To achieve passive vibration control, an adaptive flywheel design is proposed and fabricated from two different materials. The corresponding mathematical models for the adaptive flywheels are developed. A two-terminal hydraulic device and a two-terminal inverse screw device are introduced to analyze the two adaptive flywheels. Experiments are carried out to identify key parameters for both the two-terminal hydraulic system and the inverse screw system. The performance of three different suspension systems are evaluated; these are the traditional suspension system, the suspension system consisting of an ideal two-terminal device with constant flywheel and the suspension system consisting of an ideal two-terminal device with an adaptive flywheel (AFW suspension system). Results show that the AFW suspension system can outperform the other two suspension systems under certain conditions. The performance of a suspension system with the adaptive flywheel under different changing ratio is evaluated, and an optimal changing ratio is identified under certain circumstances. To obtain the steady-state response of the two-terminal device with adaptive flywheel, three different methods have been applied in this thesis. These methods are the single harmonic balance method, the multi-harmonic balance method and the scanning iterative multi-harmonic balance method, respectively. Compared to the single harmonic balance method, the multi-harmonic balance method provides a much more accurate system response. However, the proposed scanning iterative multi-harmonic balance method provides more accurate system response than the single harmonic balance method with much less computational effort.

Chainsaws have seen a constant improvement over the time of their production and are still an object of improvement by the bigger chainsaw companies. The chainsaw engine is highly developed and optimised for the assigned uses. This thesis project aims to further optimise the engine by implementing a system that allows for variable inertia on the rotational system. A high inertia is needed at higher velocity to reduce speed fluctuations but a high inertia also makes it harder for an object to accelerate, a low start inertia could help accelerate the system and then reach a higher inertia for stability at higher velocities.  The variable inertia system were developed for a Husqvarna 550 XP mk.II. Concepts were developed using the product development process and the evaluation is based on the interpreted needs of the product. The most promising concepts underwent dynamic system simulations to ensure the best performing concept is selected. The chosen concept were then further designed with an iterative process where each iteration was analysed with the finite element method to ensure structural rigidity. The developed product indicates a performance increase. The magnitude of this performance increase is mainly governed by the size constraints in the chainsaw.

Syfte och frågeställning Syftet med denna studie är att identifiera effekten av svänghjulsträning på styrkerelaterade variabler som påverkar idrottslig prestation genom en sammanställning av befintlig vetenskaplig litteratur. Studiens frågeställning var: (1) Vilken effekt har svänghjulsträning på muskeltillväxt (hypertrofi)? (2) Vilken effekt har svänghjulsträning på utvecklingen av maximal styrka? (3) Vilken effekt har svänghjulsträning på utvecklingen av Power (effektutveckling)? (4) Vilken effekt har svänghjulsträning på horisontell förflyttning? (5) Vilken effekt har svänghjulsträning på vertikal förflyttning? Metod En metaanalys för 15 experimentella studier som uppfyllt urvalskriterierna genomfördes. De inkluderade studierna kvalitetsgranskades med Pedros skala. För att möjliggöra en sammanställning av samtliga resultat analyserades resultaten i dataprogrammet Review Manager version 5.3 med Random effekt modell och presenteras med Forest plots. Jämförelserna gjordes över en period på 4-24 veckor. Resultat Svänghjulsträning under en period av 4-24 veckor visar på en statistisk signifikant utveckling  av muskulär hypertrofi (effektstorlek 0,68), maximal styrka (1,40), Power (1,0), horisontell (0,54) och vertikal förflyttning (0,60). Slutsats Det finns stöd i litteraturen för att friska individer presterar bättre på så väl dynamiska styrketest som funktionella test efter svänghjulsträning. Evidensen är särskilt stark för att svänghjulsträning utvecklar maximal styrka och Power för tränade yngre individer samt i kortare mer intensiva block. Denna metaanalys har bara sammanställt skillnader i prestation före och efter svänghjulsträning och kan därför inte säga om effekten av svänghjulsträning är större än effekten av upprepade mätningar eller annan träning. / Aim The aim of this study was to identify the effect of the flywheel training on strength-related variables that affect athletic performance by compiling existing scientific literature. Research questions: (1) What effect does flywheel training have on muscle growth (hypertrophy)? (2) What effect does flywheel training have on the development of maximum strength? (3) What effect does flywheel training have on the development of Power (effect development)? (4) What effect does flywheel training have on the development of horizontal movement? (5) What effect does flywheel training have on the development of vertical movement? Method A meta-analysis was conducted from 15 experimental studies that met the selection criteria. The quality of included studies was reviewed by Pedro scale. In order to identify possible bias in the selection process a Funnel plot was carried out. To enable the compilation of all results an analyze with Random effect model was carried out with software Review Manager Version 5.3 and presented with Forest plots. Comparisons were made over a period of 4-24 weeks. Results Flywheel training for a period of 4-24 weeks show a statistically significant increase in effect size for muscular hypertrophy (0,49), maximum strength (1,40), Power (1,00), horizontal-(0,54) and vertical movement (0,60). Conclusions There's support in published studies that healthy individuals perform better on dynamic strength tests as wells as functional test after flywheel training. The evidence is particularly strong that flywheel training develops maximum strength and Power in trained younger individuals and in shorter more intensive blocks. This meta-analysis has just compiled the differences in performance before and after flywheel training and therefore cannot say if the effect of flywheel training is greater than the effect of repeated measurements or other exercise.

