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

Solution of Question 1:-

• So to check the material properties of the rail component we have to open the 0.rad file 
• because as we know that all the details and information related to material, initial loads, mesh, the unit system used, etc about the model is stored in the 0.rad file
• Which is also called the starter input deck
• So to access that we have to first open the given 0.rad file.
  
  
  
  
  
  
• as we can see here all the details about the model is written here
• such as the density of the material, the E value of material, name of the material which is "steel", act all are written here
• so as to calculate the speed of sound in this rail component we can use the formula 
  
                                                            Δt= L/c                                                                                                                       ....(1)
  
  where Δt is the time taken by the shock wave to travel from one node to other
  L is the distance between the two closest nodes
  And c is the speed of sound which is dependent on Young's modulus of elasticity and density of the material
  
  so we can write this above formula as 
                                                 
                                                           Δt= L÷√(E/ρ)                                                                                                               ....(2)
  
  Where,                                            ................
                                                          c=√(E/ρ)                                                                                                                       ....(3)
                                                         ...............
• So by using this formula we can find the speed of sound in the rail component
• as we know from the 0.rad file that
  
                       (Young's Modulus of easlticity) E= 21000 MPa(N/mm^2)
                       (Density) ρ= 0.0078 g/mm^3
                    
  So ,  
             c= √(210000/0.0078)
             
             c= 5188.7452 m/s                        .....(answer 1)
  
  

Solution of Question 2:-

• So in question, we have to calculate the time taken for a shock wave to travel from one end of the rail to the other
• Where the length of the rail is given as L= 1000mm
• so By using the formula (1) we can find the time taken by the shock wave to travel from one end to other
  
  Given 
           L= 1000mm
           c= 5188.7452 m/s 
  
  So, 
         Δt= L/c  
         Δt= 1000/5188.7452
         Δt= 0.192724 ms
  
  

Solution Of Question 3:-

So time for sound to travel the length of rail= 0.192724 ms

Solution of Question 5:-

• So to set the frequency of animation output to a time that will give 20 animation steps(/ANIM/DT)
• First, we have to calculate the animation frequency 
• So to calculate the frequency we can use the formula 
  
                              frequency= (l/c)*time
  
  so time = no of animation steps= 20
  
  So, freqency= 0.192724*20
  
                             frequency= 3.854

Solution of Question 4,5 and 6:- 

• We can change values using two methods 
  • By changing all the values by opening the engine file (1.rad) in notepad
  • after opening the engine file in notepad 
  • change the value down below 
    • /RUN/FIRST_RUN/1/
  • to the time that we calculated which is 0.1927 which the time for which the simulation will run
  • Then change the value down below
    • TFREQ
  • to the frequency of animation output to a time that will give 20 animation steps(/ANIM/DT) that we calculated above which is 3.854
  • Then to change the /print as mentioned in the question
  • change the value written next to 
    • /PRINT/
  • which was already -10
  • Then save that file
    
    
    BEFORE CHANGING ALL THE VALUES IN ENGINE FILE USING NOTEPAD
    
    
    AFTER CHANGING ALL THE VALUES IN ENGINE FILE USING NOTEPAD
    
    
    
    
    
    
• Now the second method of updating all these values in engine file is by opening them in HyperMesh
• So first import the file using solver deck option in import
• Then in browsers--> Model--> card
• there Change the "Tfreq:" to 3.854 in ENG_ANIM_DT
• Then change the "Tstop:" to 0.1927 in ENG_RUN
• Then change "N_print" to -10 in ENG_PRINT
  
  
  
  BEFORE CHANGING Tfreq
  
  
  
  
  
  AFTER CHANGING Tfreq
  
  
  
  
  
  BEFORE CHANGING Tstop
  
  
  
  
  
  AFTER CHANGING THE Tstop
  
  
  
  
  
  
  /print as -10
  
  
  
  
  
  
  
• after this, export the solver deck file and save it
  
  
  

Solution 7:-

Objective:-

• To do 3d meshing on the given components
• By following the given quality criteria for elements
• By following the given method of meshing such as Hex meshing and tetra meshing
• To create a 2d mesh on the given geometry and create connection(1d elements) and realise them 

Theory:-

FOR HEXA MESH:-

• First imported the geometry (arm.bracket) which was a step file
• then meshed the one face of the base square plate using 5mm quads only
• then using the element offset method in 3D selected the 2 d elements and geometry to follow as the sided edges connected to the meshed  face of the plate
• then no of layers as 5 and thickness as the actual thickness of the part which was 25
• then hit middle mouse click it created a hex meshed 
  
