WO2019113718A1

WO2019113718A1 - Bidirectional tuned mass damper based on multiple composite levers

Info

Publication number: WO2019113718A1
Application number: PCT/CL2018/000039
Authority: WO
Inventors: Luis Alejandro ROZAS TORRES; Rubén Luis BOROSCHEK KRAUSKOPF; Rodrigo Alfredo AILLAPAN QUINTEROS
Original assignee: Universidad De Chile
Priority date: 2017-12-11
Filing date: 2018-12-06
Publication date: 2019-06-20
Also published as: CL2017003159A1

Abstract

The invention relates to a bidirectional tuned mass damper (BTMD) based on multiple composite levers, in which a mass (1) controls the vibration of a structure (9). According to the invention, the mass (1) of the damper is connected to the structure (9) by means of primary levers (2) and secondary levers (3), the primary lever (2) is connected to the structure (9) by means of a first pivot point (4), the primary lever (2) is connected to the secondary lever (3) by means of a second pivot (5), the secondary lever (3) is connected to the mass (1) by means of a third pivot (6), and springs (7) and shock absorbers (8) are connected between the mass (1) of the damper and the primary lever (3).

Description

BIDIRECTIONAL TUNNEL MASS DISSECTOR BASED ON MULTIPLE

COMPOSITE LEVERS

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a bidirectional tuned mass sink based on multiple composite levers, which corresponds to a type of tuned mass dissipator capable of simultaneously controlling two perpendicular vibrating modes whose frequencies are not necessarily equal.

BACKGROUND OF THE INVENTION

The tuned mass dampers are devices used in structural control, these mechanisms basically consist of a mass, spring and damper system, usually fixed to a vibrating system to reduce the demand on structural elements by dissipating energy.

This energy reduction is obtained when the frequency of the mass absorber is tuned to a particular frequency of the structure. When that frequency is reached, the damper will vibrate out of phase with the structural movement and part of the vibratory energy is transferred to the tuned mass damper.

The present invention relates to "bidirectional tuned mass dissipator based on multiple composite levers" (hereinafter DMSB) which corresponds to a type of tuned mass dissipator capable of simultaneously controlling two perpendicular vibrating modes whose frequencies are not necessarily equal. The mechanisms that make up the DMSB allow the mass of it to cover large displacements in any direction in the plane. These displacements typically occur when the DMSB is used to control vibrations produced by the effects of earthquakes, wind, excitations caused by rotating machinery, among others. Notwithstanding the above, the DMSB can also be used to control vibrations in smaller mechanisms or structures, such as those resulting from the passage of vehicles or excitations due to pedestrian crossing. Its use can also be extended to control vibrations produced by the operation of equipment resulting from its operation, impact loads, among others.

In the state of the art there are several tuned mass dissipators, like the one of the present invention. For example, document CN 102995786 discloses a horizontally adjustable two-directional tuned mass damper comprising a rectangular base that is provided with a longitudinal carriage, in which a transverse carriage is disposed on the upper part of the longitudinal carriage; the front end and the rear end of the longitudinal carriage are each provided with a first shock absorber; one end of each first shock absorber is connected to a longitudinal carriage body by a universal coupling, and the other end of the first shock absorber is connected to the base by another universal coupling; the front end and the rear end of the cross slide are respectively provided with a second damper; one end of each shock absorber is connected to a transverse body of the carriage by a universal coupling, and the other end of the second shock absorber is connected to a second sliding block by another universal coupling; two longitudinal sliding rails are respectively arranged on the two sides of the base; the second sliding blocks correspond respectively with the longitudinal sliding rails; and an equilibrium weight is disposed in the transverse carriage. The adjustable two-way tuned mass damper disclosed in this document is capable of absorbing bidirectional impacts and only needs a set of counterweights, so that the weight of the tuned mass damper is lighter than that of the traditional tuned mass damper ; and the two-way adjustable tuned dough damper is especially suitable for buildings such as a high-voltage power transmission tower and a radio tower.

