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2017-03-04

Quadratic Combination Using CQC Rule

In RF‑/DYNAM Pro – Equivalent Loads the CQC (Complete Quadratic Combination) rule has been available since version X.06.3039.

In the user interface in the "Dynamic Load Cases" tab, under "Equivalent Force Analysis", there are new options for the combination of modal responses. So far, the modal responses have been combined with the SRSS rule; this quadratic combination was always applied as an equivalent linear combination (formerly called the "Preserve Sign" option).

Now, you have a choice between the SRSS and the CQC rule. By default, the modal combinations are applied as linear combinations, which have the advantage of far smaller and signed corresponding results. However, you can deactivate this option and apply the standard form of the SRSS/CQC rule if you like.

RF-/DYNAM Pro - Equivalent Loads exports load cases for each selected mode and excitation direction. These load cases contain the required CQC parameters "Angular frequency" and "Lehr's damping".

The formulas and additional information on applying this rule are illustrated in the image.


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