17402 - Aeronautical Structures

Learning outcomes

Aim of the course is 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.).
Normal and shear stresses 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

Lessons notes will be provided before the course beginning. This material is in Italian and it is partially available at the following web page:

http://www.ingfo.unibo.it/servizi/Programmi/2007-2008/costr_aer/costruzioni_aeronautiche.html


Following texts are recommended for further investigations:

• 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
  
• V. Giavotto, "Strutture aeronautiche", edizioni CLUP Milano 1976
• D.P. Raymer, "Aircraft design: a conceptual approach", AIAA Education series, NewYork (NY) 1999
  
• A. Lausetti, "L'aeroplano progetto-strutture-installazioni", Levrotto& Bella
  
• G. Gabrielli, "Lezioni sulla scienza del progetto degli aeromobili", vol. II, Levrotto & Bella

Teaching methods

Lessons and practical applications.

Assessment methods

Final exam is constituted by a written and a oral examination: oral examination is subject to the written test approval.

Office hours

See the website of Franco Persiani