The unsymmetrical From-To cycle counting keeps more information about the loading cycles than Range-Mean counting does, because it also stores the "orientation" of each load cycle. This is important information if you want to reconstruct a time history from a Rainflow matrix.
The Rainflow counting of Simcenter Tecware (formerly called LMS Tecware) is a From-To cycle counting, and thus the default representation of the Rainflow matrices are also in From-To form.
However, Tecware also allows changing the representation to Range-Mean matrices. In fact, a Range-Mean histogram can always be derived from a From-To histogram, but not vice versa. This is because the From-To representation includes additional information (as mentioned above).
Look at the two load histories below:
They both have the same mean level and the same number of cycles, and the cycles' amplitudes are identical. The only distinctive property is the opposite polarity.
Looking at the Rainflow matrices of the two load histories, we get in the From-To representation:
The Rainflow matrix of "Load_up" shows hanging cycles, whereas the corresponding Rainflow matrix of "Load_down" shows standing cycles.
The denotation hanging and standing is motivated from the stress-strain-path. There, a hanging event is connected to the superior hysteresis branch at its upper reversal point, but a standing event is connected at its lower reversal point.
When a load cycle is just represented by its range and mean, the distinction between hanging andstanding is not possible. Thus, the Range-Mean representation for both of the signals looks like this:
The desired representation of a Rainflow matrix can be set in the "RainView layout" window, which is available via the menu Options à Layout within the Rainflow matrix display.
Rainflow matrices can only be edited in the From-To representation.
Questions? Contact Siemens PLM GTAC support or post a reply.
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