Meshing and analysing of a shaft...Introduction to Altair HyperMesh TM and Altair HyperView : Meshing and analysing of a shaft ©October 2018 by Marius Müller Page 2 1.9.Creation

Marius Müller

Introduction to Altair HyperMeshTM

and

Altair HyperViewTM

:

Meshing and analysing of a shaft

©October 2018 by Marius Müller

Graz, October 2018

Introduction to Altair HyperMeshTM and Altair HyperViewTM: Meshing and analysing of a shaft

©October 2018 by Marius Müller Page 1

Meshing and analysing of a shaft

1. Creation of geometry 1.1.Click F8 and choose XYZ

1.2.Create a node at (0/0/0)

a. Create a node at (0/0/30)






1.8.Combine the nodes with lines

i. Create a component for the lines and choose a colour

Right click on the model tree => create => Component

ii. Go to the Geometry panel and choose lines

iii. Choose linear nodes

iv. Create lines

Figure 2: Lines connected to nodes

Geometry scale: 1:2

200

Ø4

0

Ø6

0

Geometry scale: 1:2

100

Evaluation plane

92

Figure 1: Geometry of shaft

F = 500 N



1.9.Creation of surfaces

v. Create a component for the surfaces and choose a colour

vi. Go to the Geometry panel and choose surfaces

vii. Choose Spline/Filler

viii. Change “Create in:” into “Current Component”. This way the surface will be created in the current component

1.10. For creating the radius you again need a surface

ix. Create a node at (110/0/30) and draw a circle with a radius of 10 mm

x. Go to the Geometry panel and click on surfaces and choose

Spline/Filler and create a surface out of the lines

xi. Geometry panel => surface edit => trim with surface/plane => choose

the surface you want to trim and select the node where you want to trim

the surface.

xii. Trim the circle with the x-axis and the z-axis and delete the not needed

surfaces and lines

1.11. Go again to the Geometry panel and click on surfaces

xiii. Choose spin and click on one of the lines you want to spin and set the

x-axis as the rotational axis and select a node to spin around

1.12. Now click on Spline/Filler in the Geometry panel and close the open body

1.13. Then go to solids in the Geometry panel and choose Bounding Surfaces

Figure 3: Surfaces generated

Geometry scale: 1:2

Figure 4: Quarter circle generated

Geometry scale: 1:2

Figure 5: Solid generated



1.14. Delete all of the nodes: Click Shift + F2 => clear all

1.15. Delete the old surfaces: Right click on the component => Delete

2. Creation of assemblies and preparation for the mesh 2.1.Click into the model tree with the right mouse button and create the following

assemblies:

i. CAD

ii. Surfaces

iii. FEM

iv. Mesh_2D

2.2.Create the following components

i. CAD_notched_shaft

ii. Copy_notched_shaft

iii. Surf_ notched_shaft

iv. Shell_ notched_shaft

v. Hex_ notched_shaft

2.3.Move the components into the right assembly

2.4.Turn your solid shaft into the component CAD_notched_shaft

i. Go to the Tool panel and click on organise

ii. Select solids and choose the shaft and then select move

2.5.Make a copy of your shaft

i. Right click on Copy_notched_shaft => Make Current

Figure 6: Creation of assemblies



ii. Go to the Tool panel and click on organise

iii. Select solids and choose the shaft and then select copy

2.6.Cut the “Copy_nothed_shaft” into one quarter i. Only display the component “Copy_nothed_shaft”

1. Right click on the component => Isolate only

ii. Create a node on the rotation axis of the shaft:

Click F8, go to Arc center and select lines

Click on one of the circles at the beginning or the end of the

shaft and click create

iii. Go to the Geometry panel and select surface edit and click on “trim with surfs/planes, select the z-axis and the node you created before

iv. Do the same for the y-axis

v. Delete the not needed solids

Click F2 and select solids and make sure to click on “delete bounding surfs. This way you also delete the bounding surfaces

of your solid

2.7.Create a surface where you can model on

i. Make the component “SURF_notched_shaft” current ii. Go to the Tool panel and click on organise and copy the surface (the

surface in the zx-plane) of the quarter shaft

iii. Hide the solid

Surface we will model on

Figure 7: Quarter shaft

Figure 8: Surface of the notched shaft in the zx-plane

Geometry scale: 1:2



3. Meshing of the notched shaft In order to get good results in the analysis, it is necessary to generate an appropriate

mesh. Areas where high stress gradients are expected should be modelled with a fine

mesh, areas where the expected stress gradient is not that high can be modelled with

coarser elements.

