The potential of MFC actuator as a tool for reducing low velocity impact induced
delamination has been investigated using LS-DYNA explicit code. For this purpose, three
different piezoelectric actuation models were implemented through its user defined material
subroutine, namely, the linear strain model, electric field dependent model and induced strain
model. The induced strain model was found to provide the best match with experimental
results for actuation strain prediction, hence used in impact investigations.
In predicting the delamination, a newly formulated damage model was used as it was
found that the existing damage models in LS-DYNA are simplistic and rate sensitive. An
independent three-dimensional piezoelectric finite element code was developed and used to
study the effects of design and actuation parameters on the actuation characteristics of the
MFC. The parametric study was meant to determine a laminate-actuator system that would
allow sufficient presence of the piezoelectric effects in it. A selected laminate-actuator system
was later used to investigate the effects of piezoelectric control actions on the impact force
and displacement for purely elastic impact cases. For simply supported laminate it was found
that the peak impact force and displacement could be reduced by applying a counter moment
to the incoming impact load, whereas for clamped laminate the same was achieved by
regulating the laminate stiffness at the impact point.
The technique of impact force reduction confirmed that delamination could be reduced.
However, this concept could not be experimentally verified as the design requirements could
not be practically implemented. The actuator required voltages beyond its operating range to
reduce delamination even in the case of very low energy impact. This is something not
achievable with the existing piezoelectric materials. Assuming powerful piezoelectric
actuators are not impossible in near future, this study could provide useful information for an
attempt to validate this concept.