A MATHEMATICAL MODEL TO INVESTIGATE UNDERCUTTING AND TO OPTIMIZE WELD QUALITY

THE PROPOSED RESEARCH IS AIMED AT PROVIDING PLAUSIBLE EXPLANATION(S) FOR THE UNDERCUTTING FEATURE OF WELDS. A MATHEMATICAL MODEL WILL BE DEVELOPED TO SIMULATE WELD POOL MOTION. PARTICULAR EMPHASIS WILL BE PLACED ON THE VARIATION OF SURFACE TENSION WITH TEMPERATURE AND LOCAL CONCENTRATIONS OF OXYGEN AND OTHER IMPURITIES WHICH MAY DIFFUSE UP TO THE WELD POOL SURFACE THROUGH SHIELD GAS. SPATIAL VARIATION OF CONCENTRATION, WHICH IS EXPECTED TO BE QUITE SIGNIFICANT, WILL BE PROPERLY ACCOUNTED FOR. SUCH VARIATION HAS A POTENTIAL OF CAUSING SECONDARY EDDIES IN THEWELD POOL AND HENCE, THE UNDERCUTTING FEATURE ON THE SURFACE. IN PHASE I, THE MODEL WILL BE DEVELOPED BY ADAPTING AN EXISTING CFD CODE, AND A PARAMETRIC STUDY WILL BE PERFORMED TO ESTABLISH THE PROOF-OF-THE-CONCEPT. IN PHASE II, THE ADAPTED CODE WILL BE IMPROVED, VALIDATED, AND DOCUMENTED FOR ITS WIDE USE IN NASA AND THE WELDING INDUSTRY.