JP2662500B2 - Excitation / braking system for measuring structure and vibration characteristics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration / damping system capable of applying a desired vibration to a structure or applying a variable braking force to the vibration in order to examine the vibration characteristics of the structure.

[0002]

2. Description of the Related Art In recent years, the construction of long bridges has been active. In designing such a long bridge, mechanical stability is taken into account by calculating the purpose of the bridge, consistency with the topography around the bridge to be constructed, and the dynamic load of vehicles traveling on this bridge. It is necessary to guarantee. In addition, such a long bridge needs to be mechanically sufficiently stable against climate and weather, and have high reliability not to lose its function as a bridge under any weather conditions. It is also known that the bridge collapses under the influence of the wind. For example, the accident at the Tacoma Bridge (USA / Colorado River) is particularly famous. In order to design a long bridge that employs suspension bridges, cable-stayed bridges, etc., it is indispensable to investigate all possible current wind effects in advance. Aerodynamic forces act on the bridge due to the wind, causing vibration. If this vibration is not damped, the bridge will collapse.
To build a mechanically and aerodynamically stable bridge, it is necessary to employ appropriate structures to dampen vibration under any weather conditions.

In this type of mechanical characteristic investigation, a miniaturized model of an actual bridge is placed in a wind tunnel, an appropriate wind is applied to the model, and its vibration characteristics and stability are quantitatively measured. To determine the actual bridge that can be used. Here, with reference to FIG. 1, a description will be given of a conventional excitation / braking system employed in this type of measurement.

[0004] First, to prepare a model 1 of the bridge obtained by reducing the actual bridge in a predetermined ratio, and connecting one end of the connecting rod 2 _A, 2 _A 'to the position of the center axis of the longitudinal ends of the Model 1 , The other end of the support arm 2 _B, 2 _B ′ oriented perpendicular to the axis.
Is fixedly connected. Each end of the support arm 2 _B connecting the pair of support springs 3 _1, 3 ₁ 'and 3 _2, 3 _2'.
Similarly, 'to both ends of a pair of support springs 3 _3, 3 _3' support arm 2 _B connects and 3 _4, 3 ₄ ', supports the model 1 hanging in a horizontal state. In this case, the model 1 is supported so that the wind hits the side surface, and four pairs of support springs 3 _1, 3 ₁ ′-
3 Put _4, the 3 ₄ 'outside the wind tunnel. Furthermore, the longitudinal direction of the respective thin wires 5 ₁ in the axial direction perpendicular to both ends of the central portion of the model 1 of the _bridge, 5 ₂ (e.g., piano wire) was is fixed through the vibrator 4 _1, 4 ₂ Are connected. This type of vibrator is input connection 10 of _the external power source the vibrator driving current supplied from the (not shown) 4 _1, 4 _{2 ',} 10 _1' and 10 _{2 ',} 10 _2' , The movable piece is a transducer that is displaced electromechanically. In other words, this type of vibrator is an electric moving coil type transducer that has a permanent magnet on the movable piece and a built-in magnetic field generating coil that applies magnetic force to this permanent magnet in the stator that is the main body. is there. Of course, the vibrator 4 ₁ of this _like, 4 ₂ also installed outside the wind tunnel.

[0005] To perform the measurement in such an arrangement, firstly the support spring 3 _1, 3 ₁ Adjust 'to 3 _4, 3 _4' the mounting position of the appropriate wind direction of the bridge against (arrow A) The model 1 is arranged at an appropriate elevation angle, and a wind of a predetermined strength is blown. Then, providing vibration of a predetermined frequency on the model 1 by supplying a driving current to the vibrator 4 _1, 4 _2. If this vibration reaches a certain amplitude, the drive both vibrator 4 ₁ conductors of current, 4 ₂ input connection terminal 10 _{1 ',} 10 _1' and 10 _{2 ',} 10 _2' separated from this, etc. a braking resistor connected to the input connection, apply a braking to the vibration of the model ₁ exerts a vibrator 4 _1, 4 ₂ as a type of damper. This etc. Various vibration state of, that is, under steady oscillation state and damping vibration state, in order to minutely measure the movement of the model, for example, the support arm 2 for each one marker or detection in a suitable place on both sides of the _B Mirror 6
Place provided _A, 6 _B, the marker 6 _A, 6 _B, for example observed by using a light emitted from the optical measuring device (not shown), for measuring the displacement of both markers 6 _A, 6 _B . Thus, the vibration state of the model can be measured. The marker can of course be attached directly to the bridge model 1 itself if necessary.

