Assignment 2-RADIOSS Engine File Editing & 3D Meshing Challenge

Aim -

• To calculate the values and to edit the engine file with that values.
• To perform volume mesh on the given components housing model and arm bracket model.

Objective -

• To calculate the speed of sound in steel rail.
• To calculate the time for sound to travel over length of the rail.
• To edit the engine file.
• To perform shell meshing and volume meshing with tetra elements on the housing model.
• To perform volume mesh with hexahedral elements on the arm bracket model.
• To fix tet collapse issue on housing model.

Procedure -

1. Check the material properties of the rail component and calculate the speed of sound in steel rail :

 

Figure 1-Material Properties.

• To calculate the speed of sound in steel rail,Write a given data and then calculate the speed of sound in steel rail

[Given Data :

ρ=0.0078 g/`mm^3`

E=2.1x`10^5` N/`mm^2`

Nu=0.29 [Unit Less]

Speed of Sound Formula C=`root`E/ρ.

Where ρ-Density

E-Youngs Modulus

$\mathrm{\nu - Poissons\; Ratio}$

C=`root`2.1x`10^5`/0.0078

=`root`26923076.9231

C=5188.745 m/s

Speed Unit is m/s]

 

[Note : Here I have changed the units according to the solver units,In solver our units are g,mm,ms.]

 

Figure 2-Default Units System in Solver.

 

[SI Unit of Density is kg/`m^3`

Now Convert kg/`m^3` to g/`mm^3`

1kg=1000g

1m=1000mm

Unit Conversion

=1000g`/`1000`mm^3`

=g`/``mm^3`]

 

[Density =Mass/Volume

Mass Unit = g

Volume =lxbxh

Length Unit= mm

Breadth Unit=mm

Height=mm

Density =g/`mm^3`]

 

2. The length of the rail is about 1000 mm.Calculate the time takes for a shock wave to travel from one end of the rail to the other.

To calulate time,We need speed formula

Speed=Distance/Time

Speed Unit=m/s

Distance Unit=m

Time Unit=s

m/s=m/s

s=m/m/s

s=mxs/m

Time=s

Given Data:

Speed C=5188.745 m/s

Distance=1000m

5188.745=1000/Time

Time=1000/5188.745

Time t=0.1927 m/s.

OR

Time for sound to travel length of rail formula is `Delta`t=L/C

Length of rail is 1000

Where `Delta`t = Time Step

L=Length of the Rail

C=Speed of the Sound

`Delta`t=1000/5188.745

`Delta`t=0.1927 m/s

 

3.Time for sound to travel length of rail=______

• Time for sound to travel over the length of rail=Time taken for the shock wave to travel from one end of rail to other.
• Hence,Time for sound to travel over the length of rail=0.1927m/s

 

4.Edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during impact -this will require a termination time equal to the time it takes for the sound to travel the length of the rail(set on/RUN card)

• In radioss solver,For every simulation,we will be having two files called

1) Starter File

2) Engine File

• There are two parts to the Radioss simulation, the Starter and Engine. The Starter is an input data check and must successfullycomplete without errors before the simulation can be completed in the Engine. Engine and Starter file can also be combined into Single Input File Utilizing Merge starter and engine file in Export panel.

 

Figure 3-Starter and Engine File.

 

Starter File -

• The Radioss Starter takes as input the model or commonly called Starter input file runname_0000.rad and creates the Starter output file runname_0000.out. The Radioss Starter is responsible for checking the model consistency and reporting any errors or warnings in the output file. If there are no errors in the model, the Radioss Starter creates initial restart file(s),runname_0000_CPU#.rst. 

 

Figure 4-Starter File.

 

Engine File -

• The Radioss Engine takes as input the Radioss Engine file, runname_0001.rad and the initial restart file(s) created by the Radioss Starter. The Radioss Engine files describes the solution control and output for the simulation. While the Radioss Engine is running, an Engine output file, runname_0001.out, is created which contains statistics about the simulation including time, time step, current system energies, energy error, and mass error. 

