英语翻译.docx

1、英语翻译113Lesson 3Nonlinear Static Buckling AnalysisAfter successful completion of this lesson, you will be ablePerform a nonlinear large-deformation buckling analysisDefine Controls for a nonlinear buckling analysis using art lengthControl.Compare results from linear buckling and nonlinear studiesUnde

2、rstand the influence of initial disturbances on the bucking ofsymmetric structres115Case Study: Cylindrical ShellIn this lesson, we will perform a buckling analysis on a cylindricalshell. Symmetry will be utilized to simplify the calculations. First, alinear buckling analysis will be performed and i

3、ts limitations will bediscussed. A linear static analysis will then be performed to obtainparameters for a nonlinear static buckling analysis. The arc-lengthincremental control technique will be utilized to overcome inherentinstabilities in the nonlinear calculations. Finally, the results from theli

4、near and nonlinear studies will be compared and discussed.Problem StatementA shallow cylindrical arc is to beanalyzed for buckling when it issubjected to a central point load.The shell is simply supportedalong two parallel sides with theother two edges unrestrained.The parameters of the model areas

5、follows:Radius: 2540mmthickness: 6.35mmWidth: 508mmTheta section: 20 rad (11.46 deg)Material: Aluminum 1060 AlloyReference load: 1000 N center point loadStages in the ProcessLinear buckling analysisA linear buckling analysis will provide us with preliminary resultsthat can be compared with the nonli

6、near analysis.Linear static analysisTo estimate some parameters to be used in the nonlinear analysis; alinear static analysis will be performed.Nonlinear static buckling analysisA nonlinear static analysis will be used to obtain a more accurate,0prediction of buckling.Linear SucklingTo review linear

7、 buckling analysis, please refer to Lesson 3 of the SolidWorks Simulation Professional training manual. In this lesson,wewill quickly perform the linear buckling analysis to be eotrx,the nonlinear study.ProcsdureFollow the procedure below:1 Open the file.Open the file Cylindrical Shell from the Less

8、on 3folder1162 Change configuration.Because both the structure and the load are symmetrical, we willanalyze a quarter model only. In the SolidWorksConfigurationManager, activate Quarter model configurationIn the View menu, select All Annotations to view the center and edges3 Create a study.From the

9、Simulation menu, select Study Enter LinearBuckling - Quarter as the Name and select Buckling as the Type.4 Exclude solid body.The model Will be meshed using shell elements. Exclude the solid bodythat is located in the Cylindrical Shell folder of the Simulatetree.When the configuration was set up. th

10、e solid body was hidden using the FeatureManager design tree. This will insure that surface entiselected when applying loads and restraints.5 Define thickness.Right-click SurfaoeBody 1 in the Cylindrical Sell folder of theSimulation Study tree and select Edit Definition.Specify a Thin shell with a S

11、hell thickness of 6.35mmClick OK.6 Apply material .Apply Aluminum 1060 Alloy as the material.7 Create mesh.Use the default global mesh size andTolerance,11.14mm and 0.557mm,respectively.Click on Advanced and make sure thatDraft elenuts are septaClick on OK to accept and to create themesh. 1178 Creat

12、e simply supported fixture.Right-click Fixtures and select Fixed GeometryApply Immovable (No translation) boundary condition on thesupported straight edge.Click OK to save this boundary condition.Rename this boundary condition to Simply supported edge.1189 Create first Symmetry Restraint.Because onl

13、y a quarter of the shell ismodeled, we have to apply symmetryrestraints.Right-click on Fixtures and chooseAdvanced Fixtures.Under Advanced select Use referencegeometry.Choose the symmetry Straight Edge on thetop surface (as shown in the figure).Select Right Plane as the referencegeometry.In the Tran

14、slations dialog, set Normal toplane direction translation to 0 mm.In the Rotation dialog set both Along planeDir 1 and Along plane Dir 2 rotations to 0rad.Click OK to save this first symmetry restraintRename this restraint to symmetry x-dir.11910 Create second Symmetry restraintRIP-ht-click on Fixtu

15、res and chooseAdvanced Fixtures.Under Advanced select Use referencegeometry.Choose the svmmetrv Curved Edge on thetop surface (as shown in the figure).Select Front Plane as the referencegeometry.In the Translations dialog. set Normal toplane direction translation to 0 mm.In the Rotation dialog set b

