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

Aim-

• To check the material properties of the rail component and to calculate the speed of sound in steel rail.
• To calculate the time taken for a shock wave to travel from one end of the rail to the other given that the length of the rail is 1000 mm.
• To edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during impact.
• To set the frequency of animation output to a time that will give 20 animation steps in the engine file.
• To mesh the given file and connect it by any one 1D connector.
• To perform 3D meshing on the given components with given quality parameters.

Procedure-

1. Calculation of speed of sound from given material properties-

• from the given 0000.rad file we can get the material properties of steel rail.

• From the above image we can see the value of E=210000 Mpa(N/mm^2) ; $\rho$=0.0078 g/mm^3.
• Now using formula Speed of sound" C=E/$\mathrm{\rho .}$
• Now using the above mentioned formula, we can substitute the values and get the speed of light i.e,

                                         c=210000/0.0078
                                           =5188.75 mm/s

2. To calculate time taken for shock wave to cross the rail of 1000mm

    Formula for time taken t=l/c
                                      t=1000/5188.75
                                       =0.1927ms(milli seconds)

•  Time for sound to travel length of rail is = 0.1927ms.

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

SOL: frequency=(1/t)*steps
                      =(1/0.1927)*20
                      =104 Hz 

4. To edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during impact.

• The above image is the final radioss engine file after making all the changes.

5. To mesh the given file and connect it by any one 1D connector-

• Directly open the .hm file into the software and check the parts.
• Now we will translate the given mesh file to upper side by measuring the distance between two surfaces.

• now we will create sections (Rod, tube) using hyperbeam command as per given dimensions for that right click on browser menu>create>Standard section>hypermesh>thin-walled tube. We create Bar element as box.

• now we create Different properties for Rod, tube also assign material properties for each.

• Now We create Rod, tube sections to our mesh, go to 1D>>Rod>>Select node1 & node2>> property(rod)>> element type (CROD).

• After switching views we will get the final model as below.

6. To perform 3D meshing on the given components with given quality parameters-

1.Model-1(Housing Assembly)-

• Initially we will import the given model for that go to import>>import geometry>>Step file then hit import.

• then go to topo mode and do manual geometry cleanup, also defeature the fillets which are less that the min element size.
• For that go to quick edit panel, geom>>quick edit (F11), try to toggle the lines failing for min element size.

• Now go to 2D>>automesh(F12)>>select surface>>element size-5 & element type- tria.

• For 3D mesh go to 3D panel and select tertamesh, then go to tetra mesh select 2D Tria element and hit mesh.

• once we are done with meshing we will go to tool>>check elems here select 3D and go to tet collapse and set value as per given to 0.15.
• So we found some elements failing for that so to fix go to tetramesh>> tetra remesh>> select failed element and try to remesh as resolve the issue, below snap shows there are 0 elements failing for tet collapse after error

• Now for meshing of 2nd part we will follow quick mesh method,go to view>>hypermesh>>utility>>geom/mesh>>select component>>select element size>>select mesh type (tria)>>hit mesh.

• Now we will check the tet collapse error.

Steps for 3D hexa mesh of arm bracket model:

• In this model we have four components , one by one we will be meshing the model.

• We have different methods to perform 3d hexa mesh like Element offset, spin,Linear solid, solid map...etc.
• To convert it to 3D hexa elements, we will offset these elements.
• So we will go to elem offset panel in 3D page. Here, under solid layers panel, we will select the 2D elements to offset, mention the number of layers as 5 and total thickness which is measured as 25.
• Then click on offset command. This will create 3D hexa elements by offsetting the 2D elements in 5 layers to a thickness of 25.

• Now, we will mesh the component connecting the base which is arm_curve as the base component has the imprint topology of arm_curve component.

• We will make it as our current component and hide all other components. The geometry for this component is like a partial Torus. So we can spin the elements to obtain 3D hexa mesh. So we will navigate to spin panel in 3D page.

• Here under spin elems sub-panel, we will select the 2D elements from the imprint area, enter angle as 90, on spin as 25 and select x-axis as our rotation axis. For base point, we will navigate to distance panel by F4 shortcut key and create a center node with the help of three nodes option.

• This center node will be used as the base point and then we will use spin option to spin the elements. Thus the 3D hexa elements will be created along the geometry profile in 25 layer.

• To mesh the arm straight component , use 3d>linear solid option.
• We should mesh each end by 2d element and join the same in this method.
• Already one end of arm stright component is meshed by hexa element , to extract 2d element from hexa element , go to tools>faces extract faces option.
• One end of the component will have 2d elements, mesh the other end with same number of elements to avoid penta elements.

• To mesh the boss component we will be using Solid map option.
• Mesh the boss one side and solid map the element to the ither end by nodes.
• Now after meshing all the components by hexa elements we have to delete all the 2d elements present in the model.

After meshing of the component surface, we will perform solid map> general.

Conclusion-

The speed of the sound in steel and the time taken by the sound wave to travel through the length of the steel rail has been successfully calculated. These calculated values are given as the termination time and the frequency of the animation output in the engine input file by editing the .rad file directly. Then the two components (housing and arm bracket) are meshed using the 3D solid elements (tetra and hexa) with the required quality and mesh flow.