3.1.Preparation of the surface in order to generate a good mesh on it

3.2.Hiding everything beside “Surf_notched_shaft”

3.3.Cutting the geometry in order to achieve a good element quality and a fine

mesh in the area of the notch

i. Use the Geometry panel and the surface edit function to cut the surface in

a way as shown in Figure 9.

ii. The surface must be cut in the z direction above the axis of rotation (x-

axis) of the shaft in order to avoid penta elements

iii. Make sure that you have a point in the area of the evaluation plane!!!

We want to evaluate the stresses there.

3.4.Mesh the prepared surface with first order QUAD elements

i. Set the component “Shell_notched_shaft” to current ii. Press F12, select surfs and set the element size to 3 mm

iii. Make sure that “elems to current component”, “first order” and “keep connectivity are active

Geometry scale: 2:1

Figure 10: Mesh panel

Figure 9: Cut surface

Geometry scale: 1:2

Evaluation plane

92



iv. Click on the surface you want to mesh

3.5.Spin the generated 2D mesh in order to create 3D Hex elements

i. Make the component “Hex_notched_shaft” active

ii. Go to the 3D panel

iii. Click on spin

iv. Click on spin elems

v. Select the 2D elements and select an axis of rotation (x-axis) and the point

you want to spin the elements around

vi. Set the angle to 360°

vii. on spin = 36

Figure 11: Created 2D mesh

Geometry scale: 1:2

Geometry scale: 2:1

Figure 12: 3D elements created with the spin function



In order to close the hole in the middle of the shaft, we again have to create a surface.

We will create a 2D mesh on that surface and drag it along the nodes of the recently

created 3D elements.

3.6.Generate 2D elements on this surface.

3.7.Go to the 3D panel and click on solid map

i. Choose “along geom => node path” and “elems to drag” and hide all other options in this panel

ii. Mark the elements you want to drag

iii. Choose a node path and click mesh

Figure 13: 3D elements created with the spin function and surface added

Surface

Figure 14: 2D elements ready to drag

Geometry scale: 1:1



3.8.The mesh will be automatically created in a new component called solidmap

i. Convert these elements into the component “hex_notched_shaft”

Figure 15: Usage of the Solid Map function

Node path Selected elements

Figure 16: Shaft modelled with first order hex-elements



3.9.Do a quick check if all elements are connected

i. Just display the component “hex_notched_shaft”

ii. Create the faces of these solid elements

iii. Hide the solid elements

iv. Check if you have any edges remaining

v. Delete parts of the faces-elements and check if there are faces-elements

remaining in the inner part of your model

vi.

4. Creating materials and properties In order to calculate you have to define materials and properties to your model.

4.1.Create a material

i. Right click on the model tree

ii. Select Create and Material

iii. Give the material a name: “mat_steel”

iv. Type in the density, the E-Modulus and the Poisson’s ratio

v. MAT1 – isotropic, temperature independent material

Create faces Check for edges

Figure 17: Checking the elements

Figure 18: Material definition



4.2.Create a property

i. Right click on the model tree

ii. Select Create and Property

iii. Give the material a name: “prop_shaft”

iv. Choose PSOLID

v. Set the material to mat_steel

vi. Assign the property to the component “hex_notched_shaft”

5. Create a coupling element to distribute the force at the end of the

shaft

5.1.Create a new component: “rbe3_force”

