讲义教程说明tire-l04smgmodel

1、Lesson content:Introduction What is SMG/SRT? (flattened model requirement etc.)3D Model Definition Element types (general vs. cylindrical)Circumferential discretizationModel generation (road, tread surface)Step and Output RequestsEquilibrating step2-step approach to footprint analysis (displacement

2、control followed by load control) Contact, Boundary Conditions, and LoadsJob Submission and Results VisualizationTire Wizard Plug-InWorkshop 2: Three-dimensional tire modelsWorkshop 3: Visualization of three-dimensional tire modelsLesson 4: Three-dimensional Model Building 2.5 hoursIntroductionWhat

3、is SMG/SRT?Symmetric Model Generation (SMG) is a capability using which one can create a 3D model by revolving an axisymmetric cross sectionSymmetric Results Transfer (SRT) is a capability using which one can transfer the results from the axisymmetric analysis to the 3D model created through SMGRest

4、art files from the axisymmetric analysis are required for both SMG and SRTLimitations of SMG/SRT within AbaqusSMG/SRT is supported only for models with “flat” input files3D Model Definition (1/7) Starting with half-carcass axisymmetric cross section Helps reduce model size when no transverse loading

5、 (i.e. along spindle direction) is present Needs an additional SMG/SRT step to model transverse loadingHowever, boundary condition specification at the symmetry cut plane es complexNeeds linear equations on unsorted node sets Automatically taken care of by the Tire Wizard plug-inStarting with full c

6、arcass axisymmetric cross sectionSimplifies boundary condition specificationRequired if the cross-section is non-symmetric 3D Model Definition (2/7)Symmetric model generationRequires restart files from the axisymmetric analysis ( .res, .stt, .prt, and .mdl files)Revolves the axisymmetric cross secti

7、on to generate a 3D tire meshRim, all elements, surfaces and rebar layers are revolved in the reference configuration of the axisymmetric analysisRim carcass contact definition, embedded element constraints and all material definitions and assignments are carried overAll set definitions are expanded

8、 to include the revolved nodes/elementsUser specifies the circumferential discretization and element typesUser also specifies the orientation of the symmetry axis of revolution and the reference plane for the 3D model A data check analysis is mended to review the 3D model3D Model Definition (3/7)Sym

9、metric model generationSample input fileSymmetric Model Generation, Revolve3D Model Definition (4/7)Midside nodes for cylindrical elementsModel generated thru SMG, Revolve3D Model Definition (5/7)Element typesGeneral or cylindrical elements may be usedDepends on the objective of the analysisFor foot

10、print analysis, normally general elements are used at the footprint region and cylindrical elements elsewhere This is applicable also for the SST analysis using Abaqus/StandardFor transient rolling analysis using Abaqus/Explicit, only general elements are used for the whole model 3D Model Definition

11、 (6/7)Circumferential discretizationDepends on the objective of the analysisFor a footprint analysis, a finer mesh is desired at the footprint to resolve the contact with the road. A coarser mesh may be used elsewhere to reduce the analysis costThis is applicable also for the SST analysis using Abaq

12、us/StandardFor transient rolling analysis using Abaqus/Explicit, uniform circumferential refinement is desiredToo small an element size will adversely affect the stable time increment3D Model Definition (7/7)Road and tread surface generation Road is normally modeled as an analytical rigid surfaceIt

13、is positioned at a small distance away from the tread surface such that the inflated tire does not touch the roadShould be defined so that the normal points towards the tread surfaceTread surface is defined as an element-based surface Can be defined in either the 2D or 3D modelTread surface defined

14、in 3DSteps and Output Requests (1/3) A do-nothing general nonlinear static step is mended as the first analysis step following an SMG and SRT to bring the system into equilibriumThis step should have the same loads, boundary conditions, and other states that existed at the step/increment from which

15、the SRT is being performedExtra step needed because the axisymmetric constraint is no longer being used. Additionally, extra degrees of freedom have been added to the model. These necessitate a re-equilibration of the 3D systemSteps and Output Requests (2/3)Footprint loading stepSplit into two steps

16、 A first step with displacement control to bring the road into contact with the tireA second step with load control where the vehicle load replaces the prescribed displacement Displacement bring road in contact with treadFor half carcass this is the half vehicle load for the tireSteps and Output Req

17、uests (3/3)Output RequestsField output requestsRebar output must be requested, in addition to any default outputsHistory outputsReaction force and displacement of the road reference node, in addition to any default outputsContact, Boundary Conditions, and Loads (1/4)ContactRim-carcass contact is aut

