Challenge

Assignment 4-RADIOSS Material Laws Challenge

VVijayaragavan R28 Feb 2024

Aim:

To run the simualtion for the plate and rigid ball by using Jhonson Cook Material and Elasto Plastic Material with Brittle Failure as per the cases given in the question by using Radioss solver.

Objective:

Run the simulation for all the 7 cases as given in the question.
Run the simulation by changing the material,shell properties and failure parameters.
Run the simulation by converting Failure Jhonson Model to LAW 1.
Tabulate the total number of cycles, Energy Error,Mass Error and Simulation Time.
Plot the graphs for all the 7 cases.
Compare all the 7 cases results.

Theoritical:

In FEA,the materials are specified to conduct simulations and analyze how a particular material behaves under certain stress and loading conditions.
The attention should be provided to the material type chosen and the material properties provided. There could be different material properties needed as input to fully characterize a material for analysis purposes. Any unclear or illogical data provided during material characterization will lead to uncertain results.
Choosing the right material and providing the reliable material data in performing a simulation is very important.
RADIOSS provides one of the most comprehensive material and rupture libraries in the industry. The material laws and rupture criteria span across definitions for concrete, foam, rubber, steel, composites,biomaterials, and more.
In Radioss,We are specifying the materials and type,The materials are categorized in two forms called,
In the form of material cards[material law].
In the form of material properties.
In the form of material card [Material Law]:

Law 1 – Elastic.
Law 2 – Johnson-Cook.
Law 27 – Elastic-Plastic Brittle.
Law 36 – Elastic-Plastic Tabulated.
Law 42 – Ogden (Visco Hyperelastic).
Law 70 – Foam.

In the form of material properties:

Isotropic Elasticity.
Isotropic Elasto-Plastic.
Composite and Anisotropic.
Viscous.
Hydrodynamic.
Explosives.

Law 1 (Isotropic Elasticity):

This Law /MAT/ELAST defines an isotropic, linear elastic material using Hooke’s law. This law represents a linear relationship between stress and strain. It is available for truss, beam (type 3 only), shell and solid elements.
Useful for elements attached to rigid body.This material law is used to model purely elastic materials.
This law is only applicable for small deformations.
The material stiffness is determined by only two values: the Young’s modulus (E), and Poisson’s ratio (ν">ν ).
The shear modulus (G) can be computed using E and ν">
G=E2(1+ν)">G=E2(1+ν)

Isotropic Elasto-Plastic:

A built-in failure criterion based on the maximum plastic strain is available.
This model expresses materialstress as a function of strain, strain rate and temperature.
This law represents an isotropic elasto-plastic material using the Johnson-Cook material model.

Law 36 ( Isotropic Elastic Plastic Piecewise Linear Material ):

This is a Isotropic elasto-plastic material.
It's a user-defined function for the work-hardening portion of the stress-strain curve.
It's available for brick and shell elements.
Elastic portion of material stress-strain curve defined by Young modulus and Poisson’s ratio.
Material plasticity curves can be given for up an arbitrary number of strain rates.
Linear interpolation of strain-stress curve.
i) For a given strain rate.
ii) For a given plastic strain.
In order to avoid poor curve extrapolation during the strain calculation, a dummy curve defined for a high strain rate value can be added in the model—typically the highest strain rate curve is repeated.
The curves have to be defined such as they don’t intersect themselves in the strain range being used. Otherwise the calculationmay fail.

Law27 [Elasto-Plastic Material with Brittle Failure] :

This law combines an isotropic elasto-plastic Johnson-Cook material model with an orthotropic brittle failure model.
Material damage is accounted for prior to failure. Failure and damage occur only in tension. This law is applicable only for shells.
Yield surface definition same as Johnson-Cook (Law2).
Useful for modeling brittle failure of glass.
Damage and rupture defined with 4 parameters for each principal direction.

