Integrated rotational viscoelastic damper

Abstract

The integral rotary friction damper is used in the field of energy absorption and dissipation devices, using mechanical action to move. The rectangular frame is used as a frame and skeleton in a wide range of tools, machines and construction industries. The deformation of the frame from a rectangle to a parallelogram, under the influence of external factors or forces, is usually not desirable and causes instability or disruption in the performance of the system. The purpose of using the above damper is to absorb and dissipate energy resulting from undesirable deformation of the frame. In the motion method of "linear to rotational vibration converter in a rectangular frame", there are members that convert frame vibrations into rotational displacement between rotating plate members. Using the above method and by creating a gap between the rotating plate members and placing viscoelastic disks between those members and connecting those disks to the rotating surfaces, the above damper device is made. This damper is used in the construction industry to control lateral deformations of buildings caused by wind and earthquakes. It has application.

Description

Description of the invention Title of the invention Integrated rotational viscoelastic damper Technical background of the relevant invention It falls within the scope of devices that absorb and dissipate input energy using the mechanical function of motion. Technical problem and stating the objectives of the invention Rectangular frames are used as a framework and skeleton in a wide range of tools, machinery and construction industries. The deformation of the frame from a rectangular to a parallelogram under the influence of external factors and forces is usually not desirable and causes instability and disruption in the performance of the system. One of the appropriate methods for absorbing and dissipating energy and controlling unwanted deformation of the frame is the use of dampers. The main purpose of using an integrated rotational viscoelastic damper in the system is to absorb and dissipate the energy caused by the undesirable deformation of the frame under the influence of external forces. By installing this damper in the system, the unwanted deformation of the frame in response to external forces is reduced by breaking the intermolecular bonds inside the damper. This performance improvement can effectively prevent possible damage to the frame and will be very beneficial to maintain the strength and stability of the structure. A description of the state of the prior art and the history of developments related to the claimed invention. With the advent of durable materials such as steel and concrete, the use of linear structures and rectangular shapes in various industrial sectors, building frames, bridges, scaffolding, machinery support bases, etc., has become very common. In rectangular frames, for various reasons, the components move against each other, causing the frame to change shape from a rectangle to a parallelogram. There are limited methods and tools for controlling movement and displacement in these rectangular frames, and each of these methods and tools has its own advantages and disadvantages. These tools include braces of various shapes and types, frame filler plates of various shapes and materials, preventing relative rotational movement of frame members at the connection point (bracing), and the use of dampers that control and reduce movement and displacement in the frame. In dampers, energy dissipation generally occurs through friction, deformation of metallic and non-metallic materials in the plastic phase (yielding and viscoelastic), and fluid flow control (viscous). There are various methods and arrangements for creating energy dissipation mechanisms in dampers, which leads to the creation of new forms of dampers with different names and applications. A number of important parameters for selecting a specific type of damper for a system include: - Energy consumption rate - Damping capability - Hardness - Maximum displacement - Reversibility to original form - Dimensions - Production and maintenance costs - Durability - Manufacturing technology Below, we will introduce a number of available dampers. Pal friction damper: The Paul friction damper was first designed in 1982 by Canadian scientists Paul and Marshall. The system works by creating sliding friction surfaces at the intersection of cross braces in a building frame. The Paul damper consists of several groups of rectangular steel straps that are installed at the intersection of cross braces. These straps are connected to each other using high-strength steel bolts and, by changing shape, from a rectangular to a parallelogram at the intersection and nodes of the damper, create relative rotation. The Pal damper does not slip under wind load, but it moves during earthquake excitations and absorbs a significant portion of the earthquake energy. This action allows the structure to remain elastic and reduces damage to structural components. Sumitomo friction damper: This damper is manufactured by Sumitomo Metal Industries and is attached to the length of the brace. This damper device has a cylindrical wall with pads embedded inside it, and these pads slide on the inner wall of the damper, dissipating energy through friction. Rotary friction damper: This damper is known in technical references as a new friction damper and has two general forms: The first form of this damper consists of two connecting members in the