00199 - Aeronautical Structures

Learning outcomes

The course aims at providing students with:

• a general overview of different types of aircraft architectures and aeronautical structures
• an overview of airframe loads, design requirements and aeronautical regulations
• simplified methods for evaluating stresses in aircraft structures
• basic know-how about typical aircraft structures problems, like instability of thin panels and stringers

Course contents

Part I

Introduction.
Aircraft architecture. Wing geometry. Aircraft structures classification.

Stresses evaluation in thin-walled structures.
Beam sections geometric characteristics evaluation (centre of gravity, inertia moments, etc.).
Direct and shear stress evaluation in thin-walled beams. Shear centre.

Airframe loads.
Load factor determination. Symmetrical manoeuvres loads. Flight envelope.
Gust analysis and gust envelope.
Horizontal tail static and dynamic balancing loads.
Unsymmetrical loads due to a roll manoeuvre.
Landing loads: 1 and 2 degrees of freedom dynamic models; landing loads evaluation depending on aircraft attitude.

 

Part II

Aircraft structures.
Truss structures; beams.
General overview of different types of fuselages, engine mounts, cantilever and strut-braced wings, single and multiple spar wing structures.

Semimonocoque structures.
Description and definition.
Loads evaluation for a thin panel with a constant shear flow.
Evaluation of stringers normal stresses and panels shear stresses in a semimonocoque structure. Shear centre.
Multicell beam sections.
Ribs and frames analysis.
Tapered structures.
Cut-outs effects.

Joints and fittings.
Bolted and riveted joints. Loads evaluation. Joints and fittings safety margins evaluation.

Structures instability.
Introduction.
Long and short columns instability: Euler equation and Johnson relations.
Buckling of flat sheet in compression and bending.
Buckling of stiffened sheet in compression: effective sheet width.
Pure tension field beams.
Curved sheet in compression.

Readings/Bibliography

• T.H.G. Megson, "Aircraft Structures for engineering students", Arnold (London) 1999
• E.F. Bruhn, "Analysis and design of flight vehicle structures", Jacobs Publishing inc. 1973
• M.C.Y. Niu, "Airframe structural design. Practical design information and data on aircraft structures", Conmilit Press Ltd. 1988
• M.C.Y. Niu, "Airframe stress analysis and sizing", Conmilit Press Ltd. 1988
• M.C.Y. Niu, "Composite airframe structures", Conmilit Press Ltd. 1988
• D.J.Peery, J.J. Azar, "Aircraft Structures", McGraw-Hill 1982
• D.P. Raymer, "Aircraft design: a conceptual approach", AIAA Education series, NewYork (NY) 1999

Teaching methods

Lessons and practical classes.

Assessment methods

Assessment is based on a written examination lasting approximately 3 hours, aimed at evaluating students' knowledge of the topics covered during the course and their ability to apply methods for the analysis and design of aircraft structures. The examination includes numerical problems and theoretical questions on aircraft loads, structural analysis of thin-walled components, semi-monocoque structures, structural joints, and buckling phenomena. The examination topics are consistent with the course contents.

Students who pass the written examination may, at their discretion, take an additional oral examination. The oral examination is intended to assess the understanding of the theoretical concepts, the ability to interpret the results obtained in the written exercises, and the appropriate use of technical terminology.

The final assessment takes into account:

• the correctness of the solutions to the numerical problems;

• the ability to formulate and justify the calculation procedures;

• the knowledge of the theoretical principles underlying the methodologies adopted;

• the clarity of presentation and the appropriate use of engineering terminology.

To pass the examination, students must demonstrate an adequate level of preparation in both the theoretical aspects and the engineering applications covered during the course.

Use of Generative Artificial Intelligence in Examinations

For this course, the use of generative artificial intelligence tools (such as, but not limited to, ChatGPT, Copilot, Gemini, or similar systems) is not permitted during assessment activities, either directly or indirectly through electronic devices or online services. The examination is designed to assess the knowledge, competences, and reasoning skills developed independently by each student. Any use of generative AI tools during the examination constitutes a violation of the examination regulations and will be handled in accordance with the University's Code of Ethics and applicable University regulations.

In accordance with the University's Code of Ethics, students are required to conduct themselves with the highest standards of academic integrity.

Any conduct that may compromise the proper conduct of the examination is prohibited, including, but not limited to:

• cheating or plagiarism;

• accessing online learning resources;

• using or possessing unauthorized materials or equipment.

Students are reminded that the mere possession of unauthorized materials or devices during any examination will result in the immediate invalidation of the examination and referral to the competent University authorities.

Any breach of the above provisions may result in disciplinary proceedings and, where legally applicable, in any further actions provided for under the relevant laws and University regulations.

Teaching tools

Slideshows (PPT and/or PDF files)

Lecture notes

Examples and solved exercises

Office hours

See the website of Enrico Troiani

See the website of Sara Bagassi