Acoustic structural integrity monitoring system and method

Abstract

A method and system is disclosed for detecting structural damage in a structure by detecting acoustic emissions from damage in a structure to obtain acoustic emission data, and processing the acoustic emission data in accordance with a model characterising acoustic paths.

1 . A method of building a model of the effect of acoustic paths in a structure for use in the detection of a plurality of types of structural damage at each of a plurality of locations in said structure, the method comprising:
 inducing a plurality of types of acoustic emissions at each of a plurality of positions on said structure, said plurality of types of acoustic emissions corresponding to a respective plurality of types of structural damage;   detecting said acoustic emissions using at least three sensors arranged on said structure;   processing the detections for each type of acoustic emission for each position to determine model data characterising effects on each type of acoustic emission from each position of acoustic paths between said positions and said sensors; and   storing said determined model data.   
     
     
         2 . The method of  claim 1 , wherein said acoustic emissions are induced at each position sequentially. 
     
     
         3 . The method of  claim 1 , wherein said induced acoustic emissions comprise bursts of acoustic emissions at each position. 
     
     
         4 . The method of  claim 1 , wherein said model is for use in identifying structural damage in a structure, and said acoustic emissions are induced in one or more regions where structural damage is likely. 
     
     
         5 . The method of  claim 1 , wherein the determined said model data comprises at least one of differences in times of arrival of said acoustic emissions at said sensors, emission duration, wave-shape information, amplitudes of said acoustic emissions and rise times of said acoustic emissions. 
     
     
         6 . The method of  claim 1 , further comprising determining whether the acoustic emissions from each position enable each position to be uniquely identified and only storing said determined model data if the acoustic emissions enable each position to be uniquely identified. 
     
     
         7 . The method of  claim 6 , further comprising adding sensors to said structure and/or moving at least one of said sensors from a first position on said structure to a second position on said structure if each position cannot be uniquely identified, and repeating the inducing, detecting and processing steps until each position can be uniquely identified. 
     
     
         8 . The method of  claim 6 , further comprising determining optimised positions for said sensors. 
     
     
         9 . The method of  claim 8 , further comprising repeating the inducing detecting and processing steps when said sensors are in said determined optimised positions and only storing said determined model data if the acoustic emissions enable each position to be uniquely identified. 
     
     
         10 . The method of  claim 8 , wherein the determined optimised positions enable said sensors to still uniquely identify said positions even if up to a predetermined number of sensors fail. 
     
     
         11 . The method of  claim 1 , including adding to said model data by inducing acoustic emissions at one or more additional positions interspersed said positions, detecting said acoustic emissions using said sensors, processing the detections to determine additional model data and storing said additional model data in said model data. 
     
     
         12 . A system for building a model of the effect of acoustic paths in a structure for use in the detection of a plurality of types of structural damage at each of a plurality of locations in said structure, the system comprising:
 an inducing arrangement for inducing a plurality of types of acoustic emissions at each of a plurality of positions on said structure, said plurality of types of acoustic emissions corresponding to a respective plurality of types of structural damage;   at least three sensors for detecting said acoustic emissions;   a data processing system for processing detections by said at least three sensors for each type of acoustic emission for each position to determine model data characterising effects on each type of acoustic emission from each position of acoustic paths between said positions and said sensors; and   a data store for storing said determined model data.   
     
     
         13 . The system according to  claim 12 , wherein said inducing arrangement is adapted to induce said acoustic emissions at each position sequentially. 
     
     
         14 . The system of  claim 12 , wherein said inducing arrangement is adapted to induce said acoustic emissions as bursts of acoustic emissions at each position. 
     
     
         15 . The system of  claim 12 , wherein said model data is for use in identifying structural damage in a structure, and said inducing arrangement is adapted to induce acoustic emissions on one or more regions where structural damage is likely. 
     
     
         16 . The system of  claim 12 , wherein said data processing system is configured to determine said model data comprising at least one of differences in times of arrival of said acoustic emissions at said sensors, emission duration, wave-shape information, amplitude of said acoustic emissions and rise time of said acoustic emissions. 
     
     
         17 . The system of  claim 12 , wherein said data processing system is configured to determine whether the acoustic emissions enable each of said plurality of positions to be uniquely identified and to only store said determined model data in said data store if the acoustic emissions enable each position to be uniquely identified. 
     
     
         18 . The system of  claim 17 , wherein at least one said sensors is adapted to be individually moveable from a first position to a second position if it is determined by said data processing system that each of said plurality of positions cannot be uniquely identified. 
     
     
         19 . The system of  claim 17 , wherein said data processing system is adapted to determine a minimum number of said sensors that can uniquely identify each of said plurality of positions, and to determine sensor optimum positions for said minimum number of sensors. 
     
     
         20 . The system of  claim 19 , wherein said data processing system is adapted to determine the optimised positions and number of sensors to enable said sensors to still uniquely identify said positions even if up to a predetermined number of sensors fail. 
     
     
         21 . The system of  claim 12 , wherein said inducing arrangement is adapted to induce acoustic emissions at one or more additional positions interspersed said positions, said sensors are adapted to detect acoustic emissions from said additional positions, and said data processing system is adapted to process the detections to determine additional model data and add said additional model data to said model data in said data store. 
     
     
         22 . A method of simulating acoustic emissions generated from structural damage in a structure, the method comprising:
 acquiring acoustic emission data from a plurality of regions of different types of structural damage to obtain at least one acoustic emission signature associated with each of said types of structural damage; and   adapting an acoustic emission source to generate appropriate acoustic emissions at each said region to generate each respective acoustic emission signature.   
     
     
         23 . The method of  claim 22 , wherein said acquisition step is performed sequentially for different types of structural damage. 
     
     
         24 . A system for simulating acoustic emissions generated from structural damage in a structure, the system comprising:
 an acquisition system for acquiring acoustic emission data from a plurality of regions of different types of structural damage to obtain at least one acoustic emission signature associated with each of said types of structural damage; and   an acoustic emission source adaptable to generate appropriate acoustic emissions at each said region to generate each respective acoustic emission signature.   
     
     
         25 . The system of  claim 24 , wherein said acquisition system is adapted to acquire the acoustic emission data sequentially for different types of structural damage.