Method and apparatus for detection of structural damage
AssigneeBAE SYSTEMS plc
InventorsEdwin W O'Brien, Andrew R Ibbotson
Life of this patent
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Abstract
A method and apparatus for detecting and monitoring fractures in a structure by monitoring acoustic energy transmitted within the structure by receiving continuously over a period of time electrical signals from a plurality of acoustic tranducers carried by the structure in a pulse processor to form data bursts from pulses in the signals and deriving, for each of a plurality of the data bursts, delta-t values representing the differences between burst arrival times at each sensor, the delta-t values forming a delta-t pattern, and generating a damage indication signal when the delta-t pattern is repeated to a predetermined degree.
Claims21
A method of detecting and monitoring damage in a structure comprising:
- receiving continuously over a period of time electrical signals from a plurality of acoustic transducers, carried by the structure, configured to receive acoustic emissions from the structure when the structure is submitted to stress;
- and in a pulse processor,
- (a) forming digital representations pulses from the electrical signals to form data bursts,
- (b) selecting data bursts that occur in a predetermined time window to form a group of data bursts,
- (c) deriving, for each of the selected data bursts, delta-t values representing the differences between the times of occurrence of the pulses represented by the selected data bursts in the group, the delta-t values forming a delta-t pattern, and
- (d) generating a significant event indication signal when the delta-t pattern is repeated to a predetermined degree in different groups of selected data bursts.
Apparatus for use in the detection and monitoring of damage in a structure, comprising:
- a plurality of acoustic transducers configured to receive acoustic emissions from the structure when the structure is submitted to stress for mounting on a structure to be monitored;
- a signal conditioning stage coupled to the transducers and arranged to derive pulses corresponding to acoustic events sensed by the transducers;
- and
- a pulse processor unit comprising an analogue-to-digital converter (ADC) stage coupled to the signal conditioning stage and a digital signal processing stage including selection means configured to select, from digitised signals received from the ADC stage, digitised pulses to form data bursts means for selecting a group of data bursts occurring in a predetermined time window, means arranged to derive, for each selected data bursts in the group, delta-t values representing the differences between the times of occurrence of the bursts, the delta-t values forming a delta-t pattern, and
- a correlator arranged to generate a significant event indication signal when the delta-t pattern is repeated to a predetermined degree in different groups data bursts.
A structure which is monitored for damage due to cyclic loading, wherein the structure comprises a plurality of structural members, a plurality of groups of acoustic transducers configured to receive acoustic emissions from the structure when the structure is submitted to stress, each group mounted on a respective structural member, and a signal processing unit coupled to the transducers and arranged to detect groups of data bursts each comprising data bursts representing pulses in signals received from respective transducers of one of the groups of transducers during a sampling time interval, and to derive, for each of the data bursts, timing information relating to the times of arrival of the data burst forming the group, the signal processing unit further comprising a correlator arranged to generate a significant event indication signal when the timing pattern is repeated to a predetermined degree in different groups of data bursts from the said group of transducers.
Dependencies are inferred from the claim text.