• Generates animation & time history output files (Annn Tnnn).
• Outputs details of the computation (runname_0001.out).
• Generates runname_0001.rst file for restart (using runname_0002.rad engine file).

 

Figure 5-Engine File.

 

Figure 6-Engine File Keywords.

 

 

Figure 7-Radioss Process.

Procedure to Edit Engine File -

• Now import the starter file into the radioss block.
• Go to the Standard Panel >> Import >> Import Solver Deck.

 

Figure 8-Importing Model into Radioss Block.

• Import Solver Deck option should be selected to import the radioss starter file.

 

Figure 9-Selecting the Starter File to Import.

• Here the import browser will appear,Select the appropriate starter file to import into GUI.
• Switch the File Type to Radioss Block and import the model into GUI.

 

Figure 10-Model Imported into GUI.

 

• Now after importing the model into GUI,We have to enter the values in the respective control cards,what we have obtained by calculating.
• When you imported the model into GUI,15 control cards should exsist.If not we have to create the control cards manually.
• To create control cards,Go to Tools >> Control Cards >> Engine Keywords >> Create.
• Create control cards when they are not displayed in the model browser.

 

Figure 11-Creating of Control Cards.

• We can also create the control cards by enabling the solver browser panel in the default browser panel.
• To enable,Go to View >> Hypermesh >> Solver.
• Right click on the solver browser and create the control cards.

 

Figure 12-Enabling the Solver Browser Panel to Create Control cards.

 

Figure 13-Creating Control Cards.

 

• After importing the model into GUI,there will be control cards assigned to the model,In that control cards,we have to enter the values in these two control cards called ENG_ANIM_DT and ENG_RUN.

 

Figure 14-Control Cards.

 

• Now enter the values obtained for the above questions in the ENG_ANIM_DT and ENG_RUN control cards.
• The obtained value for Time Step is 0.1927s.
• Enter this value in ENG_RUN control card as shown in below figure 13.

 

Figure 15-Time Step Value.

 

• Then enter the obtained `T`frequency value in ENG_ANIM_DT control card.
• The obtained value for `T`frequency is 0.0096353.
• Enter this value in ENG_ANIM_DT control card as shown in below figure 14.

 

Figure 16-`T`frequency Value.

 

5.Set the frequency of animation output to a time that will give 20 animation steps(/ANIM/DT)

Formula to find `T`frequency is

`T`frequency = Run Time / No of Animation Steps

Run Time=0.1927

No of Animation Steps =20

=0.1927/20

=0.0096353

6.Change /print -10.

• Here the print value -10 has been already setted default,So no need to change the print value.

 

Figure 17-Print Value.

 

• After entering the values in the control cards.Run solver
• To do that,Go to Analysis panel in Panel Area >> Radioss >> Select the Input File >> Radioss.
• The panel area is shown in below figure 16.

 

Figure 18-Panel Area.

• Now select the input file and run the solver.

Figure 19-Analysis Sub-panel.

 

• After selecting the input file and completing the set up to run the solver.
• Radioss will pop the solver view stating Radioss Job Completed as shown in figure 18.

 

Figure 20-Solver Output.

• After the end of the solver output,Go and check the whether the engine has been edited or not.
• To check,Go to file location where you have saved the starter file.
• Open the FIRST_RUN_00001.rad file with notepad.
• The edited engine file is shown below in figure 19.

 

Figure 21-Edited Engine File.

 

• We have eneterd the `T`frequency value to create 20 animation files,The 20 animation files have been created which is shown in below figure 20.

 

Figure 22-20 Animation Files Created.

 

• Here in the output file,we can see in every specific cycle,the three animation files are created which is shown in below figure 21.

 

Figure 23-FIRST_RUN_00001.out File.