In the above arrangement, two types of vibration modes can be generated. That is, if both vibrators 4 _{1 and} 4 ₂ have exactly the same function and performance, and are driven by the same-phase drive current, the distance between both vibrating points with respect to the axis is equal.
The model 1 reciprocates vertically. On the other hand, if the vibrators 4 _{1 and} 4 ₂ are driven by driving currents having opposite phases, the model 1 performs torsional vibration around the axis, so-called pitching vibration, for the same reason. Actually, coupled vibration of vertical / pitching vibration occurs. To determine the stability of the bridge, the exciter 41, for both vibration modes or coupled vibration modes, under the condition that various winds are applied to the model 1 at various elevation angles _.
4 ₂ in the braking state examine the transition of vibration. In that case,
To vary the degree (attenuation factor) of the braking of the system, as described below, to connect the braking resistor external to the vibrator 4 _1, 4 _2. The vibrations to be tested are typically in the range of 0.1 to 30 Hz, and are used to experimentally determine whether the vibrations attenuate, increase gradually, or remain long-lasting under various conditions of wind and braking strength .

Next, a driving method in a braking state in both vibration modes will be described with reference to FIG. A state circuit shorted both vibrator 4 _1, 4 ₂ of the drive current input terminal (not shown) in FIG. 2a, moreover input connection 1 that comes respectively
0 ₁ ', 10 _1' and 10 ₂ ', 10 _2' is constituted with two resistors R _1, which are connected via a single resistor R _2. In this case, mechanical vibration exciter 4 ₁ was generated by _electricity, 4 ₂ of electromechanical conversion unit, in turn induces a voltage in the excitation coil by the motion of the permanent magnets of the movable piece machinery and
It functions as a kind of generator, acting as an electrical converter, and is represented by the symbol N. Power supplies of this generator N can reverse calculation from the power consumed by the external resistor R _1, R _2.

[0008] If the vibrator 4 _1, 4 ₂ are shorted inputs in phase relationship to each other in such a connection circuit (attenuation state of vertical vibration mode) is equivalent to the action of an equivalent circuit of Figure 2b . That is, consumption electric power W of the vibrator 4 ₁ or 4 ₂
Each _P leftward it is only considered only the right of dividing a closed circuit, and ^{_{W P = E 1 2 / (}} R 1 + 2R 2). Here, hereinafter, the resistance value of each resistor is referred to as a reference numeral attached to the resistor for convenience. In addition, E ₁ is each vibrator 4 ₁
Or the output voltage at that time that occurs 4 _2.

On the other hand, if the same connection circuit
Vessel 4_1,4_TwoInput terminals are short-circuited in opposite phase relationship
(Attenuation state of pitch vibration mode), E_Two= -E₁Is
Therefore, the resistance R_TwoNo current flows through. Therefore, each exciter
4₁Or 4_TwoPower consumption W _AIs W_A= (E₁-E_Two)^Two/ 2R₁= 2E₁ ^Two/ R₁ Becomes

After all, the braking force in the vertical vibration mode is the resistance R
Determined by ₁ and R _2, but the braking force at the pitch vibration mode is determined by only the resistance R _1. In an actual test, it is necessary to examine the combined vibration in which the vertical vibration mode and the pitch vibration mode are combined under various conditions regarding the wind force and the elevation angle with respect to various frequencies and various amplitudes, respectively. In performing such a huge measurement, since the resistance to be varied differs between the two modes in order to vary the braking force in the two vibration modes, it is necessary to readjust each time, and it is very complicated and the work efficiency is extremely high. bad.

[0011]

SUMMARY OF THE INVENTION In view of the above-mentioned disadvantages of the prior art, an object of the present invention is to make it possible to independently change the braking force in the vertical vibration mode and the pitch vibration mode, and to freely set the braking force. An object of the present invention is to provide a vibration and braking system of the kind mentioned at the outset, which makes it possible to increase the efficiency of the measurement.

[0012]

SUMMARY OF THE INVENTION The above-mentioned object is achieved by the present invention.
Each of the two positions of the structure
Four shakers 4_1,4_TwoMechanically connected to each other,_1,4
_TwoInput connection terminal 10 ₁′_,10₁″_,10_Two′_,10_Two″
Input the drive current from the power supply to the
A rotational displacement can be applied, and the input connection terminal
And connect a braking resistor to these input connection terminals.
Connect to shaker 4_1,4_TwoBraking force,
The vibrator 4_1,4_TwoElectrical-to-mechanical conversion capacity
And both exciters 4_1,4_TwoBetween input connection terminals of the same polarity
One resistor R each_Four,R_FiveConnect the different polarity input connection
One resistor R between terminals_6,R₇Are connected,
Excitation and braking systems for measuring vibration characteristics of structures
Has been resolved.

