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sudden increase in rotational kinetic energy enrgy

I'm carrying out a rollover analysis where body is supposed to freefall just after coming in contact and rolling about its axis,

Only load on model is gravity, but as soon as the body the model come in contact the energy shoots to e+17

17500 0.1312      0.7500E-05 SHELL     226493 -2.3% 0.7811E+05 0.1039E+07 0.2618E+05 0.1169E+07   0.000
17600 0.1320      0.7500E-05 SHELL     226151 -2.5% 0.7547E+05 0.1050E+07 0.2665E+05 0.1181E+07   0.000
17700 0.1327      0.7500E-05 SHELL     392114 -2.7% 0.7298E+05 0.1062E+07 0.2717E+05 0.1194E+07   0.000
17800 0.1335      0.7500E-05 SHELL     392259 -2.9% 0.7066E+05 0.1072E+07 0.2775E+05 0.1206E+07   0.000
17900 0.1342      0.7500E-05 SHELL     222229 -3.2% 0.6848E+05 0.1083E+07 0.2839E+05 0.1219E+07   0.000
18000 0.1350      0.7500E-05 SHELL     456836 -3.5% 0.6644E+05 0.1092E+07 0.2908E+05 0.1231E+07   0.000
18100 0.1357      0.7500E-05 SHELL     441033 -3.8% 0.6458E+05 0.1102E+07 0.2984E+05 0.1244E+07   0.000
18200 0.1365      0.7500E-05 SHELL     456836 -4.1% 0.6306E+05 0.1111E+07 0.3073E+05 0.1256E+07   0.000
18300 0.1372      0.7500E-05 SHELL     197222 -4.4% 0.6201E+05 0.1118E+07 0.3180E+05 0.1268E+07   0.000
18400 0.1380      0.7500E-05 SHELL     451688 -4.7% 0.6153E+05 0.1126E+07 0.3309E+05 0.1281E+07   0.000
18500 0.1387      0.7500E-05 SHELL     451943 -5.0% 0.6162E+05 0.1132E+07 0.3461E+05 0.1293E+07   0.000
18600 0.1395      0.7500E-05 SHELL     439923 -5.2% 0.6224E+05 0.1138E+07 0.3633E+05 0.1305E+07   0.000
18700 0.1402      0.7500E-05 SHELL     933070 -5.4% 0.6322E+05 0.1145E+07 0.3822E+05 0.1317E+07   0.000
18800 0.1410      0.7500E-05 SHELL     436857 -5.5% 0.6439E+05 0.1151E+07 0.4018E+05 0.1328E+07   0.000
18900 0.1417      0.7500E-05 SHELL     439923 -5.6% 0.6561E+05 0.1157E+07 0.4219E+05 0.1340E+07   0.000
19000 0.1425      0.7500E-05 SHELL     440756 -5.6% 0.6672E+05 0.1164E+07 0.4431E+05 0.1351E+07   0.000
19100 0.1432      0.7500E-05 SHELL     433969 -5.6% 0.6767E+05 0.1171E+07 0.4661E+05 0.1361E+07   0.000
19200 0.1440      0.7500E-05 SHELL     433370 -5.6% 0.6847E+05 0.1177E+07 0.4911E+05 0.1372E+07   0.000
19300 0.1447      0.7500E-05 SHELL     457253 -6.0% 0.6909E+05 0.1178E+07 0.5181E+05 0.1382E+07   0.000
19400 0.1455      0.7500E-05 SHELL    1585650 -7.1% 0.6940E+05 0.1169E+07 0.5469E+05 0.1392E+07   0.000
WARNING INTERFACE NB           2
GAP=   3.15000000000000      PENE=   3.14999999971815
LINE      1740244     1740245 DE-ACTIVATED FROMINTERFACE
19500 0.1459      0.4113E-11 SH_3N    1904067 99.9% 0.6939E+05 0.1143E+07 0.4126E+17 0.1397E+07   0.000
19600 0.1459      0.5668E-07 SHELL     197222 99.9% 0.6939E+05 0.1143E+07 0.4126E+17 0.1397E+07   0.000
19700 0.1462      0.7429E-09 INTER          2 99.9% 0.6974E+05 0.9476E+11 0.4126E+17 0.1402E+07   0.000
WARNING INTERFACE NB           2
GAP=   3.15000000000000      PENE=   3.14999999973051
LINE      1740245     1740246 DE-ACTIVATED FROMINTERFACE
19800 0.1462      0.1753E-08 INTER          2 99.9% 0.6974E+05 0.1105E+07 0.4450E+17 0.1402E+07   0.000
WARNING INTERFACE NB           2
GAP=   3.15000000000000      PENE=   3.14999999971615
LINE      1740245     1740627 DE-ACTIVATED FROMINTERFACE

i've done component wise energy plot for rotational energy but no such relevant data was found and their rotational energy was limited to e+3. i've checked for penetration of interface in 000.out but there isn't any . i am attaching graphs for ref

