参考说明分析offs

1、Lesson content:Random WavesGenerating Seabed/Pipe-Wall ProfilesAbaqus/CAE - LoftingScriptingModeling Suggestions: Pipe Laying Contact modeling tipsModeling Suggestions: Surface ElementsLesson 11: Modeling Tips & Special Analysis Techniques1 hourRandom Waves (1/9)Lecture 9 discussed Aqua loadingWave

2、loadingSteady currentsBuoyancyDragInertia loadsFunctionality has been extended to allow definition of random wavesRequires a free extensionKnowledge Base Article QA Random Waves (2/9)Waves breaking on a beach may appear to be regular but this is not the caseSmall fluctuations existHeightFrequencyWav

3、es cannot be represented by a single sinusoidal descriptionRequires a summation of random wavesRandom Waves (3/9)A random sea state is defined byMultiple wave trains with differentAmplitudesFrequencyPhase angleWave trains are derived fromEnergy spectrum relatingWave energy (or height) toFrequencyPha

4、se angle between each wave trainBased on a random number generatorRandom Waves (4/9)Wave spectrum definitionRelates wave energy to frequencyA number of different spectra exist in the literatureAbaqus implementation is based upon the JONSWAP spectrumJoint North Sea Wave Observation ProjectRandom Wave

5、s (5/9)JONSWAP spectrumObservations (shown below) are converted into a mathematical representationWave spectra of a developing sea for different distances of wave travel taken from the JONSWAP investigations. From Hasselmann et al. (1973).Image taken from Hasselmann K., et al. 1973. Measurements of

6、wind-wave growth and swell decay during the Joint North Sea Wave Project (JONSWAP). Ergnzungsheft zur Deutschen Hydrographischen Zeitschrift Reihe A(8) (Nr. 12): 95.Random Waves (6/9)User defines the spectrum by the following parametersSignificant wave heightMean wave periodPeak enhancement factorTw

7、o other parameters are requiredNumber of waves in the spectrumMaximum frequency of interestPhase shift is generated by a random number generatorRequires a seedRandom Waves (7/9)Keyword option*RANDOM WAVEMust follow *AQUARequired parametersTYPEThis variable should be set to JONSWAPSEEDSet to either D

8、EFAULT or a numeric value that will seed the random number generatorTwo data lines are requiredSee Knowledge Base Article QA for detailsRandom Waves (8/9)Data linesFirst LineSignificant wave heightMean wave periodPeak enhancement factorNumber of wave in seriesMaximum wave frequency of interestSecond

9、 LineX-direction cosine defining the direction of travel of this series of wavesY-direction cosine defining the direction of travel of this series of waves not required for two dimensional casesRandom Waves (9/9)The reaction forces on a column subject to random wave loadingAll nodes built inPlotting

10、 reaction forceMechanism to visualize the wave loadingGenerating Seabed/Pipe: Wall Profiles (1/4)Lofting toolset in Abaqus/CAE can be used to generate complex surface profiles from field data:Pipeline Inspection Gauge data for pipe profilesSeabed profileGenerating Seabed/Pipe: Wall Profiles (2/4)Lof

11、ting tool fits surfaces between 2-D planar profilesDefine 2-D profiles (splines based on X-Y profile data)Generating Seabed/Pipe: Wall Profiles (3/4)Lofting tool fits surfaces between 2-D planar profilesSelect the shell (or solid) lofting tool Add the 2-D profiles and choose appropriate transitionsG

12、enerating Seabed/Pipe: Wall Profiles (4/4)Seabed/Pipeline profiles often require large amounts of dataCumbersome task to manually define all 2-D profilesAlternative: Use the Abaqus Python Scripting interface to manage large data sets and generate profiles automaticallyScripting (1/6)Python scripting

13、 commonly used in AbaqusAutomating repetitive tasksPreprocessing, analysis submission and monitoring, postprocessingExtending functionalityMaterials database, results processingEnhancing the user interfaceCustomize Abaqus/CAE user interfaceScripting (2/6)Example: Automation of the lofting processRea

14、d profile data from external fileAutomatically generate profiles/define loft definitionScripting (3/6)Python resourcesDocumentationAbaqus Scripting Users GuideAbaqus Scripting Reference GuideAbaqus GUI Toolkit Users GuideAbaqus GUI Toolkit Reference Guide Seminars“Introduction to Abaqus Scripting”In

15、troduces core Python functionality and Abaqus Scripting Interface specifics“GUI Customization with Abaqus”Introduction to GUI customization using the Abaqus Scripting InterfaceScripting (4/6)Web resourcesDS PassportMy Support (SIMILIA Online Support System)Both contain a variety of scripts that are

16、prepared by support engineers and developers Scripting (5/6)Web resources (contd)Process Automation PortalProvides guidance, examples, and techniques to assist usersActive discussion forumAlmost 2000 registered usersContains more than 75 scripts, applications, and plug-insMy Support Plug-insScriptin

17、g (6/6)Python referencesOfficial Python web site: Online tutorial: /doc/current/tut/tut.htmlOther guides: News groupscomp.lang.pythoncomp.lang.python.announceMany books are available. Modeling Suggestions: Pipe Laying (1/3)Laying a section of initially straight pipe onto an undulating seabed profile

18、 can be challengingPossible approach:Step 1: Define contact between dummy flat rigid surface under gravity loadingStep 2: Lower dummy surface to establish pipe-seabed contactStep 1: Gravity LoadStep 2: Lower Dummy SurfaceModeling Suggestions: Pipe Laying (2/3)Tips:Analytical rigid surface definition

19、 for the dummy surfaceUse the penalty contact algorithm for contact between the pipeline and the “dummy” surface (to avoid over-constraints due to multiple contacts).*SURFACE BEHAVIOR, PENALTY Modeling Suggestions: Pipe Laying (3/3)Modeling Suggestions: Surface Elements (1/3)OverviewDefined just lik

20、e membrane elementsas surfaces in spaceNo inherent stiffnessBehave just like membrane elements with zero thicknessTypical applicationsUsed to bring additional mass into the model in the form of a mass per unit areaUsed to specify a surface used in a constraint, when that surface does not have structural propertiesWhen used in conjunctio