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harshitpuri

sudden increase in rotational kinetic energy enrgy

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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

 

 

Rke_components_model.PNG

Rke_model.PNG

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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

 

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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.

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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

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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?

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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.

Rahul R likes this

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Hi

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.

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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.

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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.

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