Academic literature on the topic 'Regulated spring device'

A sample-injection device has been developed at SPring-8 Angstrom Compact Free-Electron Laser (SACLA) for serial femtosecond crystallography (SFX) at atmospheric pressure. Microcrystals embedded in a highly viscous carrier are stably delivered from a capillary nozzle with the aid of a coaxial gas flow and a suction device. The cartridge-type sample reservoir is easily replaceable and facilitates sample reloading or exchange. The reservoir is positioned in a cooling jacket with a temperature-regulated water flow, which is useful to prevent drastic changes in the sample temperature during data collection. This work demonstrates that the injector successfully worked in SFX of the human A2A adenosine receptor complexed with an antagonist, ZM241385, in lipidic cubic phase and for hen egg-white lysozyme microcrystals in a grease carrier. The injection device has also been applied to many kinds of proteins, not only for static structural analyses but also for dynamics studies using pump–probe techniques.

Vine implantation in Champagne is strictly regulated. Row spacing is limited to 1,50 meter and the canopy height can not exceed 1,40 m. The traditional training system is therefore characterized by narrow spaced vines. From the late eighties, different vine training systems, such as lyres, have been tested in the Champagne area. The aim is to assess their interests in the terroir of Champagne, which is characterised by its cool climate, soil profile and its customs. Whereas the lyre training showed its limits in the Champagne context, some other training systems have been implemented such as half-widely-spaced vines. These devices are characterised by a row spacing of two meters, a consistent cover crop and a canopy up to two meters. The plots are located in various places in the area and are strictly followed each year since 2006 (and 2000 for the first sites). Phenological, agronomical and ripening parameters are controlled and compared to the traditional training system plots. Experimental vinifications are done each year so that sensory analysis can be undertaken to assess the ability of these vines to produce wines with a Champagne typicality. The results of this experimental device show interesting conclusions on the agronomical behaviour of experimental widely-spaced vines in a cool climate region. Spring frost resistance, cover crop management and ripening are some elements which show differences between the reference traditional system (REF) and the widely-spaced vines (VSL).

In this paper a NACA 6412 regulated shape will be inverted to understand the behaviour of the air flow around the shape, this with the intention of convert the lifting effect to a downforce and braking effect changing the shape of the wing, displacing the trailing edge approximately 100mm over the first stage position. Using analysis as Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) to depicts the operational parameters of the two stages of the inverted NACA 6412 air foil. To reach this displacement, the main idea is using a flexure hinge designed as a M-Shape beam, this flexure hinge works as a spring to allows to the morphing wing moves around the 100mm of trailing edge displacement and the spring-beam effect creates an inverse force, when the wing moves close to the110mm and does not exceed the yield strength of the Acrylonitrile butadiene styrene (ABS) of 74Mpa. As a result of this motion parameters, we could integrate a flexure hinge to an inverted air foil regulated to reach braking and downforce forces in order to slow down vehicles or aerodynamic devices.

For the zones of “risky farming” characteristic of the Far East of the Russian Federation, the natural production conditions of the region are an important problem in preparing the soil for further basic agricultural work. So, when carrying out early spring agricultural work, due to presence of a solid underlying layer in the form of permafrost, they shall be completed in operational terms no more than 10 days, until the permafrost base thaws and the soil has not lost its bearing capacity. In addition, due to the peculiarities of the relief, the soil does not thaw equally in depth everywhere, which reduces the quality of field work and harrowing, as the most common operation, namely. This article provides theoretical and experimental studies on the adaptation of a wheeled tractor as part of a machine-tractor unit (MTU) used in harrowing to natural production conditions by installing a device that automatically regulates the load on the working body of the disc harrow or on the propellers of the energy device, depending on the conditions of use or the state of the motion surface.

Triboelectric nanogenerators (TENGs) are a promising renewable energy technology. Many applications have been successfully demonstrated, such as self-powered Internet-of-Things sensors and many wearables, and those portable power source devices are useful in daily life due to their light weight, cost effectiveness, and high power conversion. To boost TENG performance, many researchers are working to modulate the surface morphology of the triboelectric layer through surface-engineering, surface modification, material selection, etc. Although triboelectric material can obtain a high charge density, achieving high output performance that is predictable and uniform requires mechanical energy conversion systems (MECSs), and their development remains a huge challenge. Many previous works did not provide an MECS or introduced only a simple mechanical system to support the TENG integration system device. However, these kinds of designs cannot boost the output performance or control the output frequency waveform. Currently, some MECS designs use transmission conversion components such as gear-trains, cam-noses, spiral springs, flywheels, or governors that can provide the step-up, controllable, predictable, and uniform output performance required for TENGs to be suitable for daily applications. In this review, we briefly introduce various MECS designs for regulating the output performance of TENGs. First, we provide an overview of simple machines that can be used when designing MECSs and introduce the basic working principles of TENGs. The following sections review MECSs with gear-based, cam-based, flywheel-based, and multiple-stage designs and show how the MECS structure can be used to regulate the input flow for the energy harvester. Last, we present a perspective and outline for a full system design protocol to correlate MECS designs with future TENG applications.

