AERO3460/9460 Aerospace Design 1 - University of...

AERO3460/9460 Aerospace Design 1

● Aircraft component design● Certification Rules and Regulations● Flight Environment and Performance

constraints● Aircraft structures and material. Component

Failure modes ● Typical Industry processes.

AERO3460 Aerospace Design 1Frameworks and simple fittings

MECH2400 Mech Design(CAD Drawing, Design Methodology)

ENGG1802 MechanicsForce and Moment Equlibrium

AMME2301 Mech of Solids 12D and 3D structural analysis of beamsTension,Compression,Bending and Torsion

AERO3465 Aerospace Design 22D and 3D Monocoque Structures.Box beams, shear flow, stress distribution through attachments

AERO4460 Aerospace Design 3Full Configuration Design The BIG PICTURE

1. The Physical Environment● Atmosphere● Materials – Aluminium, Steel, Magnesium, Titanium● Alternate Composite materials● Frameworks -- Stresses and Strains● Joining methods● Failure Modes ● Safety Factors and Margins of Safety

2. The Legislative Enviroment● Categories of Aircraft – Fixed wing, Rotorcraft● Normal, Utility, Aerobatic, Transport.● Performance requirements● Weight and speed limits● Design Limits● Proof of Compliance (FARs)

The Atmosphere.

http://www.aerodynamics4students.com/properties-of-the-atmosphere/

Sections :

International Standard Atmosphere (ISA) Sea Level Conditions

ISA Variation with Altitude Variation due to Local Ground Conditions

Variation of Density due to Humidity Variation of Density with Extremely High Altitude

What are the Design Loads?

Aircraft Design Category

FAR 23 – Normal, Utility, Aerobatic Light AircraftFAR 25 – Transport AircraftFAR 27 – Normal, Utility, Aerobatic RotorcraftFAR 29 – Transport Rotorcraft

Primary parameters

*Aircraft Weight *Airspeeds

Types or Loads * Direct Loads. Forces applied to structure by external Mechanisms eg. Engine thrust, wing pressure loads

* Inertial Loads. Loads applied to structure due to acceleration of Masses. eg. Self Weight, Vertical loads due to manoeuvers

* Ground Handling and Miscellaneous Loads.

Analysis of simple Frameworks

Force equilibrium --- Free Body Diagram

Analyse Internal Forces

Types of Failure :

Tension Failure --- Yield Failure --- Ultimate Failure

Compression Failure --- Material Yield --- Column Failure --- Buckling Failure

Shear Failure --- exceeding max shear stress

Bending Failure --- Tension Component --- Compression Component --- Geometric Failure

Temperature weakening of material

Failure due to repetitive Loading (Fatigue)

Calculate Material stresses

Compare to allowables for the material.

MIL-HDBK-5H

1998

Freely available on Design Unit web site.

Current Industry Standard MMPDS https://www.mmpds.org/

Commercial product $$$ contains some newer alloys.

Factor of Safety

Limit (Yield) = 1.0 !!!no margin for error!!!Ultimate = 1.5Fittings = 1.1 → 1.15

Is it safe? Design Margin of Safety

0 – perfect

0 → 1 OK not too heavy

>> 1 Over designed Try again

Negative – no good, broken Try again

Factor of Safety=Failure LoadDesign Load

Margin of Safety=Failure LoadDesign Load

−1

Done

Design is an

Iterative Process

Some words of warning:

Aerospace contractors in Australia in many cases must work With US. FAA design rules and methods.

This means all work must be done in the IMPERIAL systemof units NOT SI. slug, lb, ft, in, psi, ksi, etc...

Must pass quiz component to pass this unit. Otherwise maximum mark is 45

All students should work in a harcopy logbook in the design classes. Not an IPAD or electronic notebook.