The viscous materials are classified into two types called

1) Hyper Elastic [/MAT/OGDEN or /MAT/LAW42 : Ogden, Mooney-Rivlin].

2) Tabulated Foam [/MAT/FOAM_TAB or /MAT/LAW70: Tabulated Foam].

PROCEDURE:

Case 1(Import the FAILURE_JOHNSON_0000.rad file and run the model as it is. Give the title name as Law2_epsmax_failure.)

While opening hypermesh software,A user profile window will pop up,Switch to the radioss user profile as shown in below figure 18 and start importing the model into the solver deck.
Now after switch the user profile to radioss,import the model (starter file) into the radioss solver deck.
To import the model,Go to Standard Panel >> Import >> Import Solver Deck.
Import Solver Deck option should be selected to import the radioss starter file.
Now after importing the model into the GUI,Go to the solver browser and select the begin card to inorder to check the unit system

Now go and check the material card by selecting it in model browser inorder to check whether the appropriate properties have been assigned or not,The material property card.

Now go and check the property card.In the property the parameters have been assigned to the material given.

Now go and check the property card.In the property the parameters have been assigned to the material given.
Go to Analysis Panel >> Radioss >> Select the Input File >> Save it in Different Folder and Rename it as Law2_epsmax_failure. >> Run.
Check the Include Connectors,If there are any connectors in the model,The connectors will also be taken into account.
Type -nt 4 in options tab,This will make the simulation faster.
Where "nt" indicates No of threads,4 indicates assigning the task to 4 cores in the system.

Here save the input file in a different folder, and rename it as case-1 " Law2_epsmax_failure".
Now run the solver by hitting on radioss.
After completing the simulation,the radioss will pop up a solver window stating Radioss Job Completed which indicates the simulation has been completed.

After running the simulation,The animation files will be generated .

Now go and open the 00001.out file with notepad.

The obtained values for[Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error ].

The values obtained for this cycle are,

Energy error - 0.8%
Internal energy - 0.2721E+05
Kinetic energy - 67.81
External work - 0.2730E+05
Elappsed time - 94.89 s
Mass error - 0
Total no. of cycles - 49379

POSTPROCESSING :

1) Review the Simulation using -HyperView.

2) Plot the graphs using -Hypergraph 2D.

1) Review the Simulation using -HyperView:

Hyperview allows for loading and viewing result files obtained from several sources.
Based on the solver type of the files and the results you would like to visualize and analyze,there are differnt ways to load the input deck and their corresponding results into hyperview.
First to begin the postprocessing in the Hypermesh,Split the Screen
Import the animation file .h3d into the hyperview.

And then activate the Client HyperView.

To access the load model panel.
Select Load Model Button from the HyperView Panel and open .h3d file.

After loading the model into hyperview,It will be represented.

After importing the .h3d file into the GUI,Enable the contour.
The contour tool create contour plots of a model graphically visualize the analysis results.

To enable contour,Go to Results ToolBar >> Contour .
Now switch to the Von Misses Stress in result type and select the component,select the averaging method as simple and then click apply .
After applying ,Run the Simulation,The Simulation animation.

2) Plot the graphs using -Hypergraph 2D:

Now plot the graphs using Hypergraph 2D,We are plotting the graphs to see what is happening in the rail component.
Hypergraph 2D is a powerful data analysis and plotting tool with interfaces to many popular file formats.
It is sophisicated math engine capable of processing even the most complex mathematical expressions.
Hypergraph 2D combines these features with high quality presentation output and customization capabilities to create a complete data analysis system for any organization.

The first graph is plotted for the Rigid Wall Forces.

Rigid Wall Forces :

Here,Intially there is no contact between the plate and rigid wall.So the curve is in origin.
When the rigid ball hits on the rupture plate,the curve starts increasing and suddenly the curve starts decreasing,
Cause after reaching the ultimate stress,the elements gets deleted and there will be no contact after the elements gets deleted .
Animation,So the curve goes down and decreasing.
Now plot the graphs for all the energies.

