FEAP User Forum

FEAP => Input File Issues => Topic started by: Schandra on January 04, 2018, 09:28:12 AM

Title: uniaxial tension followed by shear
Post by: Schandra on January 04, 2018, 09:28:12 AM

Dear all,

I am trying on a simple problem of applying uniaxial tension on a unit cube and then subsequently shearing it.
I am successful in applying shear in the first step but in the second step I get shear+tension (am unable to restrict the first step).
Can you please help me in identifying my mistake.

Warm Regards,
Chandra

Title: Re: uniaxial tension followed by shear
Post by: Prof. R.L. Taylor on January 04, 2018, 04:22:40 PM

It looks like the displacements at the mid-height are not moving correctly.

I would suggest you use feap graphics to check the mesh at each stage to make sure you have set the correct boundary restraints.  You can do this by putting INTEractive commands at solution stages and then look at the ID array and plot results

This is a small problem you do not need to use PARDiso either for this problem or paraview.

Title: Re: uniaxial tension followed by shear
Post by: xuehanbing on January 04, 2018, 04:55:41 PM

Dear Schandra:
     I want to ask you how to apply shear in the first step and in the second step I get shear+tension.
    Thank you.
    xuehanbing.

Title: Re: uniaxial tension followed by shear
Post by: Schandra on January 05, 2018, 01:10:33 AM

Thanks for the comments Prof. Taylor, I shall do so.

Title: Re: uniaxial tension followed by shear
Post by: Yaakov on January 11, 2018, 04:46:45 PM

xuehanbing,

just look for the post about boundary change problem in our feap forum.

& for pure shear loading in 2 or 3 D (this case is not pure shear), we shall define the Neuman & Dirichlet BC in input file carefully.

for pure shear loading applicaitons you may see some new articles by De Borst et al.


Best,
Yaakov

Quote from: xuehanbing on January 04, 2018, 04:55:41 PM

Dear Schandra:
     I want to ask you how to apply shear in the first step and in the second step I get shear+tension.
    Thank you.
    xuehanbing.

Title: Re: uniaxial tension followed by shear
Post by: fethio on February 25, 2018, 07:23:43 AM

This post was interesting for me because it urged me to give the input file a try, then I saw it was using an isogeometric  type.

However, it didn't work. Upon running the original input file I got the error:

*ERROR* PNUMS: Problem size does not permit a solution:
         Number of nodes         =         6
         Number of elements      =         0
         Number of material sets =         1


Hmm, I guess I didn't compile FEAP the way it was supposed to be, in order for the NURb, etc commands to work.

Title: Re: uniaxial tension followed by shear
Post by: FEAP_Admin on February 25, 2018, 09:10:38 AM

You need to compile the program in the igafeap directory.

Title: Re: uniaxial tension followed by shear
Post by: fethio on February 25, 2018, 11:22:11 AM

I suppose it is necessary to add the line
   (cd igafeap; make archive)
to the Makefile is enough?

Title: Re: uniaxial tension followed by shear
Post by: Prof. R.L. Taylor on February 25, 2018, 11:38:55 AM

You need to make "ifeap",  probably just "make" is enough once you are in the igafeap directory.  The executable is in "igafeap/main"

Title: Re: uniaxial tension followed by shear
Post by: fethio on February 26, 2018, 01:19:25 PM

Thank you Prof. Taylor.