shape of a seven or eight, with friction nodes located at the junction of these members. This damper can be expanded by connecting these members in series, and as the seven and eight members are folded or unfolded, rotation is created in the nodes, causing energy dissipation. The second form consists of two parallel arms connected by two or more connecting members. The connecting members are also parallel and friction nodes are located at the junction of the connecting members and the arms. Relative displacement in the two parallel arms along the axis of the arms causes rotation at the nodes and energy dissipation. Friction damper in brace: This damper is installed as a sliding interface between the 7th and 8th or diagonal bracing members and consists of two or more groups of plates that slide one on top of the other. One group of plates has bean-shaped holes along the longitudinal axis of the brace and the other group has round holes and the plates are pressed together using high-strength bolts. As the frame changes shape from a rectangle to a parallelogram, the diameter of the frame or other components attached to the frame changes, causing displacement between the two sets of damper plates. Energy is consumed due to friction between the two sets of plates. Cylindrical friction damper with forced strain generation mechanism: The cylindrical friction damper has only two main parts: the cylinder part and the tube part. In this damper, the inner diameter of the tube part is a very small amount (a few tenths of a millimeter) smaller than the outer diameter of the cylinder part over a limited length. After the tube part and the cylinder part have a sufficient temperature difference, the cylinder part is easily placed inside the tube and has the possibility of a certain movement in and out of the tube. After thermal equilibrium, the necessary pressure for friction between the damper surfaces is created in these two parts. In this damper, the necessary pressure between the friction surfaces is not controlled by intermediate mechanical parts such as screws, but by adjusting the geometric parameters and materials of the cylinder and tube by the friction surfaces. This damper is a passive energy dissipation device used to provide additional stiffness and damping in mechanical devices subjected to shock and vibration, or in structures to improve their seismic behavior and reduce damage from earthquakes. Flowing metal dampers: The first research projects on the use of metal dampers were presented by Kelly and Skinner in the early 1970s and were continued by various and extensive research by other researchers. These devices are embedded in structures as energy absorbers and, by enduring irreversible plastic deformations, dissipate a significant portion of the energy entering the structure. In these studies, inelastic bending and torsional strains were created in steel elements. This was the first time that the idea of ​​using devices in structures that, by entering the plastic zone and absorbing energy, reduced damage to the main members of the structure was proposed. Considerable research has been done in this area, including the experiments of Bergman and Goel at the University of Michigan on X-shaped and V-shaped steel plates. In another important research project in this regard, Whitaker and colleagues at the University of Berkeley conducted research on the behavior analysis of X-shaped steel plates. A lot of other research has been done on ADAS and TADAS metal dampers in recent years. Viscoelastic damper: Viscoelastic materials used in structures to absorb and dissipate energy are usually glass or polymer materials that resist deformation. This property is one of the important characteristics of the material, and the use of these materials in structures increases the stiffness of the structural system. On the other hand, when deformation is applied to these materials, depending on the temperature and frequency of loading, some of their molecular bonds are broken, and in this process, some energy is spent on breaking these bonds. In fact, the damping of these materials is due to the breaking of molecular bonds. One common type of viscoelastic (VE) damper consists of viscoelastic layers surrounded by metal sheets. In this type, when the building vibrates, relative motion occurs between the outer metal wings and the central sheet of the damper, which causes shear deformation and, as a result, energy dissipation. In 1969, viscoelastic materials were used in the construction of the World Trade Center Twin Towers, and Tsai and Lee conducted early studies on viscoelastic dampers. Viscous damper: Viscous dampers were first used in the 19th century to dampen the effects of cannon fire on ships. They were later used in the aerospace industry for missile launches and in the military. In the first half of the 20th century, the technology was also used in automobile factories. The introduction of viscous dampers to the construction industry began with experiments conducted at the University at Buffalo. In fact, hydraulic displacement of fluids can be used effectively to achieve the desired level of vibration control. The main efforts to develop viscous dampers for structural applications have been made in recent years, drawing on experiences from the heavy and military industries. One simple design approach is based on the classic cylinder-piston model filled with a viscous fluid. In this approach, energy dissipation is achieved by converting kinetic energy into heat through the flow of the viscous fluid in the cylinder and piston. Providing a solution to an existing technical problem along with an accurate, sufficient, and integrated description of the invention This damper is made using the "linear to rotational vibration converter in a rectangular frame" motion method. The above converter is a mechanical-kinetic method, consisting of members that convert the reciprocating motion of a rectangular frame into rotational motion in the center of the frame and between the rotating members. This method is located on a two-dimensional plane, and its deformation and displacement also occur on the same plane. The members of this converter are divided into three groups: frame members, connection members, and rotational members. 