Fracture Of Cracked Members

OBJECTIVE WHY WE SHOULD STUDY FRACTURE TOUGHNESS (KIC)..?

• To detect crack of the material so that we can do initial prevention to avoid the material from fracture

• To know how strength the material so we can choose the appropriate material to construction or design

• To know the design criteria to minimize or reduce the possibility of fracture come from material.

CRACK BEHAVIOR

Commonly stress higher on the tip of the hole. So stress concentration factor, is given by Kt = stress/applied stress

THE TERMINOLOGI OF K

• In almost worst case scenario Kc << K1C, KIC usually from the graph or standard table

• KIC = plain strain fracture toughness

• K =stress intensity factors

• Kc = S(Пa)^1/2, where S = applied stress, a = crack length(mm)

• KI = FS(Пa), F= based on the type of geometry, a/b, where b is the width of the plain material

• Safety Factor nk = KIC/K = KIC/(FS(Пa)^1/2

• Safety Factor on the crack length, na = ac/a =(F/Fc.nk)^2

• Uniaxial stress (n = Stress/applied stress), Uniaxial load (n = Load/ Applied load), moment(n = moment/applied moment)

3 BASIC MODE CRACK

Example Of Geometry Assumption (Mode 1 Failure)

1. It caused by tension

2. Force are perpendicular to the crack length

3. No external force except applied stress

THE TYPE OF GEOMETRY

HOW ENGINEER PLAY FRACTURE FOR DAILY LIFE

1. Engineer almost build a graph to related the fracture toughness, applied stress and temperature.

2. Related that i get is, when the temperature decrease the fracture toughness also decrease. It means the strength of the material in low temperature is high.

3. If the fracture toughness of the material decrease the stress of the plain material is increase. It means the higher fracture toughness the low strength of material it self.