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The University of Southampton
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# SESA3026 Aircraft Structural Design

## Module Overview

The module not only introduces the fundamental concepts of aircraft structural design but also provides the analytical and numerical tools to analyse complex aerospace systems within a multidisciplinary environment. Understanding and predicting the mutual interactions between different fields (aerodynamics, structural dynamics, etc.) is instrumental to successfully design any modern future air vehicles. With the subject matters covered in Part I and Part II as background knowledge, students will be taught how to closely interconnect previously separated disciplines.

### Aims and Objectives

#### Learning Outcomes

##### Knowledge and Understanding

Having successfully completed this module, you will be able to demonstrate knowledge and understanding of:

• The loading actions acting on an aircraft
• The assessment of the fatigue life of an aircraft
• Static and dynamic aeroelasticity
• The role played by different disciplines within the context of structural design
##### Subject Specific Intellectual and Research Skills

Having successfully completed this module you will be able to:

• Derive from first principles the mathematical laws which govern the loads produced by gusts and symmetric aircraft manoeuvres, with particular reference to wing loads
• Understand the reasons for the current airframe structural configurations
• Understand fatigue life calculations in the context of the aircraft structural design
• Derive the equations which govern the elastic response of the airframe, statically and dynamically.
##### Transferable and Generic Skills

Having successfully completed this module you will be able to:

• Study and learn independently
• Demonstrate study and time management skills.
• Solve problems systematically.
##### Subject Specific Practical Skills

Having successfully completed this module you will be able to:

• Study and learn independently
• Solve problems.
• Appreciate the dangers resulting from poor design
• Critically examine the solution of numerical problems against acquired knowledge

### Syllabus

Objectives of Aircraft Structural Design (2 lectures) - Strength, stiffness and reliability requirements. Overview of loading actions including: gust and manoeuvre loads, fatigue, aeroelasticity. Limit loads and ultimate loads. Wing Structural Details (2 lectures) - General established design layouts for aircraft structures (spars, ribs, skin, stringers) and the role each components plays. Review of Manoeuvre and Gust Loads ( 4 lectures) - The flight and gust envelopes. The tail load envelope. Calculation of wing bending moments; critical cases. Introduction of Fatigue Analysis and Design (6 lectures) - Safe life and fail safe design philosophies, good design practice. The fatigue loading spectrum: the ground-air-ground cycle and gust loads; the use of ESDU data sheets S-N curves and Miner's cumulative damage law; prediction of the safe number of flights. Introduction to Vibration Theory (7 lectures) - The need for vibration theory; free and forced vibrations of the single degree of freedom oscillator. The two degree of freedom system; natural frequencies and modes, transformation to modal coordinates, generalized forces. Introduction to multi degree of freedom systems and how these systems can be analysed using computational methods. Static Aeroelasticity (6 lectures) - Static divergence of a cantilever wing; the effects of sweep and compressibility; aileron reversal; structural design features to minimise adverse aeroelastic effects. Dynamic Aeroelasticity (7 lectures) - Two degree of freedom model of dynamic response to gust loading; effect of flexibility on the wing bending moments. Flutter: classical and non-classical flutter, the energy input/dissipation mechanisms, the two degree of freedom equation of motion of a simple aerofoil, outline of solution. Mass balancing for control surfaces. Example Classes (2 lectures)

### Learning and Teaching

#### Teaching and learning methods

Teaching methods will include 36 lectures. Learning activities include directed reading and problem solving. The module will also include computer laboratory sessions and one or two wind tunnel experiences. The assignment will assess students’ knowledge be on the material taught, results produced by numerical simulations and experimentally observed.

TypeHours
Seminar2
Revision112
Tutorial2
Practical classes and workshops2
Lecture32
Total study time150

### Assessment

Tutorial sheets

#### Summative

MethodPercentage contribution
Continuous Assessment 30%
Final Assessment  70%

#### Repeat

MethodPercentage contribution
Set Task 100%

#### Referral

MethodPercentage contribution
Set Task 100%

#### Repeat Information

Repeat type: Internal & External

### Linked modules

Pre-requisites: FEEG2005

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