Assignment 2

Objective

• To check the material properties of the rail component and 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.
• To calculate time for sound to travel length of rail.
• 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.
• To change /print -10.
• 3D Meshing of Housing and Arm Bracket.

Procedure

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

        From the given FIRST_RUN_0000 file

          Unit system followed is g, mm, ms

            E=210000          

            ρ=0.0078

where,  E-Young's Modulus

            ρ-Density

Speed of sound is given by, c= √E/ρ

                                          = √210000/.0078

                                        c = 5188.7452 mm/ms

       2. To calculate the time taken for a shock wave to travel from one end of the rail to the other.

               Time required for a shock wave to propagate across the smallest distance of the element is called as time step.

                         Δt = L/C

               where, Δt = Time step

                          L  = Length of the element 

                          c  = Speed of sound

                  Length of rail, L = 1000 mm

                  Speed of sound, c = 5188.7452 mm/ms

                          Δt = 1000/5188.7452

                          Δt  = 0.19272482 ms

      3. To calculate time for sound to travel length of rail.

                     Time for sound to travel length of rail = .19272482 ms

      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.

•   Import the engile file (Open the Hypermesh. Import solverdeck > Import engine file)

•  Go to solver browser open the tree and select ENG_RUN (ENGINE_KEYWORDS > RUN > ENG_RUN)

         Change the value of Tstop to 0.19272482 ms

        5. To set the frequency of animation output to a time that will give 20 animation steps.

            We need 20 animation steps. Therefore dividing time by 20

                         T_freq = 0.19272482/20

                         T_freq  = 0.00963624  

           So change the value of T_freq to 0.00963624. (ENGINE_KEYWORDS > ANIM> ANIM/DT >)

       6. To change /print -10.

           Go to ENGINE_KEYWORDS > PRINT > ENGINE_PRINT

          Change the vale of N_Print to -10

The Edited file is

        7.  3D Meshing

1. HousingProcedure

• Import the housing.
• Hide the hub and Start the meshing of the cover.
• Go to 3D>Tetramesh>Vol Tetra
• Select the Surface, element size as 5.
• Go to Tetramesh Parameters, set min tetra size as 5 and tet collapse as 0.15
• Return to Vol Tetra and mesh.
• For elements quality, check tet collapse<0.15

• Hide the cover and mesh the Hub.
• Mesh the surface of the hub. Go to 2D > slect the surface > set element size as 5 > mesh.
• Go to 3D > Tetramesh > select the elements > mesh.
• For elements quality, check tet collapse<0.15

         2. Arm Bracket

            Procedure

• Import the Arm Bracket. There are 4 components. Mesh one by one hiding others.

        Base

• Mesh the top surface of the base. Go to 2D > automesh. Select element size as 10 and and mesh type as quads only.

• Go to 3D > Solid Layers. Select the displayed elements and set number of laters as 5 and total thickness as 25. Then click offset+.

   

     Arm Curve

• Unhide the arm curve and make it current component.
• Go to 3D > spin. Spin requires centre to spin, so go to F4 and create a spin cetre (F4 > three nodes > circle centre).
• Return to spin. Select the 2D elements of the base (top face) required to spin the elements.
• Angle 90, On spin 25, X axis and spin centre.
• Click spin-.

       Arm Straight

• Unhide arm straight and make current.
• Create the 2D faces of arm curve. Tools > Faces > select arm curve component > find faces.
• Create 2D elements on destination component of the arm straight.
• Go to 3D > Linear solid. Select from and to elements, select alignment and density as 12. Click solids.

• Delete created 2D fcaes. (Tools > Faces > Delete faces)

      Boss

• Unhide the boss and make current.
• Mesh the top of boss with 2D elements with element size as 10.
• Go to 3D > Solid map. For solid map along geometry nodes and lines are required. so project a node.
• In solid map select the face 2D elements, select the destination geometry, along line and nodes and element size as 10. Click mesh.

•  Delete all 2D elements and organise the solid elemets into Boss.

      Final Component

        Results

•  Speed of sound, c = 5188.7452 mm/ms

•  Time step, Δt  = 0.19272482 ms

•  Time for sound to travel length of rail = 0.19272482 ms

        Conclusion

• The method to check the properties of materials, to calculate the speed of sound in an element, time step, editing the engine file are determined.
• 3D meshing of the components - To mesh the components using tetra and hex elements.