EAS303_Jan2014_Seminar 1_Design and Construction of Aircraft Structure

Design & Construction of Aircraft Structure

Study Unit 1

© 2013 SIM University. All rights reserved.

Cheok Lay NgorMobile: +65-92321047Email: [email protected]

Introduction

• Explain the concept of optimal design for structural design

• Explain the importance of structural design for manufacturing and maintainability

• Identify and list the function of the major aircraft structural members as well as understand how they are constructed and joined to form the aircraft structure

• Identify the source and types of Aircraft Loads• Explain the work of a Aerospace Structures

Engineer


Aircraft Design & Construction


Source: http://webarchive.library.unt.edu/eot2008/20080923063837/http://centennialofflight.gov/essay/Theories_of_Flight/airplane/TH2G2.htm

WingGenerate Lift

Jet EngineGenerate Thrust

CockpitCommand and Control

Fuselage (Body)Hold Things Together

(Carry Payload – Passengers, Goods)

SlatChange Lift

SpoilerChange Lift and Drag(Rotate Body, braking)

AileronChange Roll

(Rotate Body)

FlapChange Lift and Drag

ElevatorChange Pitch

(Up-Down)

RubberChange View(Side-to-Side)

Vertical StabilizerControl YawHorizontal Stabilizer

Control Pitch

Aircraft Wing Designs



Simple delta wing

Complex delta wing

Highly swept wing

Moderately swept wing

Slightly swept wing

Rounded or elliptical straight wing

Rectangular straight wing

Tapered straight wing

http://webarchive.library.unt.edu/eot2008/20080923063818/http:/centennialofflight.gov/essay/Theories_of_Flight/airplane/TH2G5.htm

Aircraft Empennage Designs

© 2013 SIM University. All rights reserved.Source: http://webarchive.library.unt.edu/eot2008/20080923063538/http://centennialofflight.gov/essay/Theories_of_Flight/airplane/TH2G6.htm

Standard tail

Twin tail

T-tail V-butterfly-tail

Rudder Fin (vertical stabilizer)

Horizontal stabilizerElevator

Right fin

Horizontal stabilizer

Elevator

Left fin

Dorsal fin

Ventral fins

Rudder

Fin


Aircraft Design & Construction


Source: Image courtesy of Tim Beach/FreeDigitalPhotos.net

Source: Image courtesy of Bernie Condon/FreeDigitalPhotos.net

Placement of Aircraft Engines



Single engine

Twinengine

Threeengines

Reciprocating or turbo-engine propellors Jet engine

Spitfire

P-38

SM-79 HSTrident

F-4Phanto

m

StarfighterF-104





Placement of Aircraft Engines



Four engines

Multiengine

Reciprocating or turbo-engine propellors Jet engine

Viscount

B-36

B-52

Boeing 707


Classroom Activity (1)


• Major Aircraft Components• Fuselage, Wing, Empennage

• Roles & Functions of Aircraft• Military Fighter / Transport / Surveillance• Commercial Passenger Wide-body / Narrow-body• Business Jets• General Aviation

• Types of Aircraft Wing Design• Positions of Engines on Aircraft

Major Aircraft Structural Members


Monocoque Design

Skin (Thick)

Frame

Bulkhead

Semin-Monocoque Design

Bulkhead

Longeron

Frame

Skin

Stringer

Former

Aircraft Wing Construction

Spars

Ribs

Skin



Aircraft Hardware

• Aircraft Bolts & Screws

• Aircraft Nuts• Self-locking vs Non Self-locking nuts

• Aircraft Rivets• Solid vs Blind rivets

• Quick Release Fasteners• Dzus, Camloc, Airloc fasteners

Reference: FAA-8083-30 Chapter 5, Aircraft Materials, Processes & Hardware



Aircraft Joints

• Bolt through a Lug

• Bolts & Nuts

• Splice

• Welding

• Bonding

Aircraft Materials


Metallic Materials• Aluminum – most commonly applied• Steel – high-strength structures• Titanium – elevated temperature, corrosion resistance

Non-metallic Materials• Composite – increasingly used in high-strength structures• Plastic – window, windshield, canopy that uses

polycarbonate or acrylic• Rubber – tyres, seals

Aircraft Material - Aluminum


Alloys Typical Product Forms

Major Application Usage Rationale

2024-T3 Plate/Extrusion Lower wing surface, upper horizontal tail

surface

Good fatigue and fracture properties i.e. slow crack growth and good fatigue life, with adequate tensile strength and corrosion properties

