L’objet de cette thèse expérimentale est l’étude de la rhéologie des mousses de fluides complexes. L’utilisation de matériaux modèles permet de découpler les effets des bulles et du fluide complexe sur le comportement rhéologique des mousses. Nous caractérisons notamment le module élastique et la contrainte seuil des mousses de suspension de particules et des mousses d’émulsion. La rhéologie des mousses de particules est fortement dépendante du rapport entre la taille des particules et la taille du réseau interstitiel de la mousse (nœud et bords de Plateau). Lorsque les particules sont suffisamment petites pour être inclues dans le réseau de la mousse, elles peuvent former un squelette granulaire compact. Cette structure mise en place par le drainage de la suspension augmente sensiblement la valeur du module élastique des mousses de particules. En effet, le confinement exercé par les bulles sur le squelette granulaire est à l’origine de l’élasticité de la matrice granulaire. Lorsque taille des particules augmente, ces dernières sont exclues du réseau de la mousse et le module élastique des mousses de particules diminue avec la disparition de la matrice. Les mousses de particules avec un squelette granulaire possèdent l’avantage d’avoir deux sources d’élasticité distinctes : l’élasticité capillaire des bulles et élasticité du squelette granulaire. On peut sommer ces deux contributions pour modéliser le module élastique macroscopique de la mousse, ce n’est pas le cas des mousses d’émulsion. En effet, il existe un couplage entre bulles et la matrice d’émulsion. L’introduction des nombres capillaire élastique et capillaire de Bingham permet de décrire l’évolution respective du module élastique et de la contrainte seuil des mousses d’émulsion. Enfin, l’analyse de la contrainte seuil de ces deux types de mousses permet d’identifier la matrice de particules comme étant un fluide à seuil, et forme un parallèle intéressant entre ces deux mousses à priori dissemblables / The subject of this experimental thesis is the study of the rheology of complex fluid foams. The use of model materials allows decoupling the effects of the bubbles and the complex fluid on the rheological behavior of the foams. In particular, we characterize the elastic modulus and the yield stress of particle-loaded foams and emulsion foams. The rheology of particle-loaded foams is highly dependent on the size ratio between the particle and the interstitial foam network (node and the so called “Plateau borders”). When the particles are small enough to be included in the foam network, they can form a compact granular skeleton. This structure put in place by the drainage of the suspension substantially increases the value of the elastic modulus of the particle-loaded foams. Indeed, the confinement exerted by the bubbles on the granular skeleton is at the origin of the elasticity of the matrix (skeleton). As the size of the particles increases, they are excluded from the foam network and the elastic modulus of the foam particles decreases with the disappearance of the matrix. Particle foams with a granular skeleton have the advantage of having two distinct sources of elasticity: the capillary elasticity of the bubbles and the elasticity of the granular skeleton. These two contributions can be summed up to model the macroscopic elastic modulus of the foam, this is not the case for emulsion foams. Indeed, there is a coupling between bubbles and the emulsion matrix. The introduction of elastic capillary number and the Bingham number allows to describe the respective evolution of the elastic modulus and the yield stress of the emulsion foams. Finally, the analysis of the yield stress of these two types of foams enables to identify the matrix of particles as a yield stress fluid, and forms an interesting parallel between these two foams that are a priori dissimilar

This thesis presents a study of a novel suspension system which is placed inside a vehicle's wheel. The In-wheel suspension system isolates the sprung mass from excitations similar to conventional suspension systems. In traditional suspension systems the isolation is provided by spacious and complicated mechanisms, and mainly in the vertical direction. However, the in-wheel suspension system, not only fits the suspension mechanism inside the unused space between a wheel’s rim and hub, but also allows for isolation both in vertical and horizontal directions. The main focus of this thesis is to study, investigate, and show the feasibility of applying such suspension system to a vehicle. This research is conducted on low speed, low load, and non-powered vehicles such as hand trucks and baby strollers. This helps to escape from the complications of a complex system like a road vehicle. It also demonstrates the versatility of the in-wheel suspension idea. The objective of the project is to scrutinize a simple but practical in-wheel suspension system and demonstrate its applicability. The research begins with the dynamics modeling of an in-wheel suspension system. This suspension has been previously developed at the University of Waterloo for a wheelchair. The dynamics model evaluates the response of the suspension system and investigates the influence of various design parameters on the in-wheel suspension. The study is then continued to improve the design by replacing its rigid mechanism links with optimized compliant structures. This reduces the system's complexity and weight while boosting its performance. Furthermore, a general optimization code is developed to design and optimize flexible members for in-wheel suspension systems. The optimization program is then used to design and optimize two prototypes for hand trucks. Finally, the in-wheel suspension system for a hand truck is tested and evaluated. The experimental results also verify the simulation results and verify the developed optimization design program.

