L3: Mechanical Behaviour 2

Question 1

What is the advantage and disadvantage of the KV and Maxwell models?

Answer 1

KV: acceptable approximation for creep/recovery behaviour. Does not account for stress relaxation
Maxwell: Can account for stress relaxation. Poor description of creep and recovery

Question 2

What is the arrangement of the Standard Linear Model?

Answer 2

1 large spring in parallel with a spring and dashpot which are in series

Question 3

What is the initial extension and relaxation behaviour controlled by in the SLM?

Answer 3

Initial: the dashpot
Relaxation: the interplay of both spring and dashpot elements

Question 4

What is the asymptotic value for strain in the KV model?

Answer 4

stress/E

Question 5

What constants must be chosen to show the KV and Maxwell models are special cases of the SLM?

Answer 5

Maxwell: E2 (big spring) = 0
KV: E1 (small spring) = infinite (divide through by E1)

Question 6

Which factors form a 3D relationship for viscoelastic polymers?

Answer 6

stress-strain-time

Question 7

How is D(t) (creep compliance) determined?

Answer 7

Usually will be told to use Maxwell or KV model - D(t) = strain(t)/stress
See slides for equation for each