HIGH STRAIN RATE & HIGH TEMPERATURE LASER SPECKLE STRAIN MEASURING DEVICE

A DIGITAL SPECKLE METHOD IS PROPOSED FOR RAPIDLY DIGITIZING AND PROCESSING LASER SPECKLE DATA FOR STRAIN CALCULATIONS. ONE BEAM LASER SPECKLE METHOD IS A NON-CONTACT, REMOTE SENSING, STRAIN MEASURING TECHNIQUE WHEREBY THE 2-D STRAIN DISTRIBUTION OF AN ENTIRE SPECIMEN (OR A PART OF A STRUCTURE) SURFACE CAN BE OBTAINED. PREVIOUS WORKS OF THE PRINCIPAL INVESTIGATOR HAVE SHOWN THAT THE TECHNIQUE HAS GREAT POTENTIAL FOR BEING DEVELOPED INTO A RUGGED 2-D STRAIN MEASURING DEVICE FOR HIGH STRAIN RATE AND HIGH TEMPERATURE RATE TESTINGS. THIS PROPOSAL ADDRESSES THE ISSUE OF USING A DIGITAL CAMERA COUPLED WITH A CONTINUOUSLY PULSING LASER TO CAPTURE LASER SPECKLE PATTERNS AND THE NECESSARY SOFTWARE TO PROCESS THE SPECKLE DATA FOR YIELDING DIRECTLY STRAIN INFORMATION. THE WET PHOTOGRAPHIC PROCESS IS THUS ENTIRELY ELIMINATED. FOR HIGH TEMPERATURE APPLICATIONS WE WOULD USE PLASMA SPRAY AND APPROPIATE OPTICAL FILTERING TO CIRCUMVENT THE POSSIBLE THERMAL EFFECTS.