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Full Paper - Ship Structure Committee

1. ready to accept another fracture from the same FR If all the fractures have been entered the user can click the lt New Fracture Report gt button or the lt Return to Menu gt button to end the data entry session Data Selection Data analysis with HFDB involves first selecting a subset of the data and then displaying that subset in any one of three forms HFDB provides a selection screen on which the user may make selections based on ship class structure fractured severity and date The selections are made by using the cursor control keys to move to the desired item and then highlighting the item by pressing the space bar In this manner it is easy to make a selection such as All fractures on Alaska or California which were discovered in 1989 or 1990 It is also possible to select a single FR by its FR serial number or to select all fractures which have been entered on a particular FRS by using the three digit FRS number For experienced Paradox users there is a provision to enter Paradox make a selection using all he capabilities of the Paradox query mechanism return to B and display the selected subset Graphic Display The user can now display the selected subset The simplest ainplay is the Time Plot which displays a histogram of the selected fracture records vs time The bars of the histogram are color coded for severity ARCO Marine Inc The second display is the profile display This shows a schema
2. Paper presented THE SOCIETY OF NAVAL ARCHITECTS AND MARINE ENGINEERS _ 601 Pavonia Avenue Sulte 400 Jersey City New Jersey 07306 USA at the Marine Structural Inspection Maintenance and Monitoring Symposium heraton Nabenal Hotel Arlington Virginia March 18 19 1991 A Graphical Database for Hull Fracture Reports J Letcher and D Shook Aerohydro Incorporated Southwest Harbor Maine D Sucharski Arco Marine Inc Long Beach California ABSTRACT HFDB is the Hull Fracture Database system implemented By Aero yar Inc AHI for ARCO Marine Inc AMI The purpose of HFDB is the establishment maintenance and utilization of a graphic ouented database of structural fracture data from the AMI fleet of crude oil tankships HFDB takes its primary input from a graphics tablet allowing fracture locations to be conveniently entered from fracture report sheets supplied as part of the system Graphics tablet menus are used for auxili ata input Graphic screen displays are provided during input to visually verify the input data The data is stored in a Paradox database suited to selective retrieval Graphical output displays show locations frequency of occurrence and severity of fractures as a function of ship name ship class time interval structural element and severity The overall purpose of HFDB is to enable a human operator to discern and explore patterns of fracture experience which may lead to improved design maintenan
3. Repair Location X 720 5 Y 77 4 Z Comment Whatever comment you entered Fig 4 HFDB fracture entry screen Logging a fracture always requires entry of at least llowing information 1 A structural member selected from the permanent form 2 rs severity level selected from the permanent orm 3 The following items are optional 4 5 All these items may be entered in any order i can be re clicked as many times as necessary As each is entered it is displayed in the appropriate location on the screen for confirmation F 4 A location on the structural drawing A Fix selected from the permanent form Repair Modify Renew the default is Repair A text comment HELP ESC REDO ACCEPT Connent New Fracture Report DISPOSITION Return to Menu CT ify fgl Return to Meno _ ee LEE LED EERE SEEEELE EB 1 Ship flaska FRS No 206 FR Date 1990 64 5 FR Serial No 1 A apna cursor in the drawing area of the screen track the tablet stylus when the stylus is in the drawing box Clicking the stylus leaves a miet green Xon the screen at the cursor location The selected coordinates are echoed in the text area of the screen This is the tentative location of the fracture it can be corrected by re clicking When the user accepts the fracture record the green X changes to red l The user clicks the lt ACCEPT gt button to confirm that the fracture has been entered correctly HFDB is then
4. ARCO Marine Inc as shown in Figure 6 suggests other possibilities The need for analysis of the structure near the ship s sides between the 7th and 14th longitudinal above the baseline is evident o Figure 6 also shows the concentration of fractures at the vertical level of the transverse bulkhead horizontal girders It is evident that these fractures are most prevalent at the intersections of the horizontal irders and the ship s sides and longitudinal ulkheads Analysis of the structure in these locations could lead to a better repair which would prevent the reoccurrence of the common fractures Figure 7 shows how HFDB can be used to identify the type of structure which is failing Figure 7 is the same transverse view shown in Figure 6 but shows only fractures in flatbar tie plates Similar plots can be made for each structural type and a comparison of these plots with Figure 6 can be used to identify the yee or types of structures which fracture as well as eir locations The success of modifications over time can also be determined by accessing only fractures in modified structures These techniques give ARCO an increasingly better understanding of the fractures in its ships and improve the probability of successful remedies i Hull Fracture Database Transverse Distribution of Fractures 50 Date of Report 12 11 1990 FR None Selected Ship s PRES eet mi oie a eS a ees LOOKING FOR Independenc
