Damage Evolution

By default, rupture is deactivated for all analyses. The HIN file can be used to activate rupture for an elastic-plastic material, allowing damage to evolve as the solution progresses. If rupture is activated and rupture is predicted, the stiffness of the composite material is instantaneously reduced to a fraction of the original elastic stiffness of the composite. The stiffness of the composite material remains fixed at the reduced level for the remainder of the analysis.

Tension

In a tensile environment, the amount of stiffness degradation is controlled with the degradation parameter. This parameter can have a large influence on a progressive failure simulation. By default, the degradation parameter is set to 1E-06, or 0.000001. Use the *DAMAGEEVOLUTION keyword in the HIN file if you wish to adjust the degradation parameter.

*DAMAGEEVOLUTION, TYPE=RUPTURE
Cdeg

where TYPE=RUPTURE refers to the instantaneous stiffness degradation method. This is currently the only available option. Cdeg represents the stiffness degradation parameter. This value should lie in the range 0 < Cdeg < 1. The *DAMAGEEVOLUTION keyword must be preceded by a valid *MATERIAL keyword.

Consider the following example where we want to use a post failure stiffness that is 1.5% of the original composite stiffness.

*MATERIAL, NAME=CA-PLASTIC-1
*DAMAGEEVOLUTION, TYPE=RUPTURE
0.015

Compression

In a compressive environment, the amount of degradation is dependent on the three coefficients B1, B2, and B3. The values of these coefficients are determined during the material characterization. Use the *COMPRESSIONSTRESSDROP keyword in the HIN file if you wish to adjust one or more of the coefficients controlling the stiffness degradation.

*COMPRESSIONSTRESSDROP
B1, B2, B3

This keyword must be preceded by a valid *MATERIAL or *ENVIRONMENT keyword.

Consider the following example where we want to adjust B1 to 0.5 and B3 to 0.01.

*MATERIAL, NAME=CA-PLASTIC-1
*COMPRESSIONSTRESSDROP
0.5, , 0.01