The Refined Zigzag Theory (RZT) for homogeneous, laminated composite and sandwich
plates is developed from a multi-scale formalism starting with the inplane
displacement field expressed as a superposition of coarse and fine contributions.
The coarse displacement field is that of first-order shear-deformation theory,
whereas the fine displacement field has a piecewise-linear zigzag distribution
through the thickness. The resulting kinematic field provides a more realistic
representation of the deformation states of transverse-shear-flexible plates
than other similar theories. The condition of limiting homogeneity of
transverse-shear properties gives rise to a set of robust zigzag functions.
Unlike previously used methods, which often result in anomalous conditions
and nonphysical solutions, the present theory does not rely on
transverse-shear-stress equilibrium constraints.
For all material systems, there are no requirements for use of
transverse-shear correction factors to yield accurate results.
To model homogeneous plates with the full power of zigzag kinematics,
infinitesimally small perturbations of the transverse shear properties are used,
thus enabling highly accurate predictions of homogeneous-plate behavior
without the use of shear correction factors. The RZT predictive capabilities
to model highly heterogeneous sandwich plates have been critically assessed,
demonstrating its superior efficiency, accuracy, and a wide range of applicability.
The present theory, which is derived from the virtual work principle, is well-suited
for developing computationally efficient, C^{0}-continuous finite elements,
and is thus appropriate for the analysis and design of high-performance
load-bearing aerospace structures.