Fibre Statistics

Question 1

What is a composite?

Answer 1

material made from 2 or more constituent parts
phases have different properties
phases remain seperate

Question 2

Why make composites?

Answer 2

take advantage of properties of both phases primarily the fibres
tailoring properties

Question 3

What are unintentional flaws?

Answer 3

flaws created during manufacturing, processing and handling

Question 4

What are intrinsic flaws?

Answer 4

unavoidable and a result of the material properties

Question 5

What is the Weibull modulus and what does it tell us?

Answer 5

unitless quantity
describes the amount of scatter in the data

Question 6

What does Weibull analysis assume about the fibres?

Answer 6

• are essentially homogeneous materials
• Fail in tension
• Uniform diameters
• Uniform distribution of flaws/unit length

Question 7

What is the Characteristic strength?

Answer 7

The stress at which 63% of the fibres are predicted to fail

Question 8

Why is Weibull analysis used to characterise fibre strengths?

Answer 8

Fibres typically have a range of strengths, therefore statistical approach needed
Normal distributions are symmetrical and poorly characterise lower strength fibres
Weibull does more accurately

Question 9

What is the maximum realistic fibre volume fraction for a hexagonal fibre array?

Answer 9

70%