Assignment 4-RADIOSS Material Laws Challenge

Case 1:-  Rupture test 1 

 Epsmax failure Criteria

The elapsed time for the simulation along with the energy error accounted for are given below.

Energy error 

The energy error is .8% which is acceptable and less than 15% and the mass error is 0%. Hence the simulation is stable and ready to be analyzed.

The various energy plot was plotted and it was seen that the total energy was constant throughout the simulation. The hourglass was not recorded which means the simulation was stable. The internal energy and the Kinetic energy of the system increased as it absorbed energy during collision and rupture.

PLOT OF ALL PERMISSIBLE ENERGIES 

Plastic strain 

Von mises stress 

The elements fail after 15% for the plastic strain after the yield stress of 290 Mpa and the max stress in the simulation is 275 Mpa. 

The elements get deleted because the johnson cook failure model is applied to it which accounts for the tensile and the compressive stress so when the elements reach the Eps_max Value of 15% they are deleted as seen above.  

Case 2:-

 Epsmax failure criteria with modified Failure card.

The elapsed time for the simulation along with the energy error accounted for are given below.

Energy error 

The energy error is 4.1% which is acceptable and less than 15% and the mass error is 0%. Hence the simulation is stable and ready to be analyzed. 

The various energy plot was plotted and it was seen that the total energy was constant throughout the simulation. The hourglass was not recorded which means the simulation was stable. The internal energy system increased as it absorbed energy during collision and rupture.

Plastic strain

Von Mises Stress

The maximum stress in the simulation is 295.1MPa which is higher than the previous simulation. crack development can be seen in the simulation.
since the crack advancement is set the maximum value of 1 and Ifail_sh is activated for shell elements, we can see the crack is generated in the simulation.

Case 3:- 

 Epsmax failure criteria with no Failure card.

The elapsed time for the simulation along with the energy error accounted for are given below.

Energy error 

The energy error is 0.8% which is acceptable and less than 15% and the mass error is 0%. Hence the simulation is stable and ready to be analyzed. 

The various energy plot was plotted and it was seen that the total energy was constant throughout the simulation. The hourglass was not recorded which means the simulation was stable. The internal energy system increased as it absorbed energy during collision and rupture.

Plastic strain 

Von Mises Stress

The pre-defined failure model was deleted so as soon as the elements cross over the 270.7 Mpa stress it gets deleted as the cracking criteria were also removed.

Case 4:- 

 Epsmax failure criteria with Epsmax set to 0.

The elapsed time for the simulation along with the energy error accounted for are given below.

Energy error 

The various energy plot was plotted and it was seen that the total energy was constant throughout the simulation. The hourglass was not recorded which means the simulation was stable. The internal energy system increased as it absorbed energy during collision and rupture. 

Plastic strain 

Von Mises Stress

The elements had no failure criteria so they experienced the max stresses throughout the simulation. The max stress developed was 424.7 Mpa

Case 5:- 

Rupture Criteria with elastic material definition.

The elapsed time for the simulation along with the energy error accounted for are given below.

Energy error

The various energy plot was plotted and it was seen that the total energy was constant throughout the simulation. The hourglass was not recorded which means the simulation was stable. The internal energy system increased as it absorbed energy during collision and rupture. 

But the material was stipulated as an elastic material so the stress-strain graph was linear 

Plastic strain 

Von Mises Stress

The elements had no failure criteria so they experienced the max stresses throughout the simulation. There was a linear relationship between the stress and strain as the material was defined under M1 ELAST the max stress developed was 1089 Mpa.

Case 6:- 

Rupture criterion with Brittle material Definition.

The elapsed time for the simulation along with the energy error accounted for are given below.

Energy Error 

Various energy was plotted and it was been the kinetic energy was stable and rose till the rupture was continuing, after the final rupture all the energy balance was maintained and thus simulation is a valid one. 

Plastic Strain

Von misses Stress

 Based on the animation we see that the elements don't just disappear but also form localized groups of shell elements which denotes the rupture being brittle and cracking.

The plate gets ruptured but it breaks rather than disappear, thus also denoting the stiffness of the material. Max Stress-induced in the model was 287.47 Mpa

Case 7 

Rupture plate with isotropic elastoplastic material definition. 

The elapsed time for the simulation along with the energy error accounted for are given below.

ENERGY ERROR

The energy error was negative which accounts for 2.1% of energy loss thus indicating some energy was lost due to rupture of the rigid ball hitting the plate. 

The material card defined was Law 36 Plast tab.

This law models an isotropic elastoplastic material using user-defined functions for the strain hardening portion of the stress-strain curve for different strain rates. 

Fsmooth, Vp is the Smooth strain rate option flag and Strain rate choice flag respectively.

The Fsmooth smoothens the strain curve for the simulation while the Vp has two values:- (0) Strain rate effect on yield stress depends on the total strain rate.

                                                                                                                                  (1)Strain rate effect on yield depends on the plastic strain rate. In this case, there is no strain rate filtering

Law 36 is the user-defined function for stress and strain and it was considered for the simulation. 

Various energy was plotted and it was been the kinetic energy was stable and rose till the rupture was continuing, after the final rupture all the energy balance was maintained and thus simulation is a valid one.

Plastic stresses 

Von Mises 

The plastic strain was induced in the model and since Fsmooth was set to 1 the strain rate was smoothened thus the materials broke before disappearing and the maximum stress acting on the material model was 1133Mpa. 

The plastic strain for all the simulations.

 The stresses of all the simulations. 

The comparison table.

Based on the stresses developed in the material, and given material data for aluminum with a yield stress of 290Mpa and
the maximum stress of 424.7MPa, case 2 presents the on-field scenario compared to the rest of the cases

Conclusion:-  The comparison between different material cards and failure cards has been carried out by applying them to the given simulation                             model. Element behavior and stress development has been discussed. Based on the observation of results: case 2 presents the
                     the best on-field scenario in the simulation.