  
  
  trimmed the cut feature of the arm curve over the base plate face that was meshed so that no elements remains constant throughout the arm curve
  
  
  
  
  
  created a 2d mesh using 5mm quads only
  
  
  
  
  while selecting the destination face, geometry to follow and elements to be offseted to 3d elements in "elem offset" tool
  
  
  
  
  
  
  A good quality hexa mesh done on the base plate
  
  
  
  
  
  
  
  
• Then for the arm curve used the spin tool from 3d as the thickness of arm curve is not variable
• so to use spin tool first created a centre node to spin the elements about using distance tool
• so selected all the 2D elements over the base plate only the elements in the cut region of arm curve over the base plate
• and then selected the x-axis and the centre node as base point
• angle as 90
• and on spin as 25
• then hit on middle mouse button
  
  
  
  Creating a centre node of the arm curve  using distance tool
  
  
  
  
  
  using spin tool to create the hex mesh on arm curve
  
  
  
  
  
  
  Complete hexa mesh for the arm curve
  
  
  
  
  
• Now for the non uniform thickness arm curve 
• Used the Linear solid to create the mesh
• first of all created 2d elements at the end face of the uniform thickness arm curve by using the face tool and selecting the upper most 3d elements on the arm curve
• Then first meshd the smaller end of the arm curve with 2d elements
• and then by using linear solid
• selected the 2d elements on both the ends and the same nodes on both the ends
• and exact no of elements on both sides to avoid any penta or failing element
  
  
  
  while creating 2d elements on the face of the arm curve using face tool
  
  
  
  
  
  
  
  
  Meshed the other face with exact no of 2d quad elements as the destination face
  
  
  
  
  
  
  
  While Using Linear solid tool to get the mesh 
  
  
  
  
  
  
  
  Complete 3d mesh for part 3
  
  
  
  
  
  
  
• similarly for the boss part
• Used the element offset tool to get the mesh 
• first created exact  no of elements as it is in the ending face of the arm curve 
• over the boss face and then by creating cut lines meshed the outer face of the boss part
• and then used the elem offset tool to get the perfect 3d mesh
  
  
  
  
  while creating the 2 d quad elements over the outer surface of the boss part
  
  
  
  
  
  
  While selecting the 2d elements, geometry to follow and the thickness of the boss part in the element offset tool
  
  
  
  
  
  
• Finally after getting the complete perfect mesh 
• deleted all the 2d elements and unnecessary nodes
  
  
  
  COMPLETE 3D HEXA MESH OF ARM BRACKET 
  
  
  
  
  
  NOW FOR CREATING A 3D tetra MESH OVER THE HOUSING COMPONENT
  
  
• To create the 3 d tetra mesh first did the geometry clean up 
• so that the 2d tria elements wont fail
• then created a 2d tria mesh over the whole outer geometry 
• then fixed all the failing elements within the given criteria
• then by using 3d tetra mesh tool meshed the geometry to 3 d mesh
• by selecting the 2d elements as the tria mesh done
• and then fixed all the elements failing for the given yet collapse value
  
  
  
  After doing the 2d tria mesh
  
  
  
  
  
  After fixing all the 2d elements failing
  
  
  
  
  
  After fixing all the elements failing for tet collapse
  
  
  
  
  
  
  
  
  
  
  
  COMPLETE TETRA MESH WITHIN THE GIVEN CRITERIA SETTINGS
  
  
  
  
  
  
• Then after this for the next model created a 0.5 mm 2 d mesh
• on both the plates after doing a geometry clean up
• then created different 1d elements
  
  
  
  Craeted Rigid RBE2 link using rigid tool in 1d these are the rigid elements in this force distribution doesn't take place 
  each node carries the same force as the any of the node these are used for denoting bolts, seam welds, etc
  
  
  
  
  created rbe2 element between two master nodes of rbe2 links
  
  
  
  
  created spring elements using spring tool in 1d
  
  
  
  
  
  
  CREATED ROD ELEMENT 
  
  
  
  
  
  

Conclusion:-

• Created 3d mesh for the given quality criteria 
• two different kind of 3d mesh 
  • using hexa elements
  • using tetra elements
• learned about the calculations done while calculating the time step in the simulation
• learned about all the files involved in the perfect running of a simulation such as engine file, stater file
• learned about the different methods to alter the values in these deck files
• learned about the significance of time step the calculation involved and the properties and factors on which time step depens.