16、oth Along planeDir 1 and Along plane Dir 2 rotations to 0rad.Click OK to save this send symmetryrestraint. Rename this restraint to Symmetry z-dir12011 Create Force.Right-click External Loads and choose Force.Select the vertex at the shell symmetry point.Select Top Plane as a reference.Set the Units

17、 to SI and specify a Force of 250 N inthe Normal to plane direction. (Make sure theforce is oriented downward).Click OK to save this force definition.Rename this load condition to Center force.The total force on the model is actually 1000 N, weuse 250 N due to our symmetry conditions.12 Run the buck

18、ling analysis.The analysis will complete successfully.13 Plot Displacement results.Define URES: Resultant Displacement plot for the first bucklingmode.121The actual quantity plotted is the resultant displacement. The absolutevalues of these numbers are meaningless as they do not represent realdispla

19、cements; they only show the relative displacements (shape)relevant to the first buckling mode.14 Animate the first mode shape.In the Simulation menu, select Result Tools, Animate.You can also save the movie as an AV1 file.15 List Buckling load factor.Right-click the Results folder and select List Bu

20、ckling Load Factorsfrom the menu.Review the buckling factors and click on Close.We observe a linear buckling factor of approximately XI. linear-27.9.This implies that the shell would collapse (due to buckling) under theload of 1000 x.27.9 = 27900 N.Linear buckling:assumptions andlimitationsLinear bu

21、ckling assumes that the structure does not exhibit significantchanges in shape prior to the onset of buckling (defined by limitingsnap-through point on the equilibrium path). Therefore,the resultsmust always be taken with caution. Furthermore, the analysis dose notallow us to study the post-buckling

22、 behavior that may be of significantimportance in some applications.We will therefore solve the problem as a nonlinear study and comparethe results from both studies.Linear static studyBefore proceeding to the nonlinear buckling analysis,we perform alinear static study on this model to get an estima

23、te of the maximumdisplacement that we expect.122ProcedureFollow the procedure below:1 Create a static study.Create a static study and copy the following features from the bucklingstudy: Cylindrical Shell, Fixtures, External Loads, and Mesh.Make sure that the solid body is excluded and the she11 thic

24、kness isdefined.2 Run the study.Run the static study and plot the displacements. Notice that themaximum displacement is less than 0.5 mm.NonlinearSymmetricalBucklingTo account for the shape change during the deformation, a nonlinearanalysis will be performed. This will allow us to study the post-buc

25、kling behavior of the structure that may be of importance in somedesigns. This type of study should also give us a more accurateprediction of the buckling load factor.ProcedureFollow the procedure below:1 Create a study.From the Simulation menu, select Study . EnterNonlinear - Quarter as the Name an

26、d select Nonlinear as the Type.2 Copy definition of Materials, Fixtures, Loads, and mesh fromLinear buckling-quarter study to Nonlinear-quarterDrag-and-drop the Cylindrical Shell,external loads,fixtures, and Mesh folders from the Linear Buckling -quarter study folderonto the Nonlinear- Quarter study

27、. folder.1233 Check study properties.Right-click the Nonlinear-quarter study name and select Properties.Make sure the Initial time increment is 0.01, min step is 1e-008, Maxstep is 0.1 and No. of adjustments is 5.Start and end times will not be used for this analysis (see the followingdiscussion).Ma

28、ke sure that Use large displacement formulation is selected.Under Solver, select Direct Sparse.1244 Set the advanced options.Select the Advanced Options button.Under the Method dialog, set Control to Arc Length, and make sureIterative is NR (Newton-Raphson).Set Maximum displacement (for translation

29、DOF) to 30mm (see thefollowing discussion.Keep Maximum load-pattern multiplier at its default value of 1e8 andset Maximum number of arc steps to 100.The options Maximum load pattern multiplier and Maximumnumber of arc steps indicate how far we wish to trace the solutionalong the equilibrium path.Kee

30、p all other options at their default value.Click ok125Am Length:ParametersWhen Arc Length control methods used, we do not need to specifyany time curve (neither the loads nor the structural response arecontrolled). Therefore, when setting the properties of a nonlinear study,the End time option is no

31、t considered. The Start time is always set to0.Options Initial time increment and Max time increments are related tothe length of the arc. Exactly how they relate to one another is potimmediately apparent. It is therefore recommended to keep Initial timeincrement at 0.01 and Max equal to 0.1. When the equilibrium path isplotted after the solution has been obtained (or partial path, if theanalysis failed), we can observe whether or not to modl,parameters based on the distribution of the points.Consider