Assignment 4-RADIOSS Material Laws Challenge

RADIOSS Material Laws Challenge:

Aim: To apply different material types to the simulation model & compare the behaviour of model with different element and failure formulations.

Steps followed:

Case 1:

• Import the provided 0000 .rad file in Solver deck as shown in the image below:

• Check the units under Card panel Begin Card option as shown in the image below:

• Properties of shell are changed to recommended properties as shown in the image below:

• Material card selected for Aluminium was M2 Plastic Johnson & failure cards are kept as shown in the image below:

• Under Analysis panel we are selecting Radioss option under which we are exporting 0000.rad file & saving it to a particular location before clicking on radioss buttton as shown in the image below:

• 0001.rad file at the end of simulation is shown with Energy & mass errors under acceptable range as shown in the image below:

• Energy error is 0.8% while mass error is 0 thus both are in acceptable range with total number of cycles as 49180 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy is increasing with time because elements are absorbing kinetic energy.

• Plastic strain contour simulations is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

In the image above it can be seen that elements are deleted when they reach 15% of plastic strain value after yield stress values.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

Here also elements are deleted when they reach 15 % of plastic strain after yield stress of 290 MPa, maximum stress in the simulation is 238.2 MPa.

The elements break because Johnson-Cook failure card is applied to Aluminum material, which takes both tensile & compressive failures into account, when the elements reaches Eps_p_max value which is 0.151 by default here, they are deleted during simulation.

Case 2:

• Failure cards are edited as per question with Ifail_sh(Shell failure flag feature) set to 1 in order to generate crack in the shell element when Ixfem is set to 1 & Dadv is set to 1.0 which is criteria for crack advancement as shown in the image below:

• Under Analysis panel we are selecting Radioss option under which we are exporting 0000.rad file & saving it to a particular location before clicking on radioss buttton as shown in Case 1.
• 0001.rad file at the end of simulation is shown with Energy & mass errors under acceptable range as shown in the image below:

• Energy error is 4.1% while mass error is 0 thus both are in acceptable range with total number of cycles as 49217 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy is increasing with time because elements are absorbing kinetic energy.

• Plastic strain contour simulations is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

In the image above it can be seen that elements are deleted when they reach 15% of plastic strain value after yield stress values.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

Here also elements are deleted when they reach 15 % of plastic strain after yield stress of 290 MPa, maximum stress in the simulation is 295.1 MPa, which is higher than case 1 & crack devlopment can be seen during simulation with crack advancement maximum value being 1 & Ifail_sh is activated for all shell elements.The elements break because Johnson-Cook failure card is applied to Aluminum material, which takes both tensile & compressive failures into account, when the elements reaches Eps_p_max value which is 0.151 by default here, they are deleted during simulation.

Case 3:

• Failure card is deleted from the Assembly panel.

• Under Analysis panel we are selecting Radioss option under which we are exporting 0000.rad file & saving it to a particular location before clicking on radioss buttton as shown in Case 1.
• 0001.rad file at the end of simulation is shown with Energy & mass errors under acceptable range as shown in the image below:

• Energy error is 0.8% while mass error is 0 thus both are in acceptable range with total number of cycles as 49408 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy is increasing with time because elements are absorbing kinetic energy.

• Plastic strain contour simulations is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

In the image above it can be seen that elements are deleted when they reach 15% of plastic strain value after yield stress values.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

The maximum Von mises stress observed from the image above is 270.7MPa without any crack.

Case 4:

• Running the model with Eps_p_max=0 as shown in the image below:

• Under Analysis panel we are selecting Radioss option under which we are exporting 0000.rad file & saving it to a particular location before clicking on radioss buttton as shown in Case 1.
• 0001.rad file at the end of simulation is shown with Energy & mass errors under acceptable range as shown in the image below:

• Energy error is 1.1% while mass error is 0 thus both are in acceptable range with total number of cycles as 49304 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy & total enegy intercept each other and increases with time because elements are absorbing kinetic energy.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

In this case model does not fail as there is no failure criteria applied to the model plastic strain value(Eps_p_max) is deleted which sets it to default value of 10^30 and maximum stress 245.1 MPa.

