Curve-fitting requires experimental test data. Input your test data in a plain text file with headers to define the test data. The data file should be in table form, delimited by spaces or commas, and referencing your stress vs. strain values or combinations. AML parameter-fitting supports the following types of experimental data:
Table 7.1: Experimental Data Types
| Experiment Name | Keyword Used with TBFT,EADD |
| Uniaxial Test | unia |
| Biaxial Test | biax |
| Pure Shear Test | shea |
| Simple Shear Test | sshe |
| Volumetric Test | volu |
| Creep Test | cree |
| Shear Decay in Time Domain or Frequency Domain | sdec |
| Bulk Decay in Time Domain or Frequency Domain | bdec |
| Yield Surface vs. Pressure | ysur |
| I1J2 ( Invariant 1 vs. J2 ) | i1j2 |
| Triaxial Test | tria |
All experimental data support temperature (TEMP) as a field variable. When performing parameter-fitting for data with temperatures, multiple sets of coefficients must be generated (one for each temperature unless the model itself allows for variations in temperature).
Specify the following values at the beginning of the experimental data file to indicate column information or additional experiment information as needed:
Table 7.2: Experiment Attributes
| Experiment Attribute | Value | Description |
| ninp | Integer | Number of independent variables |
| nout | Integer | Number of dependent variables |
| integer value (1 to 3) | String | See Table Below for /index,value |
| temp | Double | Temperature |
| seqv | Double | Equivalent Stress |
| creq | Double | Equivalent Creep Strain |
| time | Double | Time |
| weight | Double | Weight to all experimental data points following this line. |
| ntol | Double | Tolerance to quantify a value as zero when calculating normalized least squares. Uses non-normalized least squares for any data point lower than this value to avoid imbalance in calculating total error of the experiment. |
Specify information about each column's purpose at the top of the experimental data
file via a
/
line:index,value
Table 7.3: Column Names for
/index,value
| Column Name | Abbreviation |
| Creep Strain | creq |
| Equiv Stress/Yield Stress | seqv |
| Frequency | freq |
| Initial Pressure | ipre |
| Lateral Strain | elat |
| Lateral Stress | slat |
| Pressure | pres |
| Square Root of J2 | sqj2 |
| Stress Invariant 1 | i1 |
| Temperature | temp |
| Time | time |
| Total Strain | epto |
| Total Stress | s |
| Shear Modulus | smod |
| Bulk Modulus | bmod |
| Shear Mod Real Component | srmd |
| Shear Mod Imaginary Component | simd |
| Bulk Mod Real Component | brmd |
| Bulk Mod Imaginary Component | bimd |