Papers by Keyword: Damper

Abstract: This paper is focused on magnetorheological (MR) dampers and their critical parts in terms of damper`s durability, which seems to be a piston-rod seal. An option to reduce the wear is to choose the proper material for that purpose. The wear measurements were conducted in an accelerated and simplified mode in a modified pin-on-flat (cylinder-on-flat) configuration, which was supposed to be more suitable for laboratory testing than original configurations. Suitable commercial materials for seals, like PTFE, NBR, SBR and polyurethanes, were tested and compared in commercial MR fluid MRF-132DG by LORD Corporation. It turned out that material H-PU95FDA had had the biggest wear resistance from all tested materials and therefore it was the most suitable material for durable seals, while PTFE seals are expected to be suitable in non-durable applications with low frictional forces.

Abstract: To control the vibrations with passive suspension system having limitation with constant damping force. By using smart material like magnetorheological fluid, it is possible to control the damping performance of suspension system using current variations in magnetic coil. Applications of this kind of damper are in front loaded washing machine and damper use in driver seat of heavy duty vehicles. Mainly flow mode MR damper is most commonly used damper for these two applications. This paper represents theoretical model and optimized design of flow mode MR damper. For any kind of MR damper design of magnetic coil is play very vital role. So for this paper mainly includes the design of coil and different parameters like number of coil distance between two coil current passing from the coil is consider for design and optimization using FEMM software. This work also includes the theoretical study of MR damper characteristics with force-displacement and force velocity plot with change in piston diameter and fluid gap.

Abstract: The paper presents a complex quarter car model obtained with ADAMS software, View module, useful in the first stage of suspension dimensioning and optimization.The model is equipped with compression and rebound stopper buffer and suspension trim corrector.The proposed quarter car model with two degrees of freedom (wheel and body) performs all these goals allowing changing:Geometrical elementsPosition of equilibrium, depending on vehicle load;Trim correction;Elastic and dissipative characteristics of the suspension and tire;Suspension stroke;Road profile, assessed either by simple or summation of harmonic functions or reproducing real roadsBuffers (for stroke limitation) position and characteristics;The models developed provide information on:Vertical stability assessed by vertical movements of the body and the longitudinal and transversal stability evaluated based on adherence characterized by wheel ground contact force and frequency of soil detachment wheel.Comfort assessed on the basis of body vertical acceleration and collision forces to the stroke ends.The body-road clearanceThe trim corrector efficiencyAll above performances evaluated function the road unevenness, acceleration, deceleration, turning regime.The damping characteristic is defined by damping forces at different speed for each strokes respectively one for rebound and other for compression.The contact force road-wheel is defined based tire rigidity law.The stopper buffer forces on rebound and compression are defined based each specific rigidity characteristics.The road excitation is realized with a function generator.The software allow the model evolution visualisation in real time, also generating the diagrams of displacements, forces, accelerations, speeds, for each elements or for relative evolution between diverse elements.The simulation was realized for unloaded and fully loaded car using a road generated by a sum of harmonic functions presented in equation (8).The excitation covers the specific frequencies area, being under the body frequencies up to the wheel proper frequencies.The realized ¼ car model, have reached the goal to evaluate the suspension trim correction advantages.The simulations confirm the trim corrector increases the suspension performances, thus for the analyzed case the trim corrector increase simultaneous:Body-ground clearance (evaluated by body higher increasing) between 18.5÷55.1 %Body stability (evaluated by maximal body displacement) between 9.8÷11.4 %Body comfort (evaluated by maximal body acceleration) between 3.4÷35.5 %Adherence (evaluated by maximal and RMS wheel-groundcontact force variation) between 7.0÷12.1 %Body and axles protection (evaluated by buffer strike force) between 10.8÷38.2 %

