workshop 20 connecting rod using 3d elements from sweep · pdf filewith the sweep distance...

WS20-1PAT301, Workshop 20, December 2005Copyright© 2005 MSC.Software Corporation

WORKSHOP 20CONNECTING ROD USING

3D ELEMENTS FROM SWEEP


Workshop ObjectivesDevelop a 3D Hex8 element model of a connecting rod. The tasks to be performed consist of IsoMesh the connecting rod mid surfaces with 2D Quad4 elements. These elements are then swept normal to themselves to create the solid elements. The completed model is analyzed, and the results postprocessed using MSC.Patran and MSC.Nastran.

Problem DescriptionObserve the deformation and von Mises stress results for the modelConnecting rod material: Aluminum with E = 10 x 106 psi and ν = 0.3Pressure load at piston = 1000.0 * sin(θ)

Software VersionMSC.Patran 2005r2MSC.Nastran 2005r2b


Key Concepts and Steps:Database: create a new database with Analysis Code = MSC.Nastran and Analysis Type = StructuralGeometry: import geometric surfaces via an IGES fileElements: mesh the surfaces with IsoMesh using Quad4 elementsElements: sweep the Quad4 elements to create the Hex8 elements. The sweeping is done for the web, flange, and piston and crankshaft areas, with the sweep distance different for the different areas.Geometry: create a cylindrical coordinate system at the top of the modelFields: create a field to be used with applied pressure loadingLoads/BCs: constrain the surfaces at the crankshaft, and apply pressure to the area of the pistonMaterials: specify an isotropic material for AluminumProperties: create a 3D solid property for the entire modelAnalysis: Solution Type = Nastran Linear Static, Solution Sequence = 101, Method = Full RunAnalysis: access analysis results by attaching the XDB file to databaseResults: plot von Mises stress and displacement results


Step 1. Create New Database and Import Geometry

Create a new database called connecting_rod_3D and import the IGES file.

a. File : New (or click on the File New icon).

b. Enter connecting_rod_3Dfor the File name.

c. Click OK.

a

b c


Step 1. Create New Database and Import Geometry (Cont.)

Import the existing IGES file.

a. File : Import…b. Select IGES as the

Source.c. Select conrod.igsd. Click Apply.

a

bd

c



Select the model preferences after importing the geometry.

a. Click OK when the IGES Report Summaryappears.

b. Select Based on Modelfor the Model Tolerance.

c. Click OK

a

b

c



These are surfaces that represent the mid-plane of the connecting rod.


Step 2. Mesh the Surfaces

IsoMesh the surfaces of the connecting rod.

a. Elements : Create / Mesh / Surface.

b. Select Quad, IsoMesh, Quad4.c. Select all the surfaces by dragging

a box around them.d. Remove check under Automatic

Calculation and enter 0.125 for the Global Edge Length.

e. Click Apply.

a

b

c

d

e


Step 3. Equivalence and Verify Free Edges

Equivalence the model to connect elements. Then, display the element edges that are free to see what elements are and are not connected.

a. Elements : Equivalence / All / Tolerance Cube.

b. Click Apply. (the magenta circles indicate the equivalenced regions)

c. Elements : Verify / Elements / Boundaries.

d. Select Free Edges.e. Click Apply. (Free edges

are indicated by the yellow lines.)

a

b

c

d

e


Step 4. Sweep the Elements

The sweep command will be used to create 3D elements from the 2D elements. The final 3D model will not have the same thickness throughout, so 3 sets of elements will be swept. The first sweep will be done for the web of the connecting rod.

a. Elements : Sweep / Element / Extrude.b. Click on Mesh Control…c. Enter 2 and click OK.d. Enter <0 0 0.1875> under Direction

Vector.e. For Base Entity List, click on the

Meshed entity Icon, then click on the Meshed Surface icon.

f. Shift-select the 6 surfaces that make up the web (indicated 1-6).

g. Click Apply.h. Change sign of the sweep vector,

-0.1875, and Apply.

a

b

c

d

e

f

g

h

5

43

1 2

6 e


Step 4. Sweep the Elements (Cont.)

