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Response Spectrum Analysis, defining input

Response Spectrum Analysis, defining input

Response Spectrum Analysis, defining input

(OP)
Hello, started using ABAQUS three weeks ago for an undergrad project.

I'm looking to perform a response spectrum analysis and dynamic explicit analysis on an assembly imported from Solidworks. I was expecting to be able to define the input (acceleration as a function of frequency) at the load step, but have been unable to locate where to define the spectrum?

After I do this, I hope to be able to apply this acceleration excitation to three fixed surfaces and track both the nodal stresses and maximum response accelerations as functions of frequency. I do not know how to apply my acceleration input to these specific locations.

Thanks!

Best regards,
--Dave

RE: Response Spectrum Analysis, defining input

Dave,

an explicit analysis is typically done in the time domain. As far I know its not possible to work with acc. vs. frequency in Abaqus explicit. Acc. vs. time is required.

If your excitation is harmonic I recommend to run a steady stat dynamic analyis with abaqus standard. Find a frame below. Its with basemotion excitation

CU



:
:
:
*NSET,NSET=fix
117,118,119,120,129,130,139,140,1460,1461,1462,1463,1464,1465,1466,1467
:
:
:
*AMPLITUDE,NAME=XI
34.7937, -1647.59, 35.936, -467.465, 38.257, 2279.74, 39.919, 1263.25,
:
:
:
*AMPLITUDE,NAME=XR
34.7937, 726.63, 35.936, 1938.45, 38.257, 255.67, 39.919, -1993.55,
:
:
:
*AMPLITUDE,NAME=YI
:
*AMPLITUDE,NAME=YR
:
*AMPLITUDE,NAME=ZI
:
*AMPLITUDE,NAME=ZR
:
**
** STEP 1
**
*STEP,NAME=FREQUENCY
*FREQUENCY,EIGENSOLVER=LANCZOS
10,,250.0000
**
** BOUNDARY
**
*BOUNDARY,TYPE=DISPLACEMENT
fix,1,3,1.000000
**OUTPUT,FIELD,VAR=ALL
*END STEP
**
**
*STEP,NAME=ACC
*STEADY STATE DYNAMICS, INTERVAL=EIGENFREQUENCY
35.,168.,20,3
*MODAL DAMPING,MODAL=DIRECT
1,10,0.0176
*SELECT EIGENMODES,GENERATE
1,10,1
*BASE MOTION,DOF=1,LOAD CASE=1,AMP=XR
*BASE MOTION,DOF=1,LOAD CASE=2,AMP=XI
*BASE MOTION,DOF=2,LOAD CASE=1,AMP=YR
*BASE MOTION,DOF=2,LOAD CASE=2,AMP=YI
*BASE MOTION,DOF=3,LOAD CASE=1,AMP=ZR
*BASE MOTION,DOF=3,LOAD CASE=2,AMP=ZI
*OUTPUT,HISTORY,VAR=PRESEL
*NODE OUTPUT,NSET=POST,VAR=PRESEL
TA,
*END STEP
**
**    
*STEP,NAME=STRESS
*STEADY STATE DYNAMICS, INTERVAL=EIGENFREQUENCY
35.,188.,2,
*MODAL DAMPING,MODAL=DIRECT
1,10,0.036
*SELECT EIGENMODES,GENERATE
1,10,1
*BASE MOTION,DOF=1,LOAD CASE=1,AMP=XR
*BASE MOTION,DOF=1,LOAD CASE=2,AMP=XI
*BASE MOTION,DOF=2,LOAD CASE=1,AMP=YR
*BASE MOTION,DOF=2,LOAD CASE=2,AMP=YI
*BASE MOTION,DOF=3,LOAD CASE=1,AMP=ZR
*BASE MOTION,DOF=3,LOAD CASE=2,AMP=ZI
*OUTPUT,FIELD,V=ALL, FREQ=1
*ELEMENT OUTPUT,VAR=ALL
*END STEP


 

RE: Response Spectrum Analysis, defining input

(OP)
Hi Pam,
Thanks for the tip regarding abaqus explicit. I had actually hoped to have a time history of some kind, but was only provided with the acceleration content as a function of frequency. The content represents (I believe) a shock transient over a moderate amount of time.
The base motion input should be quite useful in representing my loading - thanks!!

With regards to my other novice question, can anyone direct me to where I would input an acceleration spectrum in order to do a response spectrum analysis? I'm mostly a GUI user at this point, and everytime I attempt to update the keyword file of the database it gets re-written prior to submitting the job.

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