5. L GIRDERS Na 1 CARGO TANK Fig 2 A generic off center longitudinal fracture report Notice that the transverse auxiliary view has been marked THE HFDB PROGRAM HFDB is a menu driven program The main top level menu provides access to the three principal functions of interest here Data entry Data selection Display The main menu also provides access to utili functions such as backing up and restoring the fracture database and deleting erroneous fracture records Tablet Data Entry The data entry procedure is operated almost entirely through selections made on the graphics tablet Screen prompts and displays are used to guide the peos and to confirm selections before they are inally accepted Tablet selections are made by clicking the tablet stylus or tablet mouse button 1 within labeled rectangular areas on the tablet forms which are referred to as buttons The availability of various buttons is controlled by the program so that only an Eda ee set of buttons is active at any given time If the user clicks an active button the computer makes a short high pitched beep to confirm the selection is understood If the a generic FRS the operator must cli user clicks an inactive button or an inactive area of the tablet a longer lower pitched tone indicates that the click was not effective The first step of the data entry procedure is to register the Permanent Form containing the buttons that need to be
6. the primary lala ad the FRS with both the location and the severity The location should be marked with an X The severity positioned adjacent to the X should indicate the size of the fracture in feet and inches or Thru if the fracture is all the way through the structural member An FRS may be marked with more than one fracture as long as the fractures are for the same ship year and in the case of generic FRS s structure When a blank FRS has been filled out it becomes a Fracture Report FR When the FR is entered into the HFDB system in a process described below an FR serial number is assigned to it and written by the data entry operator into the space provided on the FRS p lea awT z a O T BHO FR G1 73 8l eos i sg 5 z oS 5 Sg ge ae stot kl Le 3 ua us ee ee ee ee ee ee ee ee FR Serial No LEAVE ILAK OFFice Use Onl FRS Decade C e S S E O ee ee _ a a ee Fig 1 A generic bulkhead fracture report sheet with a profile auxiliary view F 2 r Po fasg CatiFormig Pf T ae a ae se I FR Serial No KS LEAVE ILAK OF Fice Use Onl FR amp Decade Moa feo IMEE 2 OPENINGS E MEENT ON L 13 GIHERI 1 ees a Oa 0 OOE o A ease ay ee a E ET SO a a a LOG L GIMER L 5 115 0 OFCL LRLS r F CL I L193 39 8 FEL Lele 54 0 OFF CL I L AI OF CL 190 ADVT INNER BOTTOM LONG
7. ARY RESULTS ARCO Marine Inc is using HFDB to monitor and R assess hull fractures in its fleet of ten crude oil tankers in the Alaska to West Coast trade Use of the database focuses ARCO s fracture control efforts which include inspections analyses and modifications Better focus ensures better use of available resources for these tasks which in turn reduces the risks of undetected fractures and of failure to understand the cause and to effect successful remedies i Figures 5 and 6 show the longitudinal and transverse distributions of fractures in the two ships of the ARCO Alaska Class 190 000 dwt These plots are based on 346 fractures detected since 1984 The longitudinal distribution shows the concentration of fractures at the transverse bulkheads and especially the wing ballast tank bulkheads The transverse distribution shows that the fractures are concentrated at the ship s side in the lower half of the ship s depth This distribution is contrary to anecdotal information which suggests that fr cturing is more common in the upper part of the ship Although a slightly greater incidence of fracturing is recorded for the starboard side the difference with respect to the port side is not at great as anecdotal information suggests Based on anecdotal information ARCO had ostulated that the cause of the fractures was wave oads in the loaded voyage on the weather side The focused more complete view of the fracture record
8. ce and inspection rocedures and to reduced risk of structural failures in the future operation of the fleet NOMENCLATURE FRS Fracture Report Sheet FR Fracture Report HFDB Hull Fracture Database DESIGN GOALS It is anticipated that HFDB will be used over alon period of time Provisions are specifically included to allow handling of fractures roui 2059 It is also anticipated that the program will be used by people such as summer interns who have never used the program before For this reason the system has been designed to be as fool proof as possible The complete user manual is accessible as a hypertext document by pressing a function key while using the program In addition there is a complete tutorial including sample pu data and database that a new user can follow to become familiar with the system without jeopardizing the actual fracture database A goal of the system is to make it easy to enter data This is pat deat pe because if it is not easy it may very likely not be done SYSTEM IMPLEMENTATION The core of HFDB is implemented as a Paradox Application Language PAL program This prosram calls compiled programs written in Microso QuickBASIC to perform graphical functions not conducive to implementation with PAL These auxiliary programs return to the PAL propran when their functions are complete Because the fracture database is a Paradox database all of the analysis and reporting capabilities of Pa
9. e Spirit Alaska California Vertical Distribution 80 Time 15 30 35 FRS None Selected Anchorage Fairbanks Juneau Texas Prudhoe Bay Sag River Class s of Fractures E lt 3 3 6 W 6 12 M 1 2 W gt 2 m THRU Fig 6 Transverse distribution of fractures of Alaska Class ships F 6 ARCO Marine Inc Hull Fracture Database Transverse Distribution of Fractures 20 Vertical Distribution 10 Date of Report 12 11 1990 Time 16 10 50 FR None Selected FRS None Selected Ship s Independence Spirit Alaska California Anchorage Fairbanks Juneau Texas Prudhoe Bay Sag River Class s of Fractures lt 3 3 6 W 6 12 W 1 2 E gt 2 E THRU Fig 7 Transverse distribution of fractures in flatbar tie plates of Alaska Class ships F 7