 

7. 3D Meshing Tetra Mesh and Hex Mesh

 

Procedure -

1.Housing Model

Phase 1- Importing

a. Hence we are importing a given CAD geometry into hypermesh.
b. There are file formates like IGES,STEP,Parasolid where we can import these file formats into any CAD,CAE Softwares.
c. But in hypermesh student edition we can only import three file formates like

• IGES [Initial Graphics Exchange Specification].
• STEP [Standard for the Exchange of Product Model Data].
• Solidworks.

IGES,STEP,These two are standard file formats which are used most in industries.But now a days in industries,they are also using parasolid file format.

 

Figure 24-Importing Geometry.

 

Figure 25-Model Imported into GUI.

 

Phase 2- Examining 

• Before working on the model.We have to check the geometry if there are any errors like

1. Damaged Geometry.
2. Free edges in unnecessary areas.
3. Unnecessary points on the lines.
4. Unnecessary Connections and connectivity error.
   

• By assessing the given three models.We can see the components in every model.

 

Figure 26-Topo Mode.

 

Phase 3 - Creating 2D Shell Element's on the Geometry

• For this Model,I'm using 2D tria to 3D tetra method.

• First delete the solid's if it exsist's in the component.
• With the surface geometry,automesh the component from 2D panel.
• While meshing the component,Change element size to 5,In the mesh type drop down menu,switch to the trias and mesh the component.
• 2D Panel >> automesh >> surface >> displayed >> element size-5 >> mesh type-trias >> mesh.

 

 

Figure 27-Automesh Panel.

 

3.1 Start Tetra Meshing

3D Panel >> Tetramesh >> Element's >> Mesh.

Tetrameshing: Standard Tetrameshing

• Standard tetrameshing: 3D >> tetramesh panel >> Tetra Mesh sub-panel

Process:

• Generate a surface mesh of shell elements

• Check quality and connectivity of the plate elements.
• Generate the tetrahedral mesh.
• Delete the original surface mesh.
• Edit if necessary to obtain good quality.

 

Figure 28-3D Panel.

 

 

Figure 29-Tetra Mesh Panel.

 

• Requirements for the shell mesh:

• Enclose one, and only one, continuous volume..
• There can be no free edges. (Otherwise not a solid geometry)
• There can be no T-connected edges.
• There can be no duplicates in the mesh.
• Elements should not fold over and overlap each other.
• Avoid very low minimum tria angles.
• Avoid a large difference in size between adjacent elements.
• Avoid a large difference is size between two sides of a wall thickness.

• For quad elements in the shell mesh:

• Can split quads into 2 trias and create tetra elements under them.
  – OR –
• Can keep the quad element and create pyramids under them.

• Floatable Trias:

• Adjacent tria faces on the tetrahedral mesh may have their diagonal reversed
  from the shell mesh if tetras are better quality.

Figure 30:1-Flotable Trias.

 

• Fixed Trias:

• Adjacent tria faces on the tetrahedral mesh always match the shell mesh.

Figure 30:2 Fixed Trias.

 

Figure 31-Tetra Mesh.

• After Tetrameshing,Mask the elements in a particular region and see,whether the tetra element's are created as 3D(Solid).

3:2 Check whether the element's are failing for Tet Collapse

• In 2D Tetramesh,We will be checking whether element's are failing  for only min and max length.
• In 3D Tetramesh,We will be checking whether element's are failing for only tetcollapse.

3:3 Other Checks for Tetra Meshes

1. Quality checks for 2D tria elements: Before converting trias to tetras, all the quality checks as discussed for shell elements should be applied.
2. Free edges: Conversion from tria to tetra is possible only when there are no free edges.No free edges indicate the mesh is enclosing a volume.

What is Tet Collapse ?

• Tet Collapse can be calculated by measuring the distance of a node from the opposite face, then each of the four values will be divided by the Square root of the opposite face's area. The minimum of four resulting values is then normalized by dividing it by 1.24.

 

Figure 32-Tet Collapse.