18、omatically taken care of by the SMG/SRT procedureRoad-tread contact needs to be defined Frictionless contact should be used unless friction is important in the problemContact, Boundary Conditions, and Loads (2/4)Definition of boundary conditions and loadsFor the do-nothing step, the loads and BCs sh

19、ould be the same as those in the axisymmetric step/increment from which SRT is being performedThe road should be completely constrainedFor the displacement control stepAll road DOFs except the normal direction DOF should be constrainedDisplacement prescribed on the road normal DOF to bring the road

20、into contact with the tire. The actual magnitude of the displacement should be more than the initial gapFor the load control stepRelease the normal direction DOF of the road and apply the vehicle load instead. For the half-carcass model apply only half the load. CorrectIncorrectReinforcement orienta

21、tionsContact, Boundary Conditions, and Loads (3/4)For half-carcass models additional constraints are neededNeed to enforce continuity of the reinforcement across the half-carcass symmetry planeDone through boundary conditions and equation constraintsRequires special attention to circumferential disc

22、retization during SMG since “corresponding node sets” are required to define the BCs and constraintsContact, Boundary Conditions, and Loads (4/4)For half-carcass models additional constraints are neededNode sets for linear equationsJob Submission and Results Visualization (1/7)A datacheck analysis i

23、s mended for estimates of memory, size and disk estimates for the problemThis helps set appropriate value for the memory parameterJob submission from the command promptJob Submission and Results Visualization (2/7)Contact pressure between tread and road (end of footprint step)Job Submission and Resu

24、lts Visualization (3/7)Contact pressure between rim and carcassJob Submission and Results Visualization (4/7)Rebar force contoursJob Submission and Results Visualization (5/7)Rebar angle contoursJob Submission and Results Visualization (6/7)Deformed shape highlighting the twistJob Submission and Res

25、ults Visualization (7/7)Vertical load-deflection curve for the tire Tire Wizard Plug-in (1/13)The plug-in provides a GUI for creating a revolved and reflected 3D tire model from an Abaqus/CAE database of the axisymmetric modelTire Wizard Plug-in (2/13)Accessible from the Job module of Abaqus/CAEFunc

26、tionality to revolve and reflect tire modelsFunctionality to model Steady State Transport (Advanced Modeling Technique)Pre-defined loading steps for footprint loadingThe user specifies the load magnitudeThe axisymmetric model ODB must existTire Wizard Plug-in (3/13)Going from 2D to 3DFile nameName f

27、or the 3D model input fileTire Wizard Plug-in (4/13)Going from 2D to 3DCross-sectionFull cross-section by defaultFacility to toggle between the cross-section typesTire Wizard Plug-in (5/13)Going from 2D to 3DElastic propertiesActivate the use of instantaneous or long term modulus during the static p

28、re-loading stepsTire Wizard Plug-in (6/13)Going from 2D to 3DNode set including all the nodes in the modelUsed to specify velocities during SSTThe set needs to be defined at the assembly levelTire Wizard Plug-in (7/13)Going from 2D to 3DRoad typeOption to choose between a flat road and a drum for fo

29、otprint loadingTire Wizard Plug-in (8/13)Going from 2D to 3DTread SurfaceNeeds to be defined at the assembly levelFriction coefficient between the tire and the roadTire Wizard Plug-in (9/13)Going from 2D to 3DCircumferential discretizationSum of angles should be 360 degrees for full cross-section mo

30、delsFor half cross-section models, the sum of angles should be 180The other half is automatically generated by Tire WizardOption to specify the element typeThe reference cross-section is placed away from the footprintTire Wizard Plug-in (10/13)Going from 2D to 3DResults transfer informationSpecify t

31、he ODB name for the axisymmetric jobTire Wizard Plug-in (11/13)Going from 2D to 3DFootprint loadingAlways specify the total vertical loadProvide an estimate of the total deflection of the tire for the applied load10 percent of this deflection is used to bring the road in contact with the tireOnce co

32、ntact is established, the vertical load is applied to the roadTire Wizard Plug-in (12/13)The 3D input file generated by the plug-in includes:Contact pair and surface interaction definitions for road-tread contactBoundary conditions copied from the 2D modelPredefined sequence of stepsStep 1 : Equilib

33、rium with the transferred solutionStep 2 : Move the road towards the tire through prescribed boundary conditions to establish contactStep 3 : Substitute the vertical displacement BC on the road with a load equal to the vertical load (half the load for half cross-section)The plug-in currently does no

34、t transfer friction values defined using the *CHANGE FRICTION optionCan be plished by manual editing the input fileTire Wizard Plug-in (13/13)Going from a 3D half model to a 3D full modelProvide the absolute tolerance for merging nodes at the interfaceThe smaller the betterProvide a name for the resulting input fileChoose the step from which the results will be readAssumes that the 3D