REPUBLIC OF SERBIA

MINISTRY OF DEFENCE

www.mod.gov.rs

MINISTRY OF DEFENCE

Material Resources Sector

Defensive Technologies Department

Military Technical Institute

www.vti.mod.gov.rs

On the effective shear modulus of composite honeycomb sandwich panels

lamine rebhi

University of Defence in Belgrade, Military Academy, Belgrade, Serbia, rebhi.lamine@gmail.com

mirko dinulović

University of Belgrade, Faculty of  Mechanical Engineering, Belgrade, Serbia, mdinulovic@mas.bg.ac.rs

PREDRAG ANDRIĆ

École Polytechnique Fédérale de Lausanne, Institute of Mechanical Engineering, Lausanne, Switzerland, predrag.andric@epfl.ch

MARJAN DODić

University of Defence in Belgrade, Military Academy, Belgrade, Serbia, marjan.dodic@va.mod.gov.rs

BRANIMIR KRSTić

University of Defence in Belgrade, Military Academy, Belgrade, Serbia, branimir.krstic@va.mod.gov.rs

Abstract: In the present paper the effective shear modulus of composite plates with honeycomb core is determined. This elastic coefficient represents one very important property especially in constructions subjected to torsion and combined bending - torsion. The structures investigated in this research consisted of top and bottom plates (of different types of carbon fibers, T300, AS4 in epoxy matrix) and honeycomb core (HexWeb engineered core). Starting from classical lamination theory the effective shear modulus of top and bottom plates was determined for each ply in the stack up sequence. These plies were “lumped” into a single composite layer for different fiber orientations and plies thicknesses. Elastic coefficients for the HexWeb engineered core were obtained using Master and Evans relations for the equivalent properties of honeycomb cores.

To verify this approach finite element method was used to determine the displacement, stress and strain field on composite plates with honeycomb core. Two types of models were compared: the initial model where all the material components, plates and the core were modeled with their intrinsic properties and “lumped” model with calculated effective elastic coefficients.

It was found that the method of effective shear modulus calculation can be successfully used in situations where top and bottom plates are symmetric or quasi isotropic in general.

Keywords: Shear modulus, Equivalent material properties, Composite material, Honeycomb sandwich panel, Finite element analysis.