 

• Tetra elements whose collapse value falls below the value specified are highlighted when the tetra collapse function is selected.These elements remain highlighted until the Check Elems panel is exited.
• Tetra collapse calculation: At each of the four nodes of the tetra, the distance from the node to the opposite side of the element is divided by the square root of the area of the opposite side. The minimum value found is normalized by dividing it by 1.24, and then reported. As the tetra collapses, this value approaches 0.0. For a perfect tetra, this value is 1.0.
• To check the Tet Collapse,Go to Check Elements or F10 >> 3D Panel >> Tet Collapse.
• Now save failed and Go to Tool >> Mask >> Select Elements By Retrieve >> Mask >> Reverse.
• The elements failing for tet collapse will be shown in below figure 33.

 

Figure 33-Elements Failing for Tet Collapse.

 

3:4 Tetra Remeshing to clear the element's failing for tetcollapse

• Before Tetra remeshing,Go to Tetramesh parameter's >> Tick all Check Boxes of Fill Voids >> Fix midnodes >> Smoothing to get better quality.
• In Tetramesh panel,In boundry faces drop down menu change it to remeshable and mesh.

 

Figure 34-Tetra Mesh Parameters.

 

 

Figure 35-Unmask Adjacent to Tetra Remesh.

 

 

Figure 36-0 Elements Failing for Tet Collapse.

• Similarly as i did for the above component,Do the same thing for this component also,Which is shown below in figure 37.

 

Figure 37-3D Tetra Mesh Done.

 

Figure 38-Elements Failing for Tet Collapse.

• To clear the element's failing for tetcollapse Tetraremesh the element's.
• While tetraremeshing ,Make sure you are ticking the check boxes of fill voids,fix midnodes and smoothening in the tetramesh parameters panel and give the tetcollapse value.
• Unmask adjacent as shown in below figure 39 and tetra remesh the element's.

 

 

Figure 39-Unmask Adjacent to Tetra Remesh.

 

Figure 40-0 Elements Failing for Tet Collapse.

 

2. Arm Bracket Model [Hexa Mesh]

• Here the arm bracket has been imported into GUI which is shown in figure 41.

 

Figure 41-Model Imported into GUI.

'

• Next switch to the topo mode and view the model as shown in figure 42 and start meshing thr arm bracket component with hexahedral elements.

 

Figure 42-Topo Mode.

 

• Now there are four components in the model called Base,Arm Curve,Arm Straight and Bose.
• Isolate the Base Component only as shown in figure 43 and mesh the component with the shell elements and then mesh with the hexahedral elements.

 

Figure 43-Base Component.

• Now first mesh the upper surface with 2D shell elements and then create hexa elements.
• Go to the Automesh Panel >> Surfaces >> Element Type:Quad >> Enable Align,Size,Skew.

 

Figure 44-Automesh Panel.

• 2D shell elements have been created as shown in below figure 45 in order to create hexa elements.

 

Figure 45-2D Shell Elements have been Created.

• Now Go to 3D panel >> Element Offset.
• To create hexa elements.

 

 

Figure 46-3D Panel.

 

Figure 47-Element Offset Sub-Panel.

• Now select the elements to offset.
• Select all the side surfaces of base component to follow along the geometry.
• Give the number of layers as 5, to get 5 row of elements over the base component.
• The total thickness of base component is 25.Give the value as 25 and offset the elements to create hexa elements.

 

Figure 48-Selecting the Elements and Surface to Offset to Create Hexa Elements.

 

Figure 49-Elements have been offsetted to create hexa elements.

 

• Now mask the elements and see whether the hexahedral elements have been created or not.
• To check,Go to Tools >> Mask >> Elements >> Mask.
• Atlast make sure to delete the 2D shell elements by config hexa 4.

 

Figure 50-Hexa Elements Created.