All Energies Graph :

Internal energy:

Here the internal starts from origin why because there is no contact between rigid ball and rupture plate.
Then the internal energy goes on increasing,why because the deformation or displacement is happening,when the displacement increases the internal energy increases.

Kinetic energy:

Here the kinetic energy is in origin,Why because there is no initial velocity,there is a imposed velocity.
The impose velocity is for rigid ball,Why because we are imposing the rigid ball to hit on the rupture plate,So that's the reason,why impose velocity is given.
The formula for Kinetic Energy=12MV2">12MV212��2.
Here the initial velocity is zero,So the curve starts from origin.
After its increasing because,rigid ball is hitting rupture plate and again its slightly decreasing due to element breakage,After the elements deleted,there will be no contact,So its decreasing.
Why Kinetic Energy Curve is Zig-Zag ?🤔
Cause the Noise and Vibrations will be produced when the rigid ball hits the rupture plate,so the kinetic energy curve is in Zig-Zag form.

Total Energy :

Total Energy is sum of Kinetic Energy+Contact Energy+Hourglass Energy + Internal Energy.
Total Energy is the combination of all energies.
So its goes on increasing,Internal energy curve is similar to the total energy.

CASE_2:(Import the case 1 rad file, named “Law2_epsmax_failure” and perform the simulation with failure plastic strain (EPS_p_max) and fail_Johson card enabled.

Changes to be made in /FAIL/JOHNSON card:)

Here the Jhonsons Failure card is edited,and the values have been given in the failure card as per the values given the question.
But the law is same [LAW 2],Only the failure card is edited.
The values which are to be changed are Ifail_sh=1,Dadv=1,Ixfem=1.

The values have been given in the failure card .

Now run the simulation using radioss,After running the simulation,The animation and TH files will be obtained in a required location.
Now go and open the 00001.out file with notepad.
The obtained values for Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error .

The values obtained here are ,

Energy error - 4.1%
Internal energy - 0.3082E+05
Kinetic energy - 141.9
External work - 0.2980E+05
Elappsed time - 86.99s
Mass error - 0
Total no. of cycles - 49216

1) Review the Simulation using -HyperView :

After completion of running the simulation,Switch to the hyperview.
Open the appropriate .h3d file to review the simulation.
The .h3d file is loaded.

Here the maximum Eps_Max value =0.151,The elements should be deleted after reaching the Eps_Max=0.151.
But here the maximum strain shown here is 1.426E-01 which is 0.147,Why ?⋆">
Because the solver won't record when the elements get deleted,So this is the reason.
The elements will be failing and getting deleted,when the rigid ball goes on hitting the rupture plate.

2) Plot the graphs using-Hypergraph 2D:

Now switch to the Hypergraph 2D and plot the graphs.
The rigid wall forces graph is plotted.

Rigid Wall Forces

Here the curve starts from origin,because there is no contact and it goes on increasing because the deformation happens (rigid ball comes into the contact with rupture plate).
Again its suddenly decreasing,Cause the elements are cracked and deleted,there will be no contact between rigid ball and rupture plate,So its slightly decreasing.
The graph is plotted for the internal energy.

Internal Energy :

Here the curve is starting from the orgin because there is no contact and it goes on increasing due to the breakage of elements.

Kinetic Energy :

Here the kinetic energy starts from origin and goes on increasing due to deformation of elements.
Its increasing after 4ms because the deformation of elements are controlled by jhonson cook material parametrs.
And its suddenly decreasing because the elements getting deleted after crack and there will no contact,so its slightly decreasing.

Total Energy :

Total Energy is sum of Kinetic Energy+Contact Energy+Hourglass Energy + Internal Energy.
Total Energy is the combination of all energies.
So its goes on increasing,Internal energy curve is similar to the total energy.

CASE_3:(Import the case 2 rad file, named “Law2_epsmax_crack” and perform the simulation by removing the fail_Johnson failure card. Give the title name as Law2_epsmax_nofail.)

