Visualizing dynamic mode shape

The dynamic motion can be decomposed into a number of dynamic modes, which a re extracted by eigenvalue analysis of the dynamic system. Data related to dynamic modes are also important ingredients of dynamic analysis. The shape of dynamic modes can be represented by deformed shape or animation. In order to visualize dynamic modes, the system should be solved with "Mode superposition" or "Modal analysis" option in "Dynamic Analysis Options" dialog.

>  Starting and controlling mode shape display

"Mode Shape Contro l" dialog is used to control the display of mode shape. Select "Mode Shape" item from menu to open the dialog. The dialog has the same control buttons as "Step Control Panel" dialog described in the preceding section. The mode shape is animated when play button is pressed. The number of frames for animation is determined by the software regardless of the number of time steps involved in the analysis. The animation frame can be moved forward or backward one by one using forward button or backward button respectively.

<Display of dynamic mode shapes>

>  Selecting the mode to display

The dynamic modes are numbered in ascending order of their frequencies, i.e., smaller number for lower frequency and larger number for higher frequency. The mode for display is selected by its number. The number of the currently displayed mode is shown in the text box of the dialog. The number can be picked by directly editing the text or by using scroll buttons. As soon as the mode number is altered, the shape of the corresponding mode is displayed on the main window, and the frequency of the mode is indicated on "Mode Shape Control" dialog.

>  Scale of display

The mode shape is displayed with the deformation scale optimally determined by the software. The scale can be adjusted by using a slide control of the dialog.

>  Speed of animation

The speed of animation, i.e., the number of frames proceeding per second is initially determined by the software. The speed can be adjusted by using a slide control of the dialog.

>  Ending dynamic mode display

Dynamic mode display mode is going on while "Mode Shape Control" dialog is open, and can be terminated by closing the window or by starting another menu command.