Reduced Order Model Approach for Efficient Aircraft Loads Prediction

Abstract

General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms Page 1 of 9 2015-01-0066 Reduced Order Model Approach for Efficient Aircraft Loads PredictionAuthor, co-author (Do NOT enter this information. It will be pulled from participant tab in MyTechZone)Affiliation (Do NOT enter this information. It will be pulled from participant tab in MyTechZone) AbstractFlight loads calculations play a fundamental role in the development and certification of an aircraft and have an impact on the structural sizing and weight. The number of load cases required by the airworthiness regulations is in the order of tens of thousands and the analysis must be repeated for each design iteration. On large aircraft, CS-25 explicitly requires taking into account for loads prediction, airframe flexibility, unsteady aerodynamics and interaction of systems and structure, leading to computationally expensive numerical models. Thus there is a clear benefit in speeding-up this calculation process. This paper presents a methodology aiming to significantly reduce the computational time to predict loads due to gust and maneuvers. The procedure is based on Model Order Reduction, whose goal is the generation of a Reduced Order Model (ROM) able to limit the computational cost compared to a full analysis whilst retaining accuracy. The method is applied to a commercial transport aircraft modeled with beam elements, unsteady aerodynamics based on Doublet Lattice Method and servo-hydraulic actuators for the control surfaces. The aeroelastic equations of motion are formulated in the time-domain, through the Rational Function Approximation and application of the Balanced Truncation method. The results obtained with the reduced model shows a very good accuracy with respect to the full model and a significant saving in computational time. The impact of flexibility on the gust load factor is also highlighted, comparing it with the quasi-static analysis by Pratt's formula, current standard for Part 23 aircraft.

Aircraft Loads Prediction using Enhanced Simulation (ALPES)

“…The effectiveness of the developed method is demonstrated by considering loads due to gusts and pitching manoeuvres for an aeroservoelastic model of a generic transport aircraft. The PMOR approach has been extended for aeroelastic systems with concentrated structural non-linearities [9][10][11][12] . The aeroelastic response of the aircraft must be solved to compute a large number of IQs under different flight conditions, mass configurations and external excitations to show compliance with the certification requirements.…”