Lecture 13 Flashcards
(4 cards)
What different manufacturing techniques would be required for the aerospace or the automotive industries.
Aerospace: Cycle time is around 1 day
- Prepreg
- Tape laying
- Autoclave curing
Automotive: Cycle time is around 1 minute
- Extrusion compounded
- Injection Moulding
Why are short fibres used in composites?
In general terms longer fibres are better for performance, however processability may be reduced. In fast moving production processability is key to produce the large quantities required.
Why do fibres often have small diameters? Give 3 reasons.
Small diameter fibres provide sufficient flexibility in fibre production.
Smaller diameters allow for a lower probability of a large flaw being present (size effect) maximises the fibre strength.
Small diameters provide large surface area for bonding the fibre with the matrix.
What is the critical fibre length?
The critical fibre length is the minimum fibre length required to achieve a stress level in the fibre equal to the fibre strength.
The critical fibre length depends on the tensile fibre strength, matrix yield shear stress and the diameter of the fibre.
