar to the test conditions were performed on a quarter car model. The results have indicated the superiority of this model as compared to other lumped parameter models currently available. / Ph. D.

Studying the kinetic and kinematics of the rim-tire combination is very important in full vehicle simulations, as well as for the tire design process. Tire maneuvers are either quasi-static, such as steady-state rolling, or dynamic, such as traction and braking. The rolling of the tire over obstacles and potholes and, more generally, over uneven roads are other examples of dynamic events which are of importance. In the latter case, tire dynamic models are used for durability assessment of the vehicle chassis, and should be studied using high fidelity simulation models. In this study, a threedimensional finite element model (FEM) of the 16 inch TMPT Tire has been developed using the commercial software package ABAQUS. The purpose of this study is to investigate tire transient dynamic behavior for various inputs. The process of running dynamic FE tire simulations starts by statically inflating and loading the tire using an implicit method with refined mesh in the contact patch. Then, by using the "result transfer" option in ABAQUS, final state vectors are used as initial conditions for subsequent simulations. Using this sequence of loading steps helps increase the efficiency of the code. The validation of the model is performed in two stages. First, tire mode shapes and associated natural frequencies and damping values are compared with the experimental data. Second, a series of transient dynamic simulations are performed using an explicit method with a fine mesh around the circumference of the tire. Finally, the FEM model results are filtered to eliminate the numerical noise, and their correlation with the test data is investigated. Moreover, the peak values and time shifts associated with spindle forces as a function of normal load are studied. The results show that the tire dynamic response is autonomous. / Master of Science

abstract: The California Department of Transportation (Caltrans) is required to comply with the National Pollution Discharge Elimination (NPDES) permit, which includes the infiltration of stormwater runoff from highways and implementing soil based best managements practices (BMPs). Stormwater BMPs are in place to prevent pollution in stormwater runoff as well as to facilitate the stormwater discharge from the road. Per this new permit, Caltrans is to install soil based BMPs that can absorb the 85th percentile of a 24-hour stormwater event. In order to absorb the stormwater runoff, the area used is the Clear Recovery Zone (CRZ), which are the road embankments/slopes located adjacent to the roadside. The CRZ must be traversable and recoverable in order to meet roadside traffic safety standards. A major concern for Caltrans is the uncertainty on how these BMPs will affect the safety of a vehicle, if a vehicle were to interact with the soft soils. In order to provide an insight on the effects of the BMPs, the modeling and simulation of vehicle dynamics under certain interactions between the roadside, soil, and vehicle was completed. The research used computer simulations to quantify the probability of rollover accidents under several different vehicle, driving and ground conditions. The vehicles traversing typical archetype roadsides on soft soil are simulated using MsMac3D software. It was important to model the properties of the vehicle, roadside, mechanical and hydraulic properties of soils realistically in order to obtain an accurate representation of a real-world vehicle and soil interaction. The outcome was a library of simulations that provided quantifiable data on the effect that soft soils have on the safety and rollover potential of a vehicle traversing the CRZ. / Dissertation/Thesis / Masters Thesis Civil, Environmental and Sustainable Engineering 2019

Traditional methods for constructing simulation models can involve severalsteps that require manual pre-processing of large data sets. This process maybe time-consuming and prone to human errors, while also leading to modelsthat are inconvenient to customize for varying simulation scenarios. In thisthesis, we propose an alternate data preparation methodology in emergencyvehicle transport simulation, which aims to eliminate parts of the manualpre-processing. Our research is based on a previous case study using datafrom Sweden’s Southern Healthcare Region. The methodology we propose isinstantiated through a proof-of-concept software module that replacespreviously used static input sets by introducing dynamic runtime calculationsof ambulance travel times. This was done in two steps where we first evaluatedseveral routing engines according to needs extracted from the studied case.Secondly, we implemented and integrated the chosen routing engine into thepreviously mentioned module. Testing of the module showed feasible andconsistent performance, demonstrating the potential usage of our proposedmethodology in emergency vehicle transport simulation.

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