Aircraft Structural Design

Learning Outcomes

Subject Specific Intellectual and Research Skills

Having successfully completed this module you will be able to:

• Understand the reasons for the current airframe structural configurations
• Understand fatigue life calculations in the context of the aircraft structural design
• Derive from first principles the mathematical laws which govern the loads produced by gusts and symmetric aircraft manoeuvres, with particular reference to wing loads
• 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:

• Solve problems systematically.
• Study and learn independently
• Demonstrate study and time management skills.

Knowledge and Understanding

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

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

Subject Specific Practical Skills

Having successfully completed this module you will be able to:

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

Full CEng Programme Level Learning Outcomes

Having successfully completed this module you will be able to:

• As part of the courseworks and final exam, students must evaluate the impact that novel solutions to complex aircraft structural problems have on the environment and the society, linking this to recent developments in the field
• As part of the final exam, students must demonstrate comprehensive knowledge of structural design and sizing theory to the solution of complex problems and awareness of recent research developments from the wider context of engineering that have impacted the subject field
• As part of lecture series of invited external speakers, students must attend lectures given by industry experts, part of a wider CPD opportunity
• As part of a lecture series of invited external guests and material in Blackboard, students are taught to identify, select and critically evaluate technical literature, skills which are then assessed in the courseworks
• Students are assessed based on their selection and application of appropriate techniques to solve complex structural and aeroelastic problems, and discussing the limitations of those techniques
• As part of the courseworks and final exam, students must demonstrate to reach substantiated conclusions to complex structural aeroelastic problems using avaialble data and applying their engineering judgement when information is uncertain or incomplete, discussing the limitations of the chosen techniques
• As part of the module, student must select and justify the use of materials for aircraft structures and recognise their limitations when fatigue and aeroelastic aspects are included
• As part of the module, students are exposed to the multi-faceted aspects of aeronautical structures and to apply an integrated approach to the solution of complex problems with diverse systems interacting, as exemplified by invited guest lectures by Airbus, QinetiQ, Aerotech

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)

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.

Formative

This is how we’ll give you feedback as you are learning. It is not a formal test or exam.

Tutorial sheets

• Assessment Type: Formative
• Feedback: Self-assessment.
• Final Assessment: No
• Group Work: No

Summative

This is how we’ll formally assess what you have learned in this module.

Referral

This is how we’ll assess you if you don’t meet the criteria to pass this module.

Repeat

An internal repeat is where you take all of your modules again, including any you passed. An external repeat is where you only re-take the modules you failed.