Assignment 4-RADIOSS Material Laws Challenge

• Objective :
• The main objective is to compairing of the Law 2 , Law 1 , Law 27 and the Law 36 with each other .
• Study of this Laws by Comparing them into the Seven different cases .
• Analysis of the Bahavior of the Energies ,deformation of the Given Model for seven different cases .

Case 1 :

Law2_epsmax_failure model :

• In this Model , The FAILURE_JOHNSON_0000.rad file is imporeted using the Import solver deck Tool .

• Then its Elemental shell properties are checked and changed to the Recommonded if needed .

• Now this Model is made to run by the name of Law2_epsmax_Failure using the Analysis - Radioss Tool .

Results :

• In engine card the Simulation run time was set to the 5.01 miliseconds .
• The Total Number of the cycles are 49380 .
• From the Engine Out file , we can see that the Energy Error is in between -0.3 % to + 0.8 % which is acceptable for further process .
• The Energy error for the acceptance is ranges from - 15 % to + 5 % .
• The Mass Error for this model is Zero .
• The acceptable Mass Error is about max 2 % of the Total Mass of the model .
• Due to improvement in the shell properties to the recommonded , the Hourglass Energy and Contact Energy is stabalized very much to the Zero .

• Then this model Simulated in the Hyperview .
• From the simulation we can clearly see that Once the punch start to penetrate the Shell , the elements started to fail directly .
• For failure of the elements the M2_PLAS_JOHN_ZERIL / Law2 , in which the maximum Eps_max value is used for element as failing criteria .
• In Law2 the Strain rate is not taken into account .
• Once the Starin in the Elements is reaches to the Maximum Plastic Strain . It's gets deleted
• Here formation of the crack will not be happen as the values of the Ifail_sh , Dadv and Ixfem are set to zero .

Plots :

Rigid wall Resultant force

Internal energy

Kinetic Energy

Contact Energy

Hourglass Energy

Total Energy

Case 2 :

Law2_epsmax_crack :

• For importing the model Radioss setup is done with Solver deck the FAILURE_JOHNSON_0000.rad file is imported .

• In FAIL/JOHNSON/ failure Card , values of ifail_sh changed to 1 , Dadv to 1 and Ixfem to 1 .
• Then Model is made to run with Name as Law2_epsmax_Crack using the Analysis-Radioss Tool .

Results :

• The Run time is same as 1st case of 5.01 milisecond .
• Number of Cycles are 49217 .
• From the Engine out file The Energy Error is in between -0.3 % to +4.1 % .
• The Mass Error is about 0 .
• The Acceptable errors for energy error and the mass error are Between -15 % to + 5 % and maximum + 2% of the total mass
• Hence the Results are acceptable .
• The Crack Formation can be seen below .
• Elements are deleted when they reached to the Maximum Strain value ( eps_max ) .

• This Crack propagation happed becuase of the change in value of the ifail_sh = This parameter is used to define the Shell failure point .
• Whether shell will crack or gets deleted is controlled by this parameter .
• Dadv is the Criteria for the Crack advancement .
• This Dadv value changes only Real between 0 and 1 .
• Maximum accumulation damage value D , is used for the Crack initiation .
• This Dadv will be active only if Ixfem = 1 .
• Ixfem is Failure Criteria for the Element Crack Formation instead of the element or layer deletion .
• This Ixfem only compitable with the with BT Q4 (I_shell=1, 2, 3 or 4), and QEPH (I_shell=24) shell elements .
• Due to improvement in the shell properties to the recommonded , the Hourglass Energy and Contact Energy is stabalized very much to the Zero .

