For Coupled analysis, the thermal properties are also presented along with the structural. The thermal properties are listed in Thermal - Isotropic / Orthotropic / Anisotropic.

Note on reference temperature. If the reference temperature is left blank, zero is assumed. If the reference temperature does not fall between temperature values defined for work hardening or strain rate, the highest or lowest values will be used depending on whether the reference temperature is greater or lower than the given temperature range. If it falls inbetween, then values are interpolated. For Structural analysis, if Nodal LBC Temperatures (POINT TEMP) also exist then the INITIAL STATE will not be written since this is incompatible.

When User Sub. UFAIL is used, no input data is necessary and the word UFAIL is written in the 4th data block of the FAIL DATA option.

If one of these constitutive models exists and is active, the Elastic or Plastic constitutive models must be turned off (made inactive) otherwise ISOTROPIC, WORK HARD and MOONEY or some other hyperelastic option will be written to the input file which will cause an incompatibility in the analysis.

Modulus 1 and Exponent 1 will repeat for the Number of Terms and will increment as such, e.g., Modulus 2, Exponent 2 - Modulus 3, Exponent 3, etc. Same comment applies to FOAM option for repeating terms.

Marc may force you to use a Herrmann formulated element when using some Hyperelastic constitutive models.

Instantaneous values are entered for the elastic model, and the difference between the instantaneous value and the summation of the values in the series is the long-term property value.

2 1/4 Cr-Mo ORNL, Reversed Plasticity ORNL, Full Alpha Reset ORNL are the same as Oak Ridge National Labs. Generalized Plasticity is the same as Von Mises.

Perfectly Plastic is identical to Elastic-Plastic except that no hardening rules apply. Thus no WORK HARD options are created; only ISOTROPIC and STRAIN RATE options with TEMPERATURE EFFECTS, if requested. Stress vs Plastic Strain is replaced with Yield Stress data only as is 10th Cycle Yield vs. Strain replaced with 10th Cycle Yield Stress data. Thus no tabular data is necessary.

Rigid-Plastic is identical to Elastic Plastic for Hardening Rules: Power Law, Rate Power Law, Johnson-Cook, and Kumar. Piecewise Linear is identical to Von Mises. The difference here is that the ISOTROPIC option is written and does not contain E
or nu. If an Elastic constitutive model has been created it is ignored, or that is, those values are ignored (elasticity is ignored). A RIGID identifier is placed in the ISOTROPIC option.

In general, you should use true stress vs natural log of plastic strain when defining plasticity curves.

The first value of plastic strain in a stress-strain field must be zero. The corresponding yield stress for this zero plastic strain is placed in the ISOTROPIC option as the Tensile Yield Stress. If yield stress can vary with temperature, the first data point in the field must be the temperature at this yield stress, which will be placed in the TEMPERATURE EFFECTS option, unless you are using the TABLE format, in which the fully defined fields will be converted to equivalent TABLES.

The stress-strain field causes the WORK HARD, DATA option to be written if the first pair of data points of the given field is: (zero, nonzero) This indicates that true stress vs natural log plastic strain data has been supplied. This is consistent with default functionality of Marc. However, if the first data point pair is detected to be (nonzero, nonzero), then this indicates that the engineering stress/strain curve has been given, where the strain is the total strain. Thus the data is converted from engineering stress/strain to true stress/strain before writing the data to the input file. In any case, stress/strain data must begin at the yield stress. In other words, the first pair of data points cannot both be zero. If conversion is necessary, the following formulation is used:

s = Engineering Stress, e = Engineering Strain,
s = True Stress, et = True Total Strain, ee = True Elastic Strain,
ep = True Plastic Strain, E = Young’s Modulus

All of the Yield Criteria / Hardening Rules have identical inputs as for Isotropic - Plastic materials. The input property values are placed in the equivalent location on the ORTHOTROPIC or ANISOTROPIC options. The only difference is noted here for von Mises yield criteria.

Perfectly Plastic is identical to Elastic-Plastic except that no hardening rules apply. Thus no WORK HARD options are created. Stress vs Plastic Strain is replaced with Yield Stress data only as is 10th Cycle Yield vs. Strain replaced with 10th Cycle Yield Stress data. Thus no tabular data is necessary.

It is extremely important that when you define a layup (in the form on the next page), that it be done from top to bottom. Think of the top layer of the layup as being the top row of the spreadsheet and you should have no problems. As an example of how important this is, consider a cantilevered flat plate subject to an axial load with two layers. The top layer is extremely flexible compared to the bottom layer, which is relatively much stiffer than the top. Due to the shear forces created between the layers, the vertical deflection should tend to favor the side of the stiffer layer, thus the plate should bend down. If the layer is defined from bottom to top instead of top to bottom, you will get what appears to be the opposite answer where the deflection bends up. The answers are correct in both cases. The problem is how you defined the layup.

See the caution on the previous page. Layers must be defined from top to bottom.

The modifications are not saved until Apply button is pressed.