STRESS INTENSITY FACTORS FOR CRACKING METAL STRUCTURES UNDER RAPID THERMAL LOADING

THIS WORK PROPOSED TO COMBINE A NOVEL METHOD OF DIRECT INTEGRATION OF THERMAL STRESSES VIA GREEN'S FUNCTIONS, WITH AN EXISTING TECHNOLOGY FOR CALCULATING CRACK TIP STRESS INTENSITY FACTORS, TO DEVELOP A FAST AND EFFICIENT MEANS OF PREDICTING STRESS INTENSITY FACTORS OF CRACKED METALLIC STRUCTURES SUBJECTED TO RAPID THERMAL PULSES. THE END PRODUCT WILL BE A PERSONAL COMPUTER BASED SOFTWARE PACKAGE, SPECIFICALLY FOCUSED TO AIR FORCE THERMAL CRACKING PROBLEMS, WHICH IS MENU-DRIVEN, USER FRIENDLY, AND WHICH POSSESSES EXTENSIVE INTERACTIVE GRAPHICS CAPABILITIES. A UNIQUE FEATURE OF THE PROPOSED METHOD IS ITS ABILITY TO PREDICT STRESS INTENSITY FACTOR TIMEHISTORIES FROM NON-LINEAR THERMAL STRESS DISTRIBUTIONS, WHICH OCCUR FROM RAPID THERMAL PULSES, WITHOUT THE NEED TO RESORT TO TIME CONSUMING FINITE ELEMENT MODELING OF EACH AND EVERY CASE TO BE ANALYZED. THE CRACKED-STRUCTURE GEOMETRIES OF INTEREST ARE ANALYZED JUST ONCE, AND THE RESULTS ARE THEN EXTENDED TO ANY LOADING CASE OF INTEREST.