DGia
Mechanical
- Jan 27, 2016
- 5
Hello to all,
I'm trying to perform a simulation of a 3 points bending test on a composite material (made of 6 plies). I'm using NX/NASTRAN with solver 106 601. I have some problems with the results, they aren't congruents.
First at all I start with describing the FEM model. In according with the image just below, I used shell elements (CQUAD8) for the specimen, the 2 supports and the impactor. The supports are constrained in all translations and rotations (all fixed), the impactor is constrained in x,y,Rx,Ry,Rz and an enforced motion is applied in z direction (vertical axis), and the surface of the specimen has been divided in the middle (by using a divide face in the idealized part) and the center line (generated by the divide face) has been constrained in x,y,Rx,Ry,Rz (the translation in z direction is free). Contacts between specimen and supports and impactor have been defined.
NASTRAN can solve the model, but I have problems with the results. Below a picture of the displacements (magnitude), it is possible to see that they are symmetrical and this is right :
But the stresses of each ply are note axys-simmetrical and this is wrong because the impactor is exactly in the middle of the specimen :
I don't know why I have this error, maybe the material is not well defined but I checked and all look fine.
Thank you in advance for your help,
Best regards
I'm trying to perform a simulation of a 3 points bending test on a composite material (made of 6 plies). I'm using NX/NASTRAN with solver 106 601. I have some problems with the results, they aren't congruents.
First at all I start with describing the FEM model. In according with the image just below, I used shell elements (CQUAD8) for the specimen, the 2 supports and the impactor. The supports are constrained in all translations and rotations (all fixed), the impactor is constrained in x,y,Rx,Ry,Rz and an enforced motion is applied in z direction (vertical axis), and the surface of the specimen has been divided in the middle (by using a divide face in the idealized part) and the center line (generated by the divide face) has been constrained in x,y,Rx,Ry,Rz (the translation in z direction is free). Contacts between specimen and supports and impactor have been defined.
NASTRAN can solve the model, but I have problems with the results. Below a picture of the displacements (magnitude), it is possible to see that they are symmetrical and this is right :
But the stresses of each ply are note axys-simmetrical and this is wrong because the impactor is exactly in the middle of the specimen :
I don't know why I have this error, maybe the material is not well defined but I checked and all look fine.
Thank you in advance for your help,
Best regards