Integrin-mediated force application induces a conformational change in latent TGF-β1 that leads to the release of the active form of the growth factor from the extracellular matrix (ECM). Mechanical activation of TGF-β1 is currently understood as an acute process that depends on the contractile force of cells. However, we show that ECM remodeling, preceding the activation step, mechanically primes latent TGF-β1 akin to loading a mechanical spring. Cell-based assays and unique strain devices were used to produce a cell-derived ECM of controlled organization and prestrain. Mechanically conditioned ECM served as a substrate to measure the efficacy of TGF-β1 activation after cell contraction or direct force application using magnetic microbeads. The release of active TGF-β1 was always higher from prestrained ECM as compared with unorganized and/or relaxed ECM. The finding that ECM prestrain regulates the bioavailability of TGF-β1 is important to understand the context of diseases that involve excessive ECM remodeling, such as fibrosis or cancer.

The pressure control valves can perform different functions in the hydraulic systems, such as: establish maximum pressure, reduce pressure in some circuit lines, and establish sequence movements, among other functions. The main operation of these valves consists of providing a balance between pressure and the force load on a spring. Most of these valves can be positioned in many different levels, between totally open and totally closed, depending on the flow and on the pressure differential. The pressure control valves are usually named according to their primary functions, e.g., lock wire valve, sequence valve, safety valve, etc. and, their basic function is limit or to determine the pressure of the hydraulic system for the attainment of a certain function of the equipment in motion. They are also classified by the type of connections, by the size and by the selected pressure band. Instead of relief and security, discharge, counterbalance, sequence, reducing and shock suppressor valves represent the pressure control devices. In this paper, oil-hydraulic circuits are suggested for practical lessons of Hydraulic and Pneumatic Commands where they regulate valves of pressure, by acting in the following situations: limiting the maximum pressure of the system, determining a level of pressure, determining two different levels of pressure, determining at the same time two distinct levels of pressure, unloading the pump. The functions of these devices will be discussed and analyzed as an attempt to improve their position in the circuit.

A pressure transmitter was installed at a specific position in a concrete conveying line to disclose the pressure drop when compressed air was conveyed during concrete spraying. A statistical analysis of the pressure at different positions was undertaken. Experimental results demonstrated that in the accelerate zone of horizontal conveying of concrete in the line, the pressure drop mainly occurred during the acceleration, collision, and friction processes. The momentum equation was introduced during the experiment, which interpreted the pressure drop caused by the accelerated conveying of concrete. The theoretical equation was corrected based on the results of theoretical experiments by introducing the value of α, and the experimental results were then optimized, thus obtaining an approximate model of pressure drop during the conveying of concrete. In addition, experimental results were compared with a model equation that showed the reliability of the proposed model. Research conclusions are of great significance to regulate the pressure drop in the conveying line of concretes, to design working parameters of concrete spraying devices, and to predict the ultimate distance for the conveying of concrete.

The present paper analyses the results of investigations concerning the size and effects of sheet wrinkling in the case of mini cylindrical drawn parts made from aluminium alloy sheets. The wrinkling occurs in the mini drawn part walls when the blankholder is missing from the die structure or it is driven with an excessive force. By comparing to macro scale processes, the manufacturing of mini parts usually involves new concepts concerning the establishment of the following parameters: tool clearances, tool dimensional parameters, blank dimensions, working process parameters etc. In the case of mini deep drawing such objectives cannot be simply achieved by reducing the process from macro to mini scales. The present work was devoted to study the particularities of the wrinkling that occur during mini deep drawing processes and affect the quality of the mini drawn parts. The experimental investigations were performed using a mini tool having the following main components: punch with a flat bottom, die and an annular blankholder plate. The tool was installed on a mini deep drawing device having the following main components: mobile grip - connected to machine mobile head; fixed grip; helical spring - used to regulate the blankholder force and placed between the fixed grip plate and punch support. The simulation was performed using the DynaForm software and the applied criterion of plasticity was the Barlat 89 criterion.

