- Fatigue limit
**Fatigue limit**,**endurance limit**, and**fatigue strength**are all expressions used to describe a property of materials: the amplitude (or range) ofcyclic stress that can be applied to the material without causing fatigue failure.cite book

title = Mechanics of Materials

edition = Second edition

last = Beer

first = Ferdinand P.

coauthors = E. Russell Johnston, Jr.

year = 1992

publisher = McGraw-Hill, Inc.

id = ISBN 0-07-837340-9

pages = 51]Ferrous alloys andtitanium alloys cite web

url = http://www.roymech.co.uk/Useful_Tables/Fatigue/Fatigue.html

title = Metal Fatigue and Endurance

accessdate = 2008-04-18 ] have a distinct limit, an amplitude below which there appears to be no number of cycles that will cause failure. Other structuralmetals such asaluminium andcopper , do not have a distinct limit and will eventually fail even from small stress amplitudes. In these cases, a number of cycles (usually 10^{7}) is chosen to represent the fatigue life of the material.**Definitions**ASTM defines "fatigue strength", "S

_{Nf}", as the value of stress at which failure occurs after "N_{f}" cycles, and "fatigue limit", "S_{f}", as the limiting value of stress at which failure occurs as "N_{f}" becomes very large. ASTM does not define "endurance limit" but implies that it is similar to fatigue limit.cite book

title = Metal Fatigue in Engineering

edition = Second edition

last = Stephens

first = Ralph I.

year = 2001

publisher = John Wiley & Sons, Inc.

id = ISBN 0-471-51059-9

pages = 69]Some authors use "endurance limit", "S

_{e}", for the stress below which failure never occurs, even for an indefinitely large number of loading cycles, as in the case ofsteel ; and "fatigue limit" or "fatigue strength", "S_{f}", for the stress at which failure occurs after a specified number of loading cycles, such as 500 million, as in the case of aluminium. cite book

title = Advanced Strength and Applied Stress Analysis

edition = Second edition

last = Budynas

first = Richard G.

year = 1999

publisher = McGraw-Hill, Inc.

id = ISBN 0-07-008985-X

pages = 532-533] cite book

title = The Science and Engineering of Materials

edition = Fourth edition

last = Askeland

first = Donald R.

coauthors = Pradeep P. Phule

year = 2003

publisher = Brooks/Cole

id = ISBN 0-534-95373-5

pages = 287] Other authors do not differentiate between the expressions even if they do differentiate between the two types of materials.cite book

title = Mechanics of Materials

edition = Fifth edition

last = Hibbeler

first = R. C.

year = 2003

publisher = Pearson Education, Inc.

id = ISBN 0-13-008181-7

pages = 110] cite book

title = Mechanical Behavior of Materials

edition = Second edition

last = Dowling

first = Norman E.

year = 1998

publisher = Printice-Hall, Inc.

id = ISBN 0-13-905720-X

pages = 365] cite book

title = Intermediate Mechanics of Materials

last = Barber

first = J. R.

year = 2001

publisher = McGraw-Hill

id = ISBN 0-07-232519-4

pages = 65]**Typical values**Typical values of the limit ("S

_{e}") for steels are 1/2 the ultimate tensile strength, to a maximum of 100 ksi (690 MPa). For irons, aluminums, and copper alloys, "S_{e}" is typically 0.4 times the ultimate tensile strength. Maximum typical values for irons are 24 ksi (165 MPa), aluminums 19 ksi (131 MPa), and coppers 14 ksi (96.5 MPa).**History**The concept of "endurance limit" was introduced in 1870 by

August Wöhler .W. Schutz (1996). A history of fatigue. "Engineering Fracture Mechanics" 54: 263-300. [*http://dx.doi.org/10.1016/0013-7944(95)00178-6 DOI*] ] However, recent research suggests that endurance limits do not actually exist, that if enough stress cycles are performed, even the smallest stress will eventually produce fatigue failure. cite journal

journal = Fatigue & Fracture of Engineering Materials & Structures

volume = 22

issue = 7

year = 1999

pages = 559–565

title = There is no infinite fatigue life in metallic materials

last = Bathias

first = C.

doi = 10.1046/j.1460-2695.1999.00183.x]**ee also***

fatigue (material) **References**

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