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Contribution to Load Alleviation in Aircraft Pre-design and Its Influence on Structural Mass and Fatigue

Handojo, Vega (2020) Contribution to Load Alleviation in Aircraft Pre-design and Its Influence on Structural Mass and Fatigue. Dissertation, Technische Universität Berlin.

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Official URL: https://depositonce.tu-berlin.de/handle/11303/12111

Abstract

This thesis develops and demonstrates an aircraft pre-design process for loads analysis, load alleviation, structural optimization and fatigue analysis. It is shown that the consideration of maneuver and gust load alleviation in early design stages is a promising concept to reduce wing bending moments, structural mass and extend the fatigue life. The reference aircraft considered are two mid-range configurations: one with a backward and another one with a forward swept wing, respectively. In the loads analysis, quasi-steady maneuvers and dynamic 1-cos gusts are considered. For the load alleviation during maneuvers, the ailerons are deflected symmetrically with precalculated amplitudes. For the gust load alleviation, a feed-forward, proportional control algorithm is set up and the main input for the controller is the gust angle of attack. Analogous to maneuver load alleviation, the ailerons are deflected symmetrically. With the post-processed loads from the simulations, the structure of the wing and horizontal tailplane (HTP) is optimized toward mass minimization. The constraints considered are material strength, buckling stability and static aeroelastic requirements. The steps loads analysis and structure optimization of the developed design process are conducted iteratively until the wing box mass converges. For the reference aircraft, the load alleviation yields a reduction of wing box mass by 2.8% and 6.1%, respectively. Beyond that, a qualitative fatigue analysis is carried out to compare the fatigue behaviors of the active and passive aircraft (with and without load alleviation). In this step, loads due to continuous turbulence and ground-air-ground cycles are considered. For the reference missions, the fatigue life of the active aircraft is improved by 28% and 12% respectively, on top of the mass benefit. However, these numbers of fatigue life improvement are only valid for the considered loads and selected positions. If more loading conditions or structure elements are taken into account, the fatigue benefit may vary. As a conclusion, the proposed process can serve to gain an insight into the benefits of load alleviation for a given aircraft in the pre-design phase, before it advances to the next design stage.

Item URL in elib:https://elib.dlr.de/140678/
Document Type:Thesis (Dissertation)
Additional Information:Dissertation als DLR-Fachbericht im Druck
Title:Contribution to Load Alleviation in Aircraft Pre-design and Its Influence on Structural Mass and Fatigue
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Handojo, Vegavega.handojo (at) dlr.dehttps://orcid.org/0000-0001-6030-2383
Date:10 December 2020
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:No
In ISI Web of Science:No
Number of Pages:132
Status:Published
Keywords:load alleviation, loads analysis, structural optimization, fatigue analysis, aircraft pre-design, feed-forward control
Institution:Technische Universität Berlin
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Aeronautics
HGF - Program Themes:fixed-wing aircraft
DLR - Research area:Aeronautics
DLR - Program:L AR - Aircraft Research
DLR - Research theme (Project):L - Flight Physics (old)
Location: Göttingen
Institutes and Institutions:Institute of Aeroelasticity
Institute of Aeroelasticity > Loads Analysis and Aeroelastic Design
Deposited By: Krüger, Prof. Dr.-Ing. Wolf R.
Deposited On:27 Jan 2021 16:42
Last Modified:27 Jan 2021 16:42

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