7178/7075-T6 Plate/Extrusion Upper wing surface, lower horizontal tail

surface

High compression yield strength with adequate fatigue, fracture, and corrosion properties

2024-T3 Sheet Skin of body Good fatigue and fracture properties with adequate strength (tensile, compression and shear) and corrosion properties

7075-T6 Plate/Extrusion Vertical tail High strength (tensile, compression, and shear) with adequate fracture, fatigue and corrosion properties

7178/7075-T6 Extrusion Keel beam chord High compression strength with adequate fracture, fatigue, and corrosion properties

7075-T73 Forging/Extrusion Wing and body bulkhead and fittings

Excellent resistance to stress and exfoliation corrosion and adequate strength, fracture and fatigue properties

Aircraft Material – Steel & Titanium


Alloys Strength (KSI) Typical Product Forms

Major Application Usage Rationale

4340M/4330M 275-300/220-240 Bars and forgings Landing gear components, flap

track, flap carriages, fittings

High strength to weight ratio and high modulus of

elasticity

9NI-4CO-0.30C 220-240 Bars and forgings Aft Engine Mount Elevated temperature stability and high strength

15-5PH 180-200 Bars and forgings Actuators, rod ends, fittings, mechanism

Corrosion resistance and high modulus

304/321/347 Min 75 Tubing Hydraulic systems, instrument lines

Corrosion resistance, high strength and fabricability

17-4PH 180-200150-170

Casting Control levers, fittings, housings

Corrosion resistant and fabricability

TI-6AL-4V 120-160 Sheet, plate, forging,

extrusion, casting

Landing gear, firewalls, floor support

structure, hydraulic fittings, fasteners

Higher strength per pound compared to steel

TI-6AL-6V-25N 150-170 Plate and forging Fittings in landing gears, wing areas

Higher strength than TI-6AL-4V

Metallic Material Properties Data Specification (MMPDS)


DOT/FAA/AR-MMPDS-01 Metallic Materials Properties Development and Standard (Jan 2003)

Reference: Figure 1.4.4

• Elongation• Reduction in Area• Poisson Ratio, ν• Modulus of Elasticity (Young’s Modulus), E• Modulus of Rigidity, G = E / [2*(1+v)]

Reference: Figure 1.4.12.1

• Stress-Strain curve of ductile vs brittle material

• Proportional Limit• Yield Strength @ 0.2% offset• Ultimate Tensile Strength

Metallic Material Properties Data Specification (MMPDS)


DOT/FAA/AR-MMPDS-01 Metallic Materials Properties Development and Standard (Jan 2003)

Reference: Figure 1.4.8.2.2

• Creep-Rupture Curve

Reference: Figure 1.4.9.2(b)

• S-N Curve

Aircraft Loads


• Flight Loads• Ground Loads• Other Loads• From External to Internal Loads• From Internal Loads to Stresses

Structural Design Considerations


• Aero-dynamics & Lift• Loads & Stresses• Flutter• Certification Criteria• Manufacturing Producibility • Material Size Limitation• Weight• Cost• Fatigue• Material Selection• Corrosion Protection• Maintenance• Inspectability / Accessibility

Aviation Standards


• Industry standards defining airworthiness requirement for structures of aerospace vehicles

• Commercial - Federal Aviation Regulation (FAR),

- Joint Aviation Regulation (JAR)

Example: FAR, Part 25, Airworthiness standards: Transportation Category Airplanes

• Military – US Air Force, US Navy, Joint Services

Example: MIL-A-8860 ‘Airplane Strength and Rigidity, General Specification for’

Example: Joint Services Specification Guidelines 2006 (JSSG 2006) – Aircraft Structure

Workscope of Aircraft Structures Engineer


• Aircraft Design• Aircraft Modification – to reinforce or enhance a structure• Aircraft Repairs – to restore structural integrity

Summary

• Aircraft Design & Construction• Aircraft Fasteners & Joints• Aircraft Materials• Aircraft Loads• Aircraft Repairs & Certifications


Reflection Question

Discuss the differences among the following work scope of an aircraft

structures engineer:

(a) Design a new aircraft structure

(b) Modify an aircraft structure

(c) Repair an aircraft structure


Documents

EAS303_Jan2014_Seminar 1_Design and Construction of Aircraft Structure