20 guided-3d knuckle pin joint

3D Knuckle Pin Joint

Problem:

The clevis pin shown in the figure is 12 mm in diameter and has the dimensions a=12 mmand b=18 mm. The pin is machined from AISI 1018 hot-rolled steel and is to be loadedat 4400 N. Determine the Von Mises stress pattern in the pin and estimate the maximumVon Mises stress.

Joseph Shigley and Charles Mischke. Mechanical Engineering Design5th ed. New York: McGraw Hill, May 2002.

3D Knuckle Pin JointOverview

Outcomes1) Learn how to set up the problem before starting Ansys2) Increase familiarity with log file commands3) Learn how to use the contact wizard in the GUI4) Increase familiarity with post processing tools

Tutorial OverviewThis tutorial is divided into four parts:

1) Tutorial Basics2) Problem Planning3) Log File4) Solution

Anticipated time to complete this tutorial: 1 hour

AudienceThis tutorial assumes an intermediate knowledge of ANSYS 8.0; therefore, it goes intomoderate detail to explain each step. A problem planning section has been added to helpset up the problem. More advanced ANSYS 8.0 users should be able to complete thistutorial fairly quickly.

Prerequisites1) ANSYS 8.0 in house “Structural Tutorial”2) Completion of three or more Basic Machine Design Tutorials

Objectives1) Increase familiarity with log file commands2) Use the contact element wizard

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3D Knuckle Pin JointTutorial Basics

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In this tutorial:Instructions appear on the left.

Visual aids corresponding to the textappear on the right.

All commands on the toolbars arelabeled. However, only operationsapplicable to the tutorial are explained.

The instructions should be used as follows:

Bold > Text in bold are buttons, options, or selections that the user needs to click on

Example: > Preprocessor > Element Type > Add/Edit/DeleteFile would mean to follow the options as shown to the right to get you to the Element Types window

Italics Text in italics are hints and notes

MB1 Click on the left mouse buttonMB2 Click on the middle mouse

buttonMB3 Click on the right mouse

button

Some basic ANSYS functions are:

To rotate the models use Ctrl and MB3.

To zoom use Ctrl and MB2 and move themouse up and down.

To translate the models use Ctrl and MB1.

3D Knuckle Pin JointProblem Planning

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To increase your familiarity with log file commands you will solve this problem using alog file.

This lesson will lead you through the steps of writing a log file. Instructions on eachcommand (pulled from the ANSYS help file) appear in the right column. Commandsthat you should write to your log file will appear as 8 pt. Arial text in the left column.

You will begin by creating log file commands to define the material properties, the geom-etry, and the mesh. You will then paste those commands into the ANSYS command lineand build the model up to that point.

At this point you will use the contact wizard in the GUI to define contact surfacesbetween the pin and the hole. You will open the Session Editor and copy the commandsthat ANSYS used while creating the contacts and paste it into your log file.

You will finish the tutorial by writing solution and post processing log file commands.

The end result will be a log file useful for solving the entire problem.

The information contained in this tutorial will be valuable to you as youdo other analysis in ANSYS. Please pay careful attention to the instruc-tions in the right column and do not gloss over the information given foreach command.

3D Knuckle Pin JointLog File

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1) Start a new notepad file. Give it an appro-priate file name and save it to the desireddirectory.

2) The first command of the log file will bean instruction to tell ANSYS to clear what-ever database it is working on and start anew one. The syntax used to perform thisoperation is shown to the right in bold text.The options for the clear (i.e. START orNOSTART are also shown with their defini-tions. Type the following command line asthe first line in your notepad file:

/CLEAR, START

3) Enter a command to change the file nameof your project.

/FILNAME,3D Knuckle Pin Joint

4) Enter a command to give the project atitle.

/TITLE,Pin Joint

/CLEAR, ReadClears the database.

ReadFile read option:

START -- Reread start80.ans file (default).

NOSTART -- Do not reread start80.ans file.

/FILNAME, Fname, KeyChanges the Jobname for the analysis.

