Obtaining D.C. Gain using MATLAB

All the Eigen vector values for the six frequencies are uploaded in the MATLAB© Workspace. All the frequencies obtained might not contribute to the systems disturbance significantly. Hence, only the frequencies that dominate are selected. This selection is made on the basis of the D C Gain value for each mode. This D C Gain value is now calculated using MATLAB©. It is assumed that the force is applied at the node, which for a particular mode, is peak. As the case is of simply supported, again the same node is selected for the output. Now, the D C Gain is given as follows[8]:

D C Gain is calculated for each mode shape. D C Gain values obtained for each mode are as follows:

Graph of D.C. Value v/s Frequency is plotted.

MATLAB© plot for DC value vs. Mode number

From the graph, it is observed that as the mode number increases there is a significant decrease in DC Gain value. High frequency modes have less nodes displacement. For a given structure, modes with negligible D C Gain value do not contribute much to the disturbance. Hence, these high frequency modes can be ignored for controlling purpose.