Assignment 4-RADIOSS Material Laws Challenge

Objective :-

• Run the model as it is. Name it Law2_epsmax_failure.
• In/FAIL/JOHNSON, change Ifail sh=1, Dadv-1 and Ixtem=1. Run the model as Law2_epsmax_crack.
• Delete/Fail/JOHNSON card. Run the model as Law2_epsmax_nofail.
• Delete the value of EPS_p_max and run the model with name Law2.
• Convert this material model to Lawl elastic with same density, E, nu and run. Check the results.

• Open LAW27_0000.rad

  a) Change the shell properties to recommended Shell properties.

  b) Notice the material card. Johnson cook parameters but different values for EPS based failure.

c) Run the model with name Law27

Compare 7 cases as discussed in last 3 slides

Procedure :-

Case 1:

• First of all we have to open Hyper mesh for that go to import ,solver deck option and Import the file “FAILURE_JOHNSON_0000.rad”

• We can check units using the begin card.
• In this case, we need to run the simulation with the default values.
• To run the simulation, Go to Analysis, Radioss. We need to save the output files in a new folder so that we can access them easily. The file is saved as "Law2_epsmax_failure_0000.rad". After saving, click the 'include connectors' box and type in '-nt 4' in the options text box as shown below, before clicking 'Radioss'
• It is recommended to be written as "-nt 4" as shown in the image below. This means assigning the task to 4 cores in the system, to perform the simulation faster. It depends upon the process of our computer (it has a quad-core processor, then it should be taken as 4. If the system has an octa-core processor, then it is taken as 8). And "nt" means "number of threads". Then click on "Radioss", in order to run the simulation

• By clicking 'Radioss', we get the solver window as shown below, which basically tells us what the RADIOSS solver is doing. After a few minutes, radios does the job and you can check all the files in the folder which you have saved as.

• The simulation is complete, now we just need to visualize it. For that, we need to switch to the Hyperview utility.
• After that go to Hyperview, input the simulation file. For this, use h3d file. After selecting click 'apply'
• After hyperview generates the simulation animation
• We can change what is being represented by selecting the 'contour' option in the toolbar. In this case, we can change the result type to 'Von Mises' and change the averaging method to simple. Doing so creates the Von Mises stress contours as shown below.

• Next step is to carry out energy error and mass error checks and this is done by analyzing the RADIOSS engine output file. This can be accessed from the same directory as the starter and engine files and is denoted by the '.out' extension. We need to check the file that contains '_0001.out' by using any text editor.
• On opening the file and scrolling down to the end, we can see the final energy and mass error values.
• The final energy error is 0.8%, which is very acceptable. The closer to 0 it is, the better and there is no mass error. Overall, these are very good values.

• Now plot the graphs in Hypergraph 2D. We can switch to it using the same client selector option in the toolbar.
• In the Hypergraph section, we need to input a file. For this, we will be using the result file generated by the RADIOSS solver (also known as the 'T01 file'). This file is available in the same directory as the starter, engine, and animation files. The file name ends with 'T01'.

CASE 2

• The process is repeated with slight changes. Just as last time, we import “FAILURE_JOHNSON_0000.rad” via the solver deck.
• This time, we make some changes to the fail/JOHNSON card. It can be accessed via the model tab, under the “Failures” submenu.
• The following values are assigned as shown below (Ifail_sh = 1, Dadv = 1, Ixfem = 1)
• Ifail = 1,which determines the Shell element Failure method. So there are two ways in which we can see the element failing, the element will either get deleted or in some cases the cracking occurs according to the material properties.
• Ixfem: In this, we can choose that if there is any element that is failing we want that element to delete or we want the element to be crack.We are going to take Ixfem=1. Which allow failed element to cracked not to delete.
• Dadv :It gets activated when we have taken Ixfem=1. We are going to takeDadv=1. Which gives the criteria that how much an element can get break into small pieces. If it goes beyond the limit the element gets delete

• Now run the analysis and the file is saved as “Law2_epsmax_crack_0000.rad”. With connectors ticked and '-nt 4' typed in the options box, we can click the Radioss button to run the analysis.
• After the solver window completes the analysis, as usual, switch to HyperView window and run the h3d file of the current analysis - Law2_epsmax_crack.h3d and set the Von Mises stress contours:

• Now, check the energy and mass error on the RADIOSS output file Law2_epsmax_crack_0001.out
• The energy error is decent enough and is lesser than 5% and mass error is non-existent. We can go ahead and switch to Hypergraph to plot the graphs.

CASE 3

• Again, we need to switch to Hyper works and import the solver deck file “Law2_epsmax_crack_0000.rad”, the starter file created in the previous case.
• In this case delete the fail/JOHNSON card. Go to Failures > Failure_JOHNSON_1.

