22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-4.3.4

GLOBAL RESIDUAL DAMAGE EVALUATION OF IMPACTED SANDWICH PANELS AT LOW ENERGY

L. Battilomo (1), M. Marchetti (1), R. Severoni (2)
(1) University of Rome ‘La Sapienza’ - Aerospace Department, Italy; (2) Soc. AGUSTA – Centro Compositi Aerospazio, Anagni, Italy

Keywords: sandwich, low energy impact, residual damage, honeycomb, equivalent properties, finite element analysis

This paper focuses on the behavior of impact damaged sandwich panels at low energy. The aim of the work is to assess the residual mechanical properties of a helicopter main cabin panel after the impact and their correlation to the percentage of global damage. Finite element analysis was used to solve the problem. Due to the contact boundary condition, large displacements and plasticity, the dynamic impact problem treated here presents a nonlinear numerical character, which has to be taken into account in order to choose an appropriate solution technique. The numerical procedure applied consists of a local evaluation of damage (geometry and elastic constant variation) produced by a semispherical impactor. To achieve this, a continuum mechanics approach of a sandwich structure detailed model was implemented. Once this analysis was performed, new equivalent mechanical properties corresponding to the damaged area were utilized in the construction of different global models with increasing percentage of damage.

view full paper