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Formula SAE (FSAE) vehicle systems are very complex. Understanding how subsystems effect the overall vehicle is essential for making design trade-offs. FSAE is a competitive environment. Teams need to have reliable and high performing vehicles to do well in competition. The Virginia Tech (VT) FSAE team has produced a prototype electric powertrain (EPT) vehicle, VTM16e, and will take their first EPT vehicle, VTM17e, to competition in 2017. The use of model-based design (MBD) for an EPT FSAE vehicle is investigated through this thesis. The goal of the research is to build the framework of a full vehicle simulation to take knowledge gained from the VTM16e prototype vehicle, and apply it to the VTM17e competition vehicle. A top-down, bottom-up approach is taken to build a full vehicle model of an EPT FSAE vehicle. A full vehicle simulation is built with subsystems to establish an overall structure and subsystem interactions. Individual subsystems are then focused on for testing and validation. Breaking the vehicle down into subsystems allows the overall model to be incrementally improved. The battery subsystem is focused on in this thesis. Extensive testing is performed on the batteries to characterize their performance. Computer models are generated from empirical data through parameter estimation techniques. Validation of the battery models is performed and the resulting model is incorporated into the overall vehicle model. Performance limits of the vehicle are determined through model exploration, and design modifications to increase the reliability and performance for the VTM17e vehicle are proposed. / Master of Science

In 2004, students at the University of Guelph designed and constructed an all-wheel-drive Formula SAE vehicle for competition. It utilized an electronically-controlled, hydraulic-actuated limited slip center coupling from Haldex Traction Ltd, to transfer torque to the front wheels. The initial control system design was not comprehensively conceived, so there was a need for a thoroughly developed control system for the all-wheel-drive actuator augmented with commonly available sensors and a low cost controller. This thesis presents a novel all-wheel-drive active torque transfer controller using a neural network estimated slip angle velocity. This controller specifically targets a racing vehicle by allowing rapid direction changes for maneuverability but damping slip angle changes for increased controllability. The slip angle velocity estimate was able to track the actual simulated value it was trained against with excellent phase matching but with some offsets and phantom spikes. Using the estimated slip angle velocity for control realized smooth control output, excellent stability, and a fast turn-in yaw response on par with rear-wheel-drive configurations. A full vehicle simulation with software-in-the-loop testing for control software was also developed to aid the system design process and avoid vehicle run time for tuning. This design flow should significantly decrease development time for controls algorithm work and help increase innovation within the team.

The master thesis describes application of a sandwich construction for Formula Student car. It will replace the current tubular space frame according to FSAE rules. The introduction is focused on the information of international Formula Student competition, including TU Brno Racing Team. Then there are important rules for the construction of frames and composite monocoques. For the selected production technology are found strength properties of face sheets made of carbon and hybrid fibres. Another part of thesis deals with the design of the sandwich panel using analytical calculation to determine the bending stiffness. On the basis of these proposals are made three-point bending and shear tests. Using of FEM simulation is detected torsional stiffness of the tubular space frame and the monocoque concept from the proposed sandwich panels. The conclusion is devoted to a summary of the important information and possible monocoque manufacturing process.

Design decisions have a large impact early in the design process. Optimization methods can help engineers improve their early decision making, however, design problems are often ill-posed for optimization at this early stage. This thesis develops engineering methods to use optimization during embodiment design, despite these difficulties. One common difficulty in designing mechanical systems is in handling the effects that design changes in one subsystem have on another. This is made more difficult in early engineering design, when design information is preliminary. Increased efforts have been made to use numerical optimization methods in early engineering design – because of the large impact early decisions have on subsequent development activities. One step toward executing meaningful optimizations in early design is the development of an optimization framework to be used when conditions are expected to change as the design progresses and new information is gained. This thesis presents a design framework that considers such change by subjecting the parametric updating of CAD models to optimization criteria specific to the problem at hand. Under the proposed framework, a part or subassembly is parametrically modeled in CAD; when changes are made to the subsystems that interact with the part or subassembly, it is then updated subject to design objectives and constraints. In this way, the updated part or subassembly satisfies system and subsystem level optimization criteria, reducing the need for the designer to react to design changes manually. It is used to reduce the weight of a Formula SAE suspension rocker by 18%, demonstrating the utility of this framework. Next, we develop methods to help engineers by giving them options and helping them explore during configuration generation. The design of multiple-bend, progressive-die-formed springs typically comprises four steps: (i) functional specification, (ii) configuration generation, (iii) configuration selection, and (iv) detailed shape and size optimization. Configuration generation fundamentally affects the success or failure of the design effort. This presents an important problem: by not generating potentially optimal configurations for further development in detailed design, the designer may unknowingly set the design on track for sub-optimal performance. In response, a method is developed that improves configuration generation. Specifically, an optimization-based spring configuration generator – without which, the generation would typically be based solely on designer creativity, experience, and knowledge. The proposed approach allows the designer to explore numerous optimization-generated spring configurations, which feasibly satisfy the functional specifications. The feasibility study is carried out before a final configuration is chosen for detailed development. Thus streamlining the designer's efforts to develop a design that avoids sub-optimality. We use the feasibleconfiguration generator to identify twenty-two electrical contact spring configurations. All twenty-two of the configurations satisfy the design's functional specifications. Two important concepts that improve decision making in early design were chosen. First, is the concept of a paremetric CAD based framework. Second is the concept of generating iso-performing design solutions. A numerical computer-based application is explained that takes advantage of these two ideas. A genetic algorithm topology optimization framework with the ability to converge to iso-performing solutions was integrated with CATIA V5. This application is demonstrated on a Formula SAE frame where it develops a pareto frontier of designs, expands upon one compromise design by producing iso-performing solutions, and automatically produces designs with the same performance after a parametric suspension change.

