Assignment 4-RADIOSS Material Laws Challenge

OBJECTIVE:Comparison of material properties and properties with changed properties.

Compare 7 cases as discussed in last 3 slides, in a tabulated format on the basis of:

1. Total number of cycles, Energy error, mass error and simulation time.
2. Notice the animation of all 5 and describe the animations in brief on the
basis of whether the elements are being deleted or cracked.
3. Plot energies and notice any difference.
4. Based on all the results, which case would represent the on-field
scenario.
5. Prepare a ppt/docx and list down case by case result and your conclusion
as to why the failure happened.

SOFTWARE USED:Altair- Radioss.

ABOUT SOFTWARE: Radioss is a solver which is used in CAE domain.It is a powerful multiphysics design tool with optimisation and ready integration with other altair tools and third party solutions.

Example: crash, safety, impact analysis and drop test.

radioss explicit analysis may include:

1)explicit dynamic analysis.

2) transcient heat transfer and thermomechanical coupling.

3) explicit arbitary and euler legrangian formulation.

	IMPLICIT	EXPLICIT
Deformation	Small	Large
What cause large deformation	pure force,              dynamic	velocity/acceleration with           mass  (momentum) and            inertia (angular momentum)
K matrix inversion	yes	no
time step size	large	small
what limits the time step	accuracy	stability
cost per time step	large	small
what dominates the cost	matrix inversion	element processing
cost incresing for doubling mesh density	x128	x16
parallel processing	possible	not possible.

 

INTRODUCTION TO RADIOSS:

1) First radioss ,run , time steps.

2) Element properties

3) Material properties

4) Hypercrash

5)  interface modelling

6) kinetic condition

7) load defnition

8) methods to increase simulation spped -time step control.

9) output requests

10) debugging an error.

PROCEDURE:

1) Import a .rad file: In any solver it is necessary to import a .rad file why because the rad extension means  radioss file. before goint to import we need to set up in a radioss solver . below figure represents the solver.

after that import a .rad model

CASE-1: Run the model as it is and assgin the name as eps_max_failure.for this case we no need to change any material properties or normal properties. or failure johnson card.

below figure represents the case 1.

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion there is no changing of any property.below figure represents the no changing material card.

                                             

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -49379

time- 122.38s

error-0.8

mass -0.00

 

the above all are satisfied with the ideal conditon then we will proceed to the next process.

the beolw animation file show the case 1 without changing the element properties. 

                                                                              CASE -1  DISPLACEMENT FILE 

                                                                  CASE -1 VON MISES ANIMATION FILE

 

This is law 2 means : is an isotropic elasto-plastic materila .it uses johnson-cook material model. this model expresses material stress as a function of strain,strain rate and temperature. we can decide at what plastic strain the element fails.if we observe the animation file the material undergoes elasticity and after reaching the yeild strenth then only it will rupture. this means it is related to elasto plastic material.

By using the graph we can conclude more.

we can observe the rigid wall force increasing upon the graph reaches to the 8500. and then it goes down. and then it risese.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max= 27355

internal energy due to deformation increasing linearly upto plastic failure and remains almost constant after.

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=179.55

Sudden rise during the failure indicating the rate of deformation ie , displacement subjected to a velocity.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=27385

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

 

CASE-2 Change the model name from law_2 epsmax_failure_0000.rad to Law2_epsmax_crack_0000.rad

infail/johnson,  change ifail_sh=1,Dadv=1,Ixfem=1.

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion there is no changing of any property.below figure represents the no changing in failure card.

after changing the material card.

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -49216

time- 126.94s

error-4.1%

mass -0.00%

below animation file for case -2 modifing the failure card.

                                                                  CASE -2  DISPLACEMENT FILE

  

                                                                                  CASE -2  VON MISES FILE

  

Even in law 2 with modification of failure johnson observe the animation file it failed at a stress of 2.951 E+2.

SO we conclude that the while law 2 modified failure card component instint more stress.

compariosn of graphs.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max=31000 

internal energy due to deformation increasing linearly upto plastic failure and remains almost constant after.

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=215

Sudden rise during the failure indicating the rate of deformation ie , displacement subjected to a velocity.By editing the failure card we observed compared to case 1 this case kinetic energy is stabilsed due to assigining of properties.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=32000

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

 

CASE-3:delete the failure johnson card and run it as Law2_epsmax_nofail_0000.rad

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion there is no changing of any property.below figure represents the deletion of material card.

after deleting the failure johnson card.

