Questions about base or support excitation in FEAP85

[zqzhang]

Dear all,
     
       I am modelling a printed circuit board with support excitation (Two case: one is harmonic response，the other is impact response). The question is how to apply the loading as harmonic or impact loading acting in the base of printed circuit board? What command should I use to input the file? Here, the bourdary of the printed circuit board is fixed. I wrote a inputfile (see the attachments) but there are some errors.
Please, I need detail answers about it. Thank you for your help.

Best regards,
ZQ

[FEAP_Admin]

See the user manual and read the sections on proportional loads.  They will allow you to define the time variation of the load.  You can have multiple proportional loads and you can choose where you want to apply them.

[Prof. R.L. Taylor]

The BASE option is for cases where the supports have differing response.  If all the base nodes move the same you can do the loading either as you have defined it or as a body force which has the time variation you want -- that is applied like an earthquake loading.  For this case you can consult a book such as CHOPRA
author    = {A.K. Chopra},
title     = {Dynamics of Structures},
publisher = {Prentice-Hall},
address   = {Upper Saddle River, N.J.},
year      = {1995} }

[zqzhang]

Dear Prof. Taylor,
dear FEAP Admain,
       
         Thank you for your suggestion. I wrote an inputfile based on  the user manual, but there are some errors. Could you check my inputfile and point out the error?
          Thank you very much!

Best Regards
ZQ

[Prof. R.L. Taylor]

I have looked through your file and made some corrections

the main things are:

1. the parameter "pi" was not defined (it is not something feap knows about)

2 Load groups do not current ly work with the 'base' excitement.

3. Some of the commands were not within a "batch-end" pair.

As a rule it is always good to test something with a small mesh before one with several hundred dofs.  The return mesh is a small problem.

[zqzhang]

Dear Prof. Tayor,

         Thank you for your help.

 Best regards
 ZQ