In this paper a novel design of energy harvester has been proposed, which converts harmonic or random vibrations energy into useful electric power. The energy harvester comprises of mechanical motion rectifier, motion regulator, strain energy storage element and a rotary electric generator. The mechanical motion rectifier comprises of a spatial mechanism with unidirectional bearings and spherical joint that converts the linear oscillating force into unidirectional torque pulses. Further, motion regulating mechanism directs the energy flow to the strain energy storage element and drives the electric generator. The arrangement ensures that flow of vibration energy is regulated such that it is stored in the spring up to a threshold limit and thereafter dissipated to the electric generator. Rigid body simulations in Adams and Matlab have been used in design and analysis of the energy harvester with investigations for the effect of significant design parameters. Experimentation on a prototype has been performed to validate the numerical model which delivered 4.13 W of peak power and average power of 0.12–0.52 W within frequency range of 1–15 Hz. Simulation results on a real size device with higher torsion spring stiffness indicates that the harvester can operate with 69.8% efficiency and deliver 0.32–2.45 W of average power for frequency of 0.5–4 Hz.

Роботу виконано в Тернопільському національному технічному університеті імені Івана Пулюя Міністерства освіти і науки України. Захист відбувся 06 жовтня 2016 р. о 11 годині на засіданні спеціалізованої вченої ради Д58.052.02 у Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56, ауд. 58. З дисертацією можна ознайомитись у науково-технічній бібліотеці Тернопільського національного технічного університету імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56.
У дисертаційній роботі вирішено важливе науково-технічне завдання підвищення ефективності роботи різального апарата косарки сегментно-пальцевої шляхом розроблення і застосування нової конструкції привода з регульованим пружинними пристроєм, для якого обґрунтовані кінематичні, конструктивні та силові параметри, що забезпечує високу продуктивність косарки і її низьке енергоспоживання. Уточнено аналітичні залежності, якими описано кінематику приводу косарки із заданою раціональною точністю, а також складові навантаження різального апарата з приведенням їх до суми неперервних диференційованих функцій. За розробленою математичною моделлю роботи енергозберігаючого приводного механізму косарки з регульованим пружинним пристроєм обґрунтовано його конструктивні та кінематичні параметри. Ефектом роботи є значне зниження максимальних значень моментів привода, що в комплексі дозволило підвищити відносну швидкість ножа різального апарата косарки, а від того – і її продуктивність. Для розробленого дослідного зразка косарки розроблено методику повного факторного експерименту типу 23 для досліджень енергетичних параметрів приводного механізму, що містить регульований пружинний пристрій з отриманням перевідних коефіцієнтів для визначення частоти обертання кривошипа. В ході проведення натурного експерименту встановлено його раціональні конструктивні, кінематичні та силові параметри при заданій продуктивності косарки з умовою мінімального споживання потужності.
В диссертационной работе решена важная научно-техническая задача повышения эффективности работы режущего аппарата косилки сегментно- пальцевой путем разработки и применения новой конструкции привода с регулируемым пружинными устройством, для которого обоснованы кинематические, конструктивные и силовые параметры, что обеспечивает высокую производительность косилки и ее низкое энергопотребление. Проведен анализ и синтез эксплуатационных показателей косилок, где установлено, что косилки с сегментно-пальцевым режущим аппаратом потребляют в 3–4 раза меньше мощности по сравнению с ротационными. Исследованы направления повышения производительности косилок, на основе чего обоснованно наиболее рациональные. Сюда принадлежит повышение поступательной скорости агрегата с одновременным увеличением двойных ходов ножа через увеличение частоты вращения кривошипа. Это приведет к значительному росту инерционных сил через увеличение максимальных значений ускорений подвижных масс. Поэтому для исследуемого типа режущих аппаратов проведен обзор схем приводных механизмов с обоснованием их преимуществ и недостатков. Установлено, что перспективным направлением уравновешивания инерционных сил в механизме является использование упругих элементов в конструкции привода. Разработана новая конструкция режущего аппарата косилки сегментно- пальцевой с кривошипно-шатунным приводным механизмом, в состав которого входит регулируемое пружинное устройство. Роль данного устройства заключается в том, что оно даст возможность уменьшить инерционные знакопеременные усилия при возвратно-поступательном движении ножа, поглощая кинетическую энергию подвижных масс, для накопления потенциальной энергии деформации упругих элементов с отдачей этой энергии назад в систему при обратном ходу ножа. Это уменьшит энергетические затраты на привод режущего аппарата в целом с повышением надежности и ресурса работы кинематических пар и звеньев приводного механизма. При этом аналитическим путем исследованы основные кинематические параметры элементов такого привода, сформулирована расчетная модель энергопотребления в процессах скашивания и определено показатели энергоэффективности его работы. В результате