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -49407

time- 126.94s

error-0.8%

mass -0.00%

                                                           CASE -3  DISPLACEMENT FILE

                                                                             CASE -3 VON MISES FILE

 

By observing the vonmises animation file conclude that the max stress is 2.707E+02. let us conclude that by deleting the failure johnson card we observed that the stress sustaining is less compared to the above 2cases.

compariosn of graphs.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max=26900

internal energy due to deformation increasing linearly upto plastic failure and remains almost constant after.

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=325

Sudden rise during the failure indicating the rate of deformation ie , displacement subjected to a velocity.by observing this case we deleted the failure card so we observed the kinetic energy graph after deformation we cansee lot of change in deformation due to delete of material failure card.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=26500

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

the rigid wall force increases gradually upto the elastic plastic property after hitting the base sudden decrease in the force.

 

CASE-4  delete the value of Eps_max and run the material card as Law2

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion there is no changing of any property.below figure represents the no change in material card.

                                                      

after changing the eps_max to zero and run the material card as Law 2.

                                                                     

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -48736

time- 121.28s

error-3.0%

mass -0.00%

                                                           CASE -4  DISPLACEMENT FILE

                                                                             CASE -4 VON MISES FILE

 

By observing the vonmises animation file conclude that the max stress is 4.247E+04. let us conclude that by deleting the epsp_max value we observed that the stress sustaining is greater compared to the above 3cases.

compariosn of graphs.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max=65000

internal energy due to deformation increasing linearly upto fracture point because of deletion of epsp_max value to zero.the strain energy is continuous to increase at the same rate after cracking is initiated. this result is undesirable and no material posses infinite strain rate.

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=325

Sudden rise during the failure indicating the rate of deformation ie , displacement subjected to a velocity.by observing this case we deleted the failure card so we observed the kinetic energy graph after deformation we cansee lot of change in deformation due to delete of material failure card.the element is bending is at very low rate so the kinetic energy is produced is also very slow rate.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=65000

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

the rigid wall force increases gradually upto the elastic plastic property after hitting the base also no change because of the resultant force.

CASE-5:Convert this material model to law1 elastic with same density, younghs modulus(E), poissons ratio Nu.

LAW_1: Law_1 is an isotrpic , linear elastic material using hookes law.it is used for truss, beam, shell and solid components.it is only used for elastic components.To define the elasticity of the material we need to define three points which are density, modulus of elasticity, poissons ratio. 

 

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion the below figure represents the no failure in material card.

                                                      

after changing the material card to law1.

                                                                     

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -47968

time- 119.14s

error-1.3%

mass -0.00%

                                                             CASE -5 DISPLACEMENT FILE

                                                                             CASE -5 VON MISES FILE

 

By observing the vonmises animation file conclude that the max stress is 1.089E+04. let us conclude that by deleting the epsp_max value we observed that the stress sustaining is greater compared to the above 3cases.

compariosn of graphs.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max=9.0E+05

internal energy i,e. strain energy due to deformation increases linearlyas it has an infinite elastic limit. no plasticity involved.

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=3500

kinetic energy is almost remain constant, but increase during maximum deformartion.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=65000

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

the rigid wall force increases gradually upto the elastic plastic property after hitting the base also no change because of the resultant force.

 

CASE-6: Open new model as Law_27 and assign the properties

 

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion there is no changing of any property.below figure represents the no changing in failure card.

                                                      

after changing the material model to law 27

                                                      

 

                                                                     

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -49506

time- 128.47s

error-0.8%

mass -0.00%

                                                           CASE -6  DISPLACEMENT FILE

                                                                             CASE -6 VON MISES FILE

 

By observing the vonmises animation file conclude that the max stress is 2.875E+02

compariosn of graphs.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max=28000

since brittle, the strength is very high leading to a very high point.

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=425

at diiferent stages the penetraton of the plate, the elements are failin quickly and there are many rises in the energy curve caused by the deofromation i,e. displacement subjected to a velocity.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=28000

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

the rigid wall force increases rapidly because it is a law27 brittle materials.

CASE-7: LAW 36: 

 

after the importion the component will be like beolw one.

we have to put it in shaded element with mesh lines.

after importion there is no changing of any property.below figure represents the no changing in failure card.

                                                      

after changing the eps_max to zero.

                                                                     

after we will go to analysis and we have to press the radioss.

 

we will get a errors we need to note down the errors in each case.

Cycle -48736

time- 121.28s

error-3.0%

mass -0.00%

                                                                        CASE -7  DISPLACEMENT FILE

                                                                             CASE -7 VON MISES FILE

 

By observing the vonmises animation file conclude that the max stress is 4.247E+02. let us conclude that by deleting the epsp_max value we observed that the stress sustaining is greater compared to the above 3cases.

compariosn of graphs.

