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Dependence of fracture energy of ceramic on loading condition?

Submitted by rctron on

Literature suggests that the fracture strength of the ceramic tends to be higher in a dynamic loading condition than in static condition. This relates to the increase in the fracture energy in dynamic processes. Literature refers to an inelastic response prior to failure (Hugoniot elastic limit) the reason behind increased strength. Can anyone explain the phenomenon in a more lucid way, or guide me to an appropriate reference to understand this?

Stresses go beyond yield limit in perfecly-plastic model...

Submitted by ISC214 on

Hi all,

I have a problem with perfect-plasticity material model in Abaqus. I this simple 2D analysis, I am modeling a beam fixed at both ends and applying temperature loading on it that will cause yielding. The material model is perfectly plastic with,

*PLASTIC

4.85 E8, 0.0

The problem is, stresses go beyond yield limit (4.85 E8) which should not be the case for the perfectly-plastic material model. I would appreciate any comment/help/suggestion.

Regards,

Soner

 

initialization of initial condition in state variable in vumat

Submitted by SAMICORP on

i am still struggling with  defining an initial condition in vumat. i have defined mine like this:

STATEV(1:nstatev)=stateOld(KM,1:nstatev) 

          if (steptime .eq. zero) then

          STATEV(1) = 1.0d0

            STATEV(2) = 1.0d0

            STATEV(3) = 1.0d0

            STATEV(4) = 0.0d0

            STATEV(5) = 0.0d0

Damage Evolution: ABAQUS Fracture Energy Parameters

Submitted by lansa101 on

I'm using a damage evolution model in XFEM in order to model crack growth, however I am trying to identify the correct Mode I fracture energy for my problem. In particular there seems to be an issue with the units of fracture energy in ABAQUS.

I am using Damage for Traction Separation Laws, Maxps; Damage Evolution Type = Energy; Mixed bode behaviour = Power Law with power value 1; Now at the bottom what should be the input values of Normal Mode Fracture Energy, Shear Mode Fracture Energy 1st direction and Shear Mode Fracture Energy 2nd Direction.