Abstract: The VZN shock absorber concept granted with European Patent EP 1 190 184 is characterized by damping coefficients self according with road and load conditions.The simulations made on vehicles equipped with new VZN shock absorbers concept relative to standard one, indicates better behavior concerning stability, comfort and reduced dissipated energy, with fuel consumption and pollution reducing effect.Starting on these remarks the paper evaluates the influence of the damping characteristic in suspension performances and dissipated energy, based a simulation on a Californian road realized with Matlab Simulink software.Since year 2006 simulations on model ¼ cars demonstrates the VZN damper concept give skyhook behavior, decrease squat, vertical acceleration, the number and intensity of stopper bumper collision, the adherence, increasing thus the vehicle stability, comfort and reliability.Tests on models ½ car, show the VZN concept increases stability at pitch and roll and confirm the previous results obtained on ¼ models.The current work completed previous research with one demonstrating other VZN qualities e.g. its capacity to manage damping coefficient, no more and no less, assuring high performances and thus reducing the dissipated energy, with favorable effect for reducing fuel consumption and pollution.The comparison between the behaviors of the VZN shock absorber relative to the standard shock absorber has been realized for body displacement, squat, acceleration and dissipated energy.The VZN progressive damper concept gives better behavior comparative to standard one, 6% at car body bounce, 37 % for RMS acceleration and 28.4 % for dissipated energy, these means it confer better body-ground clearance, comfort and fuel consumption and pollution.The VZN damping coefficients accorded with the vehicles load and with road unevenness confer a soft response at low excitation and strong reactions at high excitations, dissipating energy function of the needs, assuring thus comfort at small and medium excitation and protecting the axles and body at hard conditions.

Abstract: Corrosion is an everyday occurrence. It provokes the materials destruction, what directly translates into the durability, survivability and reliability of the equipment, specially of working in the aggressive environments one – e.g. afloat ships or boats. Corrosion is a cause of growth of the requirements of the raw materials needed for production of more and more new products and increase amount of waste come from this production.In the paper authors show the results of the experimental tests and they describe the meaning of the selection of laser bean parameters oriented for surface of chosen steel exposed to even corrosion.

Abstract: The problem of damping of torsional vibrations of the crankshaft in a multi-cylinder engine is very important from the point of view of durability and reliability of the drive unit of the vessel or ship. Mostly dependent on the technical state of the torsional vibration damper that is located at the free end of the crankshaft. The paper presents selected results of the research that led to the acceptance criterion for assessing the technical condition of the viscous torsion damper.

Abstract: A new approach substitutes the damper of a passenger car by a cardanic gimbaled flywheel mass. The constructive design leads to a rotary damper in which the vertical movement of the wheel carrier leads to revolution of the rotational axis of the flywheel. In this arrangement, the occurring precession moments are used to control damping moments and to store vibration energy. Different damper characteristics are achieved by different velocities of the inner ring. From almost zero torque output to high torque output, this damper has a huge spread. In this paper a control concept for a LQR is presented. The objective of the control is an adequate motion of the gyroscope to a desired damping characteristic of a passenger car.

Abstract: This paper presents analytical, numerical and experimental studies of SERB TEL-150 new Romanian devices for dissipation of seismic energy for buildings affected by Romanian Vrancea earthquakes. These devices were invented to be positioned at the foundation of buildings and were tested in static cases. The purpose of these studies is to determine the analytical model of the special shape hysteresis of these new devices which is necessary to obtain the mathematical equation for these hysteresis curves. The experimental and the numerical analysis of SERB TEL-150 were performed in order to determine the experimental and the numerical hysteresis curves which are to be modeled with a modified Bouc-Wen model. These devices were invented by PhD.eng. Viorel Serban (CITON – Center for Technology and Engineering for Nuclear Projects) and they were used for equipping NAVROM building in Galati, Romania.

Abstract: A multi-function half-real object integration research platform based on virtual instrument technology was designed to meet the needs of the design of magneto-rheological damper. The platform is an integration of multifunctions which mainly includes assisted optimal design, controller management, algorithm simulation and online real-time performance test. This paper introduced the design of hardware and software in detail. The experimental results showed that the platform has many advantages in such aspects as complete functions, stable performance, accurate test and stronger visualized data analysis.

Abstract: In order to improve the accuracy of cable tension test, the motionequation of the stay cable with the rubber damper was established bases on the principleof Hamilton. First, the correction method for the damping coefficient of rubberdamper and cable tension was proposed according to the higher modal frequencyand measured frequency of cables difference. Then, take the cable of DongtingLake Bridge as an example, the cable tension was calculated by the proposedmethod and compared with the results of measurement by frequency method.Results showed that the proposed method can improve the accuracy of cabletension test and can effectively evaluate the cable tension condition of thecable-stayed bridge.