KR102497325B1 - Non-explosive Underwater Impact Test Devices and Methods Using Airbag Inflators - Google Patents

Abstract

The present invention relates to an underwater impact test using an airbag inflator. Existing underwater impact tests use air guns to form shock waves, but there is a disadvantage that they are concentrated in low frequencies compared to explosives. Therefore, an underwater shock wave with a wide frequency band is to be formed using a plurality of airbag inflators.
In addition, the airbag inflator used may have various initial pressures, and the grid in which the airbag inflator is fixedly disposed may be formed to correspond to the curved surface of the hull. Plane waves can be formed by adjusting the distance between the hull and the airbag inflator and adjusting the blasting time of each airbag inflator so as to form a plane wave to simulate an actual explosive shock wave.

Description

Non-explosive Underwater Impact Test Devices and Methods Using Airbag Inflators

The present invention relates to an underwater impact test apparatus and method, and more particularly, to a test apparatus and method for applying shock waves to a hull floating in water in order to test the survivability of the hull.

In naval warships, impact resistance is essential for maintaining combat performance and improving survivability. It is known that most cases of incapacitation of ships when torpedoes or mines explode from a long distance are caused by impact damage to major mounted equipment rather than impact damage to the ship's hull. The impact resistance performance of ships in the event of an underwater explosion at such a distance is actively studied through simulation. However, since the impact resistance performance cannot be evaluated only through these analysis results in the United States and Europe, ships built using high-performance explosives are subjected to impact tests at sea. Through this, the impact resistance performance is verified. However, the full ship impact test using actual explosives is costly and takes a long time, negatively affects marine pollution and ecosystems, and threatens the safety of ships and test personnel passing through nearby waters.

To this end, the Royal Navy is conducting underwater impact tests on ships in ports using an air gun system that generates artificial seismic waves for underwater resource exploration. An air gun generates a shock wave underwater by rapidly releasing compressed air in an internal pressure chamber, and can produce a sufficient amount of impact to enable a ship impact test. The related equipment such as the high-pressure compressor for operation is very expensive, and the air gun has a frequency of only several tens of Hz compared to the explosives. There is a problem of lack of similarity.

Therefore, the present invention has been made to solve the problems of the prior art as described above, and an object of the present invention is to utilize a hybrid type airbag inflator used to inflate an airbag in a general passenger car, which is economical, close to a plane wave, It is to improve the non-explosive underwater impact test by creating an underwater shock wave with a wider frequency band.

The present invention relates to an airbag inflator for applying shock waves to a hull, a grid in which the airbag inflator is fixed at regular intervals and spaced apart from the hull, and a buoy for disposing the grid underwater. A mooring line that fixes the buoy and connects the grid and the buoy, and a signal delay device that controls the time of the airbag inflator to send plane wave impact to the hull, and a plurality of shock waves using the plurality of airbag inflators It is characterized by forming a shock wave in a high frequency region.

In addition, the grid is characterized in that formed to correspond to the curved surface of the hull.

In addition, it is characterized in that two or more types of airbag inflators are installed in the grid.

In addition, it is characterized in that a pressure sensor and an acceleration sensor for measuring the shock wave formed by the airbag inflator are included.

In addition, the grid is characterized in that the distance from the hull is arranged within 1m.

In addition, a grid manufacturing step corresponding to the curved surface of the hull, an arrangement step of arranging the airbag inflator on the grid, an installation step in which the grid is spaced apart from the hull at a predetermined interval, and the airbag inflator is operated by the signal line to move the airbag inflator to the hull. It is characterized in that it comprises a measuring step of measuring the shock wave with a sensor within.

In the arranging step, a shock wave corresponding to an actual explosive is generated, and a plurality of airbag inflators are calculated and spaced apart on the grid so that a plane wave reaches the hull.

According to the present invention, when underwater shock waves are generated using a plurality of airbag inflators, it is possible to generate underwater shock waves similar to actual explosives in a higher frequency range than when generated with an air gun.

1 is an overall configuration diagram of the present invention
2 is a front view of the present invention
Figure 3 is an enlarged view of Figure 2
4 is an exemplary diagram of a grid
5 is a strain graph according to the number of airbag inflators
6 is an example of combining an airbag inflator and a grid;
6 is a second embodiment
7 is an exemplary view of plane wave formation through distance control;
8 is an exemplary view of forming a plane wave through time control
9 is a side view in which the grid is spaced apart from the hull;

In the present invention, when underwater shock waves are generated using a plurality of airbag inflators, it is possible to generate underwater shock waves closer to a higher frequency than when generated by an air gun, which is an existing test device. For reference, the method of generating underwater bubbles and underwater shock waves in water by compressing high-pressure gas and releasing it at high speed behaves as follows.

