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An important facet of creating high-quality vehicles is to create components that are quiet and smooth under operation. In reality, however, it is challenging to measure the sound that some automotive components make under load because it requires specialist facilities and equipment which are expensive to acquire. Furthermore, the motors used in testbeds drown out the noise emitted from much quieter components, such as a Power Transfer Unit (PTU). This thesis aims to solve these issues by outlining the steps required to virtually estimate the acoustic radiation of a PTU using the Transmission Error (TE) as the input excitation via multi-body dynamics (MBD). MBD is used to estimate the housing vibrations, which can then be coupled with an acoustic tool to create a radiation analysis. Thus, creating a viable method to measure the acoustic performance without incurring significant expenses. Furthermore, it enables noise and vibration analyses to be incorporated more easily into the design stage. This thesis analysed the sound radiated due to gear whine which arises due to the TE and occurs at the gear mesh frequency and its multiples. The simulations highlighted that the TE can be accurately predicted using the methods outlined in this thesis. Similarly, the method can reliably obtain the vibrations of the housing. The results from this analysis show that at 2000 rpm the PTU was sensitive to vibrations at 500, 1000 and 1500 Hz, the largest amplitude being at 1000 Hz. Furthermore, the Sound Power Level (SWL) was proportional to the vibration amplitudes in the system. Analytical calculations were conducted to verify the methods and showed a strong correlation. However, it was concluded that experiments are required to further verify the findings in this thesis. / En viktig aspekt i att skapa fordon av hög kvalitet är att skapa komponenter som är tysta och smidiga under drift. I verkligheten är det dock svårt att mäta ljudet som vissa fordonskompo- nenter ger under belastning eftersom det kräver specialanläggningar och utrustning, vilket är dyrt att skaffa. Dessutom maskerar motorerna som används i testbäddar ut bullret från mycket tystare komponenter, till exempel en kraftöverföringsenhet (PTU). Detta examensar- bete syftar till att lösa dessa problem genom att beskriva de steg som krävs för att virtuellt uppskatta den akustiska strålningen av en PTU med hjälp av transmissionsfelet (TE) som ingångsexcitation via flerkroppsdynamik (multi-body dynamics, MBD). MBD används för att uppskatta kåpans vibrationer, som sedan kan kopplas till ett akustiskt verktyg för att skapa en ljudutstrålningsanalys. Således skapas en genomförbar metod för att mäta den akustiska pre- standan utan att medföra betydande kostnader. Dessutom möjliggör det att lättare integrera ljud- och vibrationsanalyser i designfasen. Detta examensarbete analyserade ljudet som utstrålats på grund av kugghjulsljud, som uppstår på grund av TE och uppträder vid kuggingreppsfrekvensen och dess multiplar. Simuleringarna belyste att TE kan förutsägas exakt med de metoder som beskrivs i detta examensarbete. På samma sätt kan metoden på ett tillförlitligt sätt uppnå kåpans vibrationer. Resultaten från denna analys visar att vid 2000 rpm var PTU känslig för vibrationer vid 500, 1000 och 1500 Hz, den största amplituden var vid 1000 Hz. Dessutom var ljudeffektsnivån (SWL) proportionell mot vibrationsamplituderna i systemet. Analytiska beräkningar genomfördes för att verifiera metoderna och visade en stark korrelation. Dock drogs slutsatsen att experiment krävs för att ytterligare verifiera resultaten i detta arbete.

