Assignment 4-RADIOSS Material Laws Challenge
Aim: to compare various material law based different parameters.
CASE 1
we run case 1 as it is. No changes are done to any of the cards.
running the simulation by going to analysis -> radioss.
selecting the required file in the input file. selecting the include connectos and -nt 4 option and clicking radioss.
the above dilog box appears after completion of the simulation.
opening the 0001.out file. the last iteration tells us the about the final state of the different physical properties. for us the energy error and mass error are important. the fifth column is the energy error and the last column is the mass error is the last column. from the image we can se that the energy error is 0.8% and mass error is 0.
next we will try and visualize how the plate will act according to the parameters provided and how and the location of the stress developed. for doing that we have swicth to hyperview.
opening the required model in the load model input area and click apply. that will load the model as shown in the image above.
for us to know the behaviour and location of the stress developing we will use the tool known as contour.
this is the default dialog box of the contour tool. now selecting the required parameters for the desired answers and click apply. for our case we need
Result type: von misses
Averaging Method:Simple
the below shown gif shows us the location where the first stress in developed, the max stress developed and the loaction or node number where the max sress is developed. here we can see that the plate break of and the initally broken elements are deleted, this tells that the parameter provided by us makes a somewhat brittle material characteristics. the stress is first developed at the centre of the plate and transverse radiallt outwards, dissipating in magnitude.
the next step i plotting the graph. Opening the hypergraph.
selecting the respective T01 in the data file box
the rigid wall graph showcases that forces are flutuating but keeps increasing till 3.75ms and then decreases rapidly. till 3.75ms even though elements were getting deleted due to the ball cracking the plate there were enough element to provide resistance but after 3.75ms the elements existing in the contact area were not enough to provide any substantial resistance and the resultant force decreases.
the internal energy increase linearly till 3.9ms there is a continous conversion of the kinetic energy of the ball into the internal energy of the plate, there are elements present to resist the the ball. after 3.9ms the element left are just not sufficient enough to provide enough resistance and the energy graph plateaus.
here we can say that K.E of the plate increase substantially and rapidly after 3.9ms which indicates a jerk.
toatal energy follows a similar pattern of the internal energy.
CASE 2
in case 2 we make changes to the failure card.
Ifail_sh from 2 to 1
dadv to 1
Ixfem to 1
running the simulation in a similar way to case 1
the punch force is similar to the first case but the changes are not that rapid as the first case
Internal Energy follow the same profile as the first case, the only difference is that the plateauing value is higher.
similara to the first case, but stronger and shorter jerk.
CASE 3
in case 3 we are deleting the the failure card, keeping all the other parameter and cards same to the previous case
running the simulation by going to analysis -> radioss. selecting the required file in the input file. selecting the include connectos and -nt 4 option and clicking radioss.
opening the 0001.out file
next we will try and visualize how the plate will act according to the parameters provided and how and the location of the stress developed. for doing that we have swicth to hyperview.
since the johnson failure card is deleted, the failure behaviour of the plate now depends on eps_p_max to decide the value at which the plate's elements will crack. for this case eps_p_max value provided is .0151 which means the elements will crack at 15.1% of the plastic strain at any integration points.
Max Punch Energy: 8174.419922mJ
the steel plate was providing resistence to the incoming ball. the fluctuation we see in the value is because the elements are deleted in the process. when the entire core of the plate i deleted there is no elements to provide any resistence and the punch force decreases rapidly and eventually become zero.
internal energy increases linearly and plateaus after bulk of the elements are deleted. the difference is actually the magnitude when it starts to plateau and when it stops the energy transfer
Max Internal Energy: 27443.066406mJ
Max Kinetic Energy: 332.072906mJ
the K.E is not that substantial when compared with the other energies suggesting that the displacement of the element are very short before failure.
Max energy: 27528.367188mJ
follows a similar path of internal energy.
CASE 4
In case 4 we remove the eps_p_max value. what it does is radioss provides it with its default value of 10^30.
running the simulation by going to analysis -> radioss. selecting the required file in the input file. selecting the include connectos and -nt 4 option and clicking radioss.
opening the 0001.out file
next we will try and visualize how the plate will act according to the parameters provided and how and the location of the stress developed. for doing that we have swicth to hyperview.
we can see that the plate isnt cracking as the previous cases, this is because the criteria of cracking is too large. since we deleted the johnson failure card and removed the eps_p_max value, radioss has itself provided the default value of 10^30. due to this high value the plate elements acts a elastic material even though its not. these kind of material is known as pseudo-elastic or elasto-plastic. we can see that since the elements arent getting deleted the stress developed is also more(almost double).
the punch force increases even though not linearly, we can say that the displacement of the plate in increment rather than continous.
