RESIDUAL STRESS MODELING. RESIDUAL STRESS AND DISTORTION ASSESSMENT OF THE FLANGE TO SKIN WELD FOR THE ARES…

Public award description

RESIDUAL STRESS MODELING. RESIDUAL STRESS AND DISTORTION ASSESSMENT OF THE FLANGE TO SKIN WELD FOR THE ARES I-1 UPPER STAGE. THE CONTRACTOR WILL PERFORM SIX FINITE ELEMENT ASSESSMENTS OF WELDING RESIDUAL STRESS AND DISTORTION. THESE WILL BE USED TO PROVIDE A DESCRIPTION OF THE RESIDUAL STRESS AND DISTORTION STATE OF THE AREA OF THE SKIN-TO-FLANGE WELD OF THE UPPER STAGE OF THE ARES I-1 PROGRAM. THE SIX FINITE ELEMENT ASSESSMENTS WILL BE COMPLETED FOR TWO WELDING PROCEDURES USING THE FOLLOWING THREE MODELS: A TWO-DIMENSIONAL MODEL WITH ROTATION PREVENTED (BY GUSSET) BETWEEN THE SKIN AND THE FLANGE, A THREE-DIMENSIONAL MODEL WITHOUT STIFFENERS OF THE WELD BETWEEN THE SKIN AND THE FLANGE, AND A FULL THREE-DIMENSIONAL MODEL WITH STIFFENERS OF THE WELD BETWEEN THE SKIN AND THE FLANGE. IT SHOULD BE NOTED THAT THE SECTOR OF AXI-SYMMETRY BETWEEN GUSSETS IS 10 DEGREES PER DRAWING PROVIDED BY NASA. THE CONTRACTOR WILL USE TEMPERATURE-DEPENDENT THERMAL, PHYSICAL, AND MECHANICAL PROPOERTIES APPROPRIATE TO THE MATERIAL BEING WELDED. THESE PROPERTIES WILL BE COMMUNICATED TO NASA FOR CONFIRMATION. THE FIRST THREE FINITE ELEMENT ASSESSMENTS (FIRST WELDING PROCEDURE) ARE INTENDED TO DESCRIBE THE NASA GRC PATHFINDER 1 SEGMENT WHERE THE FLANGE IS NON-NORMALIZED ASTM A516 GRADE 70 STEEL AND THE SKIN IS NON-NORMALIZED ASTM A36 STEEL. THE LAST THREE FINITE ELEMENT ASSESSMENTS (SECOND WELDING PROCEDURE) ARE INTENDED TO DESCRIBE THE NASA GRC PATHFINDER 2 SEGMENT WHERE NOTH THE FLANGE AND THE SKIN MATERIAL WILL BE NORMALIZED ASTM A516 GRADE 70 STEEL. THE CONTRACTOR WILL USE TWO MODELS OF WELDING PROCEDURES RESPRESENTATIVE OF THE PROCEDURES FOR THE FLANGE-TO-SKIN WELDING. THICKNESSES AND WELD SIZES WILL BE PROVIDED BY NASA. NASA WILL ALSO PROVIDE INFORMATION ON THE CHOSEN WELD PROCEDURE, SUCH AS THE JOINT SHAPE SPECIFICS, NUMBER AND POSITION OF WELD PASSES AND PARAMETERS SUCH AS HEAT INPUT. A BEST ESTIMATE FOR THE WELDING INFORMATION MAY BE SUFFICIENT. NASA WILL PROVIDE ONE PROCEDURE REPRESENTATIVE OF THE PLAN FOR FLIGHT HARDWARE AND ONE PROCEDURE REPRESENTATIVE OF THE EXISTING PATHFINDER EXAMPLE. THE CONTRACTOR WILL USE THERMAL AND THERMOMECHANICAL ANALYSIS METHODS THAT CAN HANDLE MELTING AND RE-MELTING IN THE WELD AREA. THE CONTRACTOR WILL PROVIDE DESCRIPTIONS OF THE ANALYSIS AND FIGURES SHOWING THE EXTENT OF DISTORTION AND THE MAGNITUDES AND DIRECTIONS OF RESIDUAL STRESSES IN THE WELD AREA. INFORMATION WILL BE PROVIDED ON RESIDUAL STRESSES IN THE AXIAL, RADIAL AND ALONG-THE-WELD DIRECTIONS. A MID-TERM PROGRESS REPORT (POWERPOINT FORMAT) SHOULD BE DELIVERED AFTER 5 WEEKS WITH A DRAFT REPORT (POWERPOINT FORMAT THAT WILL BE REVIEWED BY NASA) DUE WITHIN NINE WEEKS OF PROJECT INITIATION. THE FINAL REPORT (WORD DOCUMENT FORMAT) WILL BE COMPLETED WITHIN AN ADDITIONAL ONE MONTH.