Here the failure card is deleted to see any changes happening the result.

Now run the simulation using radioss,After running the simulation,The animation and TH files will be obtained in a required location.
Now go and open the 00001.out file with notepad.
The obtained values for Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error .

The values obtained for this cycle are,

Energy error - 0.8%
Internal energy - 0.2744E+05
Kinetic energy - 87.8
External work - 0.2736E+05
Elappsed time - 90.73s
Mass error - 0
Total no. of cycles - 49407

1) Review the Simulation using -HyperView :

After completion of running the simulation,Switch to the hyperview.
Open the appropriate .h3d file to review the simulation.
The .h3d file is loaded.
Here the shell elements are getting deleted,when it reaches the maximum plastic strain epsmax value.

2) Plot the graphs using-Hypergraph 2D :

Now switch to the Hypergraph 2D and plot the graphs.
The rigid wall forces graph is plotted.

Rigid Wall Forces :

Here the graph plotted for the case 3 rigid wall forces is very similar to case 1 rigid wall forces.

Internal Energy:

The internal energy graph is plotted.
Here the internal energy is also somewhat similar to the previous cases 1 and 2.

Kinetic Energy:

The kinetic energy obtained here is somewhat less when compared to the previous case,The obtained kinetic energy graph .

Total Energy:

The total energy increases with increase in internal energy and kinetic energy,Cause the total energy is combination of all energies.
The obtained total energy graph.

CASE 4:(mport the case 3 rad file, named “Law2_epsmax_nofail” and perform the simulation by removing both the failure plastic strain (EPS_p_max) and the fail_Jhonson failure card.)

Here delete the value of EPS_P_Max value and run the model with the name LAW2 but the same material card.
The value of plastic strain is removed.

Now run the simulation using radioss,After running the simulation,The animation and TH files will be obtained in a required location.
Now go and open the 00001.out file with notepad.
The obtained values for( Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error )

The values obtained for the cycle are:

Energy error - 3.0%
Internal energy - 0.6487E+05
Kinetic energy - 2.969
External work - 0.6298E+05
Elappsed time - 94.68s
Mass error - 0
Total no. of cycles - 48736

1) Review the Simulation using -HyperView.

After completion of running the simulation,Switch to the hyperview.
Open the appropriate .h3d file to review the simulation.
The .h3d file is loaded.
Here EPS_P_Max=0,So the shell elements will not be deleted .

2) Plot the graphs using-Hypergraph 2D.

Now switch to the Hypergraph 2D and plot the graphs.
The rigid wall forces graph is plotted.

Rigid Wall Forces :

Here the rigid wall forces starts from origin cause there will be no contact in the beginning and it goes on increasing cause deformation is happening to the plate.
And the curve slightly decreases because of the elements breakage.

Internal Energy :

The internal energy graph is plotted which is shown below in Figure 64,her internal energy is somewhat similar to the previous case.

Kinetic Energy :

The kinetic energy is plotted, which is shown in below Figure 65.The kinetic energy is also somewhat similar to the previous case.
Kinetic Energy produced here is little bit less cause deformation of elements is happening slowly.

Total Energy :

The total energy is almost similar to the internal energy.
The total energy graph is plotted.

CASE 5:(Import the case 4 rad file and perform the simulation by changing the material card to Law 1. Keep the same value for rho, E, and nu values.)

Here change the material card to LAW1,Here it will be elastic behaviour.
Don't change any material properties,Use default material properties like
ρ = density,
E = youngs modulus and
ν = poissons ratio.

Now run the simulation using radioss,After running the simulation,The animation and TH files will be obtained in a required location.
Now go and open the 00001.out file with notepad.
The obtained values for Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error.

The values obtained for the cycle are:

Energy error - 1.3%
Internal energy - 0.8632E+06
Kinetic energy - 1677
External work - 0.8568E+06
Elappsed time - 87.73s
Mass error - 0
Total no. of cycles - 47968.