The document CN 105756219 discloses a horizontal bidirectional viscoelastic tuned mass damper system and a working method thereof. The horizontal bidirectional viscoelastic tuned mass cushion system comprises a hollow circular outer cylinder, an upper cover plate disposed above the hollow circular outer cylinder and a lower cover plate disposed below the hollow circular outer cylinder; a universal joint is disposed in the middle of the surface of the lower end of the upper cover plate; a circular viscoelastic limiting device is disposed in the middle of the upper end surface of the lower cover plate. The shock absorber system adjusted by bi-directional horizontal viscoelastic collision also comprises a first block of cylindrical mass and a second block of cylindrical mass; the central part of the circle at the upper end of the first cylindrical mass block is articulated with the universal joint through a first rigid rod, and the central part of the circle at the lower end of the first cylindrical block is connected to the central part of the cylinder. circle to the upper end of the second block of cylindrical mass through a second rigid rod; the bottom of the second block of dough cylindrical is located in the circular viscoelastic limiting device; The first cylindrical mass block is also connected to the inner wall of the hollow circular outer cylinder through a plurality of springs. The horizontal bidirectional viscoelastic tuned mass cushion system disclosed in this document is simple in structure and easy to perform and overcomes the defect of the cushioning effect of a traditional device.

CN 101021089 discloses a horizontal bidirectional multi-tuned mass damping device arranged in an area of a structure. It is characterized in that said device can be arranged by zones, in each zone the mass tuned in the direction of the guide is composed of two blocks of dough, said two blocks of dough, a guide rod and a rigid rod are part of a system; said device uses a guide and a device the lower roller and makes the roller slide along the direction of the guide to implement the control of the vibration in the direction of the guide; the mass tuned in the direction of the guide rod is provided by a mass block mentioned above, said device uses the roller of the lower part of the device and slides said roller along the guide bar to implement the control of the vibration in the direction of the guide rod. Said invention is applicable to a high-rise tower, a nuclear power plant, an underground space structure and related structures.

None of the aforementioned documents allows the mass of the same to cover large displacements in any direction in the plane, by means of pivoting bars, allowing in turn the mass of the dissipater to vibrate with different frequencies in its two main directions SUMMARY OF THE INVENTION

Like every tuned mass dissipater, the DMSB is composed of a mass which rests on systems that support its weight and at the same time allow its displacement in the plane. These systems can be of different types depending on the magnitude of the mass, being the most common: frictional sliders; bidirectional spherical wheels; low friction perpendicular rails, or similar devices. The mass of the DMSB can be materialized, if used as a vibration control device in structures, by means of a reinforced concrete box inside which it is possible to use a high density filler, such as steel balls, barite or other to reach the target mass. Other possibilities for the mass of the DMSB include the use of steel plates. In case the device is used for the control of vibrations in equipment, vibratory mechanisms or smaller structures, the mass can be materialized by any element that allows reaching the design mass of the DMSB.

As shown schematically in Figure 1, the mass is connected to the structure, equipment or vibratory mechanism to be controlled, by means of multiple compound levers, each of which has three articulated points. It is these levers that allow to accommodate the displacements of the DMSB mass in the plane. The compound levers are formed in turn by two biarticulated arms. The first one, the main arm, has at one end a pivot or articulation point anchored to the structure to be controlled. This arm, depending on the application of the DMSB, can be materialized by means of a lattice structure. At the opposite end, a second pivot point capable to move on the plane joins it with the second arm, or secondary arm. The secondary arm in turn has a connection that connects it with the mass of the DMSB, by means of a pivot point capable of moving again in the plane. The combination of the turning capabilities of the arms that make up the levers, together with the three articulated points described, make it possible for the mass to move in the plane in any direction. In Figure 2, the DMSB is shown schematically in an arbitrary deformed position.

