For more information, see set priority and initial target for block variables. The resultant freebody forces and moments across any cut in the structure. The dissipated energy by a mooring line from the floating platform as a result of its oscillation is applied to calculate the mooringinduced damping. A photograph of a typical damper at this facility is provided as figure 4. In this paper, numerical modelling of viscous wall dampers using finite element analysis tool. In the equivalent water depth truncated model test design of a deepwater semisubmersible platform, the viscous damper is designed to simulate the contribution of mooring damping to total damping of floating platform. Alternatively, viscous damping can be provided by the motion of a conductive solid. L is the angular position of the throttle plate, t. Input vibration energy to be decayed by transforming to thermal. The process through which free vibration diminishes is called damping. Those dof without nonlinear specification will remain linear by using effective stiffness, which may. Other configurations, such as single vane vwds are also available. Viscous dampers born from necessity houdaille later renamed to vibratech tvd invented the technology in 1946 view company history to reduce the risk of crankshaft failure being experienced in diesel.
Translational viscous damper with variable damping. Schematic drawings for typical configurations of double vane vwds are shown in appendix c. K, in series with an exponential damper characterized by. Each damper is 4,3 meters in length and weighs nearly 1500 kg.
Damping faq technical knowledge base computers and. How is damping specified for different parts of the structure. The additional material damping menu figure 1 allows users to specify different materialdamping properties for each material present in the analytical model. Viscous damping is a common form of damping which is formed in many engineering systems such as instruments adn shock absorbers. Understand the basic functions and features of a fluid viscous damper fvd. Match of negative stiffness and viscous damping in a passive negative stiffness damper nsd is studied for the vibration control of stay cables in this paper. In contrast, the tenco seismic brake inline seismic friction damper is a damage free approach and slips instead of yielding, and, by means of the elasticity of. The latest progress in viscous dampers as powertrain design continuously evolves to meet the demands of emission compliance, fuel savings and material reduction, so does the need for quality protection against destructive. Applied sciences free fulltext practical design method of. This paper presents the comparative study of seismic performances of xshaped metallic damper xmd and fluid viscous damper fvd under eight different earthquake ground motions and how the damper placement influences the seismic response of the building. To model a damper in sap 2000, a section of damper type is used and then it is. Link objects are very well suited for modeling the nonlinear forcevelocity relationship of viscous damping. A jarret structures damper works on the principle that rapid passage of viscous fluid through a narrow orifice or port generates high resistance, which then dissipates a large amount of energy as heat. The tmddevice is consisting of a moving mass, springs and a damping element.
Mass proportional damping in nonlinear timehistory. Parameter calculation of viscous damper applied in the. Modeling of a viscoelastic damper and its application in. Viscous dampers hdrbs and viscous dampers figure 6 comparison of viscous damper force between the models with this device 0 500 1. Therefore, the ysd is simulated by plastic wen units in sap2000, which are bilinear constitutive models.
Fluid viscous damper the viscous dampers are modeled as maxwell element, which is a nonlinear damper with a nonlinear spring. The forcevelocity relationship for this kind of damper can be characterized as fcvn, where f is the output force in pounds, v is the relative velocity across the damper in inches per second, c is a constant determined mainly by the damper diameter and the orifice area, and n is a constant exponent which can be any value from. Evaluating effects of viscous dampers on optimizing. The viscousdamper material simulates the hysteretic response of nonlinear viscous dampers. When tension in one of the brace forces the damper to slip, the mechanism shortens the other brace thus preventing buckling. Match of negative stiffness and viscous damping in a. An additional advantage of the fluid viscous dampers was that the long period rubber bearings and fluid viscous dampers would be able to fully reset the building after a seismic event with no permanent offset. Study the impact of using viscous fluid dampers in steel buildings.
For a seismic increased protection, new technologies have been developed, among these technologies there is the passive energy dissipation devices. For this purpose five, eight and ten storey reinforced concrete buildings were used and each of the dampers were installed in different. Pdf effect of viscous wall dampers on response of reinforced. A two node link element is used to link the two nodes that define the geometry of the viscous damper. Figure 3, figure 4 show the force velocity and the force displacement relationships for three different types of fvd. Viscous damping is the dissipation of energy that occurs when a particle in a vibrating system is resisted by a force the magnitude of which is a constant, independent of displacement and velocity, and the direction of which is opposite to the direction of the velocity of the particle.
Comparison of xshaped metallic dampers with fluid viscous. Unlike conventional methods, the equivalent linear viscous damping. At first, a discrete model of the stay cable with an nsd attached perpendicularly near the support is established. Rayleigh damping, mass proportional damping, elasticplastic, timehistory analysis. Improving the dynamic behavior of adjacent buildings with fluid. This study will focus on the seismic design of structures with supplemental fluid viscous dampers device. Viscous damper integration is fundamental to creating durability and efficiency in new powertrain designs. It features a powerful graphical user interface that is unmatched in terms of easeofuse and productivity. Study of nonlinear fluid viscous dampers behaviour in. Viscous damper in mechanical translational systems matlab.