• Now run the analysis and the file is saved as “Law2_epsmax_nofail_0000.rad”. With connectors ticked and '-nt 4' typed in the options box, we can click the Radioss button to run the analysis.
• After the solver window completes the analysis, as usual, switch to HyperView window and run the h3d file of the current analysis - Law2_epsmax_nofail.h3d and set the Von Mises stress contours

• Now, check the energy and mass error on the RADIOSS output file Law2_epsmax_nofail_0001.out
• The energy error is almost 0 and the mass error is non-existent. Now we can switch to Hypergraph to plot the graphs.

CASE 4

• In this case, import the case 3 starter file - Law2_epsmax_nofail_0000.rad.
• This time, delete the EPS_p_max value (make it as 0). Going to the model tab, we can go to Materials > Aluminium as shown below

Modifying EPS_p_max in materials

• After that, we can switch to the Radioss analysis section via Analysis > Radioss, save the file as 'Law2_0000.rad', enable connectors and type in '-nt 4' in the options section and run the analysis by clicking 'Radioss'.
• After the solver finishes its analysis, we can switch to Hyperview, run “Law2.h3d”, activate the Von Mises contours and view the simulation

• Now, check the energy and mass errors on “Law2_0001.out”
• The energy error is less than 5% and mass error is non-existent.

CASE 5

• In this case import the main starter file - FAILURE_JOHNSON_0000.rad.
• After that, go to Materials card > Aluminium and change the card image to M1_ELAST, which is Law 1.
• Also set the values for Rho_Initial, E & Nu as follows:
  Rho_initial = 0.0028, E = 71000.00, nu = 0.33.

• Now do the analysis and save the file as “Law1_0000.rad”. Just as before, enable connectors and type '-nt 4' in the options box. Then, we can click radioss and let the solver run the analysis.
• After the solver completes the analysis, we can switch to Hyperview, import the 'Law1.h3d' file, enable the Von Mises contours and view the simulation:

• Now, check the energy and mass error on the RADIOSS output file Law1_0001.out
• The energy error is less than 5% and the mass error is non-existent. We can then switch to Hypergraph to plot the graphs for this simulation

CASE 6

• In this case, import the 'LAW27_0000.rad' file.
• We need to use recommended shell properties in this case. Go to Properties > 5NiP. Now, we can look at the utility window and set the following attributes as follows:
  
  I_shell=24, I_smstr=2, I_sh3n=2, N=5, I_thick=1, I_plas=1

• Now, run the analysis via the Radioss tool. This time, we can save the file as 'Law27_0000.rad'. Just as before, we can enable connectors and type '-nt 4' in the options box. Then, we can click radioss and let the solver run the analysis.
• After it's done, we can generate the simulation via Hyperview with the Von Mises contours enabled as shown

• we can check the energy and mass errors on “Law27_0001.out”
• The energy error is very close to 0 and the mass error is non-existent.

CASE 7

• In this case import 'LAW27_0000.rad' again. We shall be editing certain attributes in this case.
• Go to the model tab and here, we shall be creating a new curve (as per instructions given in the week-4, Materials 7 video). Right-Click >> Create >> Curve
• Initially, there are 4 curves, we are adding the new curve named CASE7.

• Now go to Materials >> Aluminium and change the card to M36_PLAS_TAB (Law 36). After that, set the values for Rho_Initial, E & Nu as follows:
  Rho_initial = 0.0027, E = 71000.00, nu = 0.33.
• We can then add the curve using the N_funct attribute. We can change its value to 1 and by doing so, it lets us select the reference curve. We shall select the one we just made.
• Now run the analysis using the Radioss tool via Analysis > Radioss. The same process, as in previous cases, is repeated. This time, we shall name the file “LAW36_0000.rad”.
• After the analysis is complete, we can switch to Hyperview and import 'LAW36.h3d'. With Von Mises contours enabled, we can view the simulation

• An energy error of -1.1% is very acceptable since it's very close to 0. As usual, the mass error is non-existent. Now we can switch to Hypergraph to plot the graph for this simulation

Comparison of all 7 Cases

Case	No. of cycles	Mass Error	Final Energy Error	Solver simulation processing time	Condition of elements under excessive stress
Case-1	49380	0	0.8%	57.82	Deleted
Case-2	49217	0	4.1%	409.05	Elements undergo crack formationand then deletion
Case-3	49408	0	0.8%	252.43	Deleted
Case-4	48737	0	1.1%	251.78	Cannot be deleted due to lack of failure card and high default EPS_p_max value
Case-5	47969	0	1.3%	194.29	Cannot be deleted due to elastic card property
Case-6	49508	0	0.8%	358.51	Deleted
Case-7	53143	0	-1.8%	295.30	Deleted