Chap 17: a/c composite materials Flashcards
composite structures are fabricated using? and the 2 components
fabricated using fibre reinforced plastics (FRP)
a composite is made up of 2 components:
fibre
matrix
which direction makes fibre strongest when loads are applied
running direction of fibers ( 0deg warp position)
3 stress design for fibrous tape and its angle
anisotropic (0 deg)
quasi-isotropic (90 deg)
isotropic (45 / -45 deg)
common types of fibers
fibreglass (glass cloth) - electrical glass & structural glass ( E/S glass)
aramid - excellent chemical resistance that is normal in a/c ops
carbon fibre (graphite) - aka carbon-fibre reinforced plastics (CFRP), strong & stiff
2 types of resins and its 2 forms
thermoset - once cured, is irreversible
thermoplastic - can be repeatedly softened with heat even after curing
2 forms:
two-part liquid mixture
factory-mixed and frozen
types of composite structures
solid laminate (like Jenga)
sandwich assembly (honeycomb) - improved structural performance and high strength-to-weight ratio, a filler (core) between laminate surfaces
properties of composite structures
high material strength-to-weight ratio
corrosion resistance
fatigue resistance
low sensitivity to sonic vibrations
where are composite structures found in the a/c?
landing gear doors, flaps, stabiliser structures, floor beams, nacelles
types of inspection methods
visual inspection, tap test (coin), radiology, ultrasonic (high freq, sound waves), acoustic emission (sound)
thermosetting resins
phenolic - fire resistant, lower smoke
polyester - low smoke
epoxy - strength & stiffness
bismaleimide - high temperature parts
core layouts for sandwich assembly and parameters that determines the properties of core
hexagonal, flexicore, overexpanded
parameters that determine properties of core:
cell pitch
cell bisection
thickness
