• Version
• 235 Downloads
• 1,016.48 KB File Size
• 1 File Count
• March 7, 2017 Create Date
• March 7, 2017 Last Updated

National Bureau of Standards - 1974 -Fracture by Fatigue

Introduction 
In this paper ve are concerned VIth the of fatigue and the steps 
being taken to minimize Its occurrence. Fatigue failure, of course, is due 
to the repeated application Of Stress. This type Of f allure can occur In 
crystalline as vell as non—crystalline materials, Vith metals and polymers 
being of principal concern. Fatigue failure involves both the Initiation 
and propagation Of cracks, and irreversible plastic deformation plays a 
key role In both, and It may be surprising, therefore, that 
elastic, I.e., brittle material, not subject to fatigue. 
materials are not generally useful as engineering uterials. 
exception being a composite maeerial Vhlch contains brittle 
In a protective matrix. Therefore, although ductility Is a 
characteristic Of a Decal. under cyclic loading It leads to 
Aesop could find a moral here. 
a completely 
However such 
a notable 
fibers encaged 
highly desired 
E al lure. Perhaps 
In considering the various components subject to fatigue, sometimes a 
division Of these comnonentB Into two categories Is made. The first Of these 
are components Which comprise the prizary load bearing Of structures 
euch as airplanes, cars, trucks, bridges, pressure vessels. etc. The second 
category Includes the remainder Of products sub3ect to fatigue, a category 
Which Includes the bulk Of mechanical products ranging from can openers to 
aircraft turbine bladeg. This latter category can also be broadened to 
Include certain types Of wear failures Vh±ch fact result from contact 
fatfgue. Of these categories, •re attention hae been given In general 
to structural 
Of etructural 
failures of a 
failures due to fatigue. In addition to fatigue, other forms 
failure are: overload f allure of a ductile nature. overload 
brittle nature, creep, 8tregB corrogfon and