Sap2000 software uses parallel and series systems of spring and damper in linear and nonlinear analyses, respectively. Viscous dampers generally consist of a cylinder casing, piston, damping hole, damping medium viscous fluid and leader. Viscous fluid dampers, sap2000, bhuj ground motion data, passive control. When initially released in 1996, sap2000 was the first version of sap to be completely integrated within microsoft windows. Viscous damper system will be modelled as pure stiffness free damping behaviour. In the event of an earthquake or extreme wind vibration, the damper can consume the vibrations energy and protect the main structure and components from damage to ensure its safety. The translational damper block represents an ideal mechanical translational viscous damper, described with the following equations. Viscous fluidfilled damperproductssekisui polymatech co. Can the software calculate the percentage of critical damping achieved by dampers added to a model.
Direct displacementbased design for seismic retrofit of existing. Under sinusoidal excitations, forced responses of the system are derived theoretically, which results in an asymptotic. Viscous damping article about viscous damping by the. A frictionspring hysteretic damper has been implemented as a new link property. Turbulent flow viscous dampers are unidirectional with a rather complex mechanical design and require periodic maintenance, but laminar flow viscous damping units are multidirectional with a simple mechanical design and are maintenance free. The viscous damping force is proportional to the first power of the velocity across the damper, and it always opposes the motion, so that the damping force is a linear continuous function of the velocity.
A physical signal input port provides the magnitude of the translational damping coefficient. For the love of physics walter lewin may 16, 2011 duration. An adaptive iterative algorithm has been implemented and validated to solve numerically the constitutive equations within a nonlinear viscous damper with a highprecision accuracy. Behavior of ve rubber dampers is a rate dependent phenomenon 3 8. With a 1 the device is called linear viscous damper and for a 1 has not been seen often in practical application. Viscous damper in mechanical rotational systems matlab. In recent years, numerical tools such as finite element method have been utilized to optimize the structure of ve rubber damper devices 9, 10. Viscous fluidfilled damper, typically called oil filled damper, has high damping characteristics.
Rayleigh damping, mass proportional damping, elasticplastic, time history analysis. A bilinear maxwell damper has been implemented as a new link property. In part 1 we defined a viscous damper as a fundamental component to create durability and efficiency in a powertrain system by reducing torsional vibration to understand what torsional vibration is, we turn to aaron neyman, vibratech tvd snr. In order to support load of antivibration part, spring to be used in parallel. The energy lost per cycle in a damper in a harmonically forced system may be expressed as w d i f ddx 1 where f d represents the damping force. Dynamic analyses of 1story moment frame with viscous dampers. Nonlinear viscous damping technical knowledge base. Pall cross brace friction damper is a unique device which is suitable for long tensiononly cross bracing. Sap2000 represents the most sophisticated and userfriendly release of the sap series of computer programs. Seismic energy dissipation study of linear fluid viscous. The damping properties of nonlinear viscous dampers are based on the maxwell model of viscoelasticity malvern, 1969, and may be specified for each deformational degreeoffreedom dof. The absorption of the seismic input energy in the buildings and reducing its damage are the main objectives of these devices. Hdrbs or lrbs to a seismic isolated system composed by viscous dampers did not guarantee the reduction of the force on the device.
Steel mrfs, linear and nonlinear fluid viscous damper, far field ground motion. Recent enhancements sap2000 computers and structures, inc. To set the priority and initial target values for the block variables prior to simulation, use the variables tab in the block dialog box or the variables section in the block property inspector. Numerical analysis of viscous wall dampers on steel frame.
Viscous fluid dampers vfds and viscoelastic ve solid dampers belong to rate dependent passive dampers. A viscous damper is a fundamental component to create durability and efficiency in a powertrain system by reducing torsional vibration. They characterise the behaviour of the viscous damper. The block represents a translational viscous damper with variable damping coefficient. Sap2000 offers a single unified user interface for modeling, analysis and design. The modeling information in this booklet was prepared for dis by button engineering. The nonlinear damper can give a larger damping force than the two other types fig. The magnitude of the damping force is equal to the product of the physical signal input and the relative linear velocity between the two translational conserving ports.
There are four parameters in damper design, namely. Product engineer and torsional vibration analyst who stated in an exclusive interview. The beam element 3 in figure 1 is considered to be rigid. Link may be placed between any two joints or from joint to ground viscous damper with. L l1 d d1 stroke rm unit mm mm mm mm mm kn asr50100 450 540 60 110 100 50 asr100100 490 610 90 110 100 100.1259 1464 585 805 239 853 1540 659 48 860 472 1174 1248 44 604 1147 482 1520 345 953 1473 1540 843 1533 1408 330 667 429 1298 691 902 1151 1283 1194