fracture mechanics of construction made from steel and timber 3.01

Question 1

name 3 Approaches/theories of fracture mechanics

Answer 1

-stress concentration approach
-energy approach Griffith Theory
-stress intensity approach

Question 2

stress concentration approach

Answer 2

-stress concentration factor (K)
-limited to round notches
-does not work with sharp cracks

Question 3

energy approach Griffith Theory

Answer 3

-critical energy release
-no information about the stress around crack tip

Question 4

stress intensity approach

Answer 4

-stresses around crack tip
-stress intensity factor
-fracture toughness (kc)

Question 5

what is the stress concentration factor (K)

Answer 5

the increase of stresses at the notch tip related to the nominal stress

it depends on the shape and dimensions of the specimen, notch geometry as well as type of loading

Question 6

conditions for application of LEFM

Answer 6

a) Sharp crack (zero radius)
b) Propagation of a single straight crack, which transfers no stresses.
c) Crack length between defined limits
d) Linear elastic material behavior or elastic-plastic behavior with plastic
deformations in the vicinity of crack tip only.
e) Homogeneity of the material
f) Sufficient thickness of specimens or structural members (i.e. state of plane strain dominates)

Question 8

What’s fracture energy?

Answer 8

Energy required to break a material