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

Aim :-

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

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.

3.Time for sound to travel the length of the rail

4.Edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during an 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)

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

6.Change /print -10.

7.3d meshing tetra mesh and hex mesh

• Repeat class examples and, maintain the quality.
• Target tet size=5mm,hex size=10mm,tet collapse=0.15.

PROCEDURE:

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

• So to check the material properties of the material of the rail component. We have to import the component in the hypermesh.
• We have the ".rad" file. So for that, the profile should be RADIOSS.

• Now we will go to the import option. There we are going to select the 0000.rad file and import it.

• Now we will go to material property and check the values.
• Speed of sound (c) = ${\left(\frac{E}{\rho }\right)}^{\frac{1}{2}}$
• where E = Young's modulus
• $\rho$ = density 

• So speed of sound (c) = ${\left(\frac{21000}{0.0078}\right)}^{\frac{1}{2}}$=5188.745 m/s

 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.

• Shock wave travels at the speed of sound. So
• shock wave speed = speed of sound = 5188.745 m/s
• time (t) = $\frac{Dis\tan ce\left(D\right)}{speedofshockwave}$
• t = $\frac{1000}{5188.745}$=0.1935s

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

• time (t) =$\frac{Dis\tan ce\left(D\right)}{speedofsound\left(c\right)}$
• t= $\frac{1000}{5188.745}=0.1935s$

4. Edit the engine file so that the stress wave can be monitored, moving from one end of the rail to the other during an 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)

• We have to give the end time to be 0.1935s. There is two way by that we can do that.

(i). First is just open the 0001.rad file and edit the end time value in the file.

•  After giving the value

(ii). In the second method, we change the value in the hypermesh itself. There we go to the ENG_RUN card. There we change the Tstop value. There we have to give the value to be 0.1935 and after that, we have to run the file. So it will change the values in the 0001.rad file itself.

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

• frequency =$\frac{time}{no.ofrevolutions}=\frac{0.1935}{20}=0.009675$
• So to change this value. We have two methods

(i). First is just open the 0001.rad file and edit the end time value in the file

•  After giving the value

(ii). In the second method, we change the value in the hypermesh itself. There we go to the ENG_ANIM_DT card. There we change the Tfreq value. There we have to give the value to be 0.009675 and after that, we have to run the file. So it will change the values in the 0001.rad file itself.

6.Change /print -10.

• We can see that the by default PRINT value is 10. So there is no need to change that.

DEPLOYING 1D ELEMENTS BETWEEN TWO PLATES

 OBJECTIVES :-

1. To import the model.
2. To mesh the model.
3. To deploy rigid, bar, beam, and spring elements between the two meshed square plates.

 PROCEDURE :- 

• 1d elements are basically used to reduce the computational time. An object can mesh with 1d, 2d, or 3d elements, however, if it is possible to deploy 1d elements, then it should be always preferable. It is because the more the number of nodes, the more computational time to simulate the model.
• 1d elements are also used to make connections between different components. If two components have to be connected but no geometry is available to mesh, simply putting the 1d elements there would represent the connection. Thus, no need for geometry is required in such cases.
• In this assignment, a model was available as shown in fig. 1. From the figure, it can be observed that one square plate has meshed while one is not. So, to deploy 1d elements, the other plate also had to meshed. The length of the element on the meshed square plate was 0.5 units. Thus, using Geom >2D >auto mesh, the other plate also meshed with the element length of 0.5 units, 

• Now, when the parts mesh, it is always better to assign it the material and the property. Therefore, a material card was created, providing it the property of steel, and the property card was created, providing it the thickness of 1 unit. Both of these cards were assigned to the available components. Now, when the components mesh, and all set with properties, it is ready to get deployed with 1d elements.

RBE2 and RBE3 Elements :-

• There are two types of elements used to represent a rigid connection viz. RBE2 and RBE3 elements. The property of connection with the RBE2 element is that there is a single master node (or independent node) and multiple slave nodes (or dependent nodes). It means when multiple nodes are selected as slave nodes, and given one master node, the master would be the center of mass/load of all the slave nodes.
• All the load that is coming on the master node, the same load would be transferred to the slave nodes. However, using RBE3 elements, there can be multiple master nodes and a single slave node, which means whatever load that is coming on the slave node would be distributed among all the master nodes.
• Another difference between them is that RBE2 provides tremendous stiffness however RBE3 element does not provide the stiffness but distributes it to the neighboring nodes. Therefore, when infinite rigidity is required RBE2 element is used and when little deformation is also needed to be seen RBE3 element is used. Using 1D → rigid, an RBODY creates.

• meshed plates connected with a rigid RBE3 element.

ROD or Truss Element :- 

• Bar and Rod are those straight members that can be only subjected to axial loadings like tension or compression, but not bending or torsion. The cross-section of the rod is always circular.
• however, the cross-section of bar and beam can be of any circular or non-circular shape. Thus, if a member is subjected to any transverse load, it is called the beam, and if it is subjected to only axial loads, then it is called a bar.
• Moreover, if any single transverse load is applied to the bar, it is no more called a bar, it would be called a beam. Now, to deploy the rod element in the model, 1D>rods is the path. The truss element gets create after selecting the two nodes 

 Beam Element :-

• The member  which is subjected to any transverse load is called the beam. The beam can be of any shape. Using 1D >bars, the beam element was created 

Spring Element :- 

• The spring can be two-noded or three-noded. In this model, the two noded spring is created using 1D > springs

• The final image of the model with all the 1d elements deployed.

