Which of the following is a primary assumption of Classical Laminate Theory for a laminated plate?

• A. The laminate is modeled as multi-ply layers with perfect bonding, small deflections, linear elastic behavior, and negligible transverse shear distortion, described by midplane strains and curvatures.
• B. The laminate uses large deflections and includes significant transverse shear strains in the governing equations.
• C. The laminate assumes nonlinear viscoelastic behavior with time-dependent response.
• D. The laminate treats plies as perfectly independent with no interfacial bonding.

Answer: (A)

Classical Laminate Theory describes a laminated plate by modeling it as multiple plies that are perfectly bonded, so there’s no interfacial slip. It assumes the plate is thin enough for deflections to be small and the material response to be linear elastic, with negligible transverse shear distortion through the thickness. Under these conditions the entire bending and in-plane behavior is captured by the midplane strains and the curvatures; these kinematic quantities describe how the laminate stretches in the plane and how it bends, and they relate to end forces and moments through the laminate’s A, B, and D stiffness matrices. This is exactly what the option states: a stack of bonded plies, small deflections, linear elastic behavior, negligible transverse shear, described by midplane strains and curvatures. If you introduced large deflections, significant transverse shear, nonlinear viscoelasticity, or interfacial debonding, you’d be moving beyond CLT and using a different modeling approach.