1- The frame members consist of four linear members, two by two parallel to each other and arranged in a rectangular shape. The movement of the other members is dependent on the movement of the frame and in Figure (1), the frame members are shown with numbers (1) to (4). 2- The connecting members consist of two linear members that are connected to the frame on one side and to the rotary members on the other. Each connecting member is connected diagonally to the corners of the frame and in Figure (1), the connecting members are shown as (5) and (6). 3- The rotating members consist of two groups of surface members, which are hinged together at the center of the frame and allow for relative rotation around its center. In addition, one group of members is connected to the middle of the upper and lower members of the frame and another group of members is connected to the connecting members, and in Figure (1), the rotating members are shown as (7) and (8). In the above method, all members, except the frame, are connected to each other in a hinged manner (without the ability to resist rotation relative to each other in an axis perpendicular to the plane). However, the connection of frame members to the frame can be in two ways: hinged or clamped (with the ability to resist rotation relative to each other in an axis perpendicular to the plane). By securing each frame member as a fixed support, the relative movement of the member opposite it causes relative rotation between the rotating members in opposite directions. In this method, due to the internal stiffness of the members under the influence of force or displacement, very little internal deformation occurs in the members and buckling does not occur in them. Also, no significant curvature is created in the members. Therefore, the original shape of the members is maintained in this method and because the internal deformation of the members is very small compared to the amount of movement of the above transducer, this internal deformation can be ignored. The displacement limit in the nodes of the above method depends on the geometric dimensional proportions of the transducer, the dimensions of the members and the means of connection between them. In other words, the possibility of movement and displacement of the members is affected by the dimensional proportions and the means of connection. These limits are determined based on the dimensions and conditions of the geometric structure and the interactions between the elements. Therefore, in the design and use of this method, these limits should be considered and appropriate dimensions, members and means of connection should be used. Integrated rotational viscoelastic damper tool: Using the above method, by creating a gap between the rotating plate members and placing viscoelastic materials (in the form of disks) between all the rotating plate members, in such a way that these materials are completely connected to the rotating surfaces, it is possible to manufacture an integrated rotating viscoelastic damper device, the introduction, the way the members are connected, and the description of its function are as follows: The above damper members are divided into four groups: frame members, interface members, rotating plate members, and viscoelastic discs. The frame and interface members are exactly the same as the introduced converter, and other changes compared to the converter are as follows: A- Creating a gap between the rotating plate members as follows: The rotating plate members consist of two groups of plate members (circular, concentric, parallel, adjacent, and equidistant from each other), and each group can move with each other, and the plates of each group are arranged one between the plates of the other group to achieve maximum efficiency. In plate rotary members, due to symmetry and the absence of an eccentric force outside the damper plate, the number of plates in the first group, which are located in the outermost layer, is one more than the number of plates in the second group. B- Addition of viscoelastic materials, shown in Figure (1) with number (9). Viscoelastic disks are located between all the rotating plates of the first and second groups and attached to them. Given the presence of at least three rotating plates, two viscoelastic disks are used. In accordance with the odd number of rotating plates, the number of viscoelastic disks is even, and the geometric and mechanical characteristics of the disks are the same. In addition, a simple method is used to create a hinged connection as follows: The rotating members and connecting members are connected to each other or to other members by rods that are perpendicular to the rotating planes and have a completely hinged behavior. The rotating plate members are located in the center of the circles on a rod that