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Mavris,
Dimitri N.
Mavris,
Dimitri N.
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ItemDevelopment of A Certification Module for Early Aircraft Design(Georgia Institute of Technology, 2019-06) Xie, Jiacheng ; Briceno, Simon ; Mavris, Dimitri N. ; Chakraborty, ImonThe airworthiness certification process of civil transportation aircraft is expensive, timeconsuming, and subject to uncertainty. To reduce the cost and time spent on the certification process, this paper proposes an approach to incorporate certification considerations into early design stages using virtual certification techniques. As a proof of concept, this paper focuses on flight performance certification requirements and developed a certification analysis module for aircraft conceptual and early preliminary design based on FAR-25 Subpart B. The module transforms the regulations from textual documents to quantitative constraint functions and ensures the certification constraint check of the design through physics-based analysis. To validate the module, a Small Single-aisle Aircraft testing model is developed and virtually certified by the module. The certification analysis result of the testing model is benchmarked with public domain data.
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ItemFramework to Assess Effects of Structural Flexibility on Dynamic Loads Developed in Maneuvering Aircraft(Georgia Institute of Technology, 2018-06) Sarojini, Darshan ; Duca, Ruxandra ; Solano, Heriberto D. ; Chakraborty, Imon ; Briceno, Simon ; Mavris, Dimitri N.Sizing loads for major aircraft structural components are often experienced during dynamic maneuvers, several of which are described within the Federal Aviation Regulations as part of certification requirements. A simulation and analysis framework that permits such dynamic loads to be assessed earlier in the design process is an advantage for designers and aligned with the trend towards certification by analysis. Such a framework is demonstrated in this paper using the case of a business jet performing a longitudinal checked pitch maneuver. The maneuver is simulated with a six degree-of-freedom MATLAB/Simulink simulation model, using the aircraft aerodynamic characteristics, mass properties, and an adequate level of modeling for the flight control system and pilot control action. The effects of structural flexibility and deformation of the lifting surfaces and fuselage under maneuver loads are modeled by tracking a number of structural degrees-of-freedom for each. The modular nature of the simulation setup facilitates the assessment of multiple maneuvers, analysis of sensitivity to uncertainty, as well as the identification of the impact of structural flexibility through flexible versus rigid maneuver simulations.
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ItemEffects of Epistemic Uncertainty on Empennage Loads During Dynamic Maneuvers(Georgia Institute of Technology, 2018-01) Duca, Ruxandra ; Sarojini, Darshan ; Bloemer, Sebastian ; Chakraborty, Imon ; Briceno, Simon ; Mavris, Dimitri N.The Federal Aviation Regulations contain descriptions of a number of dynamic maneuvers that may lead to the development of critical loads for aircraft structural components. The structural members must be sized and designed to withstand such loads, and this must be demonstrated as part of the certification process. Given the high costs of aircraft certification and the programmatic risk associated with design modifications necessitated during later design stages, there is currently a trend towards certification by analysis. Towards this end, from the structural loads perspective, there is a need for a framework that can simulate maneuvers and evaluate the structural loads thus developed. However, in the earlier phases of design, significant epistemic uncertainty may exist with regard to the aircraft mass properties and aerodynamic characteristics, which in turn lead to uncertainty in the maneuver loads. This work demonstrates a methodology that employs sensitivity and Monte Carlo analyses to assess how maneuvering structural loads are affected by uncertainty factors. These analyses are applied to a dynamic simulation model created to simulate a representative business jet performing a checked pitch maneuver. The resultant variability of critical structural loads provides insight into the areas where epistemic uncertainty should be reduced.
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ItemA Simulation-Based Framework for Structural Loads Assessment during Dynamic Maneuvers(Georgia Institute of Technology, 2017-06) Goron, Gael ; Duca, Ruxandra ; Sarojini, Darshan ; Shah, Somil R. ; Chakraborty, Imon ; Briceno, Simon ; Mavris, Dimitri N.Federal Aviation Regulations pertaining to structural integrity are key drivers in aircraft design and certification, and often involve critical loads occurring during dynamic maneuvers. In the context of increasing costs of testing and the general trend towards parametric design, there is a need for a more thorough consideration of such dynamic load cases earlier in the design process. In this work, a simulation framework is introduced to assess structural requirements stemming from such dynamic load conditions. Relevant aspects of the dynamics of the aircraft, the control system, and the pilot are modeled in order to simulate the maneuver and thereafter obtain inertial and aerodynamic loads on the empennage during the simulated maneuver. The loads are then translated into structural shear forces and bending moments through structural post-processing routines. This approach is demonstrated for the case of a representative business jet during the checked pitch maneuver. The analyses are repeated for three weight conditions and over the flight envelope for the aircraft from which the load cases resulting in the most constraining loads are determined.