Dynamic Load Tabular Function, Form 3
Description: Defines a parametric tabular function for use in generating time-dependent dynamic loads.
Format:
Example:
| Field | Definition | Type | Default |
|---|---|---|---|
| TID | Table identification number. | Integer > 0 | Required |
| X1 | Table parameter. | Real | 0.0 |
| X2 | Table parameter. | Real ≠ 0.0 | Required |
| xi, yi | Tabular values. | Real | Required |
Remarks:
- xi must be in either ascending or descending order, but not both.
- Discontinuities may be specified between any two points except the two starting points or two endpoints. For example, in Figure 1 discontinuities are allowed only between points x2 through x7. Also if y is evaluated at a discontinuity, then the average value of y is used. In Figure 1, the value of y at x = x3 is y = (y3 + y4)/2.
- At least one continuation entry must be specified.
- Any xi-yi pair may be ignored by placing SKIP in either of the two fields.
- The end of the table is indicated by the existence of ENDT in either of the two fields following the last entry. Any continuations that follow the entry containing the end-of-table flag ENDT will be ignored.
- TABLED3 uses the algorithm
where x is input to the table, y is returned, and is supplied from the MAT1 entry. The table look-up is performed using linear interpolation within the table and linear extrapolation outside the table using the two starting or endpoints. See Figure 1. No warning messages are issued if table data is input incorrectly.
- The function is zero outside the range of the table.
- For frequency dependent loads, X1, X2, and xi are measured in cycles per unit time.
Figure 1. Example of Table Extrapolation and Discontinuity