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

Application of 3D-Random Fiber Composites for Damaged Honeycomb Panels Repair

Mirko Dinulović

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

Branimir Krstić

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

Predrag Andrić

204th Air Brigade, 24th Air Technical Battalion, Belgrade, andricp@gmail.com

Abstract: Honeycomb composite panels are used extensively in aircraft structures. One of the problems with the use of these materials is that of structural repair. Composite structures require different repair techniques than do their metal counterparts. It is crucial to develop repair methods that restore the original strength of the part without compromising its structural integrity. New repair methodology, applicable to field repair of damaged composite panels with honeycomb core is presented. To restore load bearing capacity of damaged panel specially designed core plug composed of 3D random fiber composite material is used. Numerical simulation of the stress-strain field of the repaired structure, material constitutive equations and complete repair procedure is presented in this paper. The analysis has shown that 3D random fiber composites can be successfully applied for the repair of damaged honeycomb cores at relatively small repair cost and in an efficient way, especially in cases where the aircraft downtime costs are of critical importance.

Key words: composite repair, honeycomb core, 3D random fiber composites.