Case 5:

• Changing the Law 2(Elasto-plastic material) to Law 1(Linear elastic material) with same values of Young's modulus(E),density & Possion's ratio as shown in the image below:

• Material card after analysis simulation is shown in the image below:

• Energy error is 1.3% while mass error is 0 thus both are in acceptable range with total number of cycles as 47565 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy & total enegy intercept each other and increases with time because elements are absorbing kinetic energy.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

The stress-strain relationship here is linear hence there is no failure of elements after impact of ball.

• Elastic Von mises strain is plotted in the simulation as shown in the image below:

Here the material card is following linear elastic law so there is no plastic strain & failure of elements.

Case 6:

• Import the LAW 27_0000.rad file in the import solver deck as shown in the image below:

• Change the material card to Law 27 i.e. Elasto-plastic Johnson-Cook material with an orthotropic brittle failure model as shown in the image below:

• Recomended shell propeties are used as shown in the image below:

• Material card after radioss analysis simulation is shown in the image below:

• Energy error is 0.8% while mass error is 0 thus both are in acceptable range with total number of cycles as 49501 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy is increasing with time because elements are absorbing kinetic energy.

• Plastic strain contour simulations is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

Elements are deleted in the simulation due to Eps_t,Eps_m & Eps_m values.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

Maximum Von mises stress observed is 287.7MPa, which is below plasticity yiel stress of 290 MPa.

Case 7:

• A Failure Johnson-Cook 0000.rad file is imported in solver deck.

• Create the curve with desired data given in the image below for plastic strain along X and stress along Y axis as shown in the image below:

• Change the material card to Law 36 which is for isotropic material using curve as created above as shown in the image below:

• Assign the desired plastic strain vs Stress curve within N-function by selecting curve created as shown above.

• Material card after radioss analysis simulation is shown in the image below:

• Energy error is 1.4% while mass error is 0 thus both are in acceptable range with total number of cycles as 48846 at the end of 5ms as observed from the image above.
• Energy graphs of Internal,Kinetic,Total & Hourglass energy are shown in the image below:

No hourglass energy is observed from the image above, Internal energy is increasing with time because elements are absorbing kinetic energy.

• Plastic strain contour simulations is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

Maximum Plastic strain along thickness is 2.693E-01.

• Von mises Stress plot is shown in the image below in hyperview format by selecting proper .h3d files generated during simulation:

Once Eps_p reaches Eps_p_max in one integration point the element gets deleted.

Comparision of case 1,2,3,4,5,6&7:

Case	Material Law	Simulation name	Eneregy error(%)	Simulation time(s)	No. of cycles	Max Stress(MPa)	Element behaviour
1	Law 2(Johnson-Cook material model)	Eps_max_failure	0.8	224.58	49380	238.2	Deleted
2	Law 2(Johnson-Cook material model)	Eps_max_failure_Crack 4	4.1	245.27	49217	295.1	Crack occurs then deleted
3	Law 2(Johnson-Cook material model)	Eps_max_nofail	0.8	182.95	49408	270.7	Deleted
4	Law 2(Johnson-Cook material model)	Law 2	1.1	184.86	49304	245.1	Deleted
5	Law 1(Linear elastic)	Law 1	1.3	164.83	47969	1102	Preserved
6	Law 27(Brittle failure model)	Law 27	0.8	187.38	49501	287.7	Deleted
7	Law 36(Elasto-plastic material model)	Law 36	1.4	191.05	48846	998.5	Deleted

Conclsion:

Comparision between Von mises stress,Plastic strain & element behaviour have been carried out with various material & failure cards and there values are compared for better material selection depeneding on requirement of user in tabulated format.