CONCLUSION :-

• CAE or computer-aided engineering on any model requires good observation and knowledge about the kind of manufacturing used to connect parts. In this work, the model is connected using various 1d elements. There are several options available for the element to choose to represent any specific kind of connection. Some of those elements are learned in this work.

MESHING OF HOUSING PARTS USING 3D TETRA ELEMENTS

PROCEDURE :-

• The HM file of housing parts was imported in Hypermesh. There were 2 parts, one was the cover and the other was a hub.
• They were not at all disturbed, and almost no errors were present in the geometry. Both the disc and the hub were meshed by converting 2d shell elements into 3d tetra elements, using 3D → tetra mesh → Tetra mesh. 

•  Performing the 2d shell mesh :
  Now the 2D meshing is performed using only tria elements and all the shell kept under the mentioned quality criteria.
  go to 2D>automesh> element size >5 >type >tria >mesh
  
• After the shell mesh is performed they need to be converted into solid tria elements. So select the 3D> tetra mesh option
  Then select the elements under the fixed tria/quad to tetra option and then do the mesh
  
• The fixed tria to tetra option ensures the connectivity of the tria with the tetra.

• Now we are going to create the tetra meshing with the 2-D elements. So for that, we are going to go with the 3-D> tetra mesh.

• Here we are going to select the 2-d elements and then we are going to click on the mesh.

• Now we want the tet collapse to be less than 0.15. So we are going to check that from the check elements. In that, we are going to the 3-d and we are going to give the value of tet collapse to be 0.15 and we are going to check that how many of the elements are failing for the tet collapse.

• To remove the tet collapse we are going to do the tetra remesh. So again we go to the tetra mesh and we are going to give the Tetramesh parameter and there we are going to give the tet collapse to be 0.15. There we can also give the maximum and minimum tetra size.

• Now we are going to do the remesh.

• After that, we check the tet collapse again in the mesh and check that if any elements are failing for the tet collapse.

• Final model after 3d tetra elements

 CONCLUSION :- 

• Objects whose thickness is not uniform, or if it is above 5-6 mm, generally mesh with solid elements. When the developing stresses in any object are not part of the concern, it is meshed using tetra elements, or else, it has to have meshed with 3d Hexa elements.

MESHING OF ARM BRACKET USING BRICK ELEMENTS

PROCEDURE :-

• Firstly, the arm bracket model was imported

• The meshing of any component using Hexa elements is complicated as compared to the mesh using tetra elements. Generally, tetra mesh is widely preferred when the stresses generating on the component are not the part of concern and vice versa.

• In this assignment, the arm bracket has to be meshed using only brick elements. To do that, different methods had to follow for different sections of the arm bracket.

• From the figure, it can be observed that the arm bracket model consists of four different sections.
• While meshing using Hexa elements, manual inspection is required for nodal connectivity.
• Thus, each section had meshed individually. Firstly, the face of section 1 has meshed with 2d elements of size 10 units

• Now, using 3D> Elem offset > solid layers, the 2d shell mesh is converted to 3d Hexa mesh with element thickness of 25 units and 5 layers,

• After the meshing of section 1, for the meshing of section 2, the different methods had to follow because of its curved shape

• To mesh section 2, firstly, a center of the curve is obtained for reference. It can be obtained using Geom >nodes > Arc Center, or Geom > distance >three nodes.

• After taking out the center, using 3D >spin > spin elements, the shell mesh inscribed by the curve is selected and it is spin about the center for 90º with 40 layers of elements 

• The spinning of shell m along the x-axis for 90º to create 3d Hexa mesh on the curved section.
• Once section 2 is ready with 3d Hexa mesh, for meshing of section 3, which is a tapered section, the shell mesh of section 2 is required.

• To get the shell mesh of section 2, Tool → faces → elements are used. It appears exactly like 3d Hexa mesh of section 2, it is hollow from inside.

• Now, to mesh section 3, the rows and columns of shell elements available on one side of it, the other side has to mesh with the same number of rows and columns using shell elements,

• Go to 3D> linear solid
  
• From elements and to elements can be selected as the two end faces elements respectively. The alignment node should be
  the same on both the faces
  
• Density can be set 12 >solids

• The next component to mesh is the boss. The option used for generating the mesh for this component is "Solid map". 

• Initially, one side surface has meshed with 2D quad elements 

• The same number of nodes should be there at both ends. In order to have the quad elements.
• Now With the help of a solid map tool, the destination surface, the elements to be mapped, nodes to which the connectivity should be there are selected. For a better understanding of the solver, lines along which the mesh should be generated are also selected.

• After generating the Hexa mesh. The next step is to check for the connectivity for the elements in the arm straight component and boss component.
• The final model with the entire hexa meshed 

Conclusion:- 

• Generated a 3D mesh (using tetra and Hexa elements) on the given models. By following the given quality criteria.

Learning outcomes :- 

1. Some calculations such as speed of sound, time step, T frequency values.
2. Types of files in radios like starter & Engine files.
3. Editing of engine file.
4. 3D meshing using tetra & Hexa elements.