How is stress triaxiality calculated in Abaqus?

Stress triaxiality, η=−p/q η = – p / q (available in Abaqus/Standard only in conjunction with damage initiation).

What is ductile damage in Abaqus?

The Ductile damage initiation criterion is a model for predicting the onset of damage due to nucleation, growth, and coalescence of voids in ductile metals. The model assumes that the equivalent plastic strain at the onset of damage is a function of stress triaxiality and strain rate.

What is the formula for stress triaxiality in Abaqus?

Stress Triaxiality is defined as the ratio of (HYDROSTATIC PRESSURE OR MEAN STRESS) to the EQUIVALENT STRESS. When I check the abaqus field output variables this option is available but only in the recent versions (6.8 & 6.9). The input file usage according to the documentation is TRIAX.

Why do negative triaxialities appear positive in Abaqus?

Pay attention to the fact that negative triaxialities although standing for the compressive hydrostatic stress states will appear as positive in ABAQUS. That is because the PRESSURE variable in ABAQUS is -trace (STRESS)73. The reason is simple and derived from the FEELING of PRESSURE.

Why are stress and strain conversions important for Abaqus?

Stress and strain conversions. While there are few differences between the nominal and true values at small strains, there are very significant differences at larger strain values; therefore, it is extremely important to provide the proper stress-strain data to Abaqus if the strains in the simulation will be large.

How is the triaxiality of a plastic strain defined?

The stress triaxiality is defined by mean stress divided by equivalent stress. As shown in this figure, the equivalent plastic strain at damage initiation decreases with an increase in stress triaxiality, which indicates dilatational stress damage.