JPH07209072A - Vibration intensity detector - Google Patents

Abstract

PURPOSE:To output the voltage proportional to the distortion of beams arranged at accurately equal spaces, and to improve the measuring accuracy of the transmitted power by arranging pairs of electrodes on a high-molecular piezoelectric film with an equal space, and coating it with a protecting film, and attaching it to the beams to be measured with an adhesive agent. CONSTITUTION:Pairs of electrodes 2, 3, 2-1, 3-1, 2-2, 3-2, 2-3, 3-3 are arranged on both surfaces of a rectangular high-molecular piezoelectric film 1 such as PVD (polyvinylidene fluoride), to which polarization is performed, so as to be opposite to each other in the longitudinal direction at equal spaces. Each pair of electrodes are formed by depositing a conductive metal film on the piezoelectric film 1, and lead wires 6, 7 are connected to a terminal (a) provided in one side thereof. A vibration intensity detector 01 coated with a protecting film 4 such as epoxy resin is attached to the surface of a beam 8 such as a bridge beam so that the longitudinal direction of the detector is in parallel with the longitudinal direction of the beam 8. Since each pair of electrodes are accurately arranged at equal space, generation of dimension error is eliminated, and the voltage in proportion to the distortion of the beam 8 is output to a measuring device through the lead wires 6, 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration intensity detector applied to the measurement of vibration energy of bending waves propagating in beam and plate structural members.

[0002]

2. Description of the Related Art Vibration energy (hereinafter referred to as transmission power) propagating through a beam structure in a unit time is expressed by the following equation (1).

[0003]

[Equation 1]

Here, Π: transmitted power w: out-of-plane displacement of beam D: bending rigidity of beam = Ebh³/ 12 E: Young's modulus of beam b: Width of beam h: Height of beam Conventionally, acceleration is generally used to measure the amount of propagation of vibration energy.
The meter is used. For example, measure the transmitted power of a beam
In this case, the accelerometers 9, 9-1, 9-2, 9-3 are shown in FIG.
As shown in FIG.
Then, the adhesive 5 is applied along the longitudinal direction. And out-of-plane displacement of the beam
Is measured, and the spatial differential terms ∂w / ∂x, ∂w ²/ ∂x²∂
w³/ ∂x³Is approximated by
Are seeking transmission power.

The difference between the spatial differential terms is obtained by the following equations (2) to (4).

[0006]

[Equation 2]

Here, δ: Accelerometer interval When the accelerometers 9, 9-1, 9-2, 9-3 are attached, the dimensional error between the attached accelerometers is reduced through the spacer 10 or the like.

[0008]

SUMMARY OF THE INVENTION In the above conventional method,
The dimensional error between accelerometers cannot be eliminated, which causes an error in the measurement result of the transmitted power.

FIG. 4 shows the result of calculation of an example of the relationship between the dimensional error and the measurement error for each combination of 6 cases.

[0010]

The present invention takes the following means in order to solve the above problems.

That is, as the vibration intensity detector, a rectangular polymer piezoelectric film, a plurality of electrode pairs facing each other on both sides of the polymer piezoelectric film and provided at equal intervals in the longitudinal direction, A protective film covering the molecular piezoelectric film and the electrode pair is provided.

[0012]

The vibration intensity detector of the above-described means is attached to the surface of a beam, such as a bridge, which is to be measured, with its longitudinal axis parallel to and bonded to it. Then, each electrode pair is connected to a measuring device to measure.

Then, since the respective electrode pairs are arranged in advance at exactly equal intervals, the voltage proportional to the strain on the beam surface at exactly equal intervals can be accurately detected.

Further, the vibration detector can be attached very easily without using a spacer or the like.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The parts described in the conventional example will be omitted, and the parts relating to the present invention will be mainly described.

Electrode pairs 2,3,2-1,3-1,2-2,3-2,2-3 are formed on both sides of a rectangular polymer piezoelectric film 1 made of polarized PVDF (polyvinylidene fluoride) or the like. , 3
-3 are arranged to face each other at equal intervals in the longitudinal direction.
Each electrode is formed by depositing a conductive metal film on a predetermined section of the polymer piezoelectric film 1. Lead wires 6 and 7 are connected to each terminal a on one side thereof.

Each electrode pair and the piezoelectric polymer film 1 are waterproof,
For insulation or the like, the entire surface is covered with a protective film 4 such as an insulating epoxy resin.

The above vibration intensity detector 01 is attached to the surface of the beam 8 such as a bridge to be measured with the adhesive 5 with its longitudinal axis parallel. Then, the lead wires 6 and 7 of each electrode pair are connected to a measuring device for measurement.

Then, since the electrode pairs are arranged in advance at exactly equal intervals, the voltage proportional to the strain on the beam surface at the equidistant positions can be accurately detected. From this detection output, the vibration transmission power is calculated in the same manner as in the conventional case. Therefore, accurate measurement becomes possible.

Further, the vibration detector can be attached very easily without using a spacer or the like as in the conventional case.

[0021]

As described above, in the vibration intensity detector of the present invention, the electrode pairs are arranged on the polymer piezoelectric film at equal intervals and are covered with the protective film.
Therefore, the detector can be easily attached by adhering it to the beam to be measured with an adhesive. In addition, a voltage output proportional to the distortion of the beam surface at accurate intervals is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a vibration intensity detector as an embodiment of the present invention.

FIG. 2 is a view taken along line AA of FIG. 1 of the same embodiment.

FIG. 3 is an explanatory diagram showing a vibration intensity measurement state by a conventional accelerometer.

FIG. 4 is a diagram illustrating each calculation example of a vibration intensity measurement error due to a dimensional error between detectors.

[Explanation of symbols]

 1 Polymer Piezoelectric Film 2,2-1,2-2,2-3 Electrode 3,3-1,3-2,3-3 Electrode 4 Protective Film 5 Adhesive 6,7 Lead Wire 8 Beam (Measurement Target) 9, 9-1, 9-2, 9-3 Accelerometer 10 Spacer

Claims (1)

[Claims] 1. A rectangular polymer piezoelectric film, a plurality of electrode pairs facing each other on both sides of the polymer piezoelectric film and provided at equal intervals in the longitudinal direction, the polymer piezoelectric film and the electrode pair. A vibration intensity detector comprising a protective film for covering.