For internal energy:

x-axis       min=0         max=5

y-axis       min=0         max=42000

internal energy due to deformation increasing linearly upto fracture point because of deletion of epsp_max value to zero.the strain energy is continuous to increase at the same rate after cracking is initiated. this result is undesirable and no material posses infinite strain rate.

 

For kinetic energy:

x-axis       min=0         max=5

y-axis       min=0         max=2050

Sudden rise during the failure indicating the rate of deformation ie , displacement subjected to a velocity.by observing this case we deleted the failure card so we observed the kinetic energy graph after deformation we cansee lot of change in deformation due to delete of material failure card.the element is bending is at very low rate so the kinetic energy is produced is also very slow rate.

For hourglass energy:

x-axis       min=0         max=5

y-axis       min=0         max=0

There is zero hourglass produced because QEPH reduced integration method.

 

For total energy energy:

x-axis       min=0         max=5

y-axis       min=0         max=

the total energy curve is almost similar to the internal energy curve  i,e. kinetic energy is very small indicating no energy error.

the rigid wall force increases gradually upto the elastic plastic property after hitting the base also no change because of the resultant force.

Result:

                                              CASE-1                                                                                                       CASE-2

     

                                             CASE-3                                                                                                            CASE-4

       

                                                 CASE-5                                                                                                   CASE-6

    

                                                                                                           CASE-7

                                                       

by considering all the seven cases we will conclude that material 36 it means law 36 is best compared to any other law because it can be tested in laborataries for better accuracy.below table represents the seven cases.

   

CASE NO	CURRENT LAW	CHANGE TO               LAW	CHANGE IN THE MATERIAL PARAMENTES	DESCRIPTION
1	Law 2		Run as it is	EPSmax&signmamax are the failures criterias. They are ultimate stress and strain values from the stress strain curve.
2	Law 2		change the failure parameters in johnson failure card: ifail_sh=1 Dadv=1 Ixfem=1	D1,D2&D3 (from strain rate data) are the failures criterias.
3	Law2		Delete failure_johnson material card.	Failure criterias.
4	Law2		Delete EPS_P_max	when EPS_P_max is set to zero.we get infinite strain. simulation will stop element reaches sigma max.
5	Law 2	Law 1	Keep the density,younghs modulus, and poissions ratio same as that in Law2 materialcard.	Material is completely Elastic, ie, infinite strain rate.these are no failure criterias.therefore the elements wont fail.
6	law 27			The failure parameters are et: strain at the begining of tensile failure. em:Maximum Tensile strain. dmax: maximum damage factor. ef:Max Tensile strain for element deletion.
7	Law 2	law 36	The elstic region is defined by density, Younghs modulus, and poissions ratio. The platic region is defined by the  rupture parameters.	The rupture parameters are: EPS_t: strain at the begining of Tensile Damage. Epilson_F: Tensile Failure Strain the above parameter for rupture only. EPS_P_max:Plastic Failure Strain [The last one is a combined Failure].

 

Comparision of all the 7 cases 

 

 

 

 

 

 

CASE	TOTAL NO OF CYCLES	ENERGY ERROR	MASS ERROR	TOTAL SIMULATION RUN                       TIME
1	49379	0.8%	0.00%	122.38s
2	49216	4.1%	0.00%	126.94s
3	49407	0.8%	0.00%	126.94s
4	48736	3.0%	0.00%	121.28s
5	47968	1.3%	0.00%	119.14s
6	49506	0.8%	0.00%	128.47s
7	48736	3.0%	0.00%	121.28s

 

By observing these cases  

 case 6 takes more cycles and it takes more run time than other for law_27.it is only used for brittle materials.

comparing case 1 and case 2 we will coclude that after assigning the failure johnson card in case 2 it resist the stress more compared to case 1.

After deleting the failure card in case 3 it shows it only resist the stress less than case 1. so johnson failure card is good to resist more stress.

with case 4 deleting the Eps_p_max there is strain energy and there is no brakage due to put the value to 0. so we conclude that without assigining the epspmax is used to find the how much it elasticity and plasticity.

After observing case 5 it changed to law 1 it induce maximum strain.material is completely elastic.concluding case 4 with 5, there is a large strain energy induced in case 4.

case 6 is for brittle materials.case 7 is mostly used for laboratory conditons.it is very useful to get more accurate results.compared to all cases , case 7 is more preferable.