10. finds a fracture he or she chooses from the set of FRS s for the class of ship being surveyed the FRS whose main drawing shows the location of the fracture An FRS also has boxes on which the surveyor must check off the ship name and date Some FRS s also have a secondary drawing described below There are currently five FRS types 1 Bulkhead 2 Web Frame 3 Bulkhead Web Frame 4 Centerline Girder 5 Longitudinal Girder off center A particular FRS may be unique or generic For instance a bulkhead FRS for a bulkhead in the parallel midsection of a ship would be generic the same FRS would be used for any of the several identical bulkheads in the parallel midsection A bulkhead FRS for a bulkhead in the forward tapered section of the ship would be unique Generic FRS s have a ac schematic drawing the auxiliary view which allows the FRS to be located in the ship For a generic bulkhead web frame and bulkhead web frame FRS the auxiliary ACT Anchorage Fairbanks Juneau nS ees Gand aes view is a schematic profile of the ship withthe longitudinal locations of the structures illustrated Generic longitudinal girder FRS s have a secondary drawing which is a schematic section There are no generic centerline girder FRS s When using a generic FRS any FRS with a auxiliary view the surveyor must mark the auxiliary view to uniquely identify the structure within the ship The surveyor must mark
11. permanently available during the tablet data entry procedure Figure 3 shows the Permanent Form The program needs the registration information in order to know the position of the Permanent Form on the tablet The program ae the user to click two bulls eyes labeled A and B HFDB then prompts the user to mount a Fracture Report on the tablet and register it by clicking bulls ve labeled C D E and F on the four corners of the orm Following registration HFDB prompts for identification of ship decade year and FRS b clicking appropriate marked buttons on the FR These can be entered in any order As noted above an FRS may be ei or generic On ck the stylus on the surveyor s mark on the auxiliary view which allows the proper structure to be uniquely identified On a unique FRS this step is not required Next HFDB displays the fracture entry screen Figure 4 shows an example Most of the screen is taken up with the structural drawing Below the drawing are several labeled lines containing blanks where fracture data will be filled in F 3 STRUCTURAL MEMBER Veb frone Plote Bhd Plote Horiz Grdr Plote Bhd StifFener Web StifFener Brocket FB Tie Plate Long Girder Plote longl Girder Star Fig 3 The HFDB Permanent Form ER E E ER EE PEE aa 13g AWT FRAME 68 Acquiring data for fracture record no Structural Member Web Frame Flate Severity 3 6 Fix
12. radox are available in addition to the capabilities provided by HFDB In addition the data can be exported from Paradox for use by other analysis programs THE FRACTURE DATABASE The raison d etre of HFDB is the fracture database The fracture database contains one record for each fracture The following information is recorded for each fracture FR serial number Fracture Report serial number Fracture number within fracture report FRS number identifies the fracture report sheet from which the data was entered Ship Independence Spirit Alaska California Anchorage Fairbanks Juneau Texas Prudhoe Bay Sag River Class 260MDWT 190MDWT 120MDWT 90MDWT 7OMDWT X Feet 0 at F P positive aft Y Feet 0 at centerline positive to starboard Z Feet 0 at baseline positive upwards Severity lt 3 3 6 6 12 1 2 gt 2 Thru Member Web Frame Plate Web Stiffener Bulkhead Plate Bulkhead Stiffener Longitudinal Girder Plate Longitudinal Girder Stiffener Shell Plate F B Tie Bar Longitudinal Bracket Strut Face Plate Horizontal Girder Plate Disposition Repair Modify Renew Year repaired Date entered FRACTURE REPORT SHEETS AND FRACTURE REPORTS Input to HFDB is initially entered by a shipyard surveyor on a paper form called a Fracture Report Sheet FRS An FRS is an 8 5 x 11 form with a preted Tes a particular structure in a particular class of ship When a shipyard surveyor
13. tic profile of a ship below a stacked bar chart representing the longitudinal distribution of the selected fractures Each bar is color coded to represent the occurrence of each severity There is also a description of the current selection criteria While the profile is displayed the user can use the cursor control keys to choose one or more subsets of the longitudinal bars and then display those selected fractures in section view with a color coded dot for each fracture and two stacked bar charts showing the athwartship and vertical distributions of the selected fractures While viewing each of these three displays the user may press a function key which will cause a presentation qay version of the display to be rinted by an attached PostScript laser printer everal of these displays are included below in the section on preliminary results Also available is a display of a single fracture report This display is similar to the data entry display and can be used to confirm that a fracture report has been entered correctly Hull Fracture Database Total Number of Fractures 346 50 Date of Report 12 11 1990 FR None Selected Ship s Independence Spirit Alaska California Time 15 29 30 FRS None Selected Anchorage Fairbanks Juneau Texas Prudhoe Bay Sag River Class s of Fractures E lt 3 3 6 W 6 12 E 1 2 E gt 2 m THRU Fig 5 Longitudinal distribution of fractures of Alaska Class ships PRELIMIN

Full Paper - Ship Structure Committee

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