Systems and method for locating failure events in samples under load

1. A system for locating a failure event in a sample, the system comprising:

at least one sensor configured to detect acoustic energy corresponding to the failure event in the sample;

an infrared camera configured to detect a thermal release of energy corresponding to the failure event in the sample; and

a processor configured to determine a zero time of occurrence of the failure event based on the detected acoustic energy and to analyze the thermal release of energy detected after the zero time of occurrence to locate the failure event in the sample.

2. The system of claim 1 , further comprising an X-ray source and a digital X-ray detector configured to capture an X-ray image of the sample, wherein the X-ray image is correlated with at least one of a plurality of acoustic data obtained with the sensor and a plurality of thermal data obtained with the infrared camera.

3. The system of claim 1 , wherein the failure event comprises at least one of a point event, a line event or a plane event.

4. The system of claim 1 , wherein the at least one sensor comprises a plurality of sensors.

5. The system of claim 1 , wherein the at least one sensor comprises a transducer.

6. The system of claim 1 , wherein the at least one sensor is further configured to detect a zero-time event, wherein the infrared camera records the thermal release of energy corresponding to the failure event in the sample in a plurality of frames, wherein the at least one sensor and the infrared camera are synchronized on a common time base, and wherein the processor is further configured to synchronize an event time detected by the sensor with a respective one of the frames.

7. The system of claim 1 , wherein the infrared camera comprises a focal plane array of sensors.

8. The system of claim 1 , wherein the sample comprises a plurality of plies oriented at angles in a range of about 0 degree to 180 degrees with respect to a longitudinal axis of the sample.

9. The system of claim 1 , wherein the infrared camera is configured to operate at a frame rate within a range of about 50 frames per second to about 250 frames per second.

10. A method of detecting a failure event in a sample comprising:

using at least one sensor to detect a plurality of acoustic signals corresponding to the failure event;

determining a zero time based upon the acoustic signals;

using an infrared camera to record a plurality of thermal images of the sample over a period of time;

synchronizing the at least one sensor and the infrared camera on a common time base;

generating a signal corresponding to a location and a depth of the failure event from the thermal images recorded on and after the zero time; and

determining the depth and the location of the failure event based upon the generated signal.

11. The method of claim 10 , wherein said using at least one sensor to detect and said using an infrared camera to record are performed simultaneously.

12. The method of claim 10 , wherein the thermal images comprise thermal images of a resolution element on a surface of the sample, wherein each of the recorded resolution elements corresponds to a pixel, and wherein said using an infrared camera to record step further comprises:

determining individual pixel intensity for each of the pixels in each of the thermal images;

determining mean pixel intensity for each thermal image;

obtaining pixel contrast for each of the pixels of each of the thermal images subtracting the mean pixel intensity from the intensity of the individual pixel;

developing a surface temperature-time pixel contrast curve; and

determining a depth of the failure event based upon the contrast curve.

13. The method of claim 10 , wherein determining the depth of the failure event comprises a determination based upon a heat flow relationship between an inflection point in a contrast curve and a heat-flow characteristic time.

14. The method of claim 10 , wherein said using at least one sensor to detect the plurality of acoustic signals step is performed in real time.

15. A system for locating a failure event in a sample comprising:

at least one sensor configured to detect acoustic energy corresponding to the failure event in the sample;

an infrared camera configured to detect a thermal release of energy corresponding to the failure event in the sample;

an X-ray source configured to irradiate at least a portion of the sample; and

a digital X-ray detector configured to capture at least one X-ray image of at least a portion of the sample; and

a processor configured to determine a zero time of occurrence of the failure event based on the detected acoustic energy and to analyze the thermal release of energy detected after the zero time of occurrence to locate the failure event in the sample.

16. The system of claim 15 , wherein the infrared camera comprises a focal plane array of sensors.

17. The system of claim 15 , wherein the infrared camera comprises a frame rate with a range of about 50 frames per second to about 250 frames per second.

18. The system of claim 15 , wherein the failure event comprises at least one of a point event, a line event or a plane event.

19. The system of claim 15 , wherein the at least one sensor is further configured to detect a zero-time event, wherein the infrared camera records the thermal release of energy corresponding to the failure event in the sample in a plurality of frames, wherein the at least one sensor and the infrared camera are synchronized on a common time base, and wherein the processor is further configured to synchronize an event time detected by the sensor with a respective one of the frames.

20. The system of claim 15 , further comprising means for correlating the X-ray image with at least one of a plurality of acoustic data obtained with the sensor and a plurality of thermal data obtained with the infrared camera.