is perpendicular to it, and it is possible for one or two groups of plates to rotate around that rod, and the frame members can be connected to each other in a hinged or clamped manner. If the frame is relatively displaced by an amount D to the left and right, the relative rotation angle of the two groups of rotating plates changes by an amount Q ± (according to Figures (1) to (3)). The relative rotation between two groups of rotating plates is transmitted to the viscoelastic disks in the form of a torsional force, causing shear deformation in the viscoelastic materials, absorbing and dissipating the input energy. The thickness of the viscoelastic discs depends on the distance between the rotating plates. Reducing the thickness of these discs increases the deformation caused by shear stress, which is desirable from a behavioral perspective. However, reducing the thickness of the discs, under conditions where other geometric and mechanical characteristics are constant, reduces the ultimate deflection of the viscoelastic discs and restricts the rotational movement between the plates, which leads to a decrease in the range of frame displacement and, as a result, a decrease in the energy absorption and dissipation capacity of the damper. To increase the rotational range in the discs while maintaining the desired shear deformation behavior, it is possible to use metal sheets embedded in the discs. These sheets are placed in layers between the viscoelastic materials and parallel to the rotating plates. In this case, the sheets must be completely adhered to the viscoelastic materials and the viscoelastic materials must be placed on both sides of them (such as metal sheets in rubber seismic isolators). This method increases the relative rotational range between the rotating plates and, consequently, the range of frame displacement and the ability to absorb and dissipate energy in the damper. Explanation of shapes, maps and diagrams Figure (1) shows a view of a monolithic rotational viscoelastic damper in a two-dimensional plane without displacement. Figure (2) shows a view of an integrated rotational viscoelastic damper in a two-dimensional plane with a displacement D to the right. Figure (3) shows a view of an integrated rotational viscoelastic damper in a two-dimensional plane with a displacement D to the left. As shown in Figures (1) to (3), by moving the frame by an amount of ±D, a relative rotation of ±Q is created in the rotating members. To perform the calculations, we need to have the values ​​of the following variables: Outer radius of viscoelastic material located between the rotating plates (r1) Inner radius of viscoelastic material located between the rotating plates (r2) Number of viscoelastic discs between rotating members (m) Shear stress of viscoelastic materials (τ) According to Figure (4), the value of the resistive moment of the viscoelastic damper plates (the value of the moment that causes relative rotation between the rotating members) can be calculated with the following formula: T= According to Figure (5), by applying force F to node c, the value of the torsional moment at node i can be calculated according to the following relations and the converse is also true. Having the viscoelastic torsional resistance moment of the rotating members T, the lateral force of the damper movement can be calculated: and It is necessary to explain that the results of both equations above are the same and in these two equations all parameters except the shear stress of the viscoelastic discs are constant and depend on the geometric proportions of the damper, and the shear stress of the viscoelastic discs in the above equations varies nonlinearly and depends on the temperature and frequency of loading (like other viscoelastic dampers) and will cause a change in the instantaneous force F. Figure (6) shows the 3D model of the integrated rotational viscoelastic damper. Figure (7) shows the expanded 3D model of the integral rotational viscoelastic damper with the member numbering as shown in Figure (1). A clear and precise statement of the advantages of the claimed invention over prior inventions.  Using the "linear to rotational vibration converter in a rectangular frame" method in viscoelastic damper  Ability to change the geometric parameters of the mechanism in the integrated rotational viscoelastic damper  Ability to change the geometric and mechanical parameters of the viscoelastic disk, such as inner and outer diameters, thickness, number, and material, in order to change the amount of energy dissipation of the damper. High efficiency and energy consumption due to the possibility of using large viscoelastic discs with the ability to increase their number if the number of rotating plates in the damper increases. The double function of the rotating plates, as a heat repellent, is generated due to the deformation of the viscoelastic materials during the operation of the damper.  Ability to design a right angle (the angle between the axis of the connecting member and the axis from which the connecting members are connected to the rotating member), in the initial and undeformed form of the damper and create stiffness in the frame movement  Possibility of layered deployment of metal sheets, parallel to the rotating plates, buried and adhered to viscoelastic materials, in order to improve the shear deformation behavior in the viscoelastic damper materials. The ability of the frame to return to its original state after unloading due to the presence of a restoring force in the viscoelastic discs.  