Question

Subject : mechanical of material

1. Indicate loads whether they are static or dynamic? for Cabin pressure; Lift on wings; Gust loads; and Ground loads on landing gear. 2. Considering all the external loads acting on the aircraft as the aircraft is sitting on the tarmac (so the lift may be assumed as negligible) identify the loads type (Point/Distributed) and the acting direction (Upwards/Downwards)? For the structural weight of the wing; the weight of the fuselage including the tail section; the weight of the engine mounted on the wing; The fuel in the wing; and main gear. 3. Consider a commercial transport aircraft as illustrated below: For each structure (1 to 5) is predominantly designed to sustain different types of loads such as (Bending/Tensile/ Shear/ Compression/Fatigue/Static/Dynamic), describe these loadings? 2: Upper wing cover 3: Upper fuselage shell 1: Vertical tail 5: lower fuselage 4: Fuselage side shell

Q: considering all external loads acting on the aircraft as the aircraft is sitting on tarmac ( so the lift may be assumed as negligible) identify the loads type ( point/ Distributed) and the acting directions ( Upwards/Downwards)?

Answer 1

Cabis pressure can be considered static when the plane is cruising at an altitude.

Lift on wings will always be dynamic since there can be turbulance any time So expect dynamic loading at any instant. Also climbing up and down.

Gust load is a dynamic loading

if the aircraft is stationary the ground loads on the landing gear is static.

Even when the aircraft is rolling the loading in the tyre can be considered static since the designed load of landing gear is to overcome the dynamic loads when landing.

Load distribution

Point load weight of engine Distributed weight in Aircraft wing DOBRO ODO

Distributed load of fuselage Tail weight Can be considered as a point load at CG OOOOO Fueltank weight Weight of luggage

3. Consider a commercial transport aircraft as illustrated below: For each structure (1 to 5) is predominantly designed to sustain different types of loads such as (Bending/Tensile/ Shear/ Compression/Fatigue/static/Dynamic), describe these loadings?

Vertical tail load Bending of vertical tail

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The picture below give the requred mechanical properties for most of the part.

Material properties: Corrosion FCG = Fatigue crack growth CYS = Compressive yield strength FT - Fracture toughness E- Modulus SS = Shear strength FAT = Fatigue TS = Tensile strength ( ) = Important, but not critical, design requirement Horizontal stabiliser: Upper (tension); E, FAT, FCG, FT, TS Lower (compression); CYS, E, FAT, FT, (FCG) Fixed leading edge: FAT, FT, TS, (corrosion) Seat tracks: corrosion, TS Fuselage skin: corrosion, CYS, FAT, FCG, FT, SS, TS, (E) Fuselage frames: CYS, E, FAT, FT, TS, (corrosion) Floor beams: E, TS Upper wing (compression); Skins: CYS, E, FAT, FT, (corrosion, FCG) Stringers: CYS, E, FAT, FT, (corrosion, FCG) Cargo tracks: TS, (corrosion) SOODCoed Fuselage stringers: CYS, E. FAT, FT, TS, (corrosion) pocoon Lower wing (tension); Upper spar: corrosion, CYS, E, Skins: FAT, FCG, FT, TS, (corrosion) Stringers: FAT, FT, TS, (corrosion, FCG) (FAT, FCG, FT) Lower spar: FAT, FCG, FT, TS, (corrosion)