FnameName (32 characters maximum) to be used as theJobname. Defaults to the initial Jobname as spec-ified on the ANSYS execution command, or to Fileif none specified.

KeySpecify whether to use the existing log and errorfiles or start new files.

0, OFF -- Use existing log and error files.

1, ON -- Start new log and error files (old files are closedbut not deleted).

/TITLE, TitleDefines a main title.

TitleInput up to 72 alphanumeric characters.Parameter substitution may be forced within thetitle by enclosing the parameter name or paramet-ric expression within percent (%) signs.


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5) Type the command to enter the pre-processor.

/PREP7

6) Define the beam element for the model.You are going to use a solid92 element forthis model.

ET,1,92

7) Now you are going to set scalar parame-ters that you will call during other parts ofthe command sequence. Any scalar param-eter is defined using the *SET command.

*SET,R,.006*SET,A,.012*SET,B,.018

/PREP7Enters the model creation preprocessor.

ET, ITYPE, Ename, KOP1, KOP2, KOP3, KOP4,KOP5, KOP6, INOPRDefines a local element type from the elementlibrary.

ITYPEArbitrary local element type number. Defaults to 1+ current maximum.

EnameElement name (or number) as given in the elementlibrary in Chapter 4 of the ANSYS ElementsReference. The name consists of a category prefixand a unique number, such as BEAM3. The cate-gory prefix of the name (BEAM for the example)may be omitted but is displayed upon output forclarity. If Ename = 0, the element is defined as anull element.

KOP1, KOP2, KOP3, KOP4, KOP5, KOP6KEYOPT values (1 through 6) for this element, asdescribed in the ANSYS Elements Reference.

INOPRIf 1, suppress all element solution printout for thiselement type.

*SET, Par, VALUEAssigns values to user-named parameters.

ParAn alphanumeric name used to identify this param-eter. Par may be up to 32 characters, beginningwith a letter and containing only letters, numbers,and underscores

VALUENumerical value or alphanumeric character string(up to 8 characters enclosed in single quotes) tobe assigned to this parameter.


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8) Write commands that define the materialproperties.

MP,EX,1,207E9MP,PRXY,1,0.292

9) Write commands that define the geomet-ric shapes that can be represented by blocks.

BLOCK,-B/2,-B/2-A,-D/2-A,D/2+3*A,0,-R-A/2BLOCK,B/2,B/2+A,-D/2-A,D/2+3*A,0,-R-A/2BLOCK,-B/2,B/2,-D/2-3*A,D/2+A,0,-R-A/2

10) Enter a command in the log file that willplot the volumes just created.

VPLOT

MP, Lab, MAT, C0, C1, C2, C3, C4Defines a linear material property as a constant ora function of temperature.

LabValid property label. (note only the applicable prop-erty labels are shown below).

EX -- Elastic moduli (also EY, EZ).

PRXY -- Major Poisson's ratios (also PRYZ, PRXZ).

BLOCK, X1, X2, Y1, Y2, Z1, Z2Creates a block volume based on working planecoordinates.

X1, X2Working plane X coordinates of the block.

Y1, Y2Working plane Y coordinates of the block.

Z1, Z2Working plane Z coordinates of the block.

VPLOTDisplays the selected volumes.


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11) Write commands that display the work-ing plane.

WPSTYLE,0.05,0.1,-1,1,0.003,1,0,,5

12) Write commands that rotate the workingplane to the necessary orientation for thisproblem.

WPRO,,,90.000000WPRO,270,,

WPSTYL, SNAP, GRSPAC, GRMIN, GRMAX,WPTOL, WPCTYP, GRTYPE, WPVIS, SNAPANGControls the display and style of the working plane.

SNAPSnap increment for a locational pick.

GRSPACGraphical spacing between grid points.

GRMIN, GRMAXDefines the size of a square grid to be displayedover a portion of the working plane.

WPTOLThe tolerance that an entity's location can deviatefrom the specified working plane, while still beingconsidered on the plane.

