AUTOMATED FATIGUE CRACK GROWTH MEASUREMENT

AUTOMATED, REMOTE MEASUREMENT OF FATIGUE CRACK GROWTH TO A PRECISION OF 0.025 MM IN A TEMPERATURE FIELD UP TO 2,000 DEG F CAN BE DONE WITH A RELATIVELY SIMPLE, HENCE LOW COST SYSTEM. THE KEY TO THIS SYSTEM IS THE SENSOR, AND THEREFORE, WE HAVE SELECTED TWO APPROACHES IN TWO ENERGY RANGES (VISIBLE AND X-RAY) TO PROVIDE MAXIMUM FLEXIBILITY IN IMPLEMENTING THIS SYSTEM. WE BELIEVE THE CONFIGURATION AND INTERFACES WITH THE FATIGUE TESTING MACHINE AND THE SPECIMEN FURNACE WILL BE IMPORTANT FACTORS IN THE DESIGN OF THE PROPOSED SYSTEM. THEREFORE,THE SENSOR FREQUENCY AND CONFIGURATION SHOULD NOT BE SELECTED UNTIL ALL THESE INTERFACES ARE KNOWN AND WELL UNDERSTOOD. THE PROPOSED PHASE I PROGRAM WILL EXAMINE ALL THESE INTERFACES, INTEGRATE THEM WITH THE PERFORMANCE REQUIREMENTS AND MAKE A SELECTION. A LABORATORY TEST WILL THEN BE CONDUCTED TO VERIFY FEASIBILITY AND ATTAINABLE PRECISION. A SYSTEM WILL BE DESIGNED BASED ON THE TEST DATA AND IT WILL FORM THE BASIS FOR A PHASE I PROGRAM.