This dialog displays the Ramberg-Osgood coefficients of the material.
To access this dialog, right-click 
in the Study Tasks pane, then select Details or Edit from the drop-down menu.
Ramberg-Osgood equation
The Ramberg-Osgood equation predicts the material behaviour in the non-linear regions of the stress-strain curve.
Note: The Ramberg-Osgood equation in no way alters the Moldflow analysis. It is used to provide additional material information when exporting results for structural analysis.
Data from the Stress-Strain tab is used to calculate the coefficients used in the Ramberg-Osgood equation. Each unique set of temperature, relative humidity and strain rate will generate a line in this table provided there is enough data available. The following is required:
- Minimum of fifteen data points for a given angle
- Results are available for at least two angles. Currently only 0º, 45°, and 90° are supported.
- These results must be for the tensile properties of the material. Compression results are ignored.
The graph generated from the Ramberg-Osgood equation can be viewed by clicking Plot data on the Stress-Strain tab of this dialog.
Displayed results
| Data | Explanation |
|---|---|
| Sigma Zero | The stress level at which plastic strain becomes dominant. |
| n | Ramberg-Osgood curve shape parameter |
| Alpha | Directionality influence constant. A measure of the proportion of fibers in a given direction. |
| Beta | Directionality influence constant. A measure of the proportion of fibers in a given direction. |
| Eig | The maximum allowable effective stress. This value is based on the rupture stress levels of the material at 0º, 45º and 90º of the fiber orientation. |
| Matrix Modulus | The uniaxial stiffness (force per unit area) of the plastic matrix constituent material. |
| Matrix Poisson's Ratio | The ratio of lateral contraction to uniaxial elongation of the matrix constituent material. |
| Fiber Modulus | The uniaxial stiffness (force per unit area) of the fiber constituent material. |
| Fiber Poisson's Ratio | The ratio of lateral contraction to uniaxial elongation of the fiber constituent material. |
| Maximum Von Misses matrix stress at failure | The highest point obtained on a stress-strain curve. |
| Temperature | The temperature at which the material was tested. |
| Relative humidity | The relative humidity at which the material was tested. |
| Strain rate | The strain rate at which the material was tested. |
Other dialog elements
- Calculate Mechanical Models
- When in the edit mode, this option is available. Click this button and data from the Stress-Strain tab of the dialog is used to calculate the Ramberg-Osgood coefficients. Each unique set of temperature, relative humidity and strain rate will generate a line in this table provided there is enough data available.
- View test information
- Opens a dialog box that outlines the source date and method of testing to determine the Ramberg-Osgood parameters