Virtual ergonomics (VE) tools have had an impressive impact on the automotive, aviation, and defence industries. Despite the progress made in the last four decades, the tool complexity and application potential in other industries continues to invite improvement opportunities. Firefighting is an occupation with a high musculoskeletal injury burden that can benefit from innovative VE tools. This dissertation aims to: 1) improve VE tools for traditional and novel applications, and 2) identify injury risk to firefighters during fire suppression tasks. This dissertation begins by proposing a set of joint-specific and whole-body posturing guidelines for the manual manipulation of digital human models (DHMs) in the context of automotive manufacturing. Simulation accuracy improved with the implementation of posturing guidelines. These findings are useful instructions for virtual simulation ergonomists, software developers of posture prediction algorithms, and those charged with determining manufacturing ergonomics protocols. Descriptive ergonomic analyses of 48 firefighters in full bunker gear performing three common fire suppression tasks were then performed to identify the required ergonomic action needed for these tasks. Next, two VE tools (Jack and 3DSSPP) and Microsoft Kinect® 3D motion capture data were used to conduct an in-depth analysis of the most difficult task, the high-rise pack lift. The analysis included developing a methodology for modeling the external loads due to personal protective equipment. In addition to describing the firefighter injury risk exposure during common fire suppression tasks, the results highlight the strengths, limitations, and areas for further improvement of VE technology. Overall, VE tool improvements include suggesting guidelines for manual DHM posturing, understanding the strengths and limitations of using 3D motion capture gaming technology for posturing DHMs, and developing strategies to account for external loads due to personal protective equipment. Following these improvements, VE technology shows promise as an ergonomic assessment tool for firefighters. / Thesis / Doctor of Philosophy (PhD) / Virtual ergonomics (VE), which uses digital human models in virtual workstations, allows for efficient and detailed ergonomic assessments of tasks that are otherwise difficult or impossible to perform. However, more research is needed to identify tool improvements for both traditional and new applications. This work proposes, evaluates, and ultimately recommends a set of postural guidelines for the posturing of digital human models to ensure accurate simulation and subsequent assessment of real assembly-line worker movement patterns. Next, firefighter ergonomics, a relatively new application for VE tools, is introduced by first describing the injury risks associated with common fire suppression tasks. The strengths, limitations, and potential of applying VE tools to firefighting ergonomics are then highlighted through an example of simulating the high-rise pack lift task using two VE tools. Overall, the results contribute to the evolving field of VE by challenging current methodologies and highlighting new opportunities for VE tools.

Experiments were conducted to determine the suitability of a chromized steel for use in automotive exhaust applications. Due to government regulations leading to higher temperatures and a more corrosive environment within the automotive exhaust system, Cr-lean alloys such as Type 409 no longer suffice. The high cost of increasing alloying elements to reduce the corrosion susceptibility of exhaust components has led to exhaust manufactures moving toward a sacrificially protected aluminized stainless steel (Type 409Al). Yet, costs remain high due to the stainless steel substrate. Arcanum Alloys have designed a process in which an IF steel coil is chromized using a Cr-rich slurry, creating a thin but corrosion resistant layer. This chromized layer drastically increases the corrosion resistance, without affecting the formability of the interstitial-free (IF) steel substrate and remaining cost-effective. The localized corrosion resistance of the chromized IF steel (XHOM) was measured against current generation ferritic stainless steels in a simulated interior (exhaust gas condensate) and exterior (NaCl (aq)) automotive exhaust environment. Electrochemical polarization measurements along with atmospheric corrosion tests were conducted to characterize and compare the localized corrosion susceptibility of XHOM and benchmark ferritic stainless steels. The specific tests include the following: I. Potentiodynamic polarization curves in NaCl (aq), measuring the corrosion potential (Ecorr), critical current density (icrit) and breakdown potential (Eb). II. Double loop electrochemical potentiokinetic reactivation (DLEPR) testing measuring the ratio of the activation critical current density (ia) and the reactivation critical current density (ir). III. Salt-fog testing (ASTM B117) (external) and exhaust gas condensate exposure testing (internal), measuring the mass loss, pitting density, maximum pit depth and corrosion rate. Although Type 409 and Type 439 exhibited evidence of sensitization in the mill