1) Review the Simulation using -HyperView.

After completion of running the simulation,Switch to the hyperview.
Open the appropriate .h3d file to review the simulation.
The .h3d file is loaded.
Here EPS_P_Max=0,So the shell elements will not be deleted .
The elements will not even split during the collison,Cause the LAW1 material card is assigned to the rupture plate.
So there will be an elastic behaviour[Ability to regain its original size and shape].

2) Plot the graphs using-Hypergraph 2D.

Now switch to the Hypergraph 2D and plot the graphs.
The rigid wall forces graph is plotted.

Rigid Wall Forces :

Here the rigid wall forces starts from origin cause there will be no contact in the beginning and it goes on increasing cause deformation is happening to the plate.
And the elements not getting deleted here,So its goes on increasing till to end.

Internal Eenergy :

Here the internal energy starts from origin because in the beginning ,the rigid ball is not in contact to the plate.
Its increasing when the rigid ball hits the rupture plate,its goes on increasing.
The graph obtained for internal energy.

Kinetic Energy :

Here kinetic energy is in initial condition,so its starts from origin.
It increases when the rigid ball hits the rupture plate.
And its slighlty decreasing,because after hitting the rupture plate,the rigid ball goes back to its position and there will be no contact.

Total Energy:

The total energy increases with the increase in kinetic energy and internal energy,The graph obtained for total energy.

CASE 6:(Import the case 1 rad file, named “Law2_epsmax_failure” and perform the simulation with the law 36 material card)

Here change the material card to LAW36.
A shell paremeters are changed to the recommended parameters.
It's a elasto plastic piecewise linear material.

After Defining the material card,We have to define a stress strain curve for this material.
We only want plastic region out of it,So we have to define a curve using given plastic strain and post-yield stress value manually.
The curve will be defined based on the values.
To create a Curve,Right Click on the Model Browser >> Create >> Curve >> Window Will Pop Up >> Define a Curve using Platic Strains and Post-Yield Stress Values.

[Note:For this material,we need only plastic region,So thats the reason we are defining only plasticity with the Plastic Strains and Post-Yield Stress Values.]

Now run the simulation using radioss,After running the simulation,The animation and TH files will be obtained in a required location.
Now go and open the 00001.out file with notepad.
The obtained values for Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error.

The values obtained for the cycle are:

Energy error - (-1.8)%
Internal energy - 0.3852E+05
Kinetic energy - 334.1
External work - 0.3992E+05
Elappsed time - 77.43s
Mass error - 0
Total no. of cycles - 53142.

1) Review the Simulation using -HyperView.

After completion of running the simulation,Switch to the hyperview.
Open the appropriate .h3d file to review the simulation.
The .h3d file is loaded and it.
Here the shell elements will be deleted once it reaches maximum plastic strain.
Cause the material is assigned with both elastic and plastic.

2) Plot the graphs using-Hypergraph 2D.

Now switch to the Hypergraph 2D and plot the graphs.
The rigid wall forces graph is plotted.

Rigid Wall Forces :

Similarly as explained for the above case-1.The graph obtained for the rigid wall forces.
Here the elements are getting when it reaches maximum plastic strain.

Internal Energy :

The internal increases as same as in previous case.
The obtained graph for internal energy.

Kinetic Energy :

The kinetic energy is somewhat similar to the case-5.
The obtained kinetic energy graph.

Total Energy :

The total energy increases with increase in internal energy and kinetic energy.
The obtained graoh for total energy.

CASE 7:(Open the Law27_0000.rad file and perform the simulation with the law 27 material card. Use the recommended shell properties.)

Here change the material card to LAW27 and change the shell properties to the recommended shell peroperties.
It is an isotropic elastoplastic jhonson cook material model with an orthographic brittle failure mode.

Now run the simulation using radioss,After running the simulation,The animation and TH files will be obtained in a required location.