Plots :

Rigid wall Resultant force

Internal energy

Kinetic Energy

Contact Energy

Hourglass Energy

Total Energy

Case 3 :

Law2_epsmax_nofail :

• For importing the model Radioss setup is done with Solver deck the FAILURE_JOHNSON_0000.rad file is imported .
• In This case the Failure Card (/FAIL/JOHNSON card ) is Deleted and made to run the Simulation using Radioss Solver and the Hyperview

• The Run time is same as 1st case of 5.01 milisecond .
• Number of Cycles are 49408 .
• From the Engine out file The Energy Error is in between -0.3 % to +1.2% .
• The Mass Error is about 0 .
• The Acceptable errors for energy error and the mass error are Between -15 % to + 5 % and maximum + 2% of the total mass
• Hence the Results are acceptable .
• The Crack formation cannot be seen as the Failure card is deleted in which Crack Formation and the Crack advancement was defined .
• The Element deletion is the ramained only Parameter for Failing of the Elements .
• Elements are deleted when they reached to the Maximum Strain value ( eps_max ) .
• Due to improvement in the shell properties to the recommonded , the Hourglass Energy and Contact Energy is stabalized very much to the Zero .

Plots:

Rigid wall resultant force

Internal energy

kinetic Energy

Contact Energy

Hourglass Energy

Total Energy

Case 4:

Law2 :

• For importing the model Radioss setup is done with Solver deck the FAILURE_JOHNSON_0000.rad file is imported .
• In This case the Maximum Plastic Strain (EPS_p_max) is Deleted and made to run the Simulation using Radioss Solver and the Hyperview

Results :

• The Run time is same as 1st case of 5.01 milisecond .
• Number of Cycles are 49408 .
• From the Engine out file The Energy Error is in between -0.3 % to +11% .
• The Mass Error is about 0 .
• The Acceptable errors for energy error and the mass error are Between -15 % to + 5 % and maximum + 2% of the total mass
• Hence the Results are not acceptable .
• The only Crack formation can be seen becuase of the Failure card which Crack Formation and the Crack advancement was defined .

• As we deleted the maximum plastic strain value , There is no any parameter left for elements deletion criteria .
• Due to improvement in the shell properties to the recommonded , the Hourglass Energy and Contact Energy is stabalized very much to the Zero .

Plots :

Rigid wall resultant force

Internal Energy :

Kinetic Energy

Contact Energy

Hourglass Energy

Total energy

Case 5 :

Law 1 :

• For importing the model Radioss setup is done with Solver deck the FAILURE_JOHNSON_0000.rad file is imported .
• Imported Model is with Material Of Law 2 , which is converted to the Law 1 ( Elastic Material ) with ths same Young's modeulus , Density and the Possion Ratio .

Results :

• The Run time is same as 1st case of 5.01 milisecond .
• Number of Cycles are 49408 .
• From the Engine out file The Energy Error is in between -0.3 % to +4.9% .
• The Mass Error is about 0 .
• The Acceptable errors for energy error and the mass error are Between -15 % to + 5 % and maximum + 2% of the total mass
• Hence the Results are acceptable .
• As the Material is elastic , elements are only streched .

• The only Crack formation is not happing as the Material is elastic Which are deformed only in Elastic region of the Stress Strain curve accourding to the HOOks law
• As we deleted the maximum plastic strain value , There is no any parameter left for elements deletion criteria .
• Due to improvement in the shell properties to the recommonded , the Hourglass Energy and Contact Energy is stabalized very much to the Zero .

plots :

Rigid wall Resultant Force

Internal Energy

Kinetic Energy

Contact Energy

Hourglass Energy

Total Energy

Case 6 :

Law27 :

• For importing the model Radioss setup is done with Solver deck the Law27_0000.rad file is imported .
• In this model the Johnson Cook material card but with different Elemental failure criteria as shown in below ,

• LAW27 is used to simulate material damage using a Johnson-Cook plasticity law. A damage model is incorporated into the material law to take into account the damage evolution where stress decreases up to element rupture .
  
