T-AO 187 & 201 CLASS OILER SPECTRAL FATIGUE ANALYSIS

USNS HENRY J. KAISER (T-AO 187) AND USNS PATUXENT (T-AO 201) ARE MILITARY SEALIFT COMMAND OILERS BUILT BY AVONDALE SHIPYARDS. USNS HENRY J. KAISER (T-AO 187) IS THE FIRST IN CLASS OF TWELVE SINGLE HULL OILERS AND WAS DELIVERED IN 1986. USNS PATUXENT (T-AO 201) IS THE FIRST IN CLASS OF THREE DOUBLE HULL OILERS AND WAS DELIVERED IN 1995. BOTH THE SINGLE HULL AND DOUBLE HULL OILERS HAVE IDENTICAL HULL GEOMETRY, PRINCIPAL DIMENSIONS, DECKHOUSES, PROPULSION PLANTS, AND HULL STRUCTURE FORWARD AND AFT OF THE CARGO BLOCK. THE ONLY DIFFERENCES ARE LIGHT SHIP WEIGHT AND LIGHT SHIP WEIGHT DISTRIBUTION (I.E. THE DOUBLE HULLS ARE HEAVIER) AND CARGO BLOCK SUBDIVISION (I.E. THE 187 CLASS HAS A SINGLE HULL AND THE 201 CLASS HAS A DOUBLE HULL). SINCE DELIVERY, THE PRIMARY MISSION OF THE T-AOS HAS BEEN TO PROVIDE DIESEL FUEL MARINE (DFM) AND JET FUEL (JP-5) TO NAVAL SHIPS AS UNDERWAY REPLENISHMENT SHIPS. THEY ALSO ROUTINELY PROVIDE DRY PALLETIZED CARGO. WHILE THE MAJORITY OF CARGO TRANSFERRED IS DFM AND JP-5, THE NUMBER OF PALLETS TRANSFERRED HAS DOUBLED SINCE 2006. A TYPICAL MISSION LASTS 1 TO 3 WEEKS DURING DEPLOYMENT AND DEPLOYMENTS LAST SIX MONTHS OR MORE. CURRENT PLANS ARE FOR THESE SHIPS TO OPERATE TILL 2040. GIVEN THE NEED TO IDENTIFY SUSPECT AREAS AS WELL AS GAIN AN ACCURATE PREDICTION OF FATIGUE LIFE, CONTRACTOR SUPPORT IS REQUIRED TO CONDUCT A SPECTRAL FATIGUE ANALYSIS (SFA) FOR BOTH USNS HENRY J. KAISER (T-AO 187 CLASS) AND USNS PATUXENT (T-AO 201 CLASS). IN ADDITION TO IDENTIFYING HIGH STRESS AREAS AND THE FATIGUE LIFE OF SELECTED DETAILS, THE SFA REPORT WILL ALSO IDENTIFY AND RECOMMEND PROACTIVE REPAIRS OF THOSE DETAILS MOST LIKELY TO FAIL IN THE NEXT 28 YEARS (2040). A SEPARATE GRAPHIC INSPECTION GUIDE DOCUMENT WILL ALSO BE PREPARED TO AID IN THE PERIODIC INSPECTIONS BY SHIP'S FORCE AND REGULATORY BODIES. UNDER THE AWARD CONTRACT, THE CONTRACTOR SHALL PERFORM THE FOLLOWING TASKS: A. MOTIONS ANALYSIS AND WAVE-INDUCED LOADS: PREPARE A GLOBAL HYDRODYNAMIC HULL MODEL AND CONDUCT A MOTIONS ANALYSIS TO ESTIMATE RESPONSE AMPLITUDE OPERATORS (RAOS) OF THE SHIP RESPONSES AND LOAD EFFECTS FOR A RANGE OF WAVE LENGTHS (OR EQUIVALENT FREQUENCIES), SHIP HEADINGS, AND BASE LOAD CONDITIONS. B. STILLWATER LOADS: CALCULATE THE STILLWATER SHEAR FORCES AND BENDING MOMENTS OVER A STANDARD 20 STATION WEIGHT DISTRIBUTION FOR THE THREE BASE LOAD CONDITIONS AS PART OF HULL LOADINGS IN THE GLOBAL FEA MODEL, AS WELL AS THE LOADING AT THE BOUNDARIES IN LOCAL FINER MESH FEA MODELS. ANY RECOGNIZED GENERAL PURPOSE NAVAL ARCHITECTURE SOFTWARE CODE CAN BE USED. C. GLOBAL HULL FEA MODEL AND GLOBAL HULL STRESS ANALYSIS: PREPARE A COARSE MESH, GLOBAL HULL FEA MODEL OF THE ENTIRE SHIP AND CONDUCT A STRESS ANALYSIS TO DETERMINE STRESS RAOS, THE NORMALIZED STRESS RESPONSES FOR A RANGE OF UNIT AMPLITUDE SINUSOIDAL WAVES. D. INTERMEDIATE MESH MODELS AND INTERMEDIATE STRESS ANALYSES: PREPARE TWO INCREASINGLY FINER INTERMEDIATE MESH MODELS AND CONDUCT A STRESS ANALYSES TO DETERMINE STRESS RAOS. E. LOCAL DETAIL MODELS AND STRESS ANALYSIS: PREPARE THE SIX SELECTED LOCAL MODELS AND CONDUCT A STRESS ANALYSES TO DETERMINE STRESS RAOS AND STRESSES. THE LOCAL MODELS SHALL BE SELECTED BASED ON THE RESULTS OF THE LOCAL INTERMEDIATE MESH ANALYSIS AND ON THE HISTORICAL BASIS OF KNOWN TANKER DETAILS SUSCEPTIBLE TO FATIGUE DAMAGE. F. SPECTRAL FATIGUE ANALYSIS: CONDUCT A SPECTRAL FATIGUE ANALYSIS (SFA) ON EACH LOCAL MODEL BASED ON THE STRESS RAOS DETERMINED FOR EVERY ELEMENT IN THE LOCAL MODEL. G. SPECTRAL FATIGUE ANALYSIS (SFA) REPORT: PREPARE A COMPREHENSIVE SFA REPORT FOR EACH SHIP, PRESENTING THE RESULTS OF TESTS. H. INSPECTION GUIDE: PREPARE AN INSPECTION GUIDE FOR EACH SHIP FOR USE BY SHIP'S FORCE AND REGULATORY BODY INSPECTORS. THE GUIDE WILL IDENTIFY AREAS OF HIGH STRESS AND THOSE STRUCTURAL DETAILS AND AREAS SUSCEPTIBLE TO FATIGUE FAILURE IN NEED OF PERIODIC, CLOSE UP SURVEY. THE CONTRACT IS A COMPETITIVE FIRM-FIXED PRICE CONTRACT AWARDED IN ACCORDANCE WITH FAR PART 12, "ACQUISITION OF COMMERCIAL ITEMS," USING THE PROCEDURES IN FAR PART 15, "CONTRACTING BY NEGOTIATION". SERVICES WERE PROCURED BY: MILITARY SEALIFT COMMAND, HQ CONTRACTING, N10 914 CHARLES MORRIS CT SE BUILDING 157 WASHINGTON NAVY YARD, DC 20398-5540