Max Pressure:

Maximum pressure frequency:

은 압축공기의 초기 압력,

는 압력용기의 부피,

는 에어건과 측정점의 거리이다. 또한, 일반적으로 에어건의 압력용기보다 에어백의 압력용기의 부피가 작기 때문에, 동일한 압력과 충격량을 주기 위해서는 다수의 에어백 인플레이터를 사용되어지며, 다수의 에어백 인플레이터를 배치함으로써 평면파에 가까운 수중 충격파가 시험의 대상이 되는 함정에 도달하기가 용이하다. At this time,

is the initial pressure of the compressed air,

is the volume of the pressure vessel,

is the distance between the air gun and the measuring point. In addition, since the volume of the airbag pressure container is generally smaller than that of the airgun, multiple airbag inflators are used to give the same pressure and impact. It is easy to reach the target trap.

Since the airbag inflator is a part used in many vehicles, its cost is very cheap, about 1/1000 of that of an air gun (airbag inflator: about 30,000 to 50,000 won, air gun system: about 150 million won). Since the power system for blasting the airbag inflator is not a high-voltage power source, only a device capable of simultaneously supplying electrical signals to a plurality of airbag inflators is required, and thus has an advantage of being very inexpensive.

The present invention can use a curtain airbag inflator, and is a hybrid method similar to the operation method of an air gun, which is in the spotlight as an alternative energy source for explosives.

Hereinafter, a non-explosive underwater impact test apparatus and method using an airbag inflator according to the present invention having the above configuration will be described in detail with reference to the accompanying drawings.

[1] Overall configuration and operation principle

First, Figure 1 is an overall configuration diagram of the present invention. Referring to FIG. 1 , airbag inflators 100 used in vehicles are arranged on a grid 200 at regular intervals. The grid 200 is spaced apart at a predetermined interval from the hull 300, which is a target receiving the shock wave, and is disposed in the water. Electrical signal lines are connected to each airbag inflator 100 disposed on the grid 200, and a shock wave is formed by receiving a signal from the signal generator 400.

At this time, the airbag inflator 100 can be placed within about 1 m from the hull 300, and the test can be conducted at a nearby coast or port, which results in the risk of using explosives and the time and cost of going to distant seas. efficient in terms of

2 is a front view of the present invention. Referring to FIG. 2 , airbag inflators 100 are arranged at regular intervals on the grid 200, and shock waves 110 are formed and transmitted to the hull 300 due to the explosion of the airbag inflator 100. The shock wave 110 transmitted to the hull 300 is measured through the measuring unit 310 .

At this time, the measurement unit 310 is composed of a pressure sensor and an acceleration sensor and measures the shock wave 110 transmitted to the hull 300, and the measured data is used to compare the actual explosive and the size of the shock wave and the size by frequency region. And it is possible to seek additional implementation through frequency analysis of the shock wave. The grid 200 is connected to the buoy 210 floating on the water and the mooring line 220 to maintain a constant distance from the hull 300 in the water. The buoy 210 is a buoy installed at a certain position on the water and is tied to a mooring line 220 so as not to leave a certain place.

3 is an enlarged view of FIG. 2 . Referring to FIG. 3 , airbag inflators 100 are installed vertically on the grid 200 at regular intervals. Through this, the airbag inflator 100 is vertically disposed on the hull receiving the shock wave, and the shock wave of each inflator 200 overlaps to form a shock wave similar to an explosive. At this time, by vertically arranging the airbag inflator 100 on the grid 20, the end of the airbag inflator 100 from which shock waves are emitted faces the hull and maintains a constant distance from the hull.

4 is an exemplary diagram of a grid. Referring to FIG. 4 , an airbag inflator and grid arrangement will be described as an example. The grid 200 may be formed as a quadrangular frame, and may include horizontal, vertical, and oblique straight lines or a lattice structure therein. A plurality of airbag inflators 100 are vertically arranged at regular intervals on one side of the grid 200 .

At this time, the grid 200 may have various shapes. Each airbag inflator 100 is connected with an electric wire that sends an explosion signal, and it is easy to implement multiple operations because there is no difficulty in grid installation through a simple process. For example, a screw groove may be formed in the grid to be bolted to the airbag inflator to be fixed, and the installation may be completed by connecting an electric wire that transmits an electric signal.

5 is a strain graph according to the number of airbag inflators. Referring to FIG. 5 , it is a graph when 1, 4, 9, and 16 airbag inflators are arranged and implemented. When 1, 4, and 9 airbag inflators are arranged and blasted, it can be confirmed that the amount of impact reaching the hull is small, and when 16 airbag inflators are blasted, it can be confirmed that shock waves arrive. Accordingly, more than 16 airbag inflators must be arranged in a grid, and the quantity can be adjusted according to the user's needs according to the initial pressure of the airbag inflator.