Kinetic energy storage via flywheels is an emerging avenue for hybrid vehicle research, offering both high energy and power density compared to more established electric and hydraulic alternatives. However, connecting the high speed flywheel to the relatively low speed drivetrain of the vehicle is a persistent challenge, requiring a transmission with high variability and efficiency. A proposed solution drawing inspiration from the electrical domain is the Switch-Mode Continuously Variable Transmission (SM CVT), which uses a high speed clutch to transfer energy to a torsion spring in discrete pulses with a variable duty cycle. The greatest limitation to the performance of this system is the speed and efficiency of commercial clutch technology. It is the goal of this thesis to develop a novel clutch which meets the actuation speed, controllability, and efficiency requirements of the SM CVT, with potential for reapplication in other rotary mechanical systems with switching functionality. The performance demands of the clutch were derived via a theoretical design case based on the performance requirements of a typical passenger vehicle, indicating the need for a sub-millisecond engagement and disengagement cycle. This is not met by any conventional clutch. Several concepts were considered across the fluid, electromagnetic and mechanical energy domains. A final concept was chosen which employs a friction disk style architecture, with normal force produced by compressing springs via an axial cam mounted to the flywheel. To control duty cycle, the cam was designed with a radially varying profile such that increasing radial position results in proportionally increasing ratio of high dwell to low dwell. Three synchronized followers are then translated radially on the cam by a control linkage. Analysis of the follower train dynamics and system stiffness were carried out to inform the design of a scaled benchtop prototype. Experimental testing was carried out to characterize the performance of the prototype. It was found that the intended functionality of the design was achieved, with discrete energy transfer accomplished via pulsing of the clutch. However, maximum efficiency was only 33% and torque capacity was only 65% of the intended 70Nm. Significant opportunity exists for improvement of the clutch performance in future research.

Roughly 50,000 people are injured in bicycle collisions with motor vehicles each year. The Hank Bicycle Simulator provides a virtual environment to study and reduce this tragic loss by safely investigating the interaction of bicycle riders and traffic, particularly for bicyclists crossing streets. The bicycle simulator design focuses on the bicycle and rider inertia, the predominant dynamic element for riders moving from a stopped position. The Hank Bicycle Simulator’s flywheel provides instantaneous inertial response while a servomotor provides simulated wind resistance to pedaling. This work describes the simulator design and a validation experiment that compares the simulator performance to theoretical predictions. The Hank Bicycle Simulator achieved initial acceleration with less than 0.20% error at realistic rider weights. The observed terminal velocity achieved less than 3.75%, with smaller errors for heavier riders. This allows the rider to cross a street with about a 60 ms time difference between the simulator and a real-life rider pedaling at a constant propulsive force. The Hank Bicycle Simulator was also validated through various physical experiments measuring the system inertia, the time delay of the electrical components, and the overall system performance. Such careful system validation for a mechanical feedback system is relatively rare in simulation research and is unique among previous reports of bicycle simulators.

The effect of variable inertia flywheel (VIF) on the driving speed fluctuation, and residual vibration of high speed machine systems is investigated in this thesis. Different variable inertia flywheels are proposed to an experimental purpose roller gear cam system and a commercial super high speed paper box folding machine. The effects of time varying inertia and intermittent cam motion on the dynamic responses of different high speed cam droved mechanism systems are simulated numerically. The nonlinear time varied system models are derived by applying the Lagrange¡¦s equation and torque-equilibrium equations. The dynamic responses of these two nonlinear systems under different operating speed are simulated by employing the 4th order Runge-Kutta method. The effects of VIF parameters on the dynamic responses, i.e. the output precision, variation of motor speed, and torque, during the active and dwell periods for these two systems are studied and discussed. The difference between the dynamic responses of constant inertia and variable inertia flywheel systems are also compared. The feasibility and effectiveness of depression of driving speed and torque fluctuations by analying variable inertia flywheel has also been demonstrated.

