Below is the relevant part of the deck which I am using:
SOL 111
CEND
ECHO = NONE
SPC = 1
METHOD = 1
DLOAD = 10
RANDOM = 30
SDAMPING = 20
FREQ = 40
RESVEC = YES
STRESS(PLOT,CRMS,NORPRINT)=ALL
Hi All,
I am running a random vibration analysis on some structure and I am interested in the RMS stress.
I am able to obtain it in the .op2 file by using STRESS(PLOT,CRMS,NORPRINT)=ALL, but the problem is that it also stores the stress results for the preceding frequency response analysis for...
Hello All,
I am trying to plot the RMS displacement for a structure I am working on.
I am using the below output request to get it out of Nastran.
DISPLACEMENT(PLOT,RALL,NORPRINT)=1
Next I am importing the .op2 file in Altair's HyperView and I want to plot the RMS displacement, but it is not...
Thank you very much!
Seems to be close to my results. I wonder what preprocessor you are using and also what is the logic it is using to generate the Frequency function? The increments seem to be clustered around the natural frequencies?
Not sure why you say I am enforcing displacement
I am...
I am actually running in Optistruct which is very similar to Nastran. (more confusion)
Only the header part is a bit different. I can prepare an equivalent Nastran file.
In the mean time please find attached the Optistruct deck which you can use to see the dimensions and boundary conditions...
Hi,
I am using tone/mm^3 for the density units. This is why it is 7.83e-9...
The BC's are cantilever beam indeed.
The mode #5 is a torsional mode (see below). Are you using CBEAM/CBAR ? Maybe this is why you are not capturing that mode..
Thanks again. Please see below the problem specs and also the stress results for one of the iterations I am doing. The stress seems to be stabilizing around this value (209 MPa).
Also in the attached sheet I played with different frequency steps and recorded the max stress results.
Please let me...
Hi Filipe,
Thank you very much for your reply.
I still don't have a feel for this.
I am currently doing a study on a simple beam structure (hexa meshed)to try and figure out some optimum frequency increments to select.
Also I am comparing the results with Ansys which seems to have a different...
Hello,
This may be a basic question, but I found no obvious answer on the web or the Nastran Dynamic analysis User's guide.
As stated in the Nastran Dynamic analysis user's guide the Random analysis is treated as a data reduction procedure that is applied to the results of a frequency response...
Hi ENCHTAIN!
We are using both I-Deas and Hypermesh at my workplace, but I cannot give you an advice of want you should use since I don't know what kind of mesh, and for what type of parts you will be using them. I tend to belive that regardles of that Hypermesh is a more powerfull overall...
Do you want to know how to add the FEM's of diferent parts into a sigle assembled FEM? If so you need to create an assembly from the parts who's FEM's you want to assemble and then you need to create a FE model and define the assembly FEM.