Learning Forum

[Dr. Daniel Winarski]

Hi, I successfully built a model of a multi-degree-of-freedom spring-mass system using ANSYS Modal.  I then successfully dropped this into Transient Structural, since my system was completely linear.  I apologize, but I need help in declaring the initial velocity of one of the masses (like -1 m/s in the Vertical Direction)...the other masses would have a zero initial velocity.  There are no other initial conditions (no initial displacements).  Could someone please help me by describing how to declare an initial velocity (linear velocity not rotational velocity) for one body of a multi-body system?  Thank you so very much, Daniel Winarski

[peteroznewman]

Here is your original post: https://innovationspace.ansys.com/forum/forums/topic/applying-an-initial-velocity-condition-to-a-linear-spring-mass-system/

Please use the File, Archive menu to create a .wbpz file.  Upload that file (not the .wbpj file) to a file sharing site such as Google Drive, and reply with a link to the file that anyone can download. Then I can show you using your model.

[Dr. Daniel Winarski]

Hi,

This is the link to my T3.wpbz “archive” file and an explanatory paper (in draft form):

https://drive.google.com/drive/folders/15hk0CkyCsw6xtd0LeRArVkMZfuM3YWAc?q=sharedwith:public%20parent:15hk0CkyCsw6xtd0LeRArVkMZfuM3YWAc

You don’t have to read the entire "draft" paper…..however, the figures may prove instructive. Figures 5 and 6 show the advice you generously gave me about dropping transient structural into the solution cell of modal. 

Where I am stuck now is on Figure 7, where I would like to specify an initial condition (IC) of velocity on ONLY the toroidal-shaped drop mass (shown in green).  This V(T=0) initial condition would be -3.866m/s, downward along the vertical “Z” direction. The goal then is to document the rebound of the drop mass, and how much of the initial kinetic energy of the drop mass is transferred to the basketball rim, backboard, and frame.  I sincerely apologize that I could not figure this IC out for myself.

Please allow me to point out that this work has no external funding or support of any sort.  Once published at the authors' expense, this will be publicly available at no cost what-so-ever to any and all readers.

Thank you so very much, Daniel Winarski

[Dr. Daniel Winarski]

Hi, Sir, I think I have figured this out. I assign an initial displacement ONLY for the toroidal drop mass.  Then I assign a small time step in STEP-1 of setup, so that displacement/time = -3.866ms.  Then, I proceed with STEP-2 in setup with free motion of the overall system.  Does this somewhat terse assessment sound reasonable to you?  Thanks!

[peteroznewman]

Yes, that is correct.

Here is a discussion that uses that technique: https://innovationspace.ansys.com/forum/forums/topic/set-initial-velocity-in-transient-analysis/

[peteroznewman]

You may be interested in this longer discussion. https://innovationspace.ansys.com/forum/forums/topic/response-of-a-system-to-an-excitation-on-its-frame/