5.2.Create a node in the middle of the end of the shaft

Figure 19: Property definition

Figure 20: Creating node for coupling element

Node



5.3.Go to the 1D-panal and click on rbe3

5.4.Change dependent from “calculate node” to “node”

5.5.Click on the node you created before

5.6.For the independent nodes choose all nodes of the circumference

6. Create a force acting on the dependent point of the coupling element 6.1.Right click on the model tree => Create => Load Collector

i. Name the load collector: LC_force

ii. Make sure that LC_force is active

6.2.Go to the Analysis panel

6.3.Click on forces and click on create

6.4.Type in the magnitude: 500 Newton

6.5.Choose the global z-axis as definition for the direction of the force

6.6.Load types = FORCE

6.7.Click on the dependent point of the rbe3

6.8.Click on create

Figure 21: Creating coupling element

Figure 22: Created coupling element (rbe3)



7. Create boundary conditions 7.1.Right click on the model tree => Create => Load Collector

i. Name the load collector: BC

ii. Make sure that BC is active

7.2.Go to the Analysis panel

7.3.Click on constraints

7.4.Choose all nodes at the beginning of the shaft

7.5.Set DOF1 to DOF6 to 0.0

Figure 23: Creating constraints

Figure 24: Boundary conditions and force created

Geometry scale: 1:2



8. Create a Load Step 8.1.Right click on the model tree => Create => Load Step

8.2.Analysis type: Linear static

8.3.SPC => BC

8.4.Load => LC_force

8.5.Subcase options:

i. Output:

Displacement

SPCF

Strain

Stress

In order to not create very large files during calculation, you can select from different

outputs requests which you want to have a look on later in the Post-Processing.

9. Export the model to run the calculation 9.1.Delete every component beside the components in the assembly FEM

(hex_notched_shaft; rbe3_force)

9.2.Save the model as a copy

9.3.Click on Export Solver Deck

10. Open OptistructTM

and run the calculation 10.1. Open Optistruct

TM

10.2. Read in your model (model.fem)

10.3. Click on run and wait

Export Solver Deck Figure 25: Export Solver Deck

Figure 26: Open OptistructTM

and run the calculation



11. Open HyperViewTM

and view the results 11.1. Open HyperView

TM

11.2. View the deformation / displacement

11.3. View Stresses – vonMises strsses and advanced averaging method

11.4. Create appropriate legend

11.5. Display the major stresses (P1)

11.6. Display the minor stresses (P3)

Figure 27: Legend for stresses

Figure 27: vonMises stresses



Figure 28: Major stresses

Figure 29: Minor stresses



12. Compare the results with an analytical solution

Bending moment: 𝑀𝑏𝑦 = 𝐹 ∗ 92 = 500 ∗ 92 = 46 𝑁𝑚 (1)

Moment of resistance: 𝑊𝑦𝑦 = 𝑑3 ∗ 𝜋 ∗ 132 = 6521.8 𝑚𝑚3 (2)

Bending stress: 𝜎𝑦𝑦 = 𝑀𝑏𝑦𝑊𝑦𝑦 = 7.05 𝑀𝑃𝑎 (3)

Shear force: 𝐹𝑄𝑧 = 500 𝑁 (4)

Shear stress: 𝜏𝑞 = 4∗𝐹3∗𝐴 = 0.517 𝑀𝑃𝑎 (5)

vonMises: 𝜎𝑉,𝑀 = √𝜎𝑦𝑦2 + 3 ∗ 𝜏𝑞2 = 𝟕. 𝟏𝟏 𝑴𝑷𝒂 (6)

Have a lot of fun learning how to use HypermeshTM

and HyperViewTM

!!!

Ø4

0

Geometry scale: 1:2

Evaluation plane

92

Figure 30: Shaft – Internal forces at evaluation plane

F = 500 N

FQz

Mb

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Meshing and analysing of a shaft...Introduction to Altair HyperMesh TM and Altair HyperView : Meshing and analysing of a shaft ©October 2018 by Marius Müller Page 2 1.9.Creation