*CRUSH STRESS

Define the crush stress of a material.

Warning: Crush stress is not a true material property. Where the analysis laminate deviates from the original tested laminate, the ply-by-ply data reduction process is not guaranteed to reliably predict the crush performance on the new laminate. Where crush performance is important to the function of the structure and deviation from the tested laminate is significant, the resulting laminate should be tested to confirm that the crush performance follows the ply-by-ply data reduction values.

Note: All crush stresses should be measured on the complete laminated composite. Data entry is reduced to a ply-by-ply bases, so it is possible to assess the effects of modifying layers within the analysis definition as the structure is developed.

This option is used to define the crush stress of a material. It must be used as a suboption of the MATERIAL option. The crush stress can be constant (isotropic) or orientation dependent (anisotropic), defined as a function of the incidence angle. A regularization scheme is used for the material data when the crush stress is dependent.

If specified, temperature and field dependency is evaluated only at the beginning of the analysis. Subsequent changes in temperature and/or predefined field variables will have no effect in the crushing behavior of the material.

This page discusses:

Optional parameters
Data lines to define crush stress

Optional parameters

DEPENDENCIES: Set this parameter equal to the number of field variables included in the definition of the crush stress, in addition to temperature.

Data lines to define crush stress

First line

Crush stress.
Material angle in degrees.
Temperature.
First field variable.
Second field variable.
Etc., up to five field variables.

Subsequent lines (only needed if the DEPENDENCIES parameter has a value greater than five)

Sixth field variable.
Etc., up to eight field variables per line.

Repeat this set of data lines as often as necessary to define the dependence of crush stress on the incidence angle and, if needed, on temperature and other predefined variables. The complete profile must be included, excluding the 180° data point that is assumed to be identical to the first data point at 0°. At minimum, the data should account for the perpendicular crushing impact in each ply direction for the complete composite layup; CZone for Abaqus will interpolate between the data points to account for crushing in other directions.