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*PLASTIC HARDENING

purpose

To define hardening models for plastic materials.

Theory

Refer to Linear Elastic with Plastic Hardening for further information on this feature.

Keyword Format

A block of lines that defines a plastic hardening model, repeated as often as necessary. The block begins with a line defining the model name and (optionally) a tension variation. It is followed by as many lines as necessary to define each point in the plastic hardening model.

Line defining the model name and tension variation:

NAME=Model Name [, TENSION VARIATION=Tension Variation]

Line defining a point in the plastic hardening model:

Equivalent Stress, Equivalent Plastic Strain

Each model must have at least two points defined. Plastic hardening models may only be associated with non-linear beam elements which are defined using the Rigid Riser Format for geometric properties specification.

Table Input

Notes

(a)This keyword is used to define plastic hardening models that can be associated with a particular set of elements. These models may be assigned to element sets using the *GEOMETRIC SETS keyword.

(b)Use as many lines as you need to completely define a particular force-strain curve. Simply leave Columns 1 and 4 blank for second and subsequent lines. For subsequent models, put the model name in Column 1 and specify the equivalent stress and the equivalent plastic strain data in the same way.

(c)The first point in the model defines the yield point. As a result, it is expected that the value for the Equivalent Plastic Strain be zero.

(d)If the strain in an element lies between the force-strain data points you specify, Flexcom uses linear interpolation to determine the relevant stiffness for the element.

(e)If the strain in the element lies outside the specified range of the force-strain curve, then Flexcom simply extrapolates from the first or last section of the curve as appropriate.

(f)None of the specified strain terms can have a negative value.

(g)The tension variation value defines the threshold above or below which the plastic hardening model is integrated to determine the remaining bending moment capacity, based on the axial force at a particular location. A value of zero means the integration is performed as soon as a variation is registered. If the tension variation value is omitted, then the plastic hardening model is integrated only once at the beginning of the analysis.