 | Dorbath F. A flexible wing modeling and physical mass estimation system for early aircraft design stages: Diss. … Dr.-Ing. / Deutsches Zentrum für Luft- und Raumfahrt, Lufttransportsysteme, Hamburg. - Köln: DLR, 2014. - xxiv, 130 p.: ill. - (Forschungsbericht; 2014-05). - Res. also Germ. - Bibliogr.: p.121-130. - ISSN 1434-8454
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Abstract ........................................................ v
Contents ...................................................... vii
List of Figures ................................................ xi
List of Tables ................................................. xv
Nomenclature ................................................. xvii
Abbreviations ................................................. xxi
1 INTRODUCTION ................................................. 1
1.1 Wing Mass Estimation as Part of Preliminary Aircraft
Design .................................................. 2
1.1.1 The Aircraft Design Process ...................... 2
1.1.2 Classification of Methods for Wing Mass
Estimation ....................................... 4
1.1.3 Multidisciplinary Wing Mass Estimation Process ... 5
1.2 State-of-the-Art in Wing Mass Estimation ................ 6
1.2.1 Empirical Methods for Primary Structures and
Total Wings ...................................... 6
1.2.2 Primary Wing Structures using Beam Theory ........ 8
1.2.3 Primary Wing Structures using Shell Theory ...... 11
1.2.4 Secondary Wing Structures using Empirical
Methods ......................................... 13
1.2.5 Secondary Wing Structures using Physics-Based
Models .......................................... 15
1.2.6 Physics-Based Models for Primary and Secondary
Structures ...................................... 17
1.3 Contributions of the Study ............................. 18
2 FUNDAMENTALS AND APPROACH ................................... 21
2.1 Fundamentals ........................................... 21
2.1.1 Vortex-Lattice Method ........................... 21
2.1.2 Beam Theory ..................................... 24
2.1.3 Finite Element Method ........................... 26
2.1.4 Shell Elements .................................. 29
2.2 Approach ............................................... 30
2.2.1 Extended Physics-Based Modeling ................. 30
2.2.2 CP ACS Parameterization ......................... 31
2.2.3 Central Multi-Model Generation .................. 32
2.2.4 Knowledge-Based Approach for Model Generation ... 34
2.2.5 Software Languages and Analysis Tools ........... 40
3 IMPLEMENTATION .............................................. 43
3.1 Tool Chain Overview .................................... 43
3.2 Parameterization ....................................... 44
3.3 Structural Model ....................................... 48
3.3.1 Knowledge-Based Generation of Lifting Surfaces .. 49
3.3.2 Knowledge-Based Generation of Additional
Structures ...................................... 58
3.3.3 Model Optimization Settings ..................... 68
3.3.4 Rigid Body and Deflection Templates ............. 70
3.4 Aerodynamic Loads ...................................... 71
3.4.1 Model Generation ................................ 71
3.4.2 Static Aeroelastic Loop ......................... 74
3.4.3 Loads Interpolation ............................. 75
3.5 Fuel, Landing Gear and Engine Loads .................... 76
3.5.1 Fuel Loads ...................................... 76
3.5.2 Engine Loads .................................... 78
3.5.3 Landing Gear Loads .............................. 79
3.6 Structural Analysis and Sizing ......................... 79
3.6.1 Program Workflow Overview ....................... 79
3.6.2 Types of Load Cases ............................. 81
3.6.3 Sizing .......................................... 81
3.7 Post-Processing ........................................ 88
4 VALIDATION AND APPLICATION .................................. 91
4.1 Validation of the Aerodynamic Load Estimation .......... 91
4.2 Derivation of Non-Optimum Mass Factors ................. 94
4.2.1 Reference Aircraft .............................. 95
4.2.2 Load Cases ...................................... 95
4.2.3 Non-Optimum Mass Factors ........................ 96
4.3 Demonstration of Possible Fields of Applications ....... 98
4.3.1 Strut Braced Wing ............................... 98
4.3.2 Blended Wing Body ............................... 99
4.3.3 Box Wing ....................................... 100
4.3.4 Multi-Spar Flap ................................ 101
4.3.5 Double Slotted Flap ............................ 102
4.4 Aircraft Design Study ................................. 103
4.4.1 Objective of the WingOpt Study ................. 103
4.4.2 WingOpt Tool Chain ............................. 104
4.4.3 Results of the WingOpt Study ................... 105
5 DISCUSSION AND RECOMMENDATIONS ............................. 109
5.1 Summary of Research ................................... 109
5.2 Discussion of the Model Generation Process ............ 111
5.3 Discussion of the Wing Mass Estimation ................ 113
5.4 Discussion of the Aircraft Design Study ............... 116
5.5 Recommendations ....................................... 117
References .................................................... 121
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