Can ABAQUS do base excitation vibration?

[CaptainCrunch]

Hello All,

Has anyone here experience using ABAQUS to solve base excitation analysis? I'd like to use PSD data as the input excitation to smaller structures on engines which I usually model as a base excitation (i.e. vibration comes through the structure constraints). Can ABAQUS do this? If so what are the basic setup steps?

TIA,

George

 

[derickdfc]

Yes, ABAQUS can do this quite well. Use 2 steps.
Step 1 - a normal modes analysis.
Step 2 -
*psd-definition,name=base,type=base,g=9.807
*step
*random response
*modal damping,structural
*base motion,dof=?,lcase=?
*correlation,psd=base,type=uncorrelated

The above keywords should be all you require.

Incidentally you can take this a step further and use the psd stresses obtained to estimate a fatigue life for the loading cycle input as the psd curve.(using method defined by Bishop+Sherrat. Dirlik then produced an equation which estimates the probability density of rainflow ranges from the psd response. From this curve the fraction of the total test period at a specific stress range can be estimated, and combining this with Miners rule the damage and hence life can be calculated using an S-N curve derived from material constants.) This sounds horrendous but the maths is simple and well within spreadsheet capability.