TURBINE ENGINE COMPONENT DESIGN OPTIMIZATION BY DAMAGE TOLERANCE ASSESSMENT

DAMAGE TOLERANCE ASSESSMENT (DTA) IS USED TO VALIDATE A STRUCTURE FOR REQUIRED LIFE. ITS USE AS A DESIGN TOOL, HERETOFORE UNTRIED, IS THE PRINCIPAL SUBJECT OF THIS PROPOSAL. ADVANCES IN FINITE ELEMENT ANALYSIS (FEA) AND DTA IN RECENT YEARS OFFER THE POTENTIAL TO PERFORM ANALYSIS SUFFICIENTLY RAPIDLY AND EASILY FOR THEIR INTEGRATION INTO THE DESIGN PROCESS DTA NEEDS DESCRIPTIONS OF THE STRESS FIELDS IN THE NEIGHBORHOOD OF HYPOTHECATED FLAWS; A GRAPHIC INTERFACE FROM THE FEA CAN PROVIDE THIS INFORMATION; FEA NEEDS A DESCRIPTION OF THE GEOMETRY; DESCRIPTION OF GEOMETRY IS AN INITIAL STAGE OF DESIGN. BY CYCLING THROUGH THIS PROCESS, A DESIGN CAN BE OPTIMIZED FOR ITS LIFE. GEOMETRY TRANSITION ZONES ARE WHERE STRESSES ARE HIGH, WHERE CRACKS TYPICALLY ORIGINATED. FROM TRADITION AND FOR CONVENIENCE, THESE ZONES, OR "FILLETS," INVARIABLY HAVE SECTIONS DESCRIBED BY CIRCLES. CONSIDERING THE SHAPE OF A FILLET AND NOT JUST ITS SIZE AS A DESIGN VARIABLE OFFERS A POTENTIAL MEANS TO OPTIMIZE HIGHLY LOCALIZED PARTS OF A DESIGN FOR ITS LIFE CYCLE WITHOUT AFFECTING THE OVERALL DESIGN AND FUNCTION. THE SPEED AND PRECISION REQUIRED FOR THIS PROCEDURE TO BE A PRACTICAL DESIGN TOOL ALSO ENHANCE ITS APPLICABILITY TO ITS TRADITIONAL FUNCTION OF DESIGN VALIDATION.