Composites Flashcards
DMM1: Materials Deck 9
What are the components of a composite?
the reinforcment: high strength components in the material
the matrix: connecting material between the reinforcements
What is a composite?
Combination of two or more materials resulting in better
(more useful) properties than either component
Describe the composition of fibre glass (GRP)
longth thin glass fiberes connected together with a thermoset polymer
Describe CFRP’s (carbon fibre reinforced plastics)
Carbon fibre reinforcements in a thermoset polymer matrix
Describe carbon fibres
Carbon forms flat sheets of covalently bonded atoms in hexagonal structure
Sheets bundled together into fibres
What are the three types of fibre structures?
onion skin: concentric fibres
Radial: striaght fibres point outwards
Random: chaotic arangement of fibres
What is a carbon fibre tow?
a long cord made of thousands of fibres bundelled together
Describe unidirectional CFRP
all the fibres in this tructure run in the same direction
What are the properties of unidirectional carbon fibre?
anisotropic material which is stronger along the fibres and weaker across them
Describe CFRP Laminates
layers of unidirectional CFRP and placed at different angles to give strength in many directions
What is a cross ply/biaxial lay up?
CFRP is layered at zero and 90 degrees to give strength in two directions
What is a symetrical lay up?
the angles of the layers above the center match the angles of the layers below
What is a balanced lay up?
a lay up with the same number of postive and negative layers
What are the effects of unsymetrical lay up?
Tension causes bending forces which twist and shear the material both under mechanical and thermal loads
What are the effects of an unbalanced lay up?
tension causes extension and shear deformation which can cause layers to slide apart
