Is it possible to dynamically analyze an initial deflection of a component with RFEM or RSTAB?

Answer

Yes, this is possible with the RF-/DYNAM Pro - Forced Vibrations add-on module. This application enables also using time history. It is available for both solution methods (linear Newmark analysis or modal analysis), but the procedures differ slightly.

The procedure is as follows:

  1. Define a load case that contains a load that causes the desired initial deflection.
  2. Activate the time history method of time diagrams in RF-/DYNAM Pro and define a new time diagram that has a multiplier of 0 over the entire time.

    Figure 01 - Time Diagram with Multiplier 0

  3. Then, select the defined time diagram in the dynamic load cases (which load case you combine it with is irrelevant because it multiplies the load by 0). You can then import the load case defined in the first step as the initial condition (or only the initial deformation in the modal analysis). Thus, the conditions from this load case are imported at time t = 0 and released immediately afterward.

    Figure 02 - Activation of Initial Condition/Deformation in Dynamic Load Cases

Use this procedure to simulate a vibration after an initial deflection. To illustrate this, there is an example file in the download area where this method is displayed on a single-mass oscillator.

Keywords

Forced vibration Single-mass oscillator Initial deflection Initial deformation

Reference

Downloads

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