L5 Fracture, fatigue, temperature

Question 1

Mechanical properties, what is Stiffness (E-module):

Answer 1

How much a material is deformed
elastically when loaded

Question 2

Mechanical properties, Yield limit (sigma_y):

Answer 2

At which stress the material begins to be
plasticized

Question 3

Mechanical properties, Fracture toughness (K_1c):

Answer 3

Measure of resistance to
propagating a crack

Question 4

Difference ductile and brittle fractures

Answer 4

Ductile dras ut innan den går av > <. Vid yield strength dras materialet ut.
Brittle går rakt av | |. Vid yield strength går materialet av.

Question 5

Explain fatigue

Answer 5

Fatigue failures occur due to cyclic loading at
stresses below a material’s yield strength

Question 6

Types of cyclic loading

Answer 6

(a) Low amplitude acoustic vibration
(b) High-cycle fatigue: cycling below
the yield strength
(c) Low-cycle fatigue: cycling above
the yield strength but below the
the tensile strength

Question 7

Ductility

Answer 7

How much platic strain a material can tolerate

Question 8

What happens to materials when the temperature
rises?

Answer 8

Atoms vibrate and moves more easily, Atomic bonds are getting weaker, Phase transformations and Chemical reactions

Question 9

Max operating temp is limited by (for example)

Answer 9

• Impaired mechanical properties
• Phase transformations and chemical
  changes
• Oxidation

Question 10

Min operating is limited by (for example)

Answer 10

Brittleness