static fatigue
{{merge to|Environmental stress cracking|date=February 2025|discuss=Talk:Static fatigue#Merger discussion}}
Static fatigue, sometimes referred to as delayed fracture, describes the progressive