JPH0513518B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pressure-resistant underwater sound-absorbing plate that has the required pressure resistance and does not deteriorate its sound-absorbing effect even when submerged in water under high water pressure.

[Conventional technology]

Underwater sound absorbing plates used for the purpose of absorbing underwater sound in the deep sea, etc., have traditionally been made by enclosing spherical or cylindrical air bubbles inside a rubber body that has viscoelastic properties, and the resonance of the air bubbles causes the rubber to absorb sound. Devices that absorb incident sound waves by utilizing heat loss from vibration are used, but high water pressure compresses and deforms the rubber, crushing air bubbles, and as a result, the sound absorption effect often decreases.

[Problem that the invention seeks to solve]

In view of the above-mentioned circumstances, the present invention aims to eliminate the drawbacks of conventional sound absorbing boards, and is made of materials such as reinforced plastic (FRP), polycarbonate, etc., which have approximately the same acoustic impedance as the viscoelastic body that constitutes the underwater sound absorbing board. discovered that an underwater sound-absorbing plate placed in a pressure-resistant container and covered with the container has both pressure resistance and sound-absorbing properties without impairing acoustic performance, and completed the present invention. This is what led to this.

[Means for solving problems]

The present invention comprises: (a) an underwater sound absorbing plate made of a viscoelastic material such as rubber with bubbles sealed; (b) a pressure-resistant container made of a rigid body having approximately the same acoustic impedance as the viscoelastic material; c. High water pressure. The gist of this is a pressure-resistant underwater sound-absorbing board that prevents deterioration of the sound-absorbing effect underneath.

The present invention will be described below based on examples with reference to the drawings.

〔Example〕

FIGS. 1a and 1b are a plan view showing a cross section and a side view showing a vertical cross section of a conventional underwater sound absorbing plate.

Reference numeral 1 indicates rubber, which is a viscoelastic body, and reference numeral 2 indicates a spherical bubble enclosed in the rubber.

The present invention provides such underwater sound absorbing plates as shown in FIGS. 2a and b.
As shown in FIG. 3, it is housed in a pressure-resistant container 3 to form a pressure-resistant underwater sound absorbing plate. Container 3 has upper plate 3
An inner wall 4 may be provided to support the space between a and the lower plate 3b for reinforcement. Supports can also be used instead of internal walls.

When sound waves are incident on the pressure-resistant underwater sound absorbing plate having such a structure, the bubbles cause resonance based on the relationship between the frequency of the sound waves and the size of the bubbles, which causes a vibration phenomenon in the rubber. In this case, the sound absorption coefficient can be increased by increasing the viscosity coefficient or loss coefficient of the rubber.

The amplitude of the rubber is maximum at the interface with the bubbles, and decreases as the distance from the bubbles increases. Therefore, it is better to keep the pressure-resistant container including the upper plate 3a, lower plate 3b, inner wall 4, etc. as far away from the bubbles as possible to improve the sound absorption coefficient. Sufficient pressure resistance can be maintained without damage. Therefore,
If pressure resistance is to be guaranteed, it is preferable to widen the intervals between inner walls or columns.

Since the pressure-resistant container according to the present invention is made of, for example, reinforced plastic (FRP), which has almost the same acoustic impedance as a viscoelastic material such as rubber, problems such as reflection of sound waves do not occur.

〔Effect of the invention〕

The present invention is based on the above structure, and can be used even in the deep sea where considerable external pressure is applied, without reducing the sound absorption effect, and can fundamentally improve the drawbacks of conventional products. This is an extremely useful invention.

[Brief explanation of the drawing]

Figures 1a and 1b are a plan view showing a cross section and a side view showing a vertical cross section of a conventional underwater sound absorbing plate;
Figures a and b are a plan view showing a partially cutaway cross section and a side view showing a longitudinal cross section of the product of the present invention. 1...Rubber, 2...Bubble, 3...Pressure container, 4
……inner wall.

Claims (1)

[Claims] 1 An underwater sound-absorbing plate containing air bubbles of a viscoelastic material such as rubber is housed in a pressure-resistant container made of a rigid body with almost the same acoustic impedance as the viscoelastic material, and the sound-absorbing effect deteriorates under high water pressure. A pressure-resistant underwater sound-absorbing board characterized in that it does not cause.