Now go and open the 00001.out file with notepad.
The obtained values for Energy Error,Mass Error,Internal Energy Error,Kinetic Energy Error and Contact Energy Error.

The values obtained for the cycle are:

Energy error - 0.8%
Internal energy - 0.2954E+05
Kinetic energy - 65
External work - 0.2940E+05
Elappsed time - 89.20s
Mass error - 0
Total no. of cycles - 49506.

1) Review the Simulation using -HyperView.

After completion of running the simulation,Switch to the hyperview.
Open the appropriate .h3d file to review the simulation.
The .h3d file is loaded and it .
Here the shell elements will be deleted due to brittleness .

2) Plot the graphs using-Hypergraph 2D.

Now switch to the Hypergraph 2D and plot the graphs.
The rigid wall forces graph is plotted.

Rigid Wall Forces :

The rigid wall forces starts increasing due to impact and decreases gradually,Because the elements are getting deleted and there will be no contact.
The rigid wall forces graph obtained.

Internal Energy :

Here the internal energy is similar to the previous case-3,The obtained internal energy graph.

Kinetic Energy :

Here the kinetic energy obtained is somewhat similar to the case-3 kinetic energy,The kinetic energy obtained.

Total Energy :

The total energy increase with increase in internal energy and kinetic energy,The obtained total energy graph.

Comparison of all the 7 Cases :

TOTAL

CASE	ENERGY ERROR	INTRNAL ENERGY	KINETIC ENERGY	EXTERNAL WORK	MASS ERROR	ELAPSED TIME	NO. OF CYCLES	MATERIAL USED	CHANGES IN MATERIAL PARAMETERS	ELEMENT FAILURE BEHAVIOUR
1	0.8	0.27213E+05	67.81	0.2730E+05	0	94.89	49379	Johnson cook [Law 2]	Used default parameters and runned the stimulation	Elements deleted
2	4.1	0.3082E+05	141.9	0.2980E+05	0	86.99	49216	Johnson cook [Law 2]	Changed the values for i Fail,Dadv,ixfem	Elements will be cracked and deleted
3	0.8	0.2744E+05	87.8	0.2736E+05	0	90.73	49407	Johnson cook [Law 2]	Removed the failure card from the model browser	Elements deleted
4	3	0.6487E+05	2.969	0.6298E+05	0	94.68	48736	Johnson cook [Law 2]	Removed the failure plastic strain [EPS_p_max] and fail_johnson failure card	Elements deformed ,cracked but not deleted
5	1.3	0.8632E+06	1677	0.8568E+06	0	87.73	47968	Elastic [Law 1]	Changed the material card to Law1 and keeping the same value for E,rho,nu	Elements deformed ,cracked but not deleted
6	-1.8	0.3852E+05	334.1	0.3992E+05	0	77.43	53142	Elasto_Plastic_Tabulated [Law 36]	Changed the material card to Law 36 and runned the stimulation	Elements deleted
7	0.8	0.2954E+05	65	0.2940E+05	0	89.20	49506	Elasto_Plastic_Brittle [Law 27]	Changed the material card to Law 27 and used the required element parameters	Elements deleted

RESULTS:

Hence the simulation for all the cases were carried out with different materials laws.
Hence the simulation for all the cases were runned successfully.
Hence the simulation for all the cases were reviewed by hyperview.
Hence the graphs were plotted for all the cases successfully.
Atlast,Compared all the results for those cases.

CONCLUSION AND LEARNING OUTCOMES:

I conclude that LAW 36 is more suitable in real world testings,Cause it shows the behaviour of Elasticity and Plasticity in real world.
In this challenge,I came to know bout
The different materials cards and their behaviour.
The failure criteria for the material cards.
How the deformation is happening for the elements from material cards.
Damage and rupture parameters.
How to define a plastic region curve with plastic starin and post-yield stress values.

Assignment 4-RADIOSS Material Laws Challenge

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Ship work like thisin your own course.

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Ship work like this
in your own course.