6 is a second embodiment. Referring to FIG. 6 , airbag inflators 100 having pressure containers of various sizes are disposed on a grid 200 . The airbag inflator 100 having different initial pressure values may be used in the grid 200, and as described above, shock waves are overlapped through the signal generator so that shock waves similar to explosives reach the hull.

In addition, the used airbag inflator 100 is placed on the grid 200 in consideration of the size and initial pressure of various pressure vessels according to the type of vehicle used and the location of use. For example, a disk-type airbag inflator and a cylinder-type airbag inflator for automobiles can be used.

7 is an exemplary view of plane wave formation through distance control. Referring to FIG. 7 , a plurality of airbag inflators 100 are vertically arranged at regular intervals on one surface of the grid 200 and form shock waves 110 . The grid 200 is connected to the buoy 210 floating on the water and the mooring line 220 to maintain a certain distance from the hull 300.

At this time, the shock waves 110 generated by each airbag inflator 100 are overlapped to form a size similar to that of an actual explosive shock wave, and the shock wave 110 is formed with the airbag inflator 100 so that a plane wave reaches the hull 300. The spacing H of the hull 300 is adjusted. A plane wave is a wave that travels along a straight line or plane, and is characterized by almost no change in amplitude even when it spreads far.

8 is an exemplary view of forming a plane wave through time control. Referring to FIG. 8 , a plurality of airbag inflators 100 are vertically arranged at regular intervals on one surface of the grid 200 and form shock waves 110 . The grid 200 is connected to the buoy 210 floating on the water and the mooring line 220 to maintain a certain distance from the hull 300. Each airbag inflator 100 is connected to the signal generator 400 and forms a shock wave 110 through an electrical signal. Since the power system for blasting the airbag inflator is not a high-voltage power source, there is an advantage of being inexpensive.

At this time, the signal generator 400 adjusts the operating time of each airbag inflator so that the generated shock waves 100 overlap each other so that plane waves reach the hull.

9 is a side view in which grids are spaced apart from each other on the hull. Referring to FIG. 9 , airbag inflators 100 are vertically disposed on the grid 200 at regular intervals. The grid 200 is spaced apart from the hull 300 at a predetermined interval in the water, and is manufactured in a curved surface to correspond to the curved surface of the hull 300. Accordingly, the airbag inflators 100 may be vertically disposed on the hull, and each airbag inflator 100 has a uniform distance from the hull. The airbag inflator 100 generates shock waves through electrical signals, each shock wave overlaps, and a plane wave that can simultaneously reach the hull surface is formed.

[2] Experimental Example

Table 1 is data showing the size of the shock waves of the two airbag inflators. In order to understand the characteristics of the underwater shock wave for the number of airbag inflators, two airbag inflators were blasted in the same environment. This is the maximum pressure equation of the underwater shock wave generated when air guns are grouped and blasted from AIRGUN (P.M.Krail, 2010).

max pressure

는 실험상수

는 압축가스의 초기압력,

는 압력용기의 부피,

는 발파 지점과 측정점 간의 거리를 의미한다. 실제 시험을 통해 얻어진 최대 압력값과 회귀(Regression)법을 이용하여 실험상수 K(0.157)를 구할 수 있다. 표 1을 참고하면, 실제 실험을 통해 얻어진 거리에 대한 최대 충격파 크기와 실험상수 K(0.157)을 대입한 이론 최대 충격파의 크기를 비교하였을 때, 최대 오차율은 약 17%이고, 오차율이 거리에 비례하여 감소하는 것을 확인 할 수 있다. 이는 동일한 환경에서 2개의 에어백 인플레이터 사이의 거리를 두어 중첩 발파하면서 거리가 멀어질수록 각 에어백 인플레이터에서 발생한 수중 충격파가 서로 중첩하여 평면파 형태로 퍼져나가는 특성에 기안한다. 이를 통해 에어백 인플레이터와 에어건에 의해 발생한 수중 충격파의 특성이 유사한 것을 확인할 수 있다.here,

is the experimental constant

is the initial pressure of the compressed gas,

is the volume of the pressure vessel,

means the distance between the blasting point and the measuring point. The experimental constant K (0.157) can be obtained by using the maximum pressure value obtained through the actual test and the regression method. Referring to Table 1, when comparing the maximum shock wave size for the distance obtained through the actual experiment and the theoretical maximum shock wave size by substituting the experimental constant K (0.157), the maximum error rate is about 17%, and the error rate is proportional to the distance You can check that it decreases. This is based on the characteristic that the underwater shock waves generated from each airbag inflator overlap each other and spread in the form of a plane wave as the distance increases while overlapping blasting by placing the distance between the two airbag inflators in the same environment. Through this, it can be confirmed that the characteristics of the underwater shock wave generated by the airbag inflator and the air gun are similar.

