August 8, 2021 at 6:15 pm

peteroznewman

Subscriber

There are two ways to extract that information: Harmonic Response and Transient Structural.

Harmonic Response will give you the steady state solution. Every node will have a harmonic motion and the solution will tell you the acceleration amplitude and phase of each node for each axis direction for each frequency in the range requested. For example, you could request frequencies from 10 Hz to 110 Hz in steps of 2 Hz. Therefore you can output a table of 50 frequencies, with the amplitude and phase of each node in three directions. There are 9 nodes x 4 floors x 6 outputs = 216 outputs x 50 frequencies = 10,800 pieces of information to describe the motion of the structure over that frequency range. The acceleration function over time is simply Acc(t) = A*sin(2*pi*f*t+Phase) where the Phase is in radians and A is the amplitude in m/s^2 and f is the frequency in Hz.

Transient Structural will give you 3 directions of acceleration at each node at each time step for one frequency. If the highest frequency of interest is 110 Hz, you need 20 time steps to capture that, so the sampling rate is 2,200 Hz. That means over 30 seconds there will be 66,000 time steps. Multiply that by the 3 directions x 36 nodes and you will have 7,128,000 pieces of information for one frequency. Multiply by 50 for the same frequencies as above for a total of 356 million pieces of information. It is hard to summarize that much data. That is why Harmonic Response is an attractive alternative to Transient Structural when the steady state response to a harmonic input is desired.

It will be easiest to show you how to build those models either in a recorded video or live during a Skype meeting. Would you like to schedule a Skype meeting?

Here is my discussion that includes a video on Harmonic Response: https://forum.ansys.com/discussion/687/bridge-building-in-spaceclaim-with-modal-and-harmonic-response-analysis

There are free courses on this site that would be beneficial to watch to help you understand your model.

https://courses.ansys.com/index.php/courses/mode-superposition-method/

https://courses.ansys.com/index.php/courses/topics-in-harmonic-response-analysis/

https://courses.ansys.com/index.php/courses/harmonic-analysis-of-structures/

https://courses.ansys.com/index.php/courses/damping-effects/

https://courses.ansys.com/index.php/courses/time-domain-dynamic-problems/

It will be easier if I have your Modal analysis. In Workbench, use the File, Archive menu to create a .wbpz file type and attach that to your reply. Also say what version of ANSYS you are using.

Harmonic Response will give you the steady state solution. Every node will have a harmonic motion and the solution will tell you the acceleration amplitude and phase of each node for each axis direction for each frequency in the range requested. For example, you could request frequencies from 10 Hz to 110 Hz in steps of 2 Hz. Therefore you can output a table of 50 frequencies, with the amplitude and phase of each node in three directions. There are 9 nodes x 4 floors x 6 outputs = 216 outputs x 50 frequencies = 10,800 pieces of information to describe the motion of the structure over that frequency range. The acceleration function over time is simply Acc(t) = A*sin(2*pi*f*t+Phase) where the Phase is in radians and A is the amplitude in m/s^2 and f is the frequency in Hz.

Transient Structural will give you 3 directions of acceleration at each node at each time step for one frequency. If the highest frequency of interest is 110 Hz, you need 20 time steps to capture that, so the sampling rate is 2,200 Hz. That means over 30 seconds there will be 66,000 time steps. Multiply that by the 3 directions x 36 nodes and you will have 7,128,000 pieces of information for one frequency. Multiply by 50 for the same frequencies as above for a total of 356 million pieces of information. It is hard to summarize that much data. That is why Harmonic Response is an attractive alternative to Transient Structural when the steady state response to a harmonic input is desired.

It will be easiest to show you how to build those models either in a recorded video or live during a Skype meeting. Would you like to schedule a Skype meeting?

Here is my discussion that includes a video on Harmonic Response: https://forum.ansys.com/discussion/687/bridge-building-in-spaceclaim-with-modal-and-harmonic-response-analysis

There are free courses on this site that would be beneficial to watch to help you understand your model.

https://courses.ansys.com/index.php/courses/mode-superposition-method/

https://courses.ansys.com/index.php/courses/topics-in-harmonic-response-analysis/

https://courses.ansys.com/index.php/courses/harmonic-analysis-of-structures/

https://courses.ansys.com/index.php/courses/damping-effects/

https://courses.ansys.com/index.php/courses/time-domain-dynamic-problems/

It will be easier if I have your Modal analysis. In Workbench, use the File, Archive menu to create a .wbpz file type and attach that to your reply. Also say what version of ANSYS you are using.