¡@¡@The dynamic power flow in a dual-input parallel planetary gear train system is simulated in this study. Different wind powers for the small wind turbines are merged to the synchronous generator in this system to simplify and reduce the cost of the system. Nonlinear equations of motion of these gears in the planetary system are derived. The fourth order Runge-Kutta method has employed to calculate the time varied torque, root stress and Hertz stress between engaged gears. The genetic optimization method has also applied to derive the optimized tooth form factors, e.g. module and the tooth face width. ¡@¡@The dynamic power flow patterns in this dual input system under various input conditions, e.g. two equal and unequal input powers, only single available input power, have been simulated and illustrated. The corresponding dynamic stress and safety factor variations have also been explored. Numerical results reveal that the proposed dual-input planetary gear system is feasible. To improve the efficiency of this wind power generation system. An inertia variable flywheel system has also been added at the output end to store or release the kinetic energies at higher or lower wind speed cases. A magnetic density variable synchronous generator has also been studied in this work to investigate the possible efficiency improvement in the system. Numerical results indicate that these inertia variable flywheel and magnetic density variable generator may have advantages in power generation.

Energy storage is a crucial condition for both transportation purposes and for the use of electricity. Flywheels can be used as actual energy storage but also as power handling device. Their high power capacity compared to other means of storing electric energy makes them very convenient for smoothing power transients. These occur frequently in vehicles but also in the electric grid. In both these areas there is a lot to gain by reducing the power transients and irregularities. The research conducted at Uppsala university and described in this thesis is focused on an all-electric propulsion system based on an electric flywheel with double stator windings. The flywheel is inserted in between the main energy storage (assumed to be a battery) and the traction motor in an electric vehicle. This system has been evaluated by simulations in a Matlab model, comparing two otherwise identical drivelines, one with and one without a flywheel. The flywheel is shown to have several advantages for an all-electric propulsion system for a vehicle. The maximum power from the battery decreases more than ten times as the flywheel absorbs and supplies all the high power fluxes occuring at acceleration and braking. The battery delivers a low and almost constant power to the flywheel. The amount of batteries needed decreases whereas the battery lifetime and efficiency increases. Another benefit the flywheel configuration brings is a higher energy efficiency and hence less need for cooling. The model has also been used to evaluate the flywheel functionality for an electric grid application. The power from renewable intermittent energy sources such as wave, wind and current power can be smoothened by the flywheel, making these energy sources more efficient and thereby competitive with a remaining high power quality in the electric grid.

Resistance exercise using weights typically offers constant external load during coupled shortening (concentric) and lengthening (eccentric) muscle actions in sets of consecutive repetitions until failure. However, the constant external load and the inherent capability of skeletal muscle to produce greater force in the eccentric compared with the concentric action, would infer that most actions are executed with incomplete motor unit involvement. In contrast, use of the inertia of flywheels to generate resistance allows for maximal voluntary force to be produced throughout the concentric action, and for brief episodes of greater eccentric than concentric loading, i.e. “eccentric overload”. Thus, it was hypothesized that acute flywheel resistance exercise would induce greater motor unit and muscle use, and subsequent fatigue, compared with traditional weight stack/free weight resistance exercise. Furthermore, it was hypothesized that flywheel training would induce more robust neuromuscular adaptations compared with training using weights. A total of 43 trained and untrained men were investigated in these studies. Knee extensor muscle activation, fatigue response and muscle use were assessed during exercises by recording electromyographic signals and by means of functional magnetic resonance imaging, respectively. Flywheel resistance exercise provoked maximal or near maximal muscle activation from the first repetition, induced robust fatigue, and prompted more substantial motor unit and muscle use than weight stack/free weight resistance exercise in both novice and resistance trained men. Both prior to and following five weeks of unilateral knee extension training, the eccentric muscle activation was greater with flywheel than weight stack training. Furthermore, weight stack training generated greater increases of dynamic strength and neural adaptations, while flywheel training generated more prominent hypertrophy of individual quadriceps muscles and greater improvement of maximal isometric strength. Hence, due to the preferential metabolic cost of the concentric rather than eccentric actions, the maximal activation through the entire range of the concentric action within each repetition of a set during flywheel resistance exercise probably evoked the marked fatigue, and prompted more substantial muscle use than resistance exercise using weights. Furthermore, while any cause‐effect relationship remains to be determined, results of the pesent study suggest that brief episodes of “eccentric overload” amplify muscular adaptations following concentriceccentric resistance training.

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