annealed condition, all materials exhibited a resistance to further sensitization during heat treatment, indicating sensitization will not occur during service. The electrochemical polarization curves in the NaCl (aq) resulted in XHOM yielding the highest breakdown potential, yet XHOM also exhibited the highest corrosion rate during the salt fog (ASTM B117) exposure. The latter is due to exposure of the XHOM cut edge where only the plan surface was exposed during the electrochemical polarization measurements. A galvanic couple exists between the chromized coating (cathode) and steel substrate (anode) leading to rapid corrosion of the substrate when exposed. When the cut edge of XHOM is masked, the corrosion rate drops drastically, performing comparably to the highly ferritic stainless steels. During the salt fog (ASTM B117) exposure, pitting of XHOM and Type 409 was caused by cut edge corrosion leading to corrosion product migrating down the panel surfaces and initiating under deposit pitting. A singular pit was observed on the XHOM surface, which led to delamination of the coating surrounding the pit, caused by the galvanic couple at the coating substrate/interface once the substrate was penetrated. The overall corrosion resistance ranking of the materials in the external environment incorporating corrosion rate and pit depth is as follows: Type 436 ≈ XHOM Masked Edges ≈ Type 439 > Type 409Al > Type 409 > XHOM Edges Exposed. Strain was also found to have an effect on the localized corrosion susceptibility of XHOM in NaCl (aq), unlike Type 409, which exhibited no change. The influence of the drain hole manufacturing method (punching and drilling) on the corrosion susceptibility of XHOM and Type 409 was also measured. The punching method caused a smearing effect of the chromized coating, which served to partially cover and protect the cut edge. The main corrosion mechanism that occurred within the external environment is cut edge corrosion, which led to under deposit pitting. Heat treatment of samples prior to testing in the internal exhaust environment led to an intermetallic phase change within the aluminized coating on Type 409Al, drastically reducing the corrosion resistance of the material. An as-received aluminized Type 409 (Type 409Al-A) sample was tested in exhaust condensate exposure conditions to measure the difference in corrosion rate. XHOM with the cut edges exposed exhibited a corrosion rate comparable to Type 409 and heat treated aluminized Type 409, which is promising as XHOM already has an advantage in cost and formability. The overall corrosion resistance ranking of the materials exposed in the internal exhaust environment incorporating corrosion rate and pit depth is as follows: Type 409Al-A > Type 436 > Type 439 > Type 409 ≈ XHOM Edges Exposed ≈Type 409Al-H (heat-treated). / Thesis / Master of Applied Science (MASc)

The purpose of this research was to explore traffic event severity relationships, evaluate the potentiality of a hazardous event, and develop a framework of observable event factors. Data was collected from three regions in Virginia, each assumed to exemplify a unique driving environment due to amount of traffic and infrastructure characteristics. In combination, a broad spectrum of site, traffic, and driver performance variables were accounted for. Observational techniques of surveillance, incident reporting, and inventorying were used to collect site, traffic, and driver data. This effort resulted in 368 observed traffic events that were evenly distributed among the three regions that represented metropolitan, mid-sized city, and town/rural driving environments. The 368 events were evaluated for severity and contributing variables where 1% of the events were non-injury crashes, 10% were serious, near-crashes, 24% were near-crashes, and the remaining 65% were serious errors with a hazard present. Exploratory analyses were performed to understand the general relationship between event severity levels. Binary logistic regression analyses (α = 0.05) were performed to further scope predictor variables to identify traffic event characteristics with respect to severity level, maneuver type, and conflict type. The results were that 69 of 162 observed predictor variables were valuable in characterizing traffic events based on severity. It was found that variables could be grouped to create event severity signatures for crashes, serious near-crashes, and near-crashes. Based on these signatures, it was found that there is a trend between severity levels that included a propensity for problems with straight path maneuvers, lateral and longitudinal vehicle control, and information density within the driving environment as contributing to driver error and hence crashes and near-crashes. There were also differences between the severity levels. These differences were evident in the degree of control the driver appeared to have of the vehicle, type of control regulating the driving environment, and type of road users present in the driving environment. Modifications to roadway evaluative techniques would increase awareness of additional variables that impact drivers to make more informed decisions for roadway enhancements. / Ph. D.