• EPS_t1 is starting strain produced in the elements , at which the elements start to damage . once the Principle stress reaches to SIGY value.
• EPS_m1 is the maximum Strain induced in the elements after which the stress in elements start to reduced , but still elements will not be deleted .
• EPS_f1 is the element failure strain value means when strain in the elements reaches to this value , elements gets deleted .
• Also The SHell elemental propertioes are improved to the recommonded values .

Results :

• The Law 27 used for the brittle material .
• Number of cycles are 49508 .
• The Run time is same as 1st case of 5.01 milisecond .
• From the Engine out file The Energy Error is in between -0.3 % to +0.8 % .
• The Mass Error is about 0 .
• The Acceptable errors for energy error and the mass error are Between -15 % to + 5 % and maximum + 2% of the total mass
• Hence the Results are acceptable .
• Initially small crack formation can be seen but after some time the Elements get damaged in pieces like structure .
• Because of the improved shell elements , The Hourglass energy and Contact Energy are reduced to the zero .

plots :

Rigid wall resultant force

Internal Energy

Kinetic Energy

Contact Energy

Hourglass Energy

Total Energy

Case 7 :

Law 36 :

• For importing the model Radioss setup is done with Solver deck the Law27_0000.rad file is imported.
• In this Model , values of in the Material card are edited provided in the material card for the Law 36 material .

• Young's Modulus value changed to the 71000 MPa . Eps_p_max = 0.16 , Eps_t1 = 0.1 and the Eps_t2 = 0.11 .
• Function curve is created accourding to the Value of the X and Y values by the name of Plastic-True-Stress-Strain curve and assigned this to material.

• Here the EPS_p_max is maximum Failure plastic Strain at which elements gets failed .
• EPS_t is Tensile Failure Strain at which stress in the material starts to reduce .
• EPS_m is maximum tensile failure Strain at which stress in the material becomes zero .
• The Shell elemental properties are changed to the reccomonded Properties .

• Then the Model is solved using the Radioss solver And made to run Using the Hyperview .

Results :

• The Law 36 used for the elasto- plastic material using the User defined Function .
• Number of cycles are 53143.
• The Run time is same as 1st case of 5.01 milisecond .
• From the Engine out file The Energy Error is in between -0.3 % to -1.9 % .
• The Mass Error is about 0 .
• The Acceptable errors for energy error and the mass error are Between -15 % to + 5 % and maximum + 2% of the total mass
• Hence the Results are acceptable .
• Initially small crack formation can be seen but after some time the Elements get damaged in pieces like structure .
• Because of the improved shell elements , The Hourglass energy and Contact Energy are reduced to the zero .

plots :

Rigid wall resultant force

Internal Energy

Kinetic Energy

Contact Energy

Hourglass Energy

Total Energy

Coclusion :

• In case 1 , the elements gets failed and deleted and crack formation is not happing , beacause of the Crack forming and advancements values are kept as 0 .
• In case 2 , The proper Crack formation and the element deltion process can be seen as values of the Ifail_sh , Dadv and Ixfem are changed to the 1 which will help to formation of the crack and propagation in the material , and Hence The crack formation and the Elements deltion is proper .
• In case 3 , Only element deltion can be seen as we have deleted the Failure Card .
• In Case 4 , Just Crack formation and the Propagation can be seen only as maximum elasti-plastic strain value is deleted .
• In case 5 , Elements are just streched as Law 1 is used , which Work accourding to the Hook's Law , Deformation happens only in the Elastic region , and hence material will be deformed but in the elastic region and once the load is removed material will be back to its original shape and size .
• In case 6 , This Model uses the Law 27 .LAW27 is used to simulate material damage using a Johnson-Cook plasticity law. A damage model is incorporated into the material law to take into account the damage evolution where stress decreases up to element rupture .
• In case 7 , in this model Law 36 is used , This law models an isotropic elasto-plastic material using user-defined functions for the work-hardening portion of the stress-strain curve (for example, stress vs. plastic strain) for different strain rates . Hence cracking the elements and deletion can be seen while simulation .