In order to provide the restitution and damping forces necessary for the operation of the DMSB as a vibration control mechanism, restitutive elements (springs) are available, as well as dampers in each of the composite levers. The restitutive elements can be helical tension or compression springs; Belleville type disc spring assemblies; elastomeric springs; gas springs or any other element that subject to deformation restores the initial resting position of the DMSB as outlined in figure 1. On the other hand, the dampers fulfill the function to dissipate energy and can be linear or non-linear viscous dampers; friction dampers; viscoelastic shock absorbers or any element that fulfills the function of dissipating energy. As shown in figures 1 and 2, whether these are the dampers or the restitutive elements, these components are located in such a way that one of their ends is joined to the main arm and the second end is connected to the mass of the DMSB . In turn, and depending on the design requirements, the longitudinal axes of these elements may not necessarily be parallel with the main directions of the DMSB, as shown schematically in Figure 3. The ratio between the distance measured from the joint fixed to the structure to the point where each of the components joins the main arm, with respect to the total length of said arm, defines the "lever ratio" associated with the component in question. By means of this parameter it is possible to control both the stiffness of the DMSB and its damping. The values of these parameters that define the overall behavior of the DMSB depend both on the stiffness and damping of each of the springs and dampers to be used, as well as on the respective lever factors chosen for each of these elements. It should also be noted that another important property of the lever factor is that it allows the use of springs and dampers with relatively low deformation capacity. In fact, the use of the springs and dampers in conjunction with the levers composed in the manner described above, allow the mass of the DMSB to reach displacements well above the deformation capacities of these elements. This effect of magnification of deformations, which is illustrated graphically in Figure 4 (a single lever shown by clarity is shown), can be controlled according to the design requirements by means of a suitable choice of the lever factors. Both the lever ratios and the stiffness of the springs can be adjusted in such a way that the mass of the DMSB vibrates with different frequencies according to each of its main axes. It is this feature that converts the DMSB into a bidirectional vibration control system, capable of adjusting to control two mutually perpendicular vibratory modes of different frequencies.

Many vibrational problems involve vibrations that occur in two mutually perpendicular directions. As an example of these we can mention the vibrations that occur in high buildings, products of loads seismic or wind. Additionally, these vibrations do not necessarily have the same frequency, since in general, the system to be controlled can have different dynamic properties according to each of said directions. To control this type of vibration simultaneously, the DMSB is able to vibrate in opposition to the system to be controlled with different vibrating frequencies in its two main directions. The present invention offers the possibility of adjusting these frequencies in different ways. One of these, the most direct, is simply to use restitutive elements (springs) of different rigidities in each of the two main directions of the invention, see figure 1. Another alternative is to use springs of equivalent stiffness but whose location in the levers according to the X axes and the Y axis is different from each other. In this way, by means of a change in the geometric configuration, the global stiffness of the DMSB becomes different in its main directions, vibrating in this way with different frequencies in each one of them. It is also possible to use a combination of the aforementioned alternatives, ie springs of different stiffnesses and locations.

Like any tuned mass sink, the vibration frequency of the DMSB is adjusted to match, or is close to, the vibration frequency of the equipment or structure in which it is located. In this way, when the system to be controlled begins to vibrate, the dissipator enters into resonance oscillating in opposition to the system to be controlled thereby reducing the vibrations that occur in the latter. This has as a consequence that the mass of the dissipator is subject to large displacements, which can occur according to any direction in the plane. Accommodating these displacements by means of springs and shock absorbers in a direct way is not always possible due to the restrictions in the deformations maximum that these elements are capable of supporting. That is why the present invention has a system of composite levers within which the springs and shock absorbers are installed. As schematically described in figure 2 and figure 4, when the mass of the dissipator moves in the plane, this movement is accommodated by the levers. The levers also function as geometric deformation reducers. This means that when the mass of the DMSB moves in the plane, the springs and dampers are subjected to deformations much less than the displacement of the mass. This turns out to be particularly important since the vast majority of springs and dampers on the market have limited deformation capabilities. The maximum deformations in the springs and dampers can be controlled in turn by changing their location in the levers. This together with the possibility of modifying the vibration frequencies of the invention through the alternatives described in the previous point, offer multiple adjustment possibilities that facilitate the use of the invention in a large number of applications.

Once the DMSB has been installed in the system to control its dynamic properties, frequency of vibration and damping, can be modified if required. This can be carried out relatively simply by simply changing the location of the springs and dampers on the levers. The global rigidities and damping of the DMSB in its two main directions are modified in this way, by means of a change in its geometrical configuration. As described, the multiple adjustment possibilities of the invention make it an alternative for vibration control in many areas of engineering. Among them can be mentioned:

• Control of vibrations in slender structures (tall buildings, bridges, towers of hanging or cable stayed bridges, chimneys, etc.) product of effects of seismic loads.

• Control of vibrations in slender structures (tall buildings, bridges, towers of suspended or cable-stayed bridges, chimneys, etc.) due to effects of wind action.

• Control of vibrations in industrial structures produced by the action of rotating machinery such as screens, centrifuges, fans, etc.

• Reduction of vibrations caused by pedestrian crossing effects in structures such as stairs, galleries, pedestrian bridges, etc.