Transportation facilities and services provide the cornerstones to the rescue and response operations after a big earthquake. This study appraises the transportation actions taken by the authorities in the immediate aftermath of the Loma Prieta Earthquake of October 17, 1989. The failure of several transportation structures had a significant impact on rescue operations, traffic congestion and change in travel patterns in the San Francisco Bay Area. Emphasis is placed on travel demand management strategies adopted to meet the travel needs in the Bay Area and to return traffic to normalcy. The short-term and long-term impacts of closures of certain highways due to a 7.5 magnitude earthquake are also addressed in this research. Recent predictions by the United States Geological Survey show that there is a 67 percent chance of a big earthquake of 7.5 magnitude happening in the Bay Area before the year 2020. Therefore, there is a dire need to look at the transportation problems that the Bay Area might face if the "Big One" really hits. It is also important to note that certain bridges play a major role in the cross-bay transportation. Hence, the failure of such critical links would greatly influence the mobility of the citizens in the region. A macro-level measure referred to as "Weighted Roadway Congestion index" (RCIW) is developed to assess the severity of the closures of these links. To fulfill this objective, scenario analysis is performed for the expected closures in the San Francisco Bay Area. It is important to note that the macro-level measure developed is applicable only to urban areas. This research also aims at identifying the key network parameters, such as number of lane-miles per freeway exit and freeway network connectivity that impact roadway congestion after earthquakes. / Master of Science

The Hybrid Electric Vehicle Team (HEVT) of Virginia Tech is one of 16 university teams participating in EcoCAR 3, the latest competition in the Advanced Vehicle Technology Competitions (AVTC) organized by Argonne National Labs. EcoCAR 3 tasks teams with converting a 2016 Chevrolet Camaro into a hybrid electric vehicle with 5 main goals: reducing petroleum energy use and greenhouse gas emissions while maintaining safety, performance, and consumer acceptability. Over the last 4 years, HEVT has designed and built a plugin parallel hybrid electric vehicle with a unique powertrain architecture. This work deals with utilizing the unique powertrain layout of the HEVT Camaro to improve drive quality, a key component in consumer acceptability. Although there are many ways to approach drive quality, most aspects can be analyzed in the smoothness of the vehicle longitudinal acceleration response. This research is focused on improving the drive quality of the vehicle developed for EcoCAR 3. Multiple algorithms are developed to address specific aspects of drive quality that can only be done with the powertrain developed. This begins by researching the control strategies used in modern automatic transmissions, and moves into the modeling strategy used to begin algorithm development. Two main strategies are developed and calibrated in the vehicle. The first being a strategy for reducing jerk in pure electric mode by limiting motor torque response. The second strategy aims to improve transmission shift quality by using the electric motor to reduce torque fluctuations at the driveshaft. The energy consumption impact of both of these strategies is also analyzed to ensure that drive quality does not come at the large expense of energy consumption. / Master of Science / The Hybrid electric vehicle team (HEVT) of Virginia Tech is one of 16 university teams participating in EcoCAR 3, the latest competition in the Advanced Vehicle Technology Competitions (AVTC) organized by Argonne National Labs. EcoCAR 3 tasks teams with converting a 2016 Chevrolet Camaro into a hybrid electric vehicle with 5 main goals: reducing petroleum energy use and greenhouse gas emissions while maintaining safety, performance, and consumer acceptability. Over the last 4 years, HEVT has designed and built a plugin parallel hybrid electric vehicle with a unique powertrain architecture. This work deals with utilizing the unique powertrain layout of the HEVT Camaro to improve drive quality, a key component in consumer acceptability. Multiple strategies were examined and implemented for different driving conditions, and ultimately an improvement was made. However, new challenges are introduced by having some components remain stock that limit the success of smoothing gear shifts.

