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Hi!! I haven't previous experience in FLUTTER analysis, I have not a deep knowledge in Aeroelascity.......so I can not help you too much......:-( ***************************************** Most of the time the problem is between the mouse and the chair *****************************************

Hi I don´t understand what you mean!! In a beam you can obtain torsional modes..........all is about the section of your beam, i.e not symmetric section or section with the shear center displaced...... :-( ***************************************** Most of the time the problem is between the...

Hi!! You can do it, if the thickness is small compared to its other dimensions. You must use CQUAD elements for surface meshing. In the PSHELL you must just input the thickness and property. I highly recommend you to read the NASTRAN documentation you can download it for free here...

The RBE2 is a rigid element that can transmit your torsion moment to the CBAR. If you attach the RBE2 with just one node of the CQUAD it will not works, connecting to more than one node is transmitting your torsion moment through the shear stiffness of the CQUADS. Hope this help you! ;-) I...

In the second model I have sent you the first mode is 14.79 Hz and is the torsion mode. The firs model that I have sent you was not right, the SPC was not constrained in the rotation about Z and the RBE2 was not constrained also in rotation, in the last model that I have sent you all was...

Hi again!!! I have just run the model and I have found that your SPC was not well defined, the rotation about Z was not constrained, I have fixed it and also fixed the 123456 DOF of the RBE2 element and the freq. obtained is 14.79Hz. the error comes because of the moment that the RBE2 (element...

I have connected the shaft with the rotor by means of a RBE2, I think it should works, have a look to the attached file, and let me know if it works ok?? Have a nice day ;-)http://files.engineering.com/getfile.aspx?folder=2dc8279b-0891-4abf-b702-bbd341cccda5&file=radialmesh_cbar_with_RBE2.dat

Hi again!! I know what is the problem, the problem are the CQUAD that you are using to modelate the rotor. For CQUAD element there is no stiffness associated to the rotation about the normal to the plate. The CQUAD can only represent in-plane, bending, and transverse shear behavior. That´s the...

Could you pass me the .bdf??

Hi to all, Have you tried to launch a modal analysis?? it will help you to identify if you have any unconnected elements. Also I will recommend you to make a GROUNDCHECK to check the DOF of your structure. Have a nice day!!

Hi Bharat Any SPC in your model?? it sounds like you have free body movement. If you have not any constraint that prevent the solid rigid movement in your model the first 6 modes that you will obtain are the six rigid body modes.These modes should have frequencies less than or equal to 1.0E-04...

Hi to all!! I am having problems solving one analysis with SOL 400 in Nastran. My analysis have different STEP loads. First step: only temperature 95° Second step: temperature 95° + Pressure 1100 KPa Third step: temperature 95° + Pressure 1400 KPa When solving I can see in the .sts file that...

Sorry I forgot to mention that I have some contacts defined in the problem

Hi to all!! I am having problems solving one analysis with SOL 400 in Nastran. My analysis have different STEP loads. First step: only temperature 95° Second step: temperature 95° + Pressure 1100 KPa Third step: temperature 95° + Pressure 1400 KPa When solving I can see in the .sts file that...

Hi Greg thanks for your answer. Well to check the normals I know how to do it, what I am trying to display and change is the X and Y axis of the elements and to align all in the same direction, in PATRAN is easy to do it but in Hypermesh I can´t find how to do it

Hi to all, I am just trying to check and change elements orientation (SHELL elements) in Hypermesh to align all the elements in the same direction, and I am not able to find how. I can find how to change normals and also how to change material orientations (material orientations doesn´t match...

Hi peuray It depends of the material you are using, and depends of the grade of surface hardening you want to obtain. With ion nitriding according to AMS 2759/8 you can obtain a surface hardness of 50-52 HRC with difussion zone up to 0.89mm of deep. Don´t forget that all heat treatable steels to...