таких исследований установлено, что в данном агрегате при наиболее рациональной частоте вращения кривошипа косилки n1  724 об/мин уменьшается энергопотребление через снижение максимальных значений момента привода: на холостом ходу – до 83 %; при работе с удельной нагрузкой  150 (H  м) / м2 – от 23,3 % до 46,7 %; при средней нагрузке режущего аппарата (  200 (H  м) / м2 ) – от 20,1% до 42,2 %; при работе режущего аппарата с удельной нагрузкой   250 (H  м) / м2 – от 17,6 % до 37,1 %. Для подтверждения адекватности теоретической модели технологического процесса работы приводного механизма косилки предложены оригинальные программа и методика экспериментальных исследований, которые включают этапы: разработка и изготовление регулируемого пружинного устройства; фиксирование частоты вращения кривошипа на устоявшемся режиме работы косилки; установление на приводе моментомера для фиксации величины моментов, которые передаются приводом косилки. За результатами экспериментальных исследований с позиции минимального потребления мощности энергосберегающим приводным механизмом на разных режимах работы косилки определено рациональные конструктивные параметры регулируемого пружинного устройства: жесткости первого и второго упругих элементов – 2,2 104  4,5 104 Н/м, параметр, который характеризует момент начала (окончания) работы упругого элемента – 0  0,004 м, при относительной погрешности полученных результатов теоретическим и экспериментальным путями – 12%. Установлен уровень энергоэффективности привода на разных кинематических режимах работы косилки и при скашивании культур с разными физико- механическими свойствами. Путем расчета частот колебаний элементов привода установлено, что система не достигает области резонанса. На основании расчетов прочности и долговечности за классическими теориями определенны показатели сопротивления усталости отдельных элементов привода режущего аппарата. При расчете производительности косилки и, соответственно, разработанного агрегата установлено, что W  1,09 га/ч, что на 0,35 га/ч (47,3%) больше производительности базовой конструкции косилки. Годовой экономический эффект составляет 5141 грн на одну машину, срок окупаемости – 2,7 года.
Important scientific-technological task to improve the efficiency of the cutting device operation of the segment-pin mover has been solved in the dissertation by the development and application of new design of the drive with regulated spring device. Kinematic, construction and power parameters, which provide high efficiency of the mower and its low energy consumption, have been interpreted. Analytical dependencies are specified, taking advantage of which the kinematics of the mower drive with the given rational accuracy is described, as well as the loading components of the cutting device, presenting them as the sum of continuous differential functions. Construction and kinematic parameters of the regulated spring device of the energysaving drive mechanism operation of the mower have been interpreted according to the developed mathematic model. The outcome results in the sufficient decrease of the maximum values of the drive moments, which makes possible to increase the relative speed of the mover cutter, therefore, to increase its efficiency. The method of the complete factor 23 type experiment to investigate the energy parameters of the drive mechanism, which contains regulated spring device possessing conversion factors for finding the crank rotation frequency, has been developed for the developed experimental model. During field experiment its rational construction, kinematic and power parameters under given efficiency of the mower with the minimum energy consumption, have been found.

Haptic devices and man-machine interaction have attracted intense research interest in recent years due to numerous potential applications, including medical, dental, military, and nuclear. One of the challenges involved with haptic devices is providing human operator realistic sensory feeling through force feedback output from the haptic device. In order to acquire adequate fidelity, the stiffness of the virtual environment must be sufficiently large. However, this is typically accompanied with vibration of the haptic device. Hence, one of the key issues related to haptic systems is to ensure system’s stability. Although some effort has been done to address this issue, this is so far an unresolved problem. This paper presents current closed-loop PID control method for achieving system stability on the example of one-degree-of-freedom haptic device. In order to identify parameters of the PID controller, the control system is first modeled and the equation of the current closed-loop PID control is formulated. Then, by generalizing the relationship between the motor output torque and the virtual force at the output end of the device, the current closed-loop equation is transferred into that of the force. In addition, the paper analyzes the robustness of PID controlled haptic device. To validate the method, three simulation experiments are performed, with spring model, damper model, and spring damper model. The results show that there is a set of PID parameters which result in stable haptic device. One of the advantages of the proposed method is that it can regulate PID parameters to fit different virtual environment. This provides a fundamental approach to improve stability of haptic systems. In addition, the proposed method can be embedded in the software.