WPCTYPWorking plane coordinate system type: 0 -- Cartesian1 -- Polar

GRTYPEGrid type: 1 -- Grid only.2 -- WP triad only (default).

SNAPANGSnap angle (0--180) in degrees.

WPROTA, THXY, THYZ, THZXRotates the working plane.


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13) Write commands to create a cylinder andto subtract its volume from the volume ofthe block. Three sperate cylinders will beused in this process, one for each block.Start with the left most block:

CYLIND,R, ,-B/2-A,-B/2,0,180,

VSBV,1,4

Note: In order to know the appropriate volume num-bers to use in this command, you may have to runyour log file up to this point, plot the volumes, andturn on the volume numbers.

14) Repeat the sequence of commands instep 13 for the middle and right blocks.

CYLIND,R, ,-B/2,B/2,0,180,VSBV,3,1CYLIND,R, ,B/2,B/2+A,0,180,VSBV,2,1

15) Create two additional cylinders repre-senting the pin and its head.

CYLIND,R, ,-B/2-A,B/2+1.25*A,0,180,CYLIND,1.5*R, ,-B/2-1.5*A,-B/2-A,0,180,

CYLIND, RAD1, RAD2, Z1, Z2, THETA1, THETA2Creates a cylindrical volume centered about theworking plane origin.

RAD1, RAD2Inner and outer radii (either order) of the cylinder.

Z1, Z2Working plane Z coordinates of the cylinder.

THETA1, THETA2Starting and ending angles (either order) of thecylinder. Used for creating a cylindrical sector.

VSBV, NV1, NV2, SEPO, KEEP1, KEEP2Subtracts volumes from volumes.

NV1Volume to be subtracted from.

NV2Volume to subtract.


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16) Glue the two cylinders created in step 15together and glue the pin head to the leftmost block.

VGLUE,1,2VGLUE,5,6

Note: In order to know the appropriate volume num-bers to use in this command, you may have to runyour log file up to this point, plot the volumes, andturn on the volume numbers.

17) Turn off the working plane.

WPSTYLE,,,,,,,,0

18) Set the line mesh size for all the volumes.

LESIZE,ALL,.004, , , , , , ,

19) Mesh the volumes.

VMESH,ALL

VGLUE, NV1, NV2, NV3, NV4, NV5, NV6, NV7Generates new volumes by "gluing" volumes.

NV1, NV2, NV3, NV4, NV5, NV6, NV7Numbers of the volumes to be glued.

LESIZE, NL1, SIZE, ANGSIZ, NDIV, SPACE,KFORC, LAYER1, LAYER2, KYNDIVSpecifies the divisions and spacing ratio onunmeshed lines.

NL1Number of the line to be modified. If ALL, modify allselected lines [LSEL].

SIZEIf NDIV is blank, SIZE is the division (elementedge) length. The number of divisions is automati-cally calculated from the line length (roundedupward to next integer.

VMESH, NV1, NV2, NINCGenerates nodes and volume elements within vol-umes.


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20) You will now write commands that willrefine the mesh at critical areas.

AREFINE,6,,,3,.3AREFINE,14,,,3,.3AREFINE,21,,,3,.3AREFINE,8,,,3,.3

Note: In order to know the appropriate area numbersto use in this command, you may have to run yourlog file up to this point, plot the areas, and turn onthe area numbers.

21) Plot the elements.

EPLOT

22) Run your log file up to this point. Yourmodel will appear similar to the one shownto the right.

AREFINE, NA1, NA2, NINC, LEVEL, DEPTH,POST, RETAINRefines the mesh around specified areas.

NA1, NA2, NINCAreas around which the mesh is to be refined.

LEVELAmount of refinement to be done. Specify thevalue of LEVEL as an integer from 1 to 5, where avalue of 1 provides minimal refinement, and avalue of 5 provides maximum refinement.

DEPTHDepth of mesh refinement in terms of the numberof elements outward from the indicated areas.

EPLOTProduces an element display.