Ability to install in existing frames and use that frame as part of an integrated rotational viscoelastic damper No need for advanced manufacturing technology Simple maintenance and repair, due to the use of limited parts Low depreciation and long lifespan Description of at least one implementation method for implementing the invention In buildings, beams and columns are usually used as a structural frame, which is a suitable method for transferring gravitational forces to the ground. Lateral displacement in buildings is of great importance for stability and operation, and the ratio of lateral displacement to floor height is usually limited to a certain value in building codes. To control lateral displacement and stability against forces or lateral displacements imposed on the building (such as wind and earthquake), various methods and tools are used, such as: stiffening frame connections (clamped connections between frame members), convergent and divergent bracing, with different diagonal, cross, chevron shapes, steel and concrete shear walls, masonry materials, and dampers. The selection of a method or tool for resisting lateral loads is based on parameters such as: internal conditions and nature, external factors, cost, demand, and available technology. Dampers are a new generation of lateral displacement control devices in buildings that eliminate damage to structural members by absorbing energy during earthquakes. They have received great attention in the construction industry with technological advances and reduced production costs. An integrated rotational viscoelastic damper can be installed in a building frame and, by dissipating energy and controlling the deformation of the frame during an earthquake, ensures structural stability and prevents damage to building components. Explicit mention of the industrial application of the invention In the construction industry, it can be used to control lateral deformations of the building frame caused by wind or earthquake excitation.

Claims

Claim What is claimed: Claim 1) The integrated rotational viscoelastic damper device operates using the "linear to rotational vibration converter in a rectangular frame" method and includes frame members, connectors, rotating plates, and viscoelastic disks. By creating a gap and placing viscoelastic disks between the rotating plates and connecting them to these plates, this device converts the reciprocating motion of the frame into a relative and reverse rotational motion between the rotating plates, and absorbs and dissipates the kinetic energy of the frame by changing the shear deformation in the above disks. Claim 2) According to claim 1, this damper is located in a two-dimensional plane and its deformation and displacement also occur in the same plane. Claim 3) According to claim number 1, the frame and interface members in the integral rotational viscoelastic damper are completely identical to the frame and interface members of the "linear to rotational vibration converter in a rectangular frame". Claim 4) According to claim 1, the plate-shaped rotating members in the integral rotational viscoelastic damper device consist of two groups of plate-shaped members with an odd total number of at least three plates, and in such a way that the outer plates are one more than the inner plates and are formed in a circular shape, concentric, parallel, adjacent to each other and at an equal distance from each other, and the symmetry of these members prevents the creation of an eccentric force outside the damper plate. Claim 5) According to claim number 1, the viscoelastic disks have viscoelastic mechanical properties and are located between all the rotating plates of the first and second groups and are attached to them. Considering the minimum number of rotating plates, two viscoelastic disks will be used. Since the number of rotating plates is odd, the number of viscoelastic disks is even, and the geometric and mechanical properties of all disks are the same. Claim 6) According to claim 1, for maximum efficiency, the rotating plate members of each group are arranged one next to the members of the other group, and the viscoelastic disks are located between the plates of the two groups of rotating members, and are connected to those plates. Claim 7) According to claim 1, the plate-shaped rotating members are located in the center of the damper on a rod that is perpendicular to it, and it is possible for one or two groups of plates to rotate around that rod. Claim 8) According to claim 1, the damper members are connected to each other in a hinged manner using a rod perpendicular to the rotary plates to enable rotation and movement of the above damper device in its two-dimensional plane, and in addition to this type of connection, the frame members can also be connected to each other in a fixed manner. Claim 9) According to claim 1, in order to improve the desired shear deformation behavior in viscoelastic disks, it is possible to use metal sheets buried in the disk, which are placed in layers between the viscoelastic materials and parallel to the rotating plates, in which case these sheets must be completely connected (glued) to the viscoelastic materials and viscoelastic materials must be placed on both sides of these sheets. Claim 10) According to claim 1, the integrated rotational viscoelastic damper device has the ability to return the frame to its original state after unloading due to the presence of a restoring force in the viscoelastic disks.

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