Hey everybody,
Im trying to simulate the inflation of a pneumatic bellow actuator and have used the instructions from PneuNets: as a reference in the steps I took.
However, I am encountering several problems right now when running the simulation:
1. 326 elements are distorted. Either the isoparametric angles are out of the suggested limits or the triangular or tetrahedral quality measure is bad. The elements have been identified in element set WarnElemDistorted
--> I suspect this may have something to do with my material settings. I'm trying to use TPU90A as a material, which is a hyperelastic material as I've been able to read about in several papers. To model this in Abaqus, I have used the Ogden Model but I'm not quite sure this is correct. I've tried using different mesh sizes and the warning number varies but is still always present.
2. There are 2 unconnected regions in the model.
--> honestly have no idea what this means
3. The system matrix has 3 negative eigenvalues.
--> If I understood correctly, this mean that the stiffness matrix has become unstable. How do I fix this?
4. Solver problem. Zero pivot when processing element P0503_BELLOW_V123_SIMU-1.1174 D.O.F. 1.
--> This is by far the most frequent warning and seems to have something to do with my construct being underconstrained? I have fixed one side of the model so I'm not quite sure what else to do...
Very grateful for any help!
Im trying to simulate the inflation of a pneumatic bellow actuator and have used the instructions from PneuNets: as a reference in the steps I took.
However, I am encountering several problems right now when running the simulation:
1. 326 elements are distorted. Either the isoparametric angles are out of the suggested limits or the triangular or tetrahedral quality measure is bad. The elements have been identified in element set WarnElemDistorted
--> I suspect this may have something to do with my material settings. I'm trying to use TPU90A as a material, which is a hyperelastic material as I've been able to read about in several papers. To model this in Abaqus, I have used the Ogden Model but I'm not quite sure this is correct. I've tried using different mesh sizes and the warning number varies but is still always present.
2. There are 2 unconnected regions in the model.
--> honestly have no idea what this means
3. The system matrix has 3 negative eigenvalues.
--> If I understood correctly, this mean that the stiffness matrix has become unstable. How do I fix this?
4. Solver problem. Zero pivot when processing element P0503_BELLOW_V123_SIMU-1.1174 D.O.F. 1.
--> This is by far the most frequent warning and seems to have something to do with my construct being underconstrained? I have fixed one side of the model so I'm not quite sure what else to do...
Very grateful for any help!