Mounting Plate, Stress Concentration and Damage Tolerance Analysis for Antenna Installations on Pressurized Transport Aircraft Using The FEM
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Date
2021-07
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Addis Ababa University
Abstract
During the in-service life of a given aircraft, different antennas are installed on the fuselage of the aircraft
for different operational and regulatory requirements. These antennas are part of the Communication,
Navigation and surveillance (CNS) systems of aircraft. Antennas play the greatest role in enhancing the
operational safety and functionality of a given civil or military aircraft by providing reliable communication
and navigation systems. During antenna installation, the fuselage skin loses its structural integrity. Taking
this into consideration and also fracture mechanics as a basic principle, damage tolerance analysis for
antenna installations on pressurized transport airplanes has been studied. For skin modifications, first from
a static strength point of view, the elliptical antenna mounting plate is compared with those of circular and
rectangular mounting plates. Next, based on the first result, from the stress concentration factor point of
view, the best antenna cut-out shape was studied by comparing antenna cut-out shapes such as elliptical,
circular, and square cut-outs for mounting plates subjected to biaxial loads. Then, considering the best
mounting plate shape and antenna cut-out, i.e., having the lowest stress concentration factor, damage
tolerance analysis (DTA) is done using Linear Elastic Fracture Mechanics (LEFM) and the establishing
inspection type and inspection threshold are studied. To perform the above activities, a special tool, Finite
Element Analysis (FEA), i.e., ANSYS application software, was used to perform static and fatigue
simulations along the potential crack growth path for a flaw initiating from the antenna cut-out normal to
the stress application direction. The output from finite element modelling and analysis is compared with
the analytical for the safe installation of the antenna. With respect to the above framework, the study was
done, and the result shows that the circular mounting plate is relatively better than those of the rectangular
mounting plate and the elliptical mounting plate. With regard to the cut-out shape, for the applied biaxial
tension loads, a circular cut-out is relatively better than those of the square and elliptical cut-out shapes. A
circular mounting plate with a circular antenna cut-out is better than an elliptical or rectangular mounting
plate. Starting with the initial crack length of a
i
and the progressive crack length of a
i+1
to the critical crack
length value ac, which is calculated using the fracture toughness of the skin materials, an estimated
inspection type and inspection threshold (damage detection) were established.
Description
Keywords
Antenna Installation Plate, antenna cut-out & stress concentration for biaxial tension load, Damage Tolerance Design and Analysis, Stress Intensity Factor (SIF), Inspection Interval