Proton exchange membrane (PEM) fuel cells are considered one of the best potential alternative power sources for automobiles. For this application, high efficiency and high power density are required. Pressurizing the fuel cell system can give higher efficiency, higher power density and better water balance characteristics for the fuel cell, but pressurization uses a percentage of the fuel cell output power. The compressor used to elevate the pressure has a direct effect on the system efficiency and water balance characteristics. A variety of compressors are being developed for fuel cell applications. Two compressor and expander technologies are discussed in this paper: the Opcon 1050 positive displacement twin-screw compressor and expander, and a Honeywell turbocompressor and expander. The effect of these compressors and expanders on the system at maximum load, low load, and set minimum airflow are examined. The effects of ambient conditions, stack temperature, and increased twin-screw compressor pressure are also examined. The turbocompressor proves to be a superior machine in terms of efficiency, and therefore offers the most promising effect on system efficiency of the two compressors. The twin-screw compressor, on the other hand, offers more flexible pressure ratio and better water balance characteristics at low fuel cell loads, which is an important factor with PEM fuel cell systems. Increased ambient and stack temperature has a significant negative effect on the water balance and a small positive effect on efficiency. Increasing the pressure for the twin-screw compressor significantly improves the water balance characteristics with some loss in efficiency. These results show the importance of determining the system operating range and operating conditions in the choice of a compressor for a fuel cell system / Master of Science

The aim of suspension systems in vehicles is to provide the best balance between ride and handling depending on the operating conditions of a vehicle. Active suspensions are far more effective over a variety of different road conditions compared to passive suspension systems. This is because of their ability to store and dissipate energy at different rates. Additionally, they can even provide energy of their own into the rest of the system. This makes active suspension systems an important topic of research in suspension systems. The biggest benefit of having an active suspension system is to be able to provide energy into the system that can minimize the response of the sprung mass. This is done using actuators. Actuator design in vehicle suspension system is an important research topic and a lot of work has been done in the field but little work has been done to estimate the peak control force and bandwidth required to minimize the response of the sprung mass. These two are very important requirements for actuator design in active suspensions. The aim of this study is estimate the peak control force and bandwidth to minimize the acceleration of the sprung mass of a vehicle while it is moving on a compliant surface. This makes the road surface a bi-lateral boundary and hence, the total system is a combination of the vehicle and the compliant road. Generalized vehicle and compliant road models are created so that parameters can be easily changed for different types of vehicles and different road conditions. The peak control force is estimated using adaptive filtering. A least mean squares (LMS) algorithm is used in the process. A case study with fixed parameters is used to show the results of the estimation process. The results show the effectiveness of an adaptive LMS algorithm for such an application. The peak control force and the bandwidth that are obtained from this process can then be used in actuator design. / Master of Science / Active suspension systems have been proven to be a better option compared to passive suspension systems for a wide variety of operating conditions. Active suspensions typically have an actuator system that produces a force which can reduce the disturbance caused by road inputs in the suspension. The sprung mass of a vehicle is the mass of the body and other components supported by the suspension system and the un-sprung mass is the total mass of the components which are not supported by the suspension or are part of the suspension system. The actuator is typically between the sprung mass and the un-sprung mass. When there is a single event disturbance from the road, the energy is transferred to the sprung mass, which contains the occupants, through the un-sprung mass. The actuator produces a force that reduces this acceleration in the sprung mass and hence improves ride comfort for the occupants of the vehicle. In this thesis, the single event disturbance that has been considered is a compliant road surface. This is a bi-lateral boundary since the vehicle interacts with the compliant elements under the surface of the ground. The aim of this thesis is to develop and implement a method to estimate the peak control force and bandwidth that the actuator needs to produce to eliminate or reduce the acceleration of the sprung mass which is caused by the compliant surface single event disturbance.