WORKSHOP 5: FLOAT-OVER ANALYSIS

Transcription

1 WORKSHOP 5: FLOAT-OVER ANALYSIS This workshop runs through the various phases of a deck float-over and mating process. A Topside is floating on a Barge, which is then winched into position between the Jacket legs. The Barge is ballasted using time dependent mass models, and the load of the Topside is transferred from the Barge to the Jacket legs. The model uses simple lines and winches for positioning. Contact forces between barge and jacket legs are handled using Bumpers. Exact positioning of Topside onto jacket legs is handled using Docking Cones for horizontal forces. Vertical forces are handled using fender planes and fender points. This version of the workshop is based on Sima version 3.1 and Simo version 4.4. <Product>: <Title of Workshop> WS5_Float_Over_Analysis.docx

2 1 MODELLING Open SIMA Create a new workspace called «WS5_Float_Over» Set Force Unit to N, Mass Unit to kg and Length Unit to m. (Hint: Window / Preferences / General / Units ) Create a new SIMO Task called «FloatOver» Import a SIMO System description File «sys_barge_only.dat» from USB:\Workshopfiles\WS5_Float_Over\ into existing task. Also import physical constants. If asked for, import all bodies (default). Open 3D view for this task. Edit the flat bottom as follows (Model / location / Flat Bottom): Set Z = -100m Set Size X = Size Y = 2000m 1.1 Create environment Create an environment (Model / New / Environment) with only waves, and name it Env1. Use a 3-parameter Jonswap spectrum with Hs = 1m and Tp = 10.5 s. Direction is 180 degrees. 1.2 Create Barge Go to body Barge in folder Bodies Edit Barge Select geometry from file. Choose file USB:\Workshopfiles\WS5_Float_Over\Barge.obj Translate the barge geometry +3m vertically (Z-direction) Add body points Go to body points. Copy AWinch1 and paste to AWinch2, AWinch3 and AWinch4 (note that the names change automatically in the sequence) Copy JWinch1 and paste to JWinch2, JWinch3 and JWinch4 in a similar way. SIMA: Workshop 5 Float-over analysis Page 2 of 12

3 Change the positions of the body points according to the table below: Name X Y Z AWinch AWinch AWinch AWinch JWinch JWinch JWinch JWinch The other parameters remain the same 1.3 Add Time-dependent point masses Go to Time-dependent point mass Copy Barge_TDPM1 to Barge_TDPM2, Barge_TDPM3 and Barge_TDPM4, the same way as you did for the body points. Change the positions according to the table below: Name X Y Z Barge_TDPM Barge_TDPM Barge_TDPM Barge_TDPM Change visualisation of jacket legs For the 4 bodies Jackleg1, Jackleg2, Jackleg3 and Jackleg4, change the Geometry from Default Arrow Box to Sphere. Use the default radius of 1.0m. 1.5 Add bumpers between barge and jacket Find the bumper Barge_BD1 and rename it to Bumper_side1. Create Bumper_side2, Bumper_side3, Bumper_side4 and Bumper_side5 by copy/paste (Hint: You can use ctrl-c for copy and ctrl-v for paste) Rename the bumper Bumper_side5 to Bumper_bow1. Create Bumper_bow2, Bumper_bow3 and Bumper_bow4 by copy/paste Set the end coordinates of the bumpers according to the tables below: (Hint1: Double-click on the folder Bumper data to edit all bumper positions in one table) SIMA: Workshop 5 Float-over analysis Page 3 of 12

4 (Hint2: You can use Tab to go from cell to cell, horizontally) Name Type B1 x B1 y B1 z B2 x B2 y B2 z Bumper_side1 Body Bumper_side2 Body Bumper_side3 Body Bumper_side4 Body Bumper_bow1 Body Bumper_bow2 Body Bumper_bow3 Body Bumper_bow4 Body Name Type G1 x G1 y G1 z G2 x G2 y G2 z Bumper_side1 Global Bumper_side2 Global Bumper_side3 Global Bumper_side4 Global Bumper_bow1 Global Bumper_bow2 Global Bumper_bow3 Global Bumper_bow4 Global Add new body, named «Topside», type Large Volume Body position: X = -100m, Y = 0m, Z = 6.5m. Xrot = Yrot = Zrot = 0. Include gravity. Select geometry from file. Choose file USB:\Workshopfiles\WS5_Float_Over\Topside.obj Add Structural Mass to Topside (RMB / New / Structural mass): COG = (0m, 0m, 0m) Mass = 7.0 E+6 kg Ixx = 2.0E+10 kgm 2, Iyx = 0, Iyy = 2.0E+10 kgm 2, Izx = 0, Ixy = 0, Izz = 2.0E+10 kgm 2 SIMA: Workshop 5 Float-over analysis Page 4 of 12

5 1.7 Couplings Insert couplings between Barge and Anchor bodies Create body points Anch1 to Anch4 in the origin of the anchor bodies Anchor1 to Anchor4, respectively. Create a Simple Wire Coupling between Awinch1 (on body Barge) and Anch1 (on body Anchor1) and name it Canch1. Insert the following data: Length = Flexibility = 0 Damping = 0. Ea = 2.0E+10 N Failure Mode = None Copy and Paste Canch1 to Canch2, Canch3 and Canch4, and do the modifications according to the table below: Coupling Length End point 1 End point 2 Canch Awinch1 (Barge) Anch1 (Anchor1) Canch Awinch2 (Barge) Anch2 (Anchor2) Canch Awinch3 (Barge) Anch3 (Anchor3) Canch Awinch4 (Barge) Anch4 (Anchor4) Modify the following winch characteristics for XAwinch2, XAwinch3 and XAwinch4. Winch Start time Stop time Speed XAwinch XAwinch XAwinch XAwinch Insert wire couplings between Barge and Jacket legs Create body points Jleg1, Jleg2, Jleg3, and Jleg4 in the origin of the Jacket leg bodies Jackleg1 to Jackleg4, respectively. Create a Simple Wire Coupling between Jwinch1 (on body Barge) and Jleg1 (on body Jackleg1) and name it CJleg1. Insert the following data: SIMA: Workshop 5 Float-over analysis Page 5 of 12

6 Length = Flexibility = 0 Damping = 0. Ea = 2.0E+10 N Failure Mode = None (not necessary to set breaking strength and failure time) Copy and Paste CJleg1 to CJleg2, CJleg3 and CJleg4, and do the modifications according to the table below: Coupling Length End point 1 End point 2 CJleg Jwinch1 (Barge) Jleg1 (Jackleg1) CJleg Jwinch2 (Barge) Jleg2 (Jackleg2) CJleg Jwinch3 (Barge) Jleg3 (Jackleg3) CJleg Jwinch4 (Barge) Jleg4 (Jackleg4) Modify the following winch characteristics for XJwinch2, XJwinch3 and XJwinch4. Winch Start time Stop time Speed XJwinch XJwinch XJwinch XJwinch Insert coupling fenders between Topside and Barge Create one Point Fender coupling between bodies Topside and Barge, and name it TopBarFender1 Positions of Fender Points on Topside: X Y Z SIMA: Workshop 5 Float-over analysis Page 6 of 12

7 Position of Fender Plane on Barge: (0., 0., 11.5m). Size of fender plane: Length = 80m, width = 20m. Plane normal vector = (0, 0, 1), plane parallel vector = (1, 0, 0) Dynamic friction = 3.0, Static Friction = 3.5 Shear stiffness = 2.0E+8 N/m Damping exponent = 1. Velocity limit = 0.01 m/s The fender stiffness is given by the table below: Number Distance (m) Force (N) Damping (Ns/m) E+6 1.0E E+6 3.0E E+6 1.0E E+6 1.0E E+7 1.0E E+8 1.0E E+9 1.0E E E Add fenders between topside and jacket The fenders are needed for the Topside to rest on the Jacket after ballasting barge. The docking cones (to be constructed later, in Section 1.6.5), only take up forces normal to the cone axis, not forces parallel to the cone axis. We therefore need fender planes on the jacket legs to take up the weight of the topside when placed upon the jacket. Do the following: Create one Point Berthing Fender for body Topside, and name it TopJacFender1 Attachment should be set to: Globally Fixed Plane Position of Fender Point on Body: (21.45, 17.0, 0.0) Position of Global Fender Plane: (21.45, 17.0, 4.0). SIMA: Workshop 5 Float-over analysis Page 7 of 12

8 Dimension of fender plane: Length = 2 m, Width = 2 m. Normal vector: (0, 0, 1) (default) and parallel vector (1, 0, 0) (default). Dynamic friction = 3.0, Static Friction = 3.5 Shear stiffness = 2.0E+8 Damping exponent = 1. Velocity limit = 0.01 The fender stiffness is given by the table below: Number Distance (m) Force (N) Damping (Ns/m) E+6 1.0E E+6 3.0E E+6 1.0E E+6 1.0E E+7 1.0E E+8 1.0E+06 Create new berthing fenders by copying and pasting, and assign positions for the fenders according to the table below: Fender Xglob Yglob Zglob Xbody Ybody Zbody TopJacFender TopJacFender TopJacFender TopJacFender Insert docking cones on jacket legs Create a new Docking Cone Positioning on body Topside. Name it TopJacCone1 Give it the following position and orientation: Body connection (pin) = (21.45, 17.0, 0.0) Earth connection (cone) = (21.45, 17.0, 5.0) Direction = (0, 0, -1) Use the following parameters (do not change the parameters not mentioned here): Velocity limit = 0.01 m/s, Max radial distance = 1.0 m, Failure mode = None SIMA: Workshop 5 Float-over analysis Page 8 of 12

9 Use 2 cross-sections for the force modelling: Cross-section No. Axial distance Radius no. Radial Distance (m) Force (N) Damping (Ns/m) E+7 1.0E E+8 1.0E E+9 1.0E E E E E+7 1.0E E+8 1.0E E+9 1.0E E E+5 Create new docking cones by copying and pasting, and assign positions for the docking cones according to the table below: Fender X (body) Y (body) Z (body) X (Earth) Y (Earth) Z (Earth) DockConeLeg DockConeLeg DockConeLeg DockConeLeg SIMA: Workshop 5 Float-over analysis Page 9 of 12

10 2 STATIC AND DYNAMIC SIMULATIONS 2.1 Static Calculation Use the parameters to MOP Default as basis, and change the time step from 0.01s to 0.001s Run the Static part of the condition Initial View results of the static calculation Select the Initial Condition and select Static mode, and view the position of the bodies. Check if they look reasonable The drop-down lists are found above the 3D view: Open the Conditions / Initial / Results / Dynamic folder in the Navigator, and double-click on the file pcs.lis. The results are shown as a table on the lower right screen (Static results in ) Click on the row for each body to see the static forces related to that body. 2.2 Dynamic calculation: Set the parameters to the following (parameters not listed below should not be changed) Simulation Length = s Time step = s Time increment = 0.5 s Load Ramp Duration = 10.0 s (in Numerical Procedure) SIMA: Workshop 5 Float-over analysis Page 10 of 12

11 Set the storage as follows (store the following parameters for each body): Run the Dynamic part of the condition Initial 2.3 View the animation of the dynamic calculation Change 3D view from modelled to Dynamic Set Playback speed to 10, by right-clicking in the graphical window for simulation. Start animation using the Play button Viewing result plots In the browser: Go to folder Conditions /Initial / Results / Dynamic Double-click on the file results.tda. A new folder will open in the lower right corner of the screen: Go to folder Dynamic / Barge / Global pos. (time domain) Double-click on XGtranslationTotalmotion, and the time series plot for the X-position of the barge. SIMA: Workshop 5 Float-over analysis Page 11 of 12

12 3 POSTPROCESSING Create a new Post Processor Task, and use the default name PostProcessorTask Go to the spec folder Make a workflow consisting of an Input box, a Series Extreme box and a Plot box Connect the out of the Input box to the in of the Series Extreme box. Connect the max of the Series Extreme box to the in of the Plot box. SIMA: Workshop 5 Float-over analysis Page 12 of 12