[0013] Further advantageous configurations according to the invention are set out in the dependent claims.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings based on preferred embodiments. In order to use the vibration and braking system according to the present invention in a braking state, two vibration exciters 4 are required.
_1, 4 ₂ input connection terminals 10 ₁ ′, 10 ₁ ″ and 1
0 ₂ ′, 10 ₂ ″, two resistors R _4, R _{5 in a} closed-circuit arrangement and two resistors R in a cross-connected arrangement as shown in FIG.
_6, to connect the R _7. Power supplied per vibrator 4 ₁ or 4 ₂ in the case of the braking state of the vertical vibration mode and the pitching vibration mode can be analyzed in the procedure identical to the procedure described in devices of the prior art of FIG.

[0015] For voltage generated by vertical vibration mode vibrator 4 _1, 4 ₂ transducers N are mutually phase (E ₁ = E _2), no current flows through the resistor R ₄ and R _5, the resistor R flowing through the ₆ and R _7. Therefore, the power consumption W _H becomes ^{_{W H = 4E 1 2 / (}} R 6 + R 7).

[0016] Contrary to this, in the pitching vibration mode vibrator 4 _1, 4 ₂ transducers N of the generated voltage opposite phase (E
_{Since 1} = −E ₂ ), the current does not flow through the resistors R ₆ and R _7, but flows through the resistors R ₄ and R ₅ . Therefore, the power consumption W _P becomes ^{_{W P = 4E 1 2 / (}} R 4 + R 5).

[0017] After excitation in coupled vibration modes including vertical vibration and pitching vibration, if allowed to shift to the braking state, it is possible to adjust the respective vibrator 4 _1, 4 ₂ in the braking state in a totally independent state. This is because the power consumptions W _{H and} W _P in both vibration modes obtained above are converted to the resistances R _{6 and} R ₇ and the resistance R
_4, it is because it is possible to decide in R _5. Therefore, the problem of complicated adjustment variable of the braking force of the conventional described above techniques pressurized seen in exciter 4 _1, 4 ₂ can be completely eliminated.

Furthermore, in another advantageous configuration according to the invention, the resistors R ₄ and R ₅ and the resistors R ₆ and R ₇ have the same value, respectively. That is, R ₄ = R ₅ = R _A and R ₆ = R ₇
= When R _B (see FIG. 4), a simpler expression power consumption, can be represented by ^{_{W H = 2E 1 2 / R}} B and ^{_{W P = 2E 1 2 / R}} A, should be varied accordingly The number of types of resistors can be reduced to two.

In the above description, in order to avoid complication, all the resistors shown in the drawings are represented by fixed resistors. But,
Actually, since the braking force needs to be changed over a wide range, each resistor is composed of one variable resistor or one fixed resistor and one variable resistor connected in series.

In a further advantageous configuration according to the invention,
By configuring two variable resistors R _A and two variable resistors R _B each one duplicate variable resistor with resistance connection circuit of Figure 3, the resistance adjustment requires only one operation, setting of both resistance The value can be determined reliably. Therefore, the operability of the measurement operation is significantly improved.

Here, FIG. 5 shows the last and most advantageous integrated circuit of the vibration and braking system of the present invention. The power source for supplying the drive current to both vibrators 4 _{1 and} 4 ₂ is the oscillation unit 2
0, a drive output circuit 22 _1, 22 ₂ and an unbalance adjustment circuit 24 having a resistance R ₀ implying an adjustment variable section. Frequency adjustment unit R _FQ attached to oscillation unit 20
And the amplitude adjustment unit _RAMP are adjusted appropriately, and the oscillation unit 2
An oscillating voltage having a desired frequency and a desired amplitude is generated from zero. On the other hand, the output voltage of the oscillation unit 20 is
2 ₁ was introduced directly into, for introducing the output to drive the output circuit 22 ₂ for different values of the output of the other in a non-equilibrium adjustment circuit 24 via the oscillation unit 20. Both drive output circuits 22 _1, 22 ₂
In through the switch SW to convert the voltage to a driving current, corresponding vibrator 4 _1, 4 ₂ input connection terminal 10 ₁ ', 10 _1'
And 10 ₂ ', introduced into 10 ₂ ". In this case, the unbalanced circuit 24, by adjusting the adjusting variable portion, or in-phase or reverse-phase at the same voltage as the voltage to send, for example, in the driving output circuit 22 _1, the voltage The value can be changed to an unbalanced voltage.

