Composite shell formulations: comparison of two geometrically nonlinear implementations

Resumo

Composite materials are attractive candidates for structural applications that require high specific-
strength and high specific-stiffness. Laminated composite materials are extensively used in aeronautical, aerospace,

and lately wind energy industries, where weight-sensitive structures are abundant. The structural modeling of
laminates commonly employs the Classical Lamination Theory (CLT). It is an extension of the homogeneous plate
theory introducing the elastic coupling effects present in laminates. In the CLT, the laminate stacking sequence
and material properties of each layer generate a homogenized section. Also, these structures are often slender and
may present large displacements and finite rotations, so that the adoption of a geometrically nonlinear shell model
is appropriate. This work presents the extension of a fully geometrically nonlinear triangular shell finite element
to account for laminated composite materials. The constitutive relations are derived from a quadratic potential
based on the CLT, considering small strains. The method was implemented in the Giraffe solver, accounting for
transverse shear and an additional drilling stiffness parameter. Calibration of the drilling stiffness was performed by
comparing static results from ANSYS® software, as a reference. Modal analysis was also addressed, for the same
composite proposals. Numerical results showed good agreement between Giraffe and ANSYS® implementations.