This paper describes the behavior of a new tail device to yaw smoothly small wind turbine rotors out of the wind during strong wind or gusts. The passive tail device consists of a rigid short tail, an aerodynamic rotating vane, a tail bumper, and a spring. This passive tail device reduces gyroscopic loads, is easy to adjust, can be manufactured in smaller sizes, and is much stronger than conventional vanes used in small wind machines. Besides, the energy collected with it is greater. Field test results indicate that its behavior agrees very well with simulations, and that the regulator can be advantageously utilized, as compared with conventional vanes and other mechanical or electromechanical means, in horizontal-axis wind turbines with diameters of 12 m or smaller. Here the steady-state case (quasi-steady wind velocity is assumed) is analyzed, showing the technical viability of the regulator proposed.

A powered lower limb prosthesis, which consists of a four bar mechanism, a torsional spring and a brushed DC motor, was previously designed and fabricated. To regulate the motor power input, a two level controller was proposed and built. The control algorithm includes a higher level finite state controller and lower level PID controllers. A digital signal processor (DSP) control board and MATLAB Simulink are used to realize the higher level control and a DC motor controller is used to realize the lower level PID control. Controller Area Network (CAN) communication was used to communicate between the two level controllers. To preliminarily test if the motor can generate required power, a bench test was performed. The results show that the motor needs to be overpowered to achieve the required moment.

A renewed interest in CNG fuelled engines, which has recently been boosted by the even more stringent emissions regulations, has generated considerable R&D activity in the last few years. In order to fulfill such limits, most current CNG vehicles combine advanced technical and control solutions such as VVA intake systems, new turbocharging solutions, enhanced ECU strategies, etc. The present work focuses on the complete fluid-dynamic characterization of a gaseous injection system so as to support the design of the related control module and devices. To that end, a numerical investigation into the fluid-dynamic behavior of a commercial CNG injection system has been extensively carried out by means of the GT-POWER code. A detailed geometrical model including the rail, the injectors as well as the pipe connecting the pressure regulator to the rail has been built in the GT-POWER environment. The model has been validated by comparing the experimental to the numerical outputs for the rail pressure and for the injected mass quantity. The model has hence been applied to the prediction of the pressure waves produced by the injection event and of their effect on the actually injected fuel mass. Moreover, the influence of the pressure regulator dynamics has been assessed by simulating the impact on the system behavior of a pressure noise downstream from the regulator. Finally, the possibility of reducing the rail volume, thus enhancing its dynamic response, has been investigated. The results have shown a good agreement between the predicted and the measured rail pressure and injected fuel mass flow rates over a wide range of engine operation conditions. Moreover, the dynamic simulations sketched a dependence of the injected fuel mass on the average rail pressure level, which in turn appeared to reduce for increasing engine power outputs. Finally, the reduction in the rail volume has proved not to significantly affect the injected mass flow rate.

We used three dimensional computer simulations to examine heat transport in a microchannel that encompasses a periodic array of biomimetic synthetic cilia. We modeled two different configurations of tilted cilia. Both configurations consisted of a grid of evenly spaced cilia with length L and square cross-section 0.1L×0.1L. The cilia were spaced at a distance δx between cilium rows and the inter-cilia spacing in the rows was fixed at δz = 0.25L for one configuration and δz = 0.5L for the other. The channel was filled with a viscous fluid and its top and bottom walls were maintained at different temperatures. The cilia were attached to the bottom channel wall at a specific angle and were actuated by a periodic external force applied vertically to their free ends. The periodical beating of cilia induces fluid mixing inside the fluid that facilitates heat transport. To model this multi-component system, we employed a thermal lattice Boltzmann model coupled with the lattice spring model. In order to investigate how the active cilia affect the heat transfer between the channel walls we varied three parameters in the system. Specifically, we systematically changed the tilt of the cilia, the spacing between cilia and the oscillation frequency of the cilia. Our investigations have allowed us to determine the optimal conditions for using cilia to increase the heat flux from a heated surface. Our findings could be useful for developing new methods for temperature control in microscale devices.