Max Punch Resultant Force: 21030.625mJ
since there is no crack the the energy transfer from the ball(K.E) to the plate(I.E) occurs through out the simulation, hence the I.E graph increases exponentially and doesnt plateau
Max Internal Energy: 64665.480469mJ
Max Kinetic Energy: 3.773894mJ
as there is no cracks the chances of jerk is very low hence low/non-existent K.E.
Max Total Energy: 64668.45031mJ
Increases exponentially
CASE 5
In case 5 we will convert the card image from plas_johns_zeril to M1_ELAST. providing the recommended values.
running the simulation by going to analysis -> radioss. selecting the required file in the input file. selecting the include connectos and -nt 4 option and clicking radioss.
opening the 0001.out file
next we will try and visualize how the plate will act according to the parameters provided and how and the location of the stress developed. for doing that we have swicth to hyperview.
as we have converted the card image to M1_ELAST the material characteristics are of an actual elastic material. as we can the behaviour of the plate elements are similar to that of the previous case. the difference the extrmeness to which this case can withstand the stress.when compared to the previous psuedo elastic material this case withsand almost 100times the stress.
Total Punch Force: 507928.093750mJ
the punch force curve is a smooth exponential curve suggesting that it is continous motion rather than stop start motion
Max Internal Energy:862533.375
since there is no crack the the energy transfer from the ball(K.E) to the plate(I.E) occurs through out the simulation, hence the I.E graph increases exponentially and doesnt plateau
Max Kinetic Energy: 3245.741699mJ
Max Total Energy: 865645.75mJ
case 6
For case 6 we are importing the law27 rad file provided.
changing values of the various parameters in properties to recommended values.
I_shell=24
I_smstr=2
N=5
I_thick=1
I_plas=1
running the simulation by going to analysis -> radioss. selecting the required file in the input file. selecting the include connectos and -nt 4 option and clicking radioss.
opening the 0001.out file
next we will try and visualize how the plate will act according to the parameters provided and how and the location of the stress developed. for doing that we have swicth to hyperview.
law 27 corresponds to the brittle behaviour as we can see that as the ball displaces the plate it under goes displacement as elastic material but the failure is sudden.due to this the stress developed is lot lesser than the previous 2 cases.
As we can see by 4ms enough elements are deleted so that there is no substantial resistance is developed and the forces reduce.
Max Resultant Force: 8256.720703mJ
Max Internal Energy: 29476.734375mJ
Max Kinetic Energy: 425.888275mJ
Max Total Energy: 29581.285156mJ
CASE 7
For case 7 we have to make a curve according the material behaviour. the extact points are given in the lecture.
providing the recommended values
running the simulation by going to analysis -> radioss. selecting the required file in the input file. selecting the include connectos and -nt 4 option and clicking radioss.
opening the 0001.out file
next we will try and visualize how the plate will act according to the parameters provided and how and the location of the stress developed. for doing that we have swicth to hyperview.
the brittle behaviour of this model is stronger than previous model.
| Case | No of Cycles | Energy Error | Mass error | Simulation Time | Future of Element | Von Misses Stress |
| Case 1 | 49379 | 0.8 | 0.0 | 264.16s | Deleted | 2.752E+02 |
| Case 2 | 49216 | 4.0 | 0.0 | 216.03S | Deleted | 2.951E+02 |
| Case 3 | 49407 | 0.8 | 0.0 | 205.78s | Deleted | 2.707E+02 |
| Case 4 | 48736 | 3.0 | 0.0 | 172.12s | Not Deleted | 4.247E+02 |
| Case 5 | 47968 | 1.3 | 0.0 | 229.55s | Not Deleted | 1.089E+04 |
| Case 6 | 49507 | 0.8 | 0.0 | 214.34s | Deleted | 2.875E+02 |
| Case 7 | 53129 | 0.2 | 0.0 | 200.97s | Deleted | 5.874E+02 |
Conclusion:
after running the simulatiom on 7 different cases and looking into the result we can say that case no 4and 5 are the most unrealistic cases among them. since there is no failure cards the element doesnt fails i.e no breakdown of the component, which imppossible in real life scenario. case 6 and 7 are close to the real life case which one might come across.