Be Chapter 4-Fatigue

Front 1

What is the type of failure that occurs as a result of repeated loading that can lead to failure at stresses significantly less than the normal tensile or yield strength determined by static testing methods?

Back 1

fatigue fracture

Front 2

fatigue is the cause of ___ % of fractures in ____

Back 2

90
metals

Front 3

how are fatigue fractures characterized?

Back 3

brittle, with little plastic deformation around the fracture, even for ductile materials

Front 4

What is the cause of fatigue fractures?

Back 4

1. repeated stress increases the number of dislocations
2. More and more imperfections form
3. Flaws act to nucleate cracks and lead to failure

Front 5

can fatigue fractures occur in elastic regions?

Back 5

Yes, even if bulk is undergoing elastic deformation, there is localized plastic deformation

Front 6

what are some examples of stress raisers?

Back 6

1) Small surface imperfections
2) notches, holes
3) slightly different chemistry
4) pores you add on purpose

Front 7

What is the fatigue life of a material?

Back 7

the number of cycles requires for crack initiation plus the number of cycles needed for propagation to the critical size for failure

Front 8

How can the body respond to biomaterials?

Back 8

The active substances can cause a chemical reaction such as walts, salt, and protein

Front 9

what is the term for failure that occurs as a result of cyclic stresses and chemical attack?

Back 9

corrosion fatigue