Damage tolerance specificity of thick composite structures used in Landing Gears

As the aerospace industry tends toward lighter aircraft, the use of composite materials is extended to more complex systems such as the landing gears. The application of composite technology in the landing gear environment... [ view full abstract ]

As the aerospace industry tends toward lighter aircraft, the use of composite materials is extended to more complex systems such as the landing gears. The application of composite technology in the landing gear environment faces unique challenges due to the very high loads the part has to sustain and their complex geometry. Over the last 4 years, Héroux-Devtek has been developing a Carbone/Epoxy composite drag brace to evaluate the potential of this technology.
During this project, it was found that the usual damage tolerance knowledge had been developed for thin structures and more work was required to adapt it to thick laminates. In our case, the damage tolerance was evaluated using ASTM drop weight impact tests and numerical modeling on three different thicknesses between 0.108inch and 0.745inch, using a wide range of impact energies up to 70ft-lbs.
Thick laminates were shown to exhibit a damage behavior very different from what can be observed for thin laminates. Consequently, an innovative approach based on Hertzian contact was developed to consider the behaviour of thick composite structures observed. It was combined with a model from the literature developed for thin laminates to estimate conservatively delamination area in impacted laminates.
As this approach was shown to correlate with the experimental data, the model could be used in the future for damage tolerance sizing of thick composite parts.

Keywords: Thick composites, damage tolerance, landing gear, impact damage, certification

A. Divialle a *, P. Legay b,
a. R&T Department, Héroux-Devtek, Saint-Hubert, Qc, J3Y 9G1, Canada
b. Centre Technologique en Aérospatiale, Saint-Hubert, Qc, J3Y 8Y9, Canada
* corresponding author: email: adivialle@herouxdevtek.com, phone: 450 550 2020 ext. 4837