Aircraft Materials - Composite And Non-Metallic Flashcards
Over extended honeycomb can bend in which direction?
Along the ribbon
Fibre weave strength is greatest in the direction of the
Warp
Which core material will be used in the making of a composite material flat panel?
Hexagonal core
Which of the following could best be manufactured from Perspex panel?
A passenger window
Kevlar and Nomex are types of
Advanced composite
The practical strength of fibreglass is
Along the fibre
Sound is best absorbed by a material which is
Soft and porous
Polyester resin and glass fibre cloth, becomes
GRP
A thermoplastic can be
Reheated and reformed more than once
Sandwich panels made of metal honeycomb construction are used on modern aircraft because this type of construction
Is lighter than a single sheet skin of the same strength and is more corrosion resistant
A category of plastic material that is capable of softening or flowing when reheated is described as a
Thermoplastic
The classification of high tensile strength fibreglass used in aircraft structures is
S-glass
Which is the identifying characteristic of acrylic plastics?
Acetone will not soften, but will cloud the surface
The classification for fibreglass reinforcement material that has high electrical resistivity and is commonly used in circuit boards is
E-glass
Composite fabric material is considered to be the strongest in what direction?
Warp
What are general characteristics of aramid fibre (Kevlar) composites?
High tensile strength, flexibility, stiffness and ability to conduct electricity
What generally characterises carbon/graphite fibre composites?
Stiffness, high compressive strength and corrosive effect in contact with aluminium
What is true about thermosetting plastics?
Once moulded into shape they become set and cannot subsequently be softened by reheating
Which fibre is susceptible to the ingress of moisture?
Kevlar
In a composite repair lay-up, how much should each layer extend beyond the layer below it?
1/2 inches
What is the effect of heat on a cold cure resin?
Decrease pot life
If you increase the amount of catalyst in a resin mixture
The pot life will be decreased
What two components of a three part polyester resin are dangerous to mix together directly?
Accelerator and free catalyst
What is the effect of adding too much hardener to a resin?
Makes the repair more brittle
An air driven router is used to remove honeycomb material repairs
When one outer skin is damaged
What do you do if you forget to add hardener to a composite repair?
Remove all resin and start again
Why would you use microballoons as a filler?
It is the lightest filler material
What does MSDS stand for?
Material safety data sheet
Damaged honeycomb undergoing repair can be removed with
A router
The pot life of a cold cured resin
Decreases with an increase in temperature
Thermosetting adhesive, during their curing cycle give off
Heat
The effect of a lower temperature than ambient during the curing period of a resin, will cause the curing time to
Increase
Use of excessive hardener in polyester resin leads to
Reduced pot life
The maximum length of a component is held in stores is known as the
Shelf life
What is the separation of an aramid panel layers described as?
Delamination
Tap testing a sandwich panel construction
Is crude, but works remarkably well
Which product is a serious health hazard when handling?
Asbestos
Aircraft transparent plastics are cleaned using
Warm soapy water, rinsed and dried
A thermosetting adhesive
Undergoes a chemical transformation and creates an insoluble substance
Metal fasteners used with carbon/graphite composite structures
Must be made of materials such as titanium or corrosion resistant steel
Which methods can be used to inspect fibreglass/honeycomb structures for entrapped water?
X-ray and back-lighting
When balsa wood is used to replace a damaged honeycomb core, the plug should be cut so that
The grain is perpendicular to the skin
One of the best ways to assure that a properly prepared batch of matrix resin has been achieved is to
Have mixed enough for a test sample
What are the advantages of using microballoons in repairs to laminate honeycomb sandwich panels?
Less density, lower stress concentrations
The length and time that a catalysed resin will remain in a workable state is called the
Pot life
One method of inspecting a laminated fibreglass structure that has been subjected to damaged is
Strip the damaged area of all paint and shine a strong light through the structure
When inspecting a composite panel using the ring test/tapping method, a dull thud may indicate
Separation of the laminates
What reference tool is used to determine how the fibre is to be oriented for a particular ply or fabric?
Warp clock
The strength and stiffness of a properly constructed composite lay-up depends primarily on
The orientation of the plies to the load direction
What is the material layer used within the vacuum bag pressure system to absorb excess resin during curing called?
Bleeder
Fibreglass damage that extends completely through a laminated sandwich structure
Must be repaired
Fibreglass laminate damage that extends completely through one facing and into the core
Requires replacement of the damaged core and facing
When added to wet resins, what provides strength for the repair of damaged fastener holes in composite panels?
Cotton flock and chopped fibres
The part of a replacement honeycomb core that must line up with the adjacent original is the
Ribbon direction
What is the definition of cure time?
The time required for the mixed compound to reach an initial rubbery state
OR
The period after which the surface of the compound no longer exhibits adhesive properties
In order to prevent dermatitis caused due to contact with polymer resin, one should
Remember to close the autoclave door during curing
OR
Use disposable gloves
What would be used where a high temperature application is required, e.g. a firewall?
Ceramic fibres
