PROGRAMMABLE REFLECTANCE OF ARTIFICIAL FLAWS IN RAIL MATERIALS

A PROGRAMMABLE DEFECT SIMULATOR IS NEEDED TO TEST ULTRASONIC RAIL FLAW DETECTION SYSTEMS. CALIBRATION STANDARDS CAN BE DEVELOPED WITH VARIABLE PHYSICAL CHARACTERISTICS ACCORDING TO A PREDESCRIBED SCHEME THAT SIMULATES COMMONLY-OCCURRING FLAWS (CROSS-HEAD FATIGUE CRACKS) IN RAILWAY SYSTEM RAILS. THIS PROJECT WOULD DEVELOP A METHOD OF ALTERING THE EFFECTIVE REFLECTIVITY OF A SOLID-GAS INTERFACE THROUGH THE INTRODUCTION OF A FLUSH-MOUNTED ARRAY OF CLOSE-PACKED SOLID STEEL BACKING MEMBERS WHOSE INTIMACY OF COUPLING IS PROGRAMMED FOR CONTROLLED PRESSURE VARIATIONS INDUCED THROUGH THE USE OF PIEZOELECTRIC OR MAGNETOSTRICTIVE DEVICES. A LARGE VARIETY OF REFLECTOR SHAPES WITH VARYING DEGREES OF INTERFACE TRANSMISSIVITY CORRESPONDING TO PARTIALLY CLOSED FATIGUE CRACKS WITH SHAPES (RANGING FROM SIMPLE CIRCLES TO CRESCENTS OF NUMEROUS ORIENTATIONS) CAN BESIMULATED.