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23) You will now switch to the GUI and usethe contact wizard to generate contact ele-ments between the outside surface of the pinand the inside surface of the hole. Followthe next steps closely because you will copythe commands written by ANSYS to the ses-sion editor into your log file.

24) Select the three block volumes.

> Select > Entities

The Select Entities window opens. Chooseto select volumes by number/pick and clickOK.

25) The Select Volumes window opens.Select the three block volumes and click OK.

26) Now select the areas attached to thethree block volumes.

> Select > Entities

The Select Entities window reopens. Choseto select areas attached to volumes and thenclick OK.


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27) Plot the areas.

28) Open the contact manager by clicking onits icon which is located to the right of thecommand line. This opens the ContactManager window.

29) Click on the new contact icon in theupper left corner of the Contact Managerwindow. This opens the Contact Wizardwindow.

30) Select areas for the target surface andflexible for the target type. Click on the but-ton that says Pick Target.

31) Pick the inside areas of the hole with themouse and select Apply.

32) The Contact Wizard window reappears.Click on Next. Keep this window openwhile completing the next steps.

33) Reselect all entities.

> Select > Everything

34) Repeat steps 24-27 with the exception ofchoosing the pin instead of the blocks.

Contact manager icon:


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35) Return to the Contact Wizard window.For the contact surface select areas and forthe contact element type choose surface-to-surface. Click on the button that says PickContact.

36) Select the outside (curved) surface of thepin and click Apply. When the ContactWizard window reappears click next.

37) This is the final screen of the ContactWizard. Make sure that you check CreateSymmetric Pair and Include InitialPenetration. Enter a coefficient of friction of.5. Click Create. You will now see the con-tact pairs appear on the screen and you willsee their details in the Contact Managerwindow. Close the Contact Manager win-dow.


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38) Open the session editor in the ANSYSmain menu. Copy all the commands thatwere used to create the contact pair andpaste them into your log file. The com-mands should be similar to those shown inthe columns below.

FLST,5,3,6,ORDE,2 FITEM,5,3 FITEM,5,-5 VSEL,S, , ,P51X ASLV,S !* ALLSEL,ALLVSEL,S, , , 1 ASLV,S !* CM,_NODECM,NODE CM,_ELEMCM,ELEM CM,_KPCM,KPCM,_LINECM,LINE CM,_AREACM,AREACM,_VOLUCM,VOLU /GSAV,cwz,gsav,,tempMP,MU,1,.5 MAT,1 R,3 REAL,3 ET,2,170ET,3,174KEYOPT,3,9,0KEYOPT,3,10,1 R,3,RMORE, RMORE,,0RMORE,0 ! Generate the target surface ASEL,S,,,6 ASEL,A,,,14 ASEL,A,,,21 CM,_TARGET,AREATYPE,2 NSLA,S,1ESLN,S,0ESURF CMSEL,S,_ELEMCM ! Generate the contact surface ASEL,S,,,8 CM,_CONTACT,AREATYPE,3 NSLA,S,1ESLN,S,0ESURF

!* Create Companion Pair - StartR,4 REAL,4 ET,4,170ET,5,174KEYOPT,5,9,0KEYOPT,5,10,1 R,4,RMORE, RMORE,,0RMORE,0 TYPE,4 ESEL,S,TYPE,,3 NSLE,S ESLN,S,0ESURF TYPE,5 ESEL,S,TYPE,,2 NSLE,S ESLN,S,0ESURF !* Create Companion Pair - End ALLSELESEL,ALLESEL,S,TYPE,,2 ESEL,A,TYPE,,3 ESEL,R,REAL,,3 /PSYMB,ESYS,1 /PNUM,TYPE,1/NUM,1 EPLOTESEL,ALLESEL,S,TYPE,,2 ESEL,A,TYPE,,3 ESEL,R,REAL,,3 ESEL,A,TYPE,,4 ESEL,A,TYPE,,5 CMSEL,A,_NODECM CMDEL,_NODECM CMSEL,A,_ELEMCM CMDEL,_ELEMCM CMSEL,S,_KPCM CMDEL,_KPCM CMSEL,S,_LINECM CMDEL,_LINECM CMSEL,S,_AREACM CMDEL,_AREACM CMSEL,S,_VOLUCM CMDEL,_VOLUCM /GRES,cwz,gsav CMDEL,_TARGETCMDEL,_CONTACT/MREP,EPLOT


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39) Write a command to ensure that every-thing in the model is selected.

