7/25/2019 Fracture and Fatigue QP

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1Describe the conditions that increase the susceptibility of a metal component

to failure by fatigue. How metal fatigue resistance can be measured?

(b) Fatigue is eected by temperature Discuss the eects of high and low

temper-

atures on it.

(a) ! sample has a crac" length of #.m. $he %oung&s modulus the sample

is '*+m and the speci,c surface energy is 1+m stimate the fracture

strength and compare it with its young&s modulus.

(b) ! heat treated steel chisel and a glass window pane are both brittle. /plain

why chisel is strong and the window pane is wea".

0 (a) Determine the critical crac" length in a centered crac"ed plate loaded in

mode.

f critical intensity factor

23 4 567apm and the far ,eld stress is 1 6pa.

(b) 3ite the signi,cant dierences between the following.

i. 8tress intensity factorii. 7lane stress fracture toughness

iii. 7lane strain fracture toughness.

9 Determine the thic"ness of a 1mm wide uniform plate for safe continuous

oper-

ation if the plate is to be sub:ected to a tensile load that has a ma/imum ;alue of