<?xml version="1.0" encoding="UTF-8"?>

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Altair Forum User

Can you share the .out file and T01 file.

harshitpuri

@George P Johnson i've sent the file to your dropbox

Altair Forum User

Hi,

Got the files. Will get back to you very soon.

Altair Forum User

harshitpuri

I suspect contacts. What is the contact stiffness?

harshitpuri

haven't assigned any contact stifness rather,

inacti =6, and istf=4

the contact type is 19 which breaks into type 7 and type 11

also tried with type 7 only but the problem persists

Altair Forum User

Harshit,

As discussed, our colleague from Altair India will get in touch with you.

harshitpuri

@George P Johnson THE PROBLEM PERSISTS ...

Altair Forum User

Harshit,

Can you share the model file?

Altair Forum User

Just to debug, check the if there is any increase in mass that particular component. Since rotational KE is equal to Inertia times (Omega)^2, and assuming the (Omega) is same for all parts, then mass is contributing to this high rotational KE.

harshitpuri

the mass is constant throuh out i've checked .. for all the global variables only RKE and is exceeding too much.

I've checked for individual component's RKE but none of them are contributing to that high value

<?xml version="1.0" encoding="UTF-8"?>1. mass of component

<?xml version="1.0" encoding="UTF-8"?>

harshitpuri

I've dropped file in your dropbox

harshitpuri

The gap min value for Contact is 2.6 where as i get warning , for which Gap Min and Penetration both have same value.

unable to understand

WARNING INTERFACE NB           2
GAP=   2.34000000000000      PENE=   2.33999999978523
LINE      1742160     1742161 DE-ACTIVATED FROMINTERFACE

RAMGANESH

Dear Harshit,

inacti =1, iform = 2 and istf = off , run the analysis with these changes.

harshitpuri

@RAMGANESH No change.. i'm still getting same message.

Altair Forum User

Hi Harshit,

Sorry for a late reply as I was occupied with some work.

Unfortunately I am unable to access the file through dropbox. Can you share the same file with me through a personal message?

gopal_rathore

Hi,

The problem is solved. It was due to contact stiffness as master was having less contact stifness when compared to slave and was taken care by modifying the E values for master , as both were already rigid this does not affects the solution and only the contact stiffness behaviour is properly captured.

harshitpuri

@George P Johnson & @Prakash Pagadala .. thanks for your help,

the problem solved by @gopal_rathore

jsk459

Hi @George P Johnson and @Prakash Pagadala

I have ran a quasi static model where the run got error terminated due to high kinetic energy. Please see the below .out file. But i have checked the kinetic energy for all the parts and it is very less only. Please help me with this.

image.png.5787caea8288b7fceceed8ee6308e355.png

Nachiket Kadu_22143

You have high internal energy of 99.9% and also high mass error. For internal energy you may check nodes associated with high internal energy. For mass error kindly check unit system and also enforced time step.

Nachiket Kadu_22143

Also if you can plot KE energy if its too high you can consider for more gradual increase of load.

Altair Forum User

Hi,

Before the energy error jumps to -99% we can see that a node was deactivated form the interface id 13, the time step has dropped and high mass was added to maintain the imposed time step.

It seems like there may be some penetrations in that interface, and please check for the same. If it's a Type 7 interface please provide the recommended parameters and it's always recommended to provide a Gapmin.

jsk459

Hi @George P Johnson,

There is no penetrations in the model and i have provided Gapmin as 0.05 since the components were to close to each other. I have used the recommended properties except the minstiff.

Altair Forum User

Hi,

Can you check the behavior of the model in HyperView?. That is, upload the *A001 file and run in HyperView so that it will show the results generated up til the termination and review the contact region and check whether any weird behavior is present.

If issue persist, please share the model file through the secure dropbox.

jsk459

i will check and let you know