30 Questions
What type of fabric has no fill fibers and is held together by small cross threads?
Unidirectional fabric
Which type of fabric usually has more strength in the warp direction?
Bidirectional fabric
What aspect makes plain weave fabrics different from satin weave fabrics?
Yarn slippage
Which type of weave pattern involves warp and fill yarns interlacing over and under each other?
Plain weave
What characteristic is a key advantage of woven fabrics over unidirectional materials?
Better resistance to delamination
What is the main purpose of cross threads in unidirectional fabrics?
To hold major fibre bundles in place
What is a notable characteristic of a satin weave?
Short warp yarn floats
Which type of weave is characterized by a distinctive diagonal line on the fabric's surface?
Twill weave
What type of yarn repeats on three or more warp and fill yarns in a twill weave?
Warp yarn
What does the matrix do in composite materials?
Surrounds the fiber to give it extra strength
Why were old polyester/fiberglass formulas deemed insufficient for fabricating primary structural members?
Somewhat brittle
What characteristic of newer matrix materials makes them suitable for aircraft applications?
Improved stress-distributing characteristics
What is a major concern when drilling Aramid material?
The drill bit grabbing a fiber and stretching it to its breaking point
Why is carbon fiber more susceptible to promoting galvanic corrosion when bonded to aluminum or steel?
Carbon fiber is cathodic while aluminum and steel are anodic
Why are carbon materials kept separate from aluminum components?
To prevent galvanic corrosion
Which material retains most of its strength and flexibility at temperatures up to 1200 °C?
Ceramic fiber
What is a key advantage of using carbon-fiber composites for aircraft structural components?
High strength and high rigidity
How does the compressive strength of carbon fiber compare to that of Kevlar®?
Carbon fiber is stronger in compressive strength than Kevlar®
What two components make up resin matrices?
Resin and catalyst
How are resin matrix systems often referred to by some companies?
Fiber-reinforced plastics
What do thermoplastic resins use to form the part into the desired shape?
Heat
What happens when a thermoplastic material is heated a second time?
It melts and reshapes
Which transparent thermoplastic material was commonly used in early aircrafts due to its transparency and light weight?
Cellulose acetate
Why has cellulose acetate plastic almost completely been replaced in aircraft applications?
It tends to shrink and turn yellow
What is one of the disadvantages of working with pre-preg fabrics in a maintenance facility?
The requirement to store pre-pregs in a freezer
Why should bags containing pre-preg material be opened only in a controlled environment?
To avoid contamination that could compromise bond durability
What effect does room temperature have on pre-pregs if they are not stored in a freezer?
The resins and catalysts start a chemical reaction and begin to cure
Why are thixotropic agents added to resins?
To control viscosity and weight of the resin
What happens if pre-preg material exceeds its shelf life?
It must be discarded and can become more expensive than raw fabric
What is the purpose of fillers (thixotropic agents) in resins?
To make application of the resin easier
Learn about the challenges of drilling Aramid materials and the advantages of carbon materials in aviation. Understand how carbon materials can promote galvanic corrosion when bonded to aluminium or steel.
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