This paper presents a technique for vibration suppression in a rotordynamic system. The approach implemented involves using a DC motor for simultaneous torque and radial force actuation. Here, the rotor is supported via passive permanent magnetic bearings. The permanent magnets are arranged so that, for small motions, the rotor can be treated as a spinning top that is supported radially by linear springs. The device includes an axial flux, three phase, brushless DC motor that is used to produce a torque. The same motor is also used to develop radial forces to control the vibration of the rotor. This is accomplished by using two phases of the motor for torque generation, and one phase to produce radial forces. The paper develops a set of equations that can be used to predict the radial force generated by the motor coils. These equations are used to implement a feedback control system to regulate the radial position of the rotor. Experiments are conducted to verify the coil force equations and demonstrate the effectiveness of the feedback control scheme.

The most widely accepted hypothesis to explain normal pressure hydrocephalus (NPH) points at the increase of cerebrospinal fluid (CSF) outflow resistance as the fundamental cause. Some clinical and experimental studies do not agree with this hypothesis and suggest that NPH is related to an alteration of the CSF pulse pressure waveform, while intracranial pressure (ICP) mean value has negligible effects. The current treatment of hydrocephalus is based on the first hypothesis and consists in the implantation of CSF shunts. An improved treatment can be obtained by damping the ICP pressure peaks and keeping unchanged the mean value. The target of this work is to design a special ICP regulator valve, that will be implanted in a human body and that must be characterized by a purely mechanical working principle avoiding any electrical equipment (sensors, actuators...). This device is currently patented [1] and in virtue of that the paper will focus only on the general device working principle and design methodology rather than specific data. Since the device must be implanted inside the patient head, the system must satisfy very restrictive requirements: low weight and dimensions in order to avoid possible patient discomfort or obstacles to the normal life activities, in addition, being the valve application place close to a delicate organ such the brain is, the mechanism must be very simple and must reach very high reliability standards (almost zero maintenance and possible failures). The idea is to realize a device in which the hydraulic flow is governed by a spring with variable stiffness with respect to the applied loads (intracranial pressure: characterized by both a mean constant component and by random oscillatory phenomenon). To maximize the valve effect about pressure peaks reduction, the spring will be designed with a strongly non-linear behavior characterized by bistable working principle. The systems that show this properties are innumerable, but according to the author hypothesis to realize a mechanism as simpler as possible the choice done falls into the thin curved plate (shell) category. In particular, the goal is to obtain a plate behavior called “Buckling Behavior”: under determined load conditions the plate geometric configuration must suddenly switch from an equilibrium position to another. The two target parameters which describe this phenomenon are the buckling critical load that is the applied load value for which the plate change the geometric configuration (valve activation point) and the load application point displacement (evacuation pipe opening). The adopted design method is the non-linear analysis developed in a finite element analysis (F.E.A.) environment, by which it is possible to analyze a component behavior also in case of large displacements. To identify the optimal component geometry the load application point displacement versus the acting load was evaluated as function of the main parameters describing the plate profile: plate semi-length, curvature radius and semi-length of the plate plane portion. This work represents only a preliminary study oriented to demonstrate the feasibility in realizing a biomedical valve for fluids pressure control, adopting a thin curved plate with “Buckling Behavior”. Moreover it provides useful information for the designer who wants to realize curved plate with buckling behavior showing the influence of the main geometric parameters on this phenomenon. Further in depth studies oriented to: the spring stiffness regulation for different patients, best material choice and productive process must be accomplished before the device realization.

This paper presents a novel Magentorheological (MR) brake with permanent magnets. The proposed MR brake can generate a braking torque at a critical rotation speed without an external power source, sensors, or controllers, making it simple and cost-effective device. The brake system consists of a rotary disk, permanent magnets, springs and MR fluid. Permanent magnets are attached to the rotary disk via springs, and they move outward through grooves with two different gap distances along the radial direction of the stator due to centrifugal force. Thus, the position of the magnets is dependent on the spin speed, and it can determine the magnetic fields applied to MR fluids. Proper design of the stator geometry gives the system unique torque characteristics. To show the performance of an MR brake system, the electromagnetic characteristics of the system are analyzed, and the torques generated by the brake are calculated using the result of the electromagnetic analysis. After the simulation study, a prototype brake system is constructed and its performance is experimentally evaluated. The results demonstrate the feasibility of the proposed MR brake as a speed regulator in rotating systems.