This thesis presents a study of a novel suspension system which is placed inside a vehicle's wheel. The In-wheel suspension system isolates the sprung mass from excitations similar to conventional suspension systems. In traditional suspension systems the isolation is provided by spacious and complicated mechanisms, and mainly in the vertical direction. However, the in-wheel suspension system, not only fits the suspension mechanism inside the unused space between a wheel’s rim and hub, but also allows for isolation both in vertical and horizontal directions. The main focus of this thesis is to study, investigate, and show the feasibility of applying such suspension system to a vehicle. This research is conducted on low speed, low load, and non-powered vehicles such as hand trucks and baby strollers. This helps to escape from the complications of a complex system like a road vehicle. It also demonstrates the versatility of the in-wheel suspension idea. The objective of the project is to scrutinize a simple but practical in-wheel suspension system and demonstrate its applicability. The research begins with the dynamics modeling of an in-wheel suspension system. This suspension has been previously developed at the University of Waterloo for a wheelchair. The dynamics model evaluates the response of the suspension system and investigates the influence of various design parameters on the in-wheel suspension. The study is then continued to improve the design by replacing its rigid mechanism links with optimized compliant structures. This reduces the system's complexity and weight while boosting its performance. Furthermore, a general optimization code is developed to design and optimize flexible members for in-wheel suspension systems. The optimization program is then used to design and optimize two prototypes for hand trucks. Finally, the in-wheel suspension system for a hand truck is tested and evaluated. The experimental results also verify the simulation results and verify the developed optimization design program.

Traditional vehicle suspension system is equipped with isolated shock absorbers that can only dissipate energy by themselves. Hydraulic interconnected suspension uses hydraulic circuits to connect each shock absorber, so that the energized hydraulic fluid can be utilized to counter unwanted body motion to improve the overall dynamic performance. The hydraulic interconnected suspension is a proven concept that has shown good potential in controlling body rolling and decoupling the warp mode from other dynamic modes. Hydraulic interconnected suspension is still passive and lack of adaptivity, while some active or semi-active suspension technologies allow the shock absorbers to counter the road disturbances using external power input. Active suspensions such as electro-magnetic shock absorbers use the variable viscosity of magnetofluid to alter the damping characteristics of the suspension to adapt to quickly changing road conditions. The energy demand from an active suspension can reach the level of kilowatts in certain cases, which results in lowered fuel efficiency of the vehicle. To find a balanced solution to dynamic performance and energy efficiency, this paper introduces a new form of energy-harvesting suspension that is integrated in a hydraulically interconnected suspension (HIS) system. The combined energy-harvesting and hydraulic interconnection features provide improved energy efficiency and vehicle dynamics performance. A single cylinder model is built in AMESim for preliminary study and validated in a bench test. The bench test results proved the authenticity of the theoretical model, and the model is then used to predict the system performance and guide the hardware construction. Based on the proven single cylinder model, and a full car model are developed to validate the effectiveness of the overall system design. Different dynamic input scenarios are used for model simulation, which includes single-wheel sinusoidal input, braking test and double lane change test. In the double lane change test, the EHHIS sees averagely 70% improved in roll angle relative to a conventional suspension, and averagely 22% improvement relative to simple hydraulically interconnected suspension. The power generated is found to reach maximum at 4 Ω external resistance and the highest average power generated is more than 70 watts at 2 hz 20 mm sinusoidal input. A road test of a half vehicle EHHIS system is done. From the road test results, the EHHIS meets the expectations of reducing roll angles. The riding comfort is evaluated with the RMS value of the vertical acceleration and is found to have minimum compromise from the greater damping coefficient. / Master of Science / Better road handling dynamics and riding comfort has always been after by the automotive industry. The vehicle body may experience all kinds of movement such as roll, pitch and bounce, every type of these motion can cause safety risks and passenger fatigue. Traditional vehicle suspension system is equipped with isolated oil shock absorbers that can only dissipate energy by pushing the oil through damping valves. A concept called hydraulic interconnected suspension can use hydraulic circuits to connect each shock absorber, so that the energized hydraulic fluid can be utilized to counter unwanted body motion to improve the overall riding experience. The hydraulic interconnected suspension (HIS) is a proven concept that has shown good potential in stabilizing the vehicle body in rough road conditions. Hydraulic interconnected suspension is still passive and lack of adaptivity, while active suspensions such as electro-magnetic shock absorbers can use external power supply to force the to adapt to quickly changing road conditions. The energy demand from an active suspension can reach the level of kilowatts in certain cases, which results in lowered fuel efficiency of the vehicle. Additionally, actively supplying power to the system always have the risk of functional failure due to power loss. To find a balanced solution to dynamic performance and energy efficiency, this paper introduces a new form of energy-harvesting suspension that is integrated in a hydraulically interconnected suspension (EHHIS) system. The combined energy-harvesting and HIS system provide improved energy efficiency as well as vehicle dynamics performance. Each system is composed of four connected hydraulic cylinders on each wheel and other auxiliaries. To investigate the effectiveness of the entire system, a single cylinder model is first built in AMESim for preliminary study and validated in the experiments. The bench test results proved the authenticity of the theoretical model, and the model is then used to predict the system performance and guide the hardware construction. Based on the proven single cylinder model, and a full car model are developed to validate the effectiveness of the overall system design. Different road condition scenarios are used for model simulation, which includes single-wheel sinusoidal input, braking test and double lane change test. In the double lane change test, the EHHIS system sees averagely 70% improved in roll angle relative to a conventional suspension, and averagely 22% improvement relative to simple hydraulically interconnected suspension. In the breaking test, the EHHIS-equipped vehicle experiences smoother pitching behavior and less oscillations. The power generated is found to reach maximum at 4 Ω external resistance and the highest average power generated is more than 70 watts at 2 hz 20 mm sinusoidal input.

