Temperature compensation for acoustic structural monitoring

A structure evaluation apparatus comprising:

• a controller comprising a processor and a memory, the controller being configured to:
• locate positions of sources of a plurality of elastic waves detected by a plurality of elastic wave sensors that detect elastic waves generated from a structure on the basis of the plurality of elastic waves;
• correct information based on the position locations using a correction value which is determined according to a temperature of the structure;
• and
• evaluate a deterioration state of the structure on the basis of the corrected information,
• wherein:
• the information is corrected using a first correction value or a second correction value as the correction value,
• the first correction value being a value for correcting a density for each area of an elastic wave source density distribution which represents a distribution showing density values determined according to the number of elastic wave sources in each area,
• the second correction value being a value for correcting a threshold for detecting elastic wave hits, wherein the controller corrects the density for each area in the elastic wave source density distribution using the first correction value obtained based on the temperature of the structure, a correction line, and the elastic wave source density distribution, and
• the correction line is obtained based on:
• a relationship between Young's modulus corresponding to the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution;
• a relationship between the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution;
• or
• a relationship between an acoustic impedance corresponding to the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution.

A structure evaluation method executed by a computer comprising:

• detecting a plurality of elastic waves generated from a structure using a plurality of elastic wave sensors;
• locating positions of sources of a plurality of elastic waves on the basis of the detected plurality of elastic waves;
• correcting information based on the position location using a correction value which is determined according to a temperature of the structure;
• and
• evaluating a deterioration state of the structure on the basis of the corrected information,
• wherein:
• the information is corrected using a first correction value or a second correction value as the correction value,
• the first correction value being a value for correcting a density for each area of an elastic wave source density distribution which represents a distribution showing density values determined according to the number of elastic wave sources in each area,
• the second correction value being a value for correcting a threshold for detecting elastic wave hits, wherein the correcting the density for each area in the elastic wave source density distribution using the first correction value obtained based on the temperature of the structure, a correction line, and the elastic wave source density distribution, and
• the correction line is obtained based on:
• a relationship between Young's modulus corresponding to the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution;
• a relationship between the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution;
• or
• a relationship between an acoustic impedance corresponding to the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution.

A non-transitory computer readable recording medium storing a computer program which enables a computer to execute the following processing:

• locating positions of sources of a plurality of elastic waves detected by a plurality of elastic wave sensors that detect elastic waves generated from a structure on the basis of the plurality of elastic waves;
• correcting information based on the position location in the position locating step using a correction value which is determined according to a temperature of the structure;
• and
• evaluating a deterioration state of the structure on the basis of the corrected information,
• wherein:
• the information is corrected using a first correction value or a second correction value as the correction value,
• the first correction value being a value for correcting a density for each area of an elastic wave source density distribution which represents a distribution showing density values determined according to the number of elastic wave sources in each area,
• the second correction value being a value for correcting a threshold for detecting elastic wave hits, wherein the correcting corrects the density for each area in the elastic wave source density distribution using the first correction value obtained based on the temperature of the structure, a correction line, and the elastic wave source density distribution, and
• the correction line is obtained based on:
• a relationship between Young's modulus corresponding to the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution;
• a relationship between the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution;
• or
• a relationship between an acoustic impedance corresponding to the temperature of the structure and the density of elastic wave sources in the elastic wave source density distribution.