IGF::OT::IGF THIN-PLY COMPOSITES ARE BEING CONSIDERED BY NASA FOR SPACE EXPLORATION APPLICATIONS, WHERE THE…

Public award description

IGF::OT::IGF THIN-PLY COMPOSITES ARE BEING CONSIDERED BY NASA FOR SPACE EXPLORATION APPLICATIONS, WHERE THE SUPPRESSION OF MICROCRACKS COULD GIVE RISE TO LINERLESS CRYOGENIC TANKS. IN THIS PROPOSED PHASE I STTR EFFORT, MATERIAL TESTING COUPLED WITH HEALTH MONITORING TECHNIQUES WILL BE USED TO QUANTIFY DAMAGE ACCUMULATION WITHIN COMPOSITE MATERIALS, BOTH STANDARD PLY THICKNESS AND OF THE THIN-PLY DESIGN. A MULTI-SCALE PHYSICS BASED APPROACH, VERIFIED WITH EMPIRICAL DATA, WILL BE USED TO DEVELOP A DESIGN TOOL CAPABLE OF PREDICTING THE USEABLE LIFE OF A COMPOSITE STRUCTURE SUBJECTED TO CYCLIC LOADS. A FRACTURE MECHANICS BASED MODEL IN A MULTI-SCALE FRAMEWORK IS PROPOSED AS A DESIGN TOOL FOR MODELING THIN-PLY LAMINATES. THE KEY VARIABLE OF THE MODEL, THE MICROCRACKING CRITICAL ENERGY RELEASE RATE (CERR), IS TO BE CALIBRATED TO QUASI-STATIC AND FATIGUE TESTING. ACOUSTIC EMISSION (AE) MONITORING WILL BE USED TO QUANTIFY THE CRACK DENSITY AS A FUNCTION OF LOAD HISTORY. THE MODEL WILL BE INTERROGATED WITH CERRS TO BEST MATCH THE CRACK DENSITY AS A FUNCTION OF LOAD OBSERVED DURING THE EXPERIMENTS. IF THE CERR IS INDEED A MATERIAL PROPERTY, THE SAME VALUE SHOULD EXIST REGARDLESS OF PLY THICKNESS AND FIBER ARCHITECTURE. THE DESIGN TOOL WILL INCLUDE A STAND-ALONE PROGRAM TO PERFORM THIS CALIBRATION OF THE CERR FOR CROSS-PLY LAMINATES. ADDITIONALLY, A USER MATERIAL (UMAT) WILL BE WRITTEN TO LINK THE MICRO-CRACKING MODEL TO A STRUCTURAL LEVEL MODEL IN A COMMERCIAL FINITE ELEMENT CODE.