Distance (m) Actual peak
pressure (kPa) Theoretical peak pressure (kPa) 0.5 567.3 567.55 0.7 333.06 405.39 0.9 287.67 315.30

[3] Underwater impact test method

The underwater impact test method of the present invention will be described. The description below is divided into manufacturing phase, arrangement phase, installation phase, and measurement phase. First, in the fabrication step, a grid is formed in a polygon or a circle, and a structure in the form of horizontal, vertical, and oblique straight lines or a grid is formed on the inside. After the production stage, the airbag inflator is placed vertically on one side of the grid. After the arrangement step, the installation step includes a measurement step in which the airbag inflator is installed at a predetermined distance from the hull surface, and after the installation step, the airbag inflator generates a shock wave and measures the shock wave with a sensor in the hull.

At this time, in the manufacturing step, the grid can be manufactured on the ground, and time consumption can be reduced in preparing a plurality of grids and conducting multiple tests. In addition, it is manufactured in a curved surface to correspond to the curved surface of the hull. It can withstand shockwaves from multiple airbag inflators and is designed to allow multiple tests through replacement of airbag inflators.

In the arranging step, pressure containers of various sizes and airbag inflators having initial pressures may be arranged, and the arrangement interval may be adjusted accordingly. Airbag inflators are placed on one side of the grid facing the hull, and the number and position of airbag inflators to be placed on the grid are calculated to correspond to the shock wave of the actual explosives. In addition, each airbag inflator is operated through a current signal connected to an electric wire.

In the installation step, the grid on which the airbag inflator is arranged is connected to the hull and the buoy floating on the surface with a mooring line, and is spaced apart from the hull in the water. The distance between the airbag inflator and the hull is adjusted so that shock waves from the airbag inflator overlap each other and plane waves reach the hull. In addition, it is possible to test shock waves in various directions of the hull using a plurality of grids.

In the measurement step, the electric wire connected to each airbag inflator is connected to a signal generator, and when the signal generator transmits an electric signal, a shock wave is generated. The signal generator controls the operation time of each airbag inflator so that the shock waves overlap to form a plane wave, and the formed shock waves are measured through a pressure sensor and an acceleration sensor in the hull.

The present invention is not limited to the above-described embodiments, and the scope of application is diverse, and anyone with ordinary knowledge in the field to which the present invention belongs without departing from the gist of the present invention claimed in the claims Of course, various modifications are possible.

100: airbag inflator
110: shock wave
200: grid
210: buoy 220: mooring line
300: hull
310: measuring unit
400: signal generator

Claims (7)

an airbag inflator that applies shock waves to the hull;
a grid in which the airbag inflator is fixed at regular intervals and spaced apart from the hull;
a buoy for disposing the grid underwater;
a mooring line fixing the buoy and connecting the grid and the buoy; and
A signal delayer for controlling the time of the airbag inflator to send a plane wave impact to the hull;
An underwater impact test apparatus using an airbag inflator, characterized in that a shock wave in a high frequency region is formed due to a plurality of shock waves using the plurality of airbag inflators.
According to claim 1,
The underwater impact test apparatus using an airbag inflator, characterized in that the grid is formed to correspond to the curved surface of the hull.
According to claim 1,
An underwater impact test apparatus using an airbag inflator, characterized in that two or more airbag inflators are installed in the grid.
According to claim 1,
The underwater impact test apparatus using the airbag inflator
An underwater impact test apparatus using an airbag inflator, characterized in that it includes a pressure sensor and an acceleration sensor disposed on the hull and measuring shock waves formed by the airbag inflator.
According to claim 1,
The grid is an underwater impact test apparatus using an airbag inflator, characterized in that the distance from the hull is disposed within 1 m.
In the underwater impact test method using the airbag inflator using the underwater impact test apparatus using the airbag inflator of claim 1,
Grid manufacturing step corresponding to the curved surface of the hull;
a disposing step of arranging the airbag inflator on the grid;
An installation step in which the grid is spaced apart from the hull at a predetermined interval; and
a measuring step of operating the airbag inflator by a signal and measuring a shock wave with a sensor installed in the hull;
Underwater impact test method using an airbag inflator comprising a.
According to claim 6,
Wherein the arranging step generates a shock wave corresponding to an actual explosive and calculates and arranges a plurality of airbag inflators on the grid so that a plane wave reaches the hull.

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