ALLSEL,ALL

40) Write a command to enter the solver.

/SOLU

41) Choose the solver type and tolerance.

EQSLVE,PCG,1E-8

41) Apply a symmetric boundary constrainton all areas at Z = 0. First select all areas atZ = 0. Second, apply the symmetric con-straint. Last, don’t forget to reselect all areaswhen finished.

ASEL,S,LOC,Z,0DA,ALL,SYMM ALLSEL,ALL

ALLSEL, LabT, EntitySelects all entities with a single command.

LabTType of selection to be made:ALL -- Selects all items of the specified entity type and allitems of lower entity types (default).

/SOLUEnters the solution processor.

EQSLV, Lab, TOLER, MULTSpecifies the type of equation solver.

PCG -- Pre-conditioned Conjugate Gradient iterativeequation solver. Useful for plates, shells, 3-Dmodels, large 2-D models, p-method analyses,and other problems having symmetric, sparse, def-inite or indefinite matrices for nonlinear analysis.

ASEL, Type, Item, Comp, VMIN, VMAX, VINC,KSWPSelects a subset of areas.

TypeS -- Select a new set (default)

LOC X, Y, or Z center (picking "hot spot" locationin the active coordinate system).

COMP either X, Y, or Z component.

DA, AREA, Lab, Value1, Value2Defines DOF constraints on areas.


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42) Apply degree of freedom constraints tothe top of the left and rightmost blocks.

DA,4,ALL,DA,10,ALL,

Note: In order to know the appropriate area numbersto use in this command, you may have to run yourlog file up to this point, plot the areas, and turn onthe area numbers.

43) Apply X direction degree of freedomconstraints on the inside surface of the leftand right blocks and on the outside surfacesof the center block.

DA,30,UXDA,27,UXDA,28,UXDA,29,UX

44) Apply the load to the bottom of the cen-ter block as a surface pressure.

SFA,15,1,PRES,-2.037E7

45) Write a command to plot the elementsand solve the model.

EPLOTSOLVE

SFA, AREA, LKEY, Lab, VALUE, VALUE2Specifies surface loads on the selected areas.

AREAArea to which surface load applies.

LKEYLoad key associated with surface load.

LabValid surface load label. Ex: PRES = Pressure.


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46) Enter the post processor.

/POST1

47) Plot nodal solution for the Von Misescomponent of stress.

PLNSOL, S,EQV, 0,1.0

48) Change the contour display to bettershow the stress pattern.

/CTYPE,0

/CVAL,1,-10E6,-5E6,0,10E6,20E6,45E6,60E6,75E6/REPLOT

49) Save the log file.

/POST1Enters the database results postprocessor.

PLNSOL See ANSYS help for information regard-ing the arguments for this function (too long to listhere).

/CTYPE, KEY, DOTD, DOTS, DSHP, TLENSpecifies the type of contour display.

KEY0 -- Standard contour display.

/CVAL, WN, V1, V2, V3, V4, V5, V6, V7, V8Specifies nonuniform contour values on stress dis-plays.

WNWindow number (or ALL) to which commandapplies (defaults to 1).

V1, V2, V3, V4, V5, V6, V7, V8Up to 8 contour values may be specified (inascending order). The 0.0 value (if any) must notbe the last value specified.

3D Knuckle Pin JointSolution

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50) Copy the contents of the log file into thecommand line in ANSYS and press enter.Close any warning boxes that appear. Themodel will take several minutes to solve.

Your model should look similar to the oneshown below.

20 guided-3d knuckle pin joint

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