Learning Forum

[Cpwtub]

Hi guys,nIs it possible to extract reaction force at a node of interest under a harmonic load (Harmonic analysis) . Preferably in complex form?.nAre there any available examples?. nThank you very much!nn

[BenjaminStarling]

nensure you have nodal forces enabled under output controls, or use the OUTRES command. Then inser a user defined result, select the nodes you are interested in, and put the expression, ENFOX, ENFOY, ENFOZ, or ENFOVECTORS.n

[Cpwtub]

nThank you very much. I ll try it.nBut would that be possible to extract frequency response of the nodal reaction forces in harmonic analysis?nBest regardsn

[BenjaminStarling]

Now I understand what the issue is. Mechanical currently does not have the option to plot results over the frequency domain, other than the predefinded frequency response options.nOne option is to create a result at each frequency then export to excel and create your own frequency response curves. This is cumbersome but I may actually prefer this method as you will likely want the response in tabular form for your calculations, and creating results at all sets just takes two clicks. Unfortunately it is the export to excel which takes time, especially if you have many frequencies to extract results.nThe other option is to use MAPDL. /POST26 allows you to plot any result in the frequency domain. The downside of this is that ENFO results are element based. Therefore manually going through each element is cumbersome. This can be looped with APDL but I would need a bit of time to provide guidance on this loop.nIf the boundary you are looking to extract the frequency response on is restrained, you may be able use the F result. This is easier to loop, a rough example is shown below. This will plot the result but I am fairly sure you should also be able to output to a text file. This same example works for ENFO, but would require two extra loops to go through the elements, and then sum the ENFO result at nodes shared between elements.ncmsel,s,surface,nodes !component of nodes to get frequency responsen/post26nn_next=ndnext(0)nvari_n=1n?*DOWHILE,n_nextnRFORCE,vari_n,n_next,F,XnXVAR,1nPLVAR,vari_nnvari_n=vari_n+1n*ENDDOnThis example plots one node at a time without pausing in between. It should be adaptable to plot multiple nodes at a time, pause, export image, and to export multiple nodes to text file.nI am not super familiar with this process, and the above code may not work straight away. Other commands to look at are in the POST26 family, namely NSOL, ESOL, PRCPLX and some others.nhttps://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v202/en/ans_cmd/Hlp_C_CH2_8.htmln

[BenjaminStarling]

I forgot to actually loop the above example. Inside the loop you will need to remove the nodes incrementally. You can loop element selections in a similar manner using elnext(0)nnsel,u,node,,n_nextncm,s,surace,nodesnn_next=ndnext(0)nn