Unacceptable Frequency
Unacceptable Frequency
(OP)
Hi,
I did analyze a MOL pump padestal and its motor experimentally using Modal Analysis technique. We got 5 natural frequencies and mode shapes. Then, I modeled the structure in MSc/Nastran and Abaqus. I asked for 20 modes when running the analysis.Yes, I got 5 of them were quite similar to the experimental values. HOWEVER, the low modes values were too low and unacceptable - about 0.6 and 0.5 Hz. Why I got such values?What are the reasons for that?
I did analyze a MOL pump padestal and its motor experimentally using Modal Analysis technique. We got 5 natural frequencies and mode shapes. Then, I modeled the structure in MSc/Nastran and Abaqus. I asked for 20 modes when running the analysis.Yes, I got 5 of them were quite similar to the experimental values. HOWEVER, the low modes values were too low and unacceptable - about 0.6 and 0.5 Hz. Why I got such values?What are the reasons for that?





RE: Unacceptable Frequency
check your model,s boundary conditions once..There may not be sufficinet restraints...or those low frequency modes may be local modes,which U can negelect and see only see global modes.Take alook at th e animated mode shapes.
cheers!
RE: Unacceptable Frequency
cheers
RE: Unacceptable Frequency