Time Domain Statistics allow you to view statistics and probability distributions for a Time Response Analysis.
By default, statistics are calculated over the Full Time Series (all the steps) in the time response analysis. Changing the Statistics Calculated Over setting to Cropped Time Series allows you to specify Cropping from Start of Time Series and Cropping from End of Time Series times. The calculated statistics will then be restricted to this time frame.
In the Details panel, select a Result Type in one of the Result A-E fields. You can select from any quantity which has been calculated in the time response analysis, such as Wave Surface Elevation, Structure Motions and Forces, Connection Forces, Tether/Riser Properties, or Time Step Error.
Each of the Result A-E sets includes a Result Source selection. Where there are multiple Time Response Analysis systems in the Outline tree, you may select any as a Result Source for the current Result Set. This allows results from similar Time Response Analyses – for example, cable tension statistics under different environments – to be compared in the same table of probability distributions.
When a result type is selected, the Result object expands with further information in the Details panel.
Note: You can include any of the results in your design points by clicking the checkbox next to the result in the Details panel. However, output values can only be parameterized when their Result Source is defined as the current analysis system.
If you wish to calculate statistics for the translation motion of the structure, the Reference Point at which the result is reported can be the Center of Gravity of the selected Structure, or any Connection Point on that structure.
The Motion Relative To input can be used to set the frame of reference for the reported translation motion. This may either be the Origin of the Fixed Reference Axes (FRA), the Center of Gravity of another structure, a Connection Point on another structure, or a Fixed Point.
Note: When the Type is set to Structure Position, the SubType is set to Actual Response, the Component is set to Global Z, and the Reference Point is a Connection Point, the result may also be reported relative to the Wave Surface.
The selected Connection Point must have its Include in Results option set to Yes before the analysis is solved.
Probability Density Functions are available by clicking the Properties tab at the bottom of the graphical view. The distributions are shown as histograms, where the number of bins for each histogram is automatically determined as a function of the number of time steps. Mean and standard deviations are plotted as dot-dashed and dashed lines, respectively.
You can also use the Statistics Shown As setting to optionally plot these histograms as Cumulative Distribution Functions.
