Determining Hz from a modal anaylsis
Determining Hz from a modal anaylsis
(OP)
Hello there.
First post, just new to the forum. Was hoping someone could help out.
I have ran a modal analysis on a plane model in FEMAP, and also carried out experimental work to determine the mode shapes. I then ran the analysis in Abaqus 6.7-1 as I prefer it, and I know how to have more control over meshing. The problem I get is, the mode shapes correspond with FEMAP and my experimental work.
However the frequency is giving in cycles/time. I know cycles/second = Hz. What correlation does the cycles/time give? As the values output do not match either my FEMAP or experimental expectations. I have looked in the INP file but I cannot find any time to calculate it from.
Hoping someone can shed some light on how to convert from this cycles/time into Hz.
Thanks
Jonathan
First post, just new to the forum. Was hoping someone could help out.
I have ran a modal analysis on a plane model in FEMAP, and also carried out experimental work to determine the mode shapes. I then ran the analysis in Abaqus 6.7-1 as I prefer it, and I know how to have more control over meshing. The problem I get is, the mode shapes correspond with FEMAP and my experimental work.
However the frequency is giving in cycles/time. I know cycles/second = Hz. What correlation does the cycles/time give? As the values output do not match either my FEMAP or experimental expectations. I have looked in the INP file but I cannot find any time to calculate it from.
Hoping someone can shed some light on how to convert from this cycles/time into Hz.
Thanks
Jonathan





RE: Determining Hz from a modal anaylsis
corus
RE: Determining Hz from a modal anaylsis
Thanks for your feedback
RE: Determining Hz from a modal anaylsis
corus
RE: Determining Hz from a modal anaylsis
thanks again
RE: Determining Hz from a modal anaylsis
I'm just moving towards dynamic response and I've been stuck in modal analysis for some time now. The modal frequencies given by ABAQUS and that obtained from hand calculations does not match.
I use Step>Linear Perturbation>Frequency and use either Lanczos or sub-space solver.
I stick with the SI units and am very meticulous about it.
Please help, anyone?
RE: Determining Hz from a modal anaylsis
There was a factor of about 6.28 by which the results from hand-calculations was greater than the result from ABAQUS. Turns out, ABAQUS gives the results in Hz and hand-calculations is in rad/sec.