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coupling between plasticity and damage

Hello all,

 I am Nilesh and doing
study of Continuum damage mechanics, in that context, I have some doubt s

     Can anyone tell
me?

1. As in plasticity we have yield surface  and in damage we have damage surface  but in this case,  does damage surface working same ( for
isotropic and kinematics damage???? ) Like in isotropic and kinematic
hardening??? I mean expansion and movement for isotropic and kinematic damage
case???

2. If we can define our surface in thermodynamic force space ( as stated )
then why most of author’s wrote damage surface in strain space???? What is the 
difference between two surfaces??? And does we have same thermodynamics force
space in case of plasticity

 3, where can I find
this coupling of plasticity and damage algorithm???? (Any paper / thesis / notes)  I mean for perfect elastoplastic damage , isotropic hardening and isotropic damage  and kinematic hardening and kinematic damage ???

4. What is strong and weak coupling in damage mechanics??
And how do I understand which is good for which application??

 Thanks in advance,

Best Regards,

Nilesh

Dan Cojocaru's picture

Coupled damage-plasticity is discussed in 'Damage Mechanics' (Chapter 7) by Voyiadjis and Kattan 

 

Nilesh,

I think there many papers exist in CDM. For instance, Voyiadjis and Dorgan recently have a paper in pressure in Interntional journal of plasticity in this regard:

George Z. Voyiadjis *, Robert J. Dorgan, Framework using functional forms of hardening internal state variables in modeling elasto-plastic-damage behavior, International Journal of Plasticity xxx (2007) (in press)

I wrote a paper on damage plasticity for metals, where the damage is to start right after yielding (this essentially means any plastic flow introduces some irreversible plastic damage to the metal, and therefore, damage surface in CDM is the yield surface). The new ingradient is the third stress invariant is introduced in to the damage accumulation process through a fracture envelope. Here is the paper.

Liang Xue,  Damage accumulation and fracture initiation in ncracked ductile solids subject to triaxial loading, International Journal of Solids and Structures 44 (2007) 5163–5181.

I assume you are doing fracture stuff. One reason for using strain measurement is for large strain, I think, is the strain is more convenient for deformation, which we relate to damage. The yield surface can be equally expressed by elastic strain, but these strain will be too small and the measuring error can be much more than the stress measurement.

 

Rashid K. Abu Al-Rub's picture

Check my papers on this topic. I have published several papers on the coupling between plasticity and damage for different material. Both coupled plasticity-damage constiutive modeling and the corresponding computational algorithms are presented in these papers. Check the first paper since it discusses how to enhance a strong coupling between plasticity and damage using thermodynamic laws.

Abu Al-Rub, R.K., Voyiadjis, G.Z. “On the coupling of anisotropic damage and plasticity models for ductile materials,” International Journal of Solids and Structures, Vol. 40, No. 11, pp. 2611-2643, 2003.

Voyiadjis, G.Z., Abu Al-Rub, R.K., Palazotto, A.N. “Thermodynamic formulations for non-local coupling of viscoplasticity and anisotropic viscodamage for dynamic localization problems using gradient theory,” International Journal of Plasticity, Vol. 20, No. 6, pp. 981-1038, 2004.

Abu Al-Rub, R.K., Voyiadjis, G.Z. “A finite strain plastic-damage model for high velocity impacts using combined viscosity and gradient localization limiters, Part I: Theoretical formulation,” International Journal of Damage Mechanics, Vol. 15, No. 4, pp. 293–334, 2006.

Voyiadjis, G.Z., Abu Al-Rub, R.K. “A finite strain plastic-damage model for high velocity impacts using combined viscosity and gradient localization limiters, Part II: Numerical aspects and simulations,” International Journal of Damage Mechanics, Vol. 15, No. 4, pp. 335–373, 2006.

Cicekli, U., Voyiadjis, G.Z., Abu Al-Rub, R.K., “A plasticity and anisotropic damage model for plain concrete,” International Journal of Plasticity, doi: 10.1016/j.ijplas.2007.03.006 (in press).

Rashid K. Abu Al-Rub, Ph.D. Texas A&M University

Thank you very much for giving me valuable input

Best Regards,

Nilesh

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