Working with the Moment Center Tool

When checking equilibrium, it is often necessary to compute moments of forces or sets of forces about particular reference points. Dr. Frame provides facilities to make such calculations relatively simple. First, choose the Show Effective Moments command from the Options menu as shown (or simply press the '6' key):

This causes a line to be drawn from each displayed force vector to the current center of moment as shown (the default center of moment is the grid origin):

Using the Center of Moment Tool (), one can then set the point about which moments are calculated by clicking at the desired point:

In the figure below, support reactions are being drawn, too, and it is straightforward to verify that moment equilibrium is indeed satisfied.

Moments are currently taken with respect to the geometry as displayed on the screen. If displacements are turned on, then the scaled displaced locations will be used--either set the displacement scale to 1.0 if you really want to investigate moments in the deformed configuration (which can cause equilibrium to appear not satisfied for linear analysis), or be sure to turn off displacements when using this tool.

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Using Dr. Frame2D