Performance evaluation of different patch configurations

The settling time is defined as the time required for the response curve to reach within a range of 5 per cent of the amplitude. This is an important parameter for structures such as flexible wings etc. The study of variation of settling time with gain is done for the response amplitude at the centre of the plate. Settling time and damping ratio for different configurations are plotted in Figures 23.1(a) and (b) for a gain value of 50.

Figure 23.1: Comparison of (a) settling time and (b) damping ratio for different configuration of PVDF patches for a gain = 50

According to the numerical simulation, Configuration B (covering 50 per cent of the top surface of laminate) and configuration D (totally covering the top surface) show better vibration suppression. When the PVDF film covers half of the upper surface along the clamp side (Configuration B), the patch has the best vibration suppression capability as the response at the centre of the plate reaches the tolerable limit in 8 seconds [see Figure 23.1(a)]. Second best performance is observed in fully covered film where the response takes slightly more time (8.5 seconds) to settle.

Figure 23.1(b) shows the damping ratio for the different configurations. Damping ratio is highest in case of patch B. Patch C has inferior vibration suppression capability and is characterized by lower damping properties. Patch A covering only a quarter of the top surface, shows better vibration control performance than Patch C.