METHOD AND APPARATUS FOR DETECTING DAMAGE TO HIGH-PRESSURE TANK

• US 20100107765A1
• Filed: 07/11/2008
• Published: 05/06/2010
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Original Assignee: National Institute of Advanced Industrial Science and Technology (Government of Japan)
• Inventors: Yamabe, Junichirou, Murakami, Yukitaka
• Granted Patent: US 8,240,209 B2
• Time in Patent Office: Days
• US Class Current: 73/587
• CPC Class Codes: G01N 2291/106 one or more transducer arrays
• CPC Class Codes: G01N 2291/2695 Bottles, containers
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/227 related to high pressure, tension or stress conditions

Abstract

There are provided a method and an apparatus for detecting damage to a high-pressure tank, with which a sign of failure of a high-pressure tank containing a high-pressure fluid can be detected early and non-destructively.

An acoustic emission sensor (AE sensor) 1 is used for the non-destructive detection of a sign of failure that occurs upon filling a high-pressure tank 2 with a fluid. One AE signal detected by the AE sensor 1 is counted as one hit, the hit rate indicating the change in hits over time is found, and a sign of failure is detected from the change in the hit rate. When microcracks develop in the high-pressure tank 2, and a plurality of these microcracks join together and grow into a single, macroscopic crack, the hit rate of the AE signal no longer increases with respect to an increase in the internal pressure of the high-pressure tank 2, eventually reaching a saturation state. The hit rate in this saturation state is used to determine that there is a sign of failure.

Claims

1. A method for detecting damage to a high-pressure tank, in which an acoustic emission sensor for detecting acoustic emissions generated by the deformation of a material, or by microcracks in a material, or by the failure of a material in which said microcracks have grown, is used for the non-destructive detection of a sign of failure that occur when a high-pressure tank for storing a high-pressure fluid is filled with said fluid,

wherein a group of acoustic emission signals which are made up of elastic waves of the same frequency generated continuously for a short period, and which are signals received by the acoustic emission sensor, are counted as one hit, and a hit rate indicating the change in the hit over time is found, and

the sign of failure is detected from the change in the hit rate.

2. The method for detecting damage to a high-pressure tank according to claim 1,

wherein the sign of failure is detected by finding the change in the hit rate with respect to an internal pressure of the high-pressure tank corresponding to the hit rate.

3. The method for detecting damage to a high-pressure tank according to claim 2,

wherein the pressure of the high-pressure tank and the acoustic emission signal are measured while the high-pressure tank is filled with the fluid, and

the sign of failure is determined from a value at which the hit rate, which has been increasing in proportion to the pressure of the high-pressure tank when said pressure is less than the maximum usage pressure, does not increase further and reaches a saturation state.

4. The method for detecting damage to a high-pressure tank according to claim 1,

wherein the detection of the acoustic emission signal is performed by bringing the acoustic emission sensor into contact with the high-pressure tank.

5. An apparatus for detecting damage to a high-pressure tank, comprising:

an acoustic emission sensor that detects acoustic emissions generated by the deformation or failure of a material, and that detects these acoustic emissions generated from a crack produced when a high-pressure tank for storing a high-pressure fluid is filled with said fluid;

memory means for storing an output value of the acoustic emission sensor;

calculation means for calculating the change over time in the size and/or shape of the stored output value;

determination means for determining from the change over time whether or not the output value is a sign of failure; and

output means for outputting the determination result and/or the content of the memory means as output data.

6. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the calculation means calculates, from the output value, a hit rate that indicates the number of hits per unit of time of the acoustic emission signal, which is a signal received by the acoustic emission sensor, and calculates the change in the hit rate, and

the determination means determines whether or not there is a sign of failure by using the change in the hit rate to find a value at which the hit rate does not increase further and reaches a saturation state.

7. The apparatus for detecting damage to a high-pressure tank according to claim 5,

comprising pressure measurement means for measuring a pressure of the high-pressure tank,

wherein the pressure value measured simultaneously with the acoustic emission sensor is stored in the memory means in association with the output value,

the calculation means calculates, from the output value and the pressure value corresponding to this output value, a hit rate that indicates the number of hits per unit of time of the acoustic emission signal, which is a signal for the acoustic emission received by the acoustic emission sensor, and calculates the change in the hit rate, and

the determination means determines that there is a sign when the hit rate, which has been increasing in proportion to the pressure of the high-pressure tank when said pressure is less than the maximum usage pressure, does not increase further and reaches a saturation state.

8. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the output value is measured either continuously, periodically, or after a specific time has elapsed.

9. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the acoustic emission sensor outputs the output value when the value of the acoustic emission is a specific reference value or more.

10. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the calculation means calculates the hit rate as the number of hits when the output value stored in the memory means is a specific reference value or more.

11. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the output means sends the output data to an external system by wired or wireless connection means.

12. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the apparatus for detecting damage to a high-pressure tank has fixing means for fixing the acoustic emission sensor to the high-pressure tank so as to come into contact therewith.

13. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the apparatus for detecting damage to a high-pressure tank is installed in a moving body.

14. The apparatus for detecting damage to a high-pressure tank according to claim 5,

wherein the apparatus for detecting damage to a high-pressure tank has a preamplifier for amplifying the acoustic emission signal detected by the acoustic emission sensor, and

the amplified acoustic emission signal is stored in the memory means as the output value of the acoustic emission sensor.