FAILURE PREDICTION BY A NOVEL NON-DESTRUCTIVE X-RAY TECHNIQUE

A RECENT BREAKTHROUGH IN FATIGUE FAILURE PREDICTION HAS BEEN DEMONSTRATED BY A METHOD KNOWN AS DARC (DIGITAL AUTOMATED ROCKING CURVE) DIFFRACTOMETRY. THIS METHOD IS A NON-DESTRUCTIVE X-RAY PROCEDURE WHICH MEASURES DIRECTLY THE ACCRUED MICROSTRUCTURAL DAMAGE, THUS PERMITTING AN ASSESSMENT OF THE REMAINING USEFUL LIFE. THIS TECHNIQUE IS A DEPARTURE FROM THE CONVENTIONAL X-RAY METHODS WHICH ARE NORMALLY USEFUL OVER ONLY THE FIRST 10-20% OF COMPONENT LIFE. DARC DIFFRACTOMETRY, BY COMPARISON, IS USEFUL OVER THE FULL RANGE OF FATIGUE LIFETIMES. IT IS PROPOSED HERE TO BROADEN THE RANGE OF APPLICABILITY OF THE DARC TECHNIQUE. PRELIMINARY WORK ON THE AGE-HARDENED ALUMINUM ALLOY 2024-T4 IS EXTREMELY PROMISING, AND WARRANTS FURTHER INVESTIGATION. IN THE PROPOSED STUDY, ALLOYS SUCH AS AA 2024, 7075, 7050 AND 7150 WHICH HAVE WIDE USAGE AS STRUCTURAL MATERIALS WILL BE INVESTIGATED. THIS TECHNIQUE CAN ALSO BE USED TO STUDY CORROSION FATIGUE FAILURE IN THE ABOVE MENTIONED ALLOYS.