Now sweep the flange section of the connecting rod.

a. Elements : Sweep / Element / Extrude.

b. Click on Mesh Control…c. Enter 4 and click OK.d. Enter <0 0 0.375> under

Direction Vector.e. For Base Entity List, click on

the Meshed entity icon, then click on the Meshed Surface icon.

f. Shift-select the 6 surfaces that make up the flange (indicated 1-6).

g. Click Apply.h. Change sign of the sweep

vector, -0.375, and Apply.

1 2

43

5 6

f a

b

c

d

e

g

h

e



Now sweep the piston and crank sections of the connecting rod.

a. Elements : Sweep / Element / Extrude.

b. Click on Mesh Control…c. Enter 5 and click OK.d. Enter 0.46875 under

Direction Vector.e. For Base Entity List, click on

the Meshed Entity icon, then click on the Meshed Surface icon.

f. Shift-select the 18 surfaces, 9 that make up the piston and 9 that make up the crank(as indicated).

g. Click Apply.h. Change sign of the sweep

vector, -0.46875, and Apply.

a

b

c

d

e

g

h

f

e



Change the views and see what the 3D model looks like.

a. Click on the Smooth Shaded icon.

b. Click on the Fit View icon.

c. Click on the Iso 1 View icon.

Here are three different views of the connecting rod (From left to right, Iso 1 View, Front View, and Right Side View). It may be helpful to try other views as well.

ab c


Step 5. Equivalence the Solid

Check to see what elements are not connected using theVerify command.

a. Elements : Verify / Element / Boundaries.

b. Select Free Edges.c. Click Apply.

The yellow lines indicate element free edges. Notice that these lines should not exist, i.e. the elements should be connected here. This can be resolved by using the Equivalence command.

a

b

c


Step 5. Equivalence the Solid (Cont.)

Equivalence 3D mesh and check the free edges again.

a. Elements : Equivalence / All / Tolerance Cube.

b. Click Apply.c. Elements : Verify /

Element / Boundaries.d. Select Free Edges ande. click Apply.

The yellow lines indicate free edges. Notice that the lines that were here previously no longer exist. That indicates that the elements here are now connected.

a

b

c


Step 6. Delete Surface 2D Mesh

Delete the 2D elements on thesurfaces.

a. Elements : Delete / Mesh/ Surface.

b. Select entire model by dragging a box around it.

c. Click Apply.

a

bc


Step 7. Create a Cylindrical Coordinate System

Create a cylindrical coordinate frame that will be used as a reference frame for the field.

a. Click on the wireframeicon

b. Click on the Point Sizeicon.

c. Click on the View Corners icon. Drag a box around the piston end of the rod.

d. Geometry : Create / Coord / 3Point.e. Type : Cylindricalf. Click on the Point icon.g. Select Point 2 for the Origin(center

of piston). Enter [x2 y2 1] for the Point on Axis 3, and select point 41(as indicated).

h. Click Apply.i. Click on Front view icon.

ac

d

ef

g

h

b

g

i


Step 8. Create a Field

Create a field that will be usedas a reference for the load.

a. Fields : Create / Spatial / PCL Function.

b. Enter sin_load for the Field Name.

c. Select Coord 1(the newly created cylindrical coord. frame) for the Coordinate System.

d. Enter sinr(‘T) for the Scalar Function

e. Click Apply.

a

b

cd

e


Step 9. Create Loads and Boundary Conditions

Create a pressure from the piston using the sin_load field.

a. Loads/BCs : Create / Pressure/ Element Uniform.

b. Enter piston_pressure for the New Set Name.

c. Click on Input Data…d. Enter 1000 for the Scale

Factor, and for the Pressure click on the sin_load field.

e. Click OK.f. Click Select Application

Region…g. Select FEM for the Geometry

Filter.h. Click on Select 3D Element

Faces, then use the Polygon Pick icon for Free face of element.

a

b

c

d

ef

g

h

h


Step 9. Create Loads and Boundary Conditions (Cont.)

