CASE STUDY ABOUT LAW 1,LAW 2, LAW 27 AND LAW 36 MATERIAL CARDS WITH DIFFERENT PARAMETERS USING RADIOSS SOLVER IN HYPERMESH.

OBJECTIVE:

The main aim of this project is to analyze the different material card cases given and to derive the case which represents the on-field scenario.

DESCRIPTION:

case1:

• imported the given failure_johnson_0.rad file in the hypermesh GUI.
• simulation is done with the material card of law2_PLAST_JOHNS and failure johnson card shown below.

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

Observation:

• the material seems to be stiff.
• there is a sudden rupture at 4.0001e+00 ms.
• where the internal energy increases gradually until the material gets rupture.
• the maximum vonmises stress observed is 2.752E+02 i,e.275.2 N/mm^2.
• there is a small peak in kinetic energy at the time of rupture.
• the number of cycles for the simulation is 49379.
• the energy error ranges from -0.6% to 1.3%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• the removal of elements is due to the values Ixfem=0(elements get removed) and equivalent plastic strain,eps_p_max=0.151 i,e.15.1%.
• the contact energy and hourglass energy is removed completely.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.

case2:

• modifications to the failure johnson card are done as shown below.

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

observation:

• Here, the crack in the elements occurs at the beginning as shown below, due to the value Ixfem=1.
• 
• but the equivalent plastic strain  eps_p_max=0.151 makes the deletion when the plastic strain reaches 15.1%.
• 
• also done observation by assigning eps_p_max=0.80 and ixfem=1, where the crack develops when the elements fail before it reaches 80%.
• 
• where the internal energy increases gradually until the material gets rupture.
• the rupture happens at 4.5ms.
• the maximum vonmises stress observed is 2.951E+02 i,e.295.1 N/mm^2.
• the number of cycles for the simulation is 49216.
• the energy error ranges from -1.1% to 5.9%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• the contact energy and hourglass energy is removed completely.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.
• there is a small peak in kinetic energy at the time of rupture.

case3:

• simulation is done with the material card as shown below, but not with the failure johnson card.

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

observation:

• the removal of elements is due to the value equivalent plastic strain,eps_p_max=0.151 i,e.15.1%.
• the maximum vonmises stress observed is 2.707E+02 i,e.270.7 N/mm^2.
• the rupture starts at 4ms.
• the number of cycles for the simulation is 49407.
• the energy error ranges from -0.6% to 1.2%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• where the internal energy increases gradually until the material gets rupture.
• the contact energy and hourglass energy is removed completely.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.
• there is a small peak in kinetic energy at the time of rupture.

case4:

• simulation is done with the eps_p_max=0 in the material card and with the failure johnson card as shown below

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

observation:

• there is no sudden rupture happening in the aluminum material.
• the internal energy increases gradually throughout the simulation of 5ms.
• the maximum vonmises stress observed is 2.451E+02 i,e.245.1N/mm^2.
• the removal of elements is due to the value Ixfem=0(just remove the elements).
• the number of cycles for the simulation is 49303.
• the energy error ranges from -0.6% to 1.2%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• the kinetic energy, contact energy, and hourglass energy is removed completely.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.

case5:

• converted the material card to law1 elastic, as shown below.

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

observation:

• there is no rupture in the material.
• the maximum vonmises stress observed is 1.089E+04 i,e.10890 N/mm^2.
• the element removal or cracks are absent in this case, because of law1-isotropic linear material stressed within hooks law. 
• the number of cycles for the simulation is 47968.
• the energy error ranges from -0.6% to 4%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• the internal energy increases gradually throughout the simulation of 5ms.
• there is a small peak in kinetic energy at the end of the simulation.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.
• the kinetic energy, contact energy, and hourglass energy is removed completely.

case6:

• simulation is done with the material card of law-27_PLAST_BRIT, as shown below.

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

observation:

• the internal energy increases gradually until the material gets rupture.
• comparing the effect of rupturing in material, here the rupture seems to be high.
• the elements which fail get deleted, because of the brittle failure mode eps_t,eps_m,eps_f, and d_max.
• the maximum vonmises stress observed is 2.875E+02 i,e.287.5N/mm^2.
• the number of cycles for the simulation is 49506.
• the energy error ranges from -0.6% to 1.1%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• where the internal energy increases gradually until the material gets rupture.
• there is a small peak in kinetic energy at the time of rupture.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.
• the contact energy and hourglass energy is removed completely.

case7:

• simulation is done with the law-36 PLAST_TAB material card with the input stress strain curve as shown below.

• imported the .h3d file in the Hyperview and .T01 in Hypergraph.
• the animation for vonmesis stress is observed and the graph for internal energy, kinetic energy, contact energy, hourglass energy, total energy are plotted.

observation:

• here the material seems to be very stiff comparing with before cases.
• the material rupture at 3.5ms
• the maximum vonmises stress observed is 7.597E+02 i,e.759.7N/mm^2.
• the internal energy increases gradually until the material gets rupture.
• the elements which fail get deleted, because of the values eps_t,eps_m,eps_f.
• the number of cycles for the simulation is 53134.
• the energy error ranges from -1.1% to 0.7%.
• there is no amount of mass added to the material, mass error=0.
• the simulation time is 5.010 ms.
• the internal energy increases gradually until the material gets rupture.
• there is a small peak in kinetic energy at the time of rupture.
• the total energy increases gradually as shown in the plot, approximately follows the same path as the internal energy develops.
• the contact energy and hourglass energy is removed completely.

COMPARISION BETWEEN THE CASES:

• in energy error perspective, case7 has 1.1% of dissipation and 0.7% of energy addition, in comparing with other cases it has high dissipation and low energy addition.
• in no.of cycles perspective, case5 has 47968 no.of cycles and is the lowest number in comparing with other cases.
• in max vonmises stress perspective, case4 has the stress value of 245.1N/mm^2, is the least value in comparing with other cases.

result:

• So, in confronting the best case on behalf of von mises stress value, case 4 has the best maximum von mises stress value and energy added to the material is 1.2% also within the limit of 5% and it takes 49303 cycles for the simulation, is the third smallest value in comparison with the other cases.

CONCLUSION:

Hence, the run of simulation for all seven cases has been completed, analyzed and derived the best representation of the on-field scenario as case4 successfully.