Department of Mechanical and Aerospace Engineering
Development of Refined Higher Order Theories for Modeling
Composites including Delamination and Smart Materials
Abstract
A new higher-order laminate theory has been developed
to study the presence of delamination in composite laminates of
arbitrary thickness. Delamination buckling, postbuckling and
growth problems have been studied in detail. The refined
displacement field proposed in the theory accounts for
transverse shear effect through the thickness and is capable of
representing displacement discontinuity conditions at surfaces
of existing delamination as well as satisfying the transverse
shear stress-free conditions at surfaces and at the delamination
interface. The developed higher-order theory has been used in
the analysis of laminated composite plates and shells with
delamination. The results of the theory correlate very well
with experimental data and elasticity solutions. The transverse
shear effects on delamination buckling is found to be very
significant and large deviations are observed from the results
obtained using classical laminate theory. The higher-order
theory provides an adequate framework for analysis of
delaminated composite plates and shells with arbitrary
thicknesses. The procedure is computationally very efficient.
The theory is being extended to model smart structures such
as composite box beams with surface bonded actuators and sensors.
The resulting three-dimensional model approximates the elasticity
solution so that the cross-sectional properties are not reduced
to one-dimensional beam parameters. The developed theory is
then used to model the load carrying member of helicopter rotor
blades with moderately thick-walled sections. Static analysis
of the smart box-beam under varying degree of actuation has
been performed. The study shows that embedded piezoelectric
actuation significantly reduces the deflection along the box
beam span and therefore can be used to control the magnitude of
blade vibrations.