Composite monocoque frames are becoming increasingly more popular inperformance cars. Compared to their steel and aluminum counterparts theyprovide additional torsional stiffness at the cost of less weight. This thesiscovers the complex optimization process of a monocoque applied within theregulations of a Formula Student competition. It aims to give the reader a goodunderstanding of the rules and how they affect the optimization process whilegenerating an optimized design used in the competition of Formula StudentGermany -21 by KTH Formula Student. The rules of Formula Student dictate the structural requirements on themonocoque based on a steel space frame. All materials except low carbon steelused in the structure require proof of equivalence through regulated testingmethods. However, this thesis shows that the regulated setup can severelyaffect results through a deep analysis of the testing methodology.The torsional stiffness of the monocoque is analyzed and optimized accordingto the results of a free-size optimization. Both through slight adjustmentsin chassis geometry and the laminate, resulting in a theoretical torsionalstiffness of 9.9 kNm/deg, more than five times as much as the old space frame.Weighing in at 20 kg, a significant weight reduction of about 10 kg, eventhough it was larger, with a surface area of about 4.2 m2. This design will be the first monocoque manufactured within KTH FormulaStudent since 2010. Therefore, a lot of focus was put on analyzing the rulesand lay the ground for future development by conducting tests on optimizedpanels. These results have the potential to further reduce the weight of a futuremonocoque with a different geometry. / Allt fler sportbilar använder självbärande karosser i komposit. Till skillnadfrån deras stål och aluminium motsvarighet så tillåter kompositkonstruktionenen styvare konstruktion för samma vikt. Denna rapport går igenom denkomplicerade optimeringsprocessen för en självbärande kaross i kolfiber appliceratinom tävlingen Formula Student. Målet med rapporten är att läsaren ska fåen bättre förståelse av reglerna och dess påverkan på optimeringsprocessensamtidigt som en optimerad design presenteras för användandet i “FormulaStudent Germany -21” åt KTH Formula Student. Reglerna inom Formula Student ställer strukturella krav på den självbärandekarossen baserat på en standard för stålrörsramar. Alla material förutomlåg kols stål som används i strukturen kräver att ekvivalens bevisas genomspecifika tester. Denna rapport visar att dessa tester kan generera olika resultatgenom en djup analys av metodiken. Torsions styvheten av karossen analyseras och optimeras enligt reglernagenom en så kallad free-size optimization". Genom att variera geometri ochkomposit utvecklades en kaross som var mer än 5 gånger så styv som dentidigare stålrörsramen med en teoretisk torsions styvhet på 9.9kNm/deg. Meden vikt på 20 kg reducerades även vikten 10 kg, även om den var större, ochhade en area på cirka 4.2m2. Denna design kommer att vara den första självbärande komposit karossentillverkad inom KTH Formula Student sedan 2010. Efter den djupa analysen avreglerna, testas då de optimerade panelerna, vilket lägger grunden för framtidautvecklingen. Dessa resultat har potential att reducera vikten ytterligare av enframtida kaross, genom ändringar i geometrin.

Several standardized courses for Formula SAE (FSAE) testing are introduced and described with sufficient detail to be reproduced by any Formula SAE team. Basic analysis methods for the courses are given as well as explanations of how those analyses could be used. On-car data from the Global Formula Racing (GFR) SAE cars is used to verify the analysis methods, give estimates to unknown variables, and show the relevance of the standard testing courses. Using the courses and methods described in this paper should allow standardized comparison of FSAE car performance, as well as provide a method to verify simulations and evaluate changes in vehicle performance from tuning. Instrumentation of all suspension member forces with strain gauge load cells is shown to be an extremely powerful tool for measuring vehicle performance and quantifying vehicle dynamic characteristics. The design and implementation of strain gauge load cells is described in detail to provide a template for reproducing similar results in other vehicles. Data from the GFR 2011 FSAE car is used throughout the paper to: show the design process for making effective suspension member load cells, show the calibration processes necessary to ensure quality data is collected, illustrate the calculation of suspension corner forces, and show the effectiveness of measuring vehicle dynamic characteristics with this technique. Using the methods described in this paper should provide data that allows a more complete and thorough understanding of on-car vehicle dynamics. This data may be used to validate vehicle models. / Graduation date: 2012