[0022] In vibration state, connect the drive output circuit 22 ₁ by a switch SW, 22 ₂ to each vibrator 4 _1, 4 _2, to introduce the power to vibrator 4 _1, 4 _2. To go to the braking state, switches the switch SW, the vibrator 4 _1, 4 ₂ input connection terminal 10 ₁ ', 10 _1' and 10 ₂ ', 10 _2' variable damping resistor R _A, the R _B Connecting.

In the above, the excitation / braking system for examining the vibration characteristics has been described using a model of a bridge in a wind tunnel as an example. However, it goes without saying that the system can be directly connected to other structures, such as actual bridges, buildings, etc., and to investigate vibration characteristics including translational and rotational movements.

[0024]

As described above, when the vibration / braking system according to the present invention is used, the braking force for the vertical vibration mode and the pitch vibration mode can be independently and freely varied.
Tests on the vibration stability of structures performed under various conditions can be efficiently executed.

[Brief description of the drawings]

FIG. 1 is a layout view of a measurement instrument for wind tunnel test generally used when measuring the mechanical strength of a bridge.

FIGS. 2A and 2B are a resistance connection diagram (a) of a vibration and braking system according to a conventional technique for changing a braking characteristic of a vibration exciter, and an equivalent circuit diagram (b) of the circuit for facilitating analysis.

FIG. 3 is a resistance connection diagram of a vibration / braking system according to the present invention that varies a braking characteristic of a vibration exciter.

FIG. 4 is an advantageous resistance connection diagram of a vibration and braking system according to the invention for varying the braking characteristics of a vibration exciter.

FIG. 5 is an overall connection diagram of the vibration and braking system according to the present invention.

[Explanation of symbols]

1 Model 2 _A, 2 _A 'connecting rod 2 _B, 2 _B' supporting arm 3 ₁ to 3 _4, 3 ₁ 'to 3 _4' supporting spring 4 _1, 4 ₂ vibrator 5 _1, 5 ₂ connecting wires 6 _{A ,} 6 _B markers 10 _{1 ',} 10 _1', 10 _{2 ',} 10 _2' input connection _{R 1 ~R 7, R A,} R B braking variable resistor SW change-over switch 20 oscillation unit 22 _1, 22 ₂ drive output Circuit 24 Unbalanced adjustment circuit

Claims (5)

(57) [Claims] 1. The method according to claim 1, wherein the two positions of the structure are different from each other.
Each exciter (4_1,4_Two) Are connected mechanically,
Shaker (4_1,4_Two) Input connection terminal (10₁′_, 10₁″_,
10_Two′_,10_TwoInput the drive current from the power supply to
Translational and rotational displacements can be applied to the structure;
Disconnect the input connection terminal from the power supply and connect a variable braking resistor.
Continue with the shaker (4_1,4_Two) Can provide braking force
Vibration and braking systems for measuring the vibration characteristics of structures
And the vibrator (4_1,4_Two) Electric-mechanical conversion
With the ability, both shakers (4_1,4_Two) Unipolar input connection end
One resistor (R_Four,R_Five) Connect different
One resistor (R_6,R₇)
A vibration / braking system, characterized by connecting 2. A resistance variable braking homopolar (R _4, R ₅₎ have the same resistance value (R _A), the resistance variable damping of the different poles (R _6,
R ₇₎ also vibration-damping system according to claim 1, characterized in that the same resistance value (R _B). 3. A variable damping resistor pairs (R _4, R ₅ and R
_{6. The} vibration / braking system according to claim 2, wherein each of R _6, R ₇ ) comprises one double variable resistor. Wherein said structure is supported in a wind tunnel spring (3 ₁ -
This is a model (1) of a bridge supported by 3 _4, 3 ₁ ′ to 3 ₄ ′), and a vibrator (4 _1, 4 ₂ ) has a connecting wire (5 ₁ ) at the center in the longitudinal direction of the model (1). _, 5 ₂ ).
Braking system. 5. The electric exciter (4 _1, 4 ₂ ) is an electric moving type converter comprising a movable piece having a permanent magnet and a main body having a built-in magnetic field generating coil for applying a magnetic force to the permanent magnet. The vibration / braking system according to any one of claims 1 to 4, characterized in that: