OrcaFlex Manual - Orcina

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VIV Toolbox, Frequency Domain Models Output options (SHEAR7 version 4.5 and later) The options control whether or not SHEAR7 is instructed to output .anm, .dmg and .fat files. Out file selection (SHEAR7 version 4.6 and later) Specifies which out files (.out, .out1, .out2) are generated. Line Specifies the OrcaFlex Line to be described in the SHEAR7 data file. Output summary Locations 456 w These data specify the locations at which a summary of the response is given in the SHEAR7 .out file. A value of '~' can be used for the Arc Length Range Start to mean 'End A'. Likewise, a value of '~' for Arc Length Range End means 'End B'. Reduced Velocity Bandwidths For SHEAR7 version 4.3/4.4 you specify the single-mode and multi-mode reduced velocity bandwidth. For SHEAR7 version 4.5 you specify just a single value for reduced velocity bandwidth. For SHEAR7 version 4.6 you specify a value for reduced velocity bandwidth for each section. Structural Damping Ratio Corresponds to the SHEAR7 data item of the same name. Power Ratio Cutoff Level Corresponds to the SHEAR7 data item of the same name. In SHEAR7 version 4.4 and earlier this data item was named cutoff level. Primary zone amplitude limit (SHEAR7 version 4.5 and later) Corresponds to the SHEAR7 data item of the same name. Number of Lift Coefficient Tables (SHEAR7 version 4.3/4.4 only) This is the number of tables you want SHEAR7 to read from the common.cl file. Current Profile The discretisation option allows you to control how the current profile is output. You can specify that the current profile contains one entry for each node in the line. However this can give rise to numerical problems in SHEAR7, especially for finely segmented models, and so it is preferable to discretise the current more coarsely using the regular spacing option. You also specify the probability of occurrence (a number between 0 and 1) of the flow profile and the flow profile ID. The current speed is exported as zero for any part of the line which uses a P-y model. This allows for hydrodynamic damping, using the still water coefficient, but excludes any excitation due to current. Young's Modulus Young's modulus for the strength member. SHEAR7 uses this for computing stress and damage rate. For SHEAR7 version 4.6 you specify this value per section. For earlier SHEAR7 versions you specify a single global value. Power Ratio exponent (SHEAR7 version 4.5 and later) Corresponds to the SHEAR7 data item of the same name. S-N Curves Specifies the S-N curves to be used by SHEAR7 for its fatigue calculations. An endurance limit can be specified – this is called the "cutoff stress range" in the SHEAR7 documentation. For SHEAR7 version 4.6 you can define multiple S-N curves each with an endurance limit and then select which one to use on a section by section basis. For earlier SHEAR7 versions you specify a single S-N Curve and endurance limit which apply to the entire line.
w Stress Concentration Factors 457 VIV Toolbox, Frequency Domain Models Specify a global stress concentration factor for the line and optionally a number of local stress concentration factors. VIV Diameter The VIV diameter specifies the diameter used by the VIV model. Separate values can be specified for each section. The value specified is used for all nodes in that section. For a node at the intersection of two sections the VIV diameter of the following section is used. The VIV Diameter can be set to '~', which is taken to mean 'same as the section normal drag diameter'. Strouhal Type, Strouhal Number The Strouhal type and number defines the relationship of flow velocity and cylinder diameter to the local vortex shedding frequency. Strouhal Type can be Rough Cylinder or User Specified. Rough Cylinder corresponds to the SHEAR7 Strouhal code 200. If User Specified is chosen then you must also specify a Strouhal Number. Lift Coefficient Table, Lift Coefficient Factor Lift Coefficient Table specifies which table is used from the common.cl file. Lift Coefficient Factor corresponds to the SHEAR7 data item called Lift Coefficient Reduction Factor. Reduced Velocity Damping Coefficients Damping Coefficients for still water, low and high reduced velocity are specified. SHEAR7 structural zones When OrcaFlex generates the SHEAR7 data file it assumes a one-to-one mapping between OrcaFlex sections and SHEAR7 structural zones. This has some implications for how you create your OrcaFlex model. Essentially, anywhere on your line where you need SHEAR7 structural zone data to change you must ensure that there is an OrcaFlex section boundary. SHEAR7 structural zone data comprises the following: � Hydrodynamic and strength diameters. � Added mass coefficient, lift coefficient and Strouhal number. � Area moment of inertia, mass per unit length and tension variation. � Hydrodynamic damping coefficients. Since most of these properties are constant within an OrcaFlex section you will naturally introduce section boundaries at the locations where they change. However, there are a few exceptions. Lift coefficient, Strouhal number and hydrodynamic damping coefficients are SHEAR7 specific data which are specified in OrcaFlex on the Section Data page of the SHEAR7 data form. You may need to introduce OrcaFlex section boundaries which coincide with the locations where these properties change. Area moment of inertia and tension variation are used by SHEAR7 to calculate modal frequencies. Typically these parameters would not be used since OrcaFlex produces a modes file which is more accurate than the internal SHEAR7 modal calculations. The mass per unit length is also used by SHEAR7 to calculate modal frequencies and again this aspect of the SHEAR7 calculation would be bypassed when using a modes file produced by OrcaFlex. However, the mass per unit length is used by SHEAR7 to compute damping ratio. For almost all situations in OrcaFlex the mass per unit length is constant along a section. One exception to this is a free-flooding line with sections that cross the water surface. Because SHEAR7 has a single mass parameter for a structural zone this means that the mass is effectively smeared across the zone. A freeflooding line has greater mass below the water surface because it is full of water. Quite often this issue is of little significance but if you wish you can also change your OrcaFlex model to arrange that there is a section boundary at the water surface. Similar issues arise when the slug flow contents method is specified. The other modelling choice in OrcaFlex that leads to properties varying along the length of a section is when profiled line types (e.g. stress joints) are used. Although it may be tempting to use many structural zones to represent the variation of properties the SHEAR7 manual strongly recommends not doing so. Accordingly OrcaFlex outputs a single structural zone for a profiled line type section which has the effect of smearing properties and we believe that this is the correct approach to take in the vast majority of cases.
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w Orcina Ltd. Daltongate Ulverston
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Contents 4 w 3.4 Libraries 40 3.4.1
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Contents 6 w 5.6 Dynamic Analysis 1
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Contents 8 w 6.5.23 Wave Scatter Co
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Contents 10 w 8.12 Results 444 8.13
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Introduction, Installing OrcaFlex
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Introduction, Parallel Processing M
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Introduction, References and Links
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Introduction, References and Links
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w 2 TUTORIAL 2.1 GETTING STARTED 21
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w 23 Tutorial, Dynamic Analysis sha
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w 3 USER INTERFACE 3.1 INTRODUCTION
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w Simulation Paused 27 User Interfa
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w Keys on Main Window New model Ope
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w Rotate viewpoint left (decrement
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w General: StaticsMethod: Whole Sys
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w A text data file saved by OrcaFle
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w 37 User Interface, Model Browser
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w Cut/Copy Cut or Copy the selected
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w 3.4.1 Using Libraries 41 User Int
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w 43 User Interface, Libraries Once
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w 3.5.1 File Menu New Deletes all o
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w New Vessel New Line New 6D Buoy N
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w 3.5.5 View Menu Change Graphics M
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w Preferences 51 User Interface, Me
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w 53 User Interface, 3D Views 3D Vi
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w 55 User Interface, 3D Views � D
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w 57 User Interface, 3D Views a lin
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w 59 User Interface, 3D Views � F
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w Replay Period 61 User Interface,
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w Frame interval in real time 63 Us
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w Numeric 65 User Interface, Data F
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w � For lines you must specify th
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w 69 User Interface, Results this i
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w 71 User Interface, Results Let th
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w 73 User Interface, Results remain
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w Results 75 User Interface, Result
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w Replays 77 User Interface, Graphs
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w Axes 79 User Interface, Spreadshe
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w Command Line Parameters 81 User I
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w Wire Frame Graphics Codec 83 User
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Automation, Batch Processing Multi-
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Automation, Batch Processing 88 w N
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Automation, Batch Processing Assign
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Automation, Batch Processing Line T
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Automation, Batch Processing SHEAR7
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Automation, Batch Processing PolarT
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Automation, Batch Processing Figure
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Automation, Text Data Files Data in
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Automation, Text Data Files Selecte
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Automation, Text Data Files SHEAR7L
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Automation, Text Data Files 4.3.2 A
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Automation, Post-processing 108 w F
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Automation, Post-processing 110 w N
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Automation, Post-processing Referen
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Automation, Post-processing Command
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Automation, Post-processing Figure:
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w 5 THEORY 5.1 COORDINATE SYSTEMS 1
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w 125 Theory, Object Connections Di
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w 127 Theory, Static Analysis Final
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w 129 Theory, Static Analysis metho
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w 131 Theory, Dynamic Analysis for
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w Static Starting Position Simulati
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w 135 Theory, Friction Theory The n
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w where μ = magnitude of the vecto
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w 139 Theory, Extreme Value Statist
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w where σ = GPD scale parameter ξ
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w 143 Theory, Environment Theory Th
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w where Pu(z) = Nc(z/D)su(z)D Pu-su
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w 147 Theory, Environment Theory
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w Repenetration Offset After Uplift
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w 151 Theory, Environment Theory sp
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w Extrapolation Stretching 153 Theo
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w 155 Theory, Environment Theory st
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w 157 Theory, Vessel Theory individ
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w 159 Theory, Vessel Theory RAOs ca
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w 161 Theory, Vessel Theory Notes:
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w 163 Theory, Vessel Theory ω is t
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w surge/sway/heave M M.L roll/pitch
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w 167 Theory, Vessel Theory that co
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w 169 Theory, Vessel Theory separat
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w 171 Theory, Vessel Theory At this
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w Segment 1 Segment 2 Segment 3 Act
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w 175 Theory, Line Theory � If to
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w where component of M2 in the Sx2
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w The hysteresis model is described
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w � (90,90,90) sets Ex along -GX,
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w = v1 + p' + ω×p Therefore its a
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w y End A Stress ID z Stress OD O S
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w 5.12.16 Hydrodynamic and Aerodyna
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w 189 Theory, Line Theory Another w
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w Drag Chain Seabed Interaction 191
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w 193 Theory, Line Theory OrcaFlex
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w 195 Theory, 6D Buoy Theory clashi
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w 197 Theory, 6D Buoy Theory For Lu
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w 199 Theory, 6D Buoy Theory (due t
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w 201 Theory, 6D Buoy Theory Note:
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w α is the angle between the relat
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w 5.13.6 Contact Forces Contact For
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w Dynamic Analysis 207 Theory, Winc
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w 209 Theory, Shape Theory Finally,
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System Modelling: Data and Results,
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Page 406 and 407: System Modelling: Data and Results,
Page 432 and 433: Modal Analysis, Theory 432 w For si
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Page 436 and 437: Fatigue Analysis, Commands 436 w Fo
Page 438 and 439: Fatigue Analysis, Load Cases Data f
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Page 442 and 443: Fatigue Analysis, Analysis Data 442
Page 444 and 445: Fatigue Analysis, Integration Param
Page 446 and 447: Fatigue Analysis, Fatigue Points Ba
Page 448 and 449: Fatigue Analysis, How Damage is Cal
Page 450 and 451: VIV Toolbox, Frequency Domain Model
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OrcaFlex Manual - Orcina

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