Arbetet har genomförts på tio veckor och har gått ut på att ta reda på om det är lämpligt att använda sig av fiberkomposit i en fjädringsanordning på en el-mopeds bakhjul. Detta i syfte att sänka fordonets vikt. Om det är lämpligt att använda sig av dessa material är en svår fråga som måste behandlas och vinklas på olika sätt. Det finns säkerhetsaspekter att ta hänsyn till men även miljö och hållbarhet. För att hitta material som klarar av de belastningar konstruktionen kommer utsättas för gjordes intervjuer och även litteraturstudier i cykler som sedan upprepades. Kraven som ställs på konstruktionen är dels att den ska klara av yttre störfaktorer såsom fukt, UV-ljus men självklart även de belastningar som uppstår under färd d v s acceleration, inbromsning, kurvtagning osv. Kraven som bör ställas på konstruktionen är att den ska vara tillräckligt böjstyv för att ta upp krafter men ändå kunna fjädra. Den bör även vara vridstyv vid kurvtagning. Fjädringens slaglängd kan, enligt en konkurrentanalys, variera mellan 44-100 mm. Den beror dock på hur konstruktionen kommer se ut och vikten på fordonet med förare. Samtliga material som hittades i CES (en materialdatabas) har högre sträckgräns än ett allmänt fjäderstål. Även tillverkningsmetoderna togs fram i CES utifrån de material som hittades. Materialen utvärderades mot varandra i en Pugh-matris för att få en rangordning, detsamma gjordes för tillverkningsmetoderna. Materialen och tillverkningsmetoderna poängsattes efter sin rangordning och stämdes därefter av vilka som kan använda vilka tillverkningsmetoder. Den slutgiltiga rangordningen visar vilka material som är mer och mindre mångsidiga när det gäller tillverkningsmetoder. Även två vanliga fjädringstyper jämfördes ihop med tillverkningsmetoder för att undersöka vilka metoder som kunde ta fram dessa geometrier / The work has been carried out for ten weeks and has gone on to find out whether it is appropriate to make use of fiber composites in a suspension device on an electric mopeds rear-wheel. This in order to reduce vehicle weight. If it is appropriate to make use of these materials is a difficult issue that must be dealt with and angled in different ways. There are safety issues to consider, but also the environment and sustainability. To find materials that can withstand the loads that the structure will be exposed to, interviews and even literary studies were made in cycles repeatedly. The requirements of the design says that it will withstand external interference factors such as moisture, UV light, but of course also the loads that occur during acceleration, braking, cornering, etc. The requirements that should be imposed on the design is that it must be sufficiently resistant to bending to take up the forces but yet spring. It should also be rigid when cornering. The stroke, according to a competitor analysis, varies between 44-100 mm. It depends a lot on the design and the weight of the vehicle, driver included. All of the materials found in CES (a material database) have a yield strength higher than that of a regular spring steel. The manufacturing methods found in CES were based on the materials found. The materials were evaluated against each other in a Pugh-matrix to get a ranking, the same was done for the manufacturing methods. The materials and manufacturing methods were scored, based on their rankings, and then compared against each other. The final ranking shows the materials that are more or less versatile in terms of manufacturing. Even two common suspension types are compared together with manufacturing methods to investigate the methods that could produce these geometries.

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