(a) A large medium carbon steel crane hook is thought to contain penny- shaped internal cracks. If the non-destructive test equipment used on the hook is not capable of detecting cracks smaller than 20 mm diameter, determine the fracture toughness required from this steel if the safety factor on stress is to be 2. The yield stress of the AISI 1045 grade steel is 1050 MNm². Note: For this crack geometry, the 'compliance function' Y in the Stress Intensity Factor (K)) may be taken as 1. (b) A surface crack of 2.5 mm depth and a certain length is found in a thick rectangularcomponent. The component is schedule to be repaired in 6 months. The component is subjected to zero to maximum stress of 340 MPa, 50 times per hour. It was known that for this component catastrophic failure occurs when the crack size reaches 12 mm in depth. Assuming that the crack geometrical shape (aspect ratio) remains constant during crack growth, will the component fail before repair? For the crack geometry, the stress intensity factor may be taken as Κι = 1.2σνπα The Paris law da dN = C(AK) constants for the material are C=5.6 x 1012 and m = 3, where da -3/2 is m/cycle and AK is in MNm3

Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
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(a)
A large medium carbon steel crane hook is thought to contain penny-
shaped internal cracks. If the non-destructive test equipment used on
the hook is not capable of detecting cracks smaller than 20 mm
diameter, determine the fracture toughness required from this steel if
the safety factor on stress is to be 2. The yield stress of the AISI 1045
grade steel is 1050 MNm².
Note: For this crack geometry, the 'compliance function' Y in the
Stress Intensity Factor (K)) may be taken as 1.
(b)
A surface crack of 2.5 mm depth and a certain length is found in a thick
rectangularcomponent. The component is schedule to be repaired in 6
months. The component is subjected to zero to maximum stress of 340
MPa, 50 times per hour. It was known that for this component
catastrophic failure occurs when the crack size reaches 12 mm in
depth. Assuming that the crack geometrical shape (aspect ratio)
remains constant during crack growth, will the component fail before
repair?
For the crack geometry, the stress intensity factor may be taken as
Κι = 1.2σνπα
The Paris law
da
dN
= C(AK) constants for the material are
C=5.6 x 1012 and m = 3, where
da
-3/2
is m/cycle and AK is in MNm3
Transcribed Image Text:(a) A large medium carbon steel crane hook is thought to contain penny- shaped internal cracks. If the non-destructive test equipment used on the hook is not capable of detecting cracks smaller than 20 mm diameter, determine the fracture toughness required from this steel if the safety factor on stress is to be 2. The yield stress of the AISI 1045 grade steel is 1050 MNm². Note: For this crack geometry, the 'compliance function' Y in the Stress Intensity Factor (K)) may be taken as 1. (b) A surface crack of 2.5 mm depth and a certain length is found in a thick rectangularcomponent. The component is schedule to be repaired in 6 months. The component is subjected to zero to maximum stress of 340 MPa, 50 times per hour. It was known that for this component catastrophic failure occurs when the crack size reaches 12 mm in depth. Assuming that the crack geometrical shape (aspect ratio) remains constant during crack growth, will the component fail before repair? For the crack geometry, the stress intensity factor may be taken as Κι = 1.2σνπα The Paris law da dN = C(AK) constants for the material are C=5.6 x 1012 and m = 3, where da -3/2 is m/cycle and AK is in MNm3
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