R. Abarca, D. Arenillas, O. Castro, B. Masiá, E. Menga, M. Barth

DOI Number: N/A

Conference number: IFASD-2015-114

Main Landing Gear Doors (MLGD) are affected by significant dynamic loads during flight, mainly due to the aerodynamic excitation. In commercial aircraft this loadcase can drive the structural sizing of the MLGD attachments and thus their weight. Therefore, an accurate prediction early in the design is essential to ensure light and reliable aircraft structures. If the complex physics of the phenomena is to be captured, a multidisciplinary approach involving unsteady aerodynamics and structural dynamics is required combining experimental data and theoretical models. As a test case, a state-of-the-art commercial aircraft is selected, with a large availability of data from flight tests for model validation. The unsteady aerodynamic excitation is quantified using a semi-empirical approach based on experimental and simulation data. Dedicated Wind Tunnel Tests (WTT) are performed with unsteady pressure sensors on the MLGD model. In parallel, numerical simulations are performed to accurately define the integration surfaces associated to the pressure probes. The thus obtained unsteady aerodynamic excitation is expressed as cross-spectral matrix of pressures. The structural dynamics of the MLGD is captured by a representative Finite Element Method (FEM) model including the supporting structure. A Ground Vibration Test (GVT) is conducted to validate its dynamic behavior, including damping. The dynamic loads are calculated combining the unsteady aerodynamic excitation and the structural model based on random response analysis. All the operation geometries combining the main and Nose Landing Gear (NLG) and their associated doors are considered in order to capture the critical configurations. The obtained dynamic loads in the MLGD attachments are compared with flight test measurements, validating this predictive methodology as a powerful approach to produce early and reliable dynamic loads due to aerodynamic excitations.

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In Categories: 2. IFASD 2015, Structural Dynamics & Shimmy
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