FEAP User Forum

FEAP => General questions => Topic started by: fantico on June 22, 2013, 02:08:15 PM

Title: Damage model in FEAP
Post by: fantico on June 22, 2013, 02:08:15 PM

Greetings,

I'm trying to run an example using the damage model implemented in FEAP (Simo 1987). I have a couple of questions:

1 - Does this model run in explicit?

2 - I'm following the definition made by Simo (1987) using a value of beta (damage limit) and alpha (rate) (eq. 2.10) to run an example (attached). I checked the variation of the equivalent strain (wengy) defined in edam3f.f  and this one never changes during the simulation. Therefore, damage never activates. Could anyone tell me what is wrong?

Thank you in advance,

Federico 

Title: Re: Damage model in FEAP
Post by: Prof. R.L. Taylor on June 29, 2013, 05:46:34 AM

There is no reason that the model should not damage, however, we have not tested the damage in explicit mode.  Can you post a problem input file you are testing?

Title: Re: Damage model in FEAP
Post by: Prof. R.L. Taylor on June 29, 2013, 07:09:40 AM

There are bugs with the damage initiation.

Using the modified neohookean model you can do the following changes:
In directory /elements/material/finite

1.  In subprogram neoh3f.f
     a.) Add common block: include 'elengy.h'
     b.) Before call to viscfd insert:  estore = d(22)*trbe3*1.5d0
          This is the energy

2. In subprogram
    a.) Add common block: include 'elengy.h'
    b.) Before call to edam3f add: wengy = estore

Test to see if this helps.  Note that there are other models that can use the viscoelastic damage and similar changes would be necessary to correct all of them.

Title: Re: Damage model in FEAP
Post by: Prof. R.L. Taylor on June 29, 2013, 08:08:37 AM

In version 8.3 the plane stress is done by modlfd.  The computations in fld2d1.f (stype.eq.1) are not needed and should be removed.  It is better to test damage using the mixed element.  Earlier versions of feap do not do plane stress in finite deformation for most material models.