Select the solid element faces forthe application region for thepressure.

a. Set Preferences/Picking to Enclose entire entity. Close.

b. Start by clicking on element just above point 41 and continue to select the element faces on the inner surface. Once all the faces have been selected to element just above point 43, (as indicated) go back to the original point (marked by a small box).

c. Click Add.d. Click OK.e. Click Apply.

a

a

b

c

d

a



Zoom in on the crank section of the connecting rod in order to create the nodal constraints.

a. Click on the Fit view icon.

b. Click on the View corners icon and zoom in on the upper section of the crank, by dragging a box around it.

Above is the illustration of the piston pressure. Above is the illustration of the crank section.

ab



Constrain select displacements at the crank shaft.

a. Loads/BCs : Create /Displacement / Nodal.

b. Enter fixed_crank for the New Set Name.

c. Click on Input Data…d. Enter <0 0 0> under

Translations.e. Click OK.

a

b

c

d

e



Select the application region to finish creating the nodal constraints.

a. Click on Select Application Region…

b. Select FEM for the geometry filter.

c. Click on Select Nodes, then use the Polygon Pick for Nodes.

d. Select the nodes on the upper free faces of the crank shaft region(as indicated).

e. Click OK.f. Click Apply.

a

b

d

e

f

c

d

c



Above is an illustration of the fixed displacements at the crank. Notice that the node at these points are also included.

Above is a better illustration of the pressure and fixed displacements. Just click the Fit View, then Smooth Shaded, then Iso 1 View icons. It may be helpful to try other views as well.


Step 10. Create Material Properties

Create a material property that will be applied to the model.

a. Materials: Create / Isotropic / Manual Input

b. Enter Aluminum for the Material Name.

c. Click on Input Properties…d. Enter 10E6 and 0.3 for the

Elastic Modulus and Poisson Ratio, respectively.

e. Click OKf. Click Apply.

a

b

c

d

ef


Step 11. Create Element Properties

Create the element properties for the connecting rod.

a. Properties : Create / 3D / Solid.b. Enter 3D_connecting_rod for

the Property Set Name.c. Click on Input Properties…d. Click on the Material Prop Name

icon, and select Aluminum from Select Existing Material.

e. Click OK.f. Click on Select Members and

FEM icon and select entire model. Then, click Add.

g. Click Apply.

a

b

c

d

e

f

g

f


Step 12. Check Load Cases

Check the default load case,Default, and make sure that thecorrect loads and boundaryconditions are being applied.

a. Load Cases : Modify.b. Select the load case

Default.c. Check to see that the

Loads/ BCs are correct.d. Click Cancel.

a

b

c

de


Step 13. Run the Analysis

Send the model to MSC.NastranAnd run the analysis.

a. Analysis : Analyze / EntireModel / Full Run.

b. Click on Translation Parameters…

c. Select XDB and Print.d. Click OK.e. Click on Solution Type…f. Select Linear Static.g. Click OK.h. Click Apply.

a

b

c

d

e

f

gh


Attach the XDB file.a. Analysis : Access Results /

Attach XDB / Result Entities.b. Click on Select Results File...c. Select

connecting_rod_3D.xdband click OK.

d. Click Apply.

Step 14. Check the Results

a

b

c

d


Create a deformation plot.a. Results : Create /

Deformation.b. Select

Displacements, Transitional.

c. Click Apply.

Step 14. Check the Results (Cont.)

a

b

c



Do not show the undeformed shape and erase the geometry to be able tosee the deformed shape better.

a. Click on the Display Attributes icon.

b. Remove the check from theShow Undeformed box.

c. Click on the Plot/Erase icon.d. Click Erase under Geometry.e. Click OK.f. Display: Coordinate Frames.g. Click on Unpost Allh. Click OK.i. Click Apply i

d

g

h

a

c

b e

f



Plot the Von Mises stress.a. Results : Create /

Fringe.b. Select Stress,

Tensor.c. Click Apply.

a

b

c

workshop 20 connecting rod using 3d elements from sweep · pdf filewith the sweep distance...

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