 

• Now Keep the 2D shell elemnents of base component cause these 2D shell elements are useful to generate hexa elements,So keep the 2D shell elements.
• The other component arm curve has been shown as shown in below figure 51 to generate hexa elements.The 2D shell elements of base component has also shown tp generate hexa elements.

 

Figure 51-Arm Curve Component has been Shown to Generate Hexa Elements.

 

• Here the spin tool is used to generate the hexa elements for the arm curve component as shown in below figure 52.

 

Figure 52-3D Panel.

• To spin the elements,First we have to create a center node called base node to create hexa elements.
• To Create,Go to Geometry >> Nodes >> Arc Center >> Lines >> Create.
• Node has been created as shown in the below figure 53.

 

Figure 53-Base Node Created.

 

Figure 54-Spin Sub-Panel.

• Here select the elements to spin in 2D elements option as shown in below figure 55.
• Select x axis to spin the elements in x axis and select the base node.
• Specify the angle as 90 through which to spin the elements.
• Specify 25 number of elements to generate along the path of the spin.
• And spin - in opposite direction.

 

Figure 55-Elements Selected to Spin.

 

Figure 56-Elements Spinned.

 

Figure 57-Hexa Elements Created.

 

• The Arm Straight Component should be meshed next.The Arm Straight component has been enabled as shown in below figure 58.

 

Figure 58-Arm Straight Component Enabled.

• To mesh this arm straight component,The linear solid tool is used to mesh the component with the hexa elements.
• For this tool,We should have both source geometry and destination geometry.
• The source geometry 2D Quad Shell Elements has been created by using faces tool as shown in below figure 59 and 60.

 

Figure 59-Tool Panel.

 

Figure 60-Faces Sub-Panel.

 

Figure 61-2D Quad Shell Elements Created for Source Geometry.

• Now mesh the destination geometry with same number 2D Quad Shell Elements as shown in below figure 62.

 

Figure 62-Meshed Destination Geometry.

 

Figure 63-Linear Solid Sub Panel.

• Here select the elements in the source geometry and select the elements in the destination geometry as shown in below figure 64.
• Now align the nodes in the both source and destination geometry.
• Give an appropriate density value and hit on solids to create hexa elements.

 

Figure 64-Selecting the Source and Destionation Geometry,Aligning Nodes in Source and Destination Geometry.

 

Figure 65-Hexa Elements Created to Arm Straight Component.

 

• Check whether the hexa elements have been created or not.
• To check mask the elements and see as shown in below figure 66.

 

Figure 66-Hexa Elements Created.

• Next component is bose,Enable the bose component in the model browser.
• For this component,Solid Map tool is used to generate hexa elements.

 

Figure 67-Bose Component Enabled.

• Now project the node to the surface to select the node path in along geometry.
• To project,Go to Tool >> Project >> To Surface >> Nodes >> Duplicate >> Select Surface >> Surface Normal >> Project.

 

Figure 68-Project Panel.

• Now mesh the top surface of boss with 2D Quad Shell Elements as shown in below figure 69.

 

Figure 69-Bose Component Meshed and Increased the Nodes of the Elements to be Uniform.

 

Figure 70-Solid Map Panel.

 

Figure 71-Selecting the destination surface,elements to drag,and selecting the surfaces,lines,node path to drag the elements along geometry.

• Here if there is no connectivity in the elements,Then equivalenec the nodes with the tolerance value of 3.5.

 

Figure 72-Equivalencing the Nodes.

 

Figure 73-Final Hexa Mesh of Arm Bracket Model.

 

Final CAD Model Image-

 

Figure 74-Final CAD Model Image.

 

Result -

• Hence the Engine File has been edited successfully with the values calculated.
• Hence the 3D Meshing has been generated for Housing Model with Tetra Elements.
• Hence the 3D Meshing has been generated for the Arm Bracket Model with Hexa Elements.

Learning Outcome-

In this Week 2 Challenge,I came to know

• The types of files for the Radioss Block
• How to edit the Engine File.
• How to mesh the component with hexa elements.