• Protection system for vibration sensitive equipment such as: optical equipment, equipment used for the manufacture of semiconductors and nanotechnology, among others.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understanding of the invention and constitute a part of this description and show one of the preferred embodiments.

Figure 1 shows a schematic plan view of the constituent elements of the bidirectional tuned mass dissipator based on multiple composite levers of the present invention. Figure 2 shows a schematic plan view with an arbitrary deformation of the bidirectional tuned mass sink based on multiple composite levers of the present invention.

Figure 3 shows a schematic view of the composite levers in rest state of the composite levers of the bi-directional tuned mass dissipator based on multiple composite levers of the present invention.

Figure 4 shows a schematic view of the composite levers in the state of deformation of the composite levers of the bi-directional tuned mass dissipator based on multiple composite levers of the present invention. DESCRIPTION OF THE INVENTION

The present invention relates to "bidirectional tuned mass dissipator based on multiple composite levers" (hereinafter DMSB) which corresponds to a type of tuned mass dissipator capable of simultaneously controlling two perpendicular vibrating modes whose frequencies are not necessarily equal. The mechanisms that make up the DMSB allow the mass of it to cover large displacements in any direction in the plane. These displacements typically occur when the DMSB is used to control vibrations produced by the effects of earthquakes, wind, excitations caused by rotating machinery, among others. Notwithstanding the above, the DMSB can also be used to control vibrations in smaller mechanisms or structures, such as those resulting from the passage of vehicles or excitations due to pedestrian crossing. Its use can also be extended to control vibrations produced by the operation of equipment resulting from its operation, impact loads, among others. According to what is shown in figure 1, the mass (1) of the dissipator is connected to the structure (9) by means of main levers (2) and secondary levers (3). The main lever (2) is connected to the structure (9) by means of a first pivot point (4). The main lever (2) is connected to the secondary lever (3) by means of a second pivot (5). The secondary lever (3) is connected to the ground

(1) by means of a third pivot (6). The springs (7) and the dampers (8) are connected between the mass (1) of the heatsink and the main lever (3).

Figure 2 shows the deformed DMSB in an arbitrary position. It is possible to observe that the mass (1) of the dissipator moves. For this, the main levers (2) and the secondary levers (3) move causing the springs (7) and shock absorbers (8) located on the left, upper and lower part of figure 2 to stretch as a result of the displacement of the mass (1) and the main levers

(2) and the secondary levers (3). To the right of the drawing, the springs (7) and dampers (8) are compressed by absorbing energy from the displacement of the mass (1).

As shown in Figures 3 and 4, the main lever (2) and the secondary lever (3) form composite levers which are formed in turn by two Particulate arms. The first of them, main arm (2), has at one end a pivot point (4) or articulation anchored to the structure (9) to be controlled. At the opposite end, a second pivot point (5) capable of traveling in the plane joins it with the second arm or secondary arm (3). The secondary arm (3) in turn has a connection that connects it with the mass (1) of the DMSB, by means of a pivot point (6) able to move again in the plane. The combination of the turning capabilities of the arms that make up the levers (2, 3), together with the three articulated points described (4, 5, 6), enable the mass (1) to move in the plane in any direction. In Figure 2, the DMSB is shown schematically in an arbitrary deformed position.

Claims

1.- A bidirectional tuned mass dissipator based on multiple compound levers (DMSB) where a mass (1) controls the vibration of a structure (9), CHARACTERIZED because:

the mass (1) of said dissipator is connected to the structure (9) by means of main levers (2) and secondary levers (3);

the main lever (2) is connected to the structure (9) by means of a first pivot point (4);

the main lever (2) is connected to the secondary lever (3) by means of a second pivot (5);

the secondary lever (3) is connected to the ground (1) by means of a third pivot (6); Y

between the mass (1) of the heatsink and the main lever (3) springs (7) and dampers (8) are connected.

2. The dissipator according to claim 1, characterized in that the mass (1) has means that support its weight.

3. The heatsink according to claim 2, CHARACTERIZED in that the means are frictional sliders; bidirectional spherical wheels; low friction perpendicular rails, or similar devices.

4. The dissipator according to any of claims 1 to 3, characterized in that the mass (1) can be materialized by a reinforced concrete box inside which it is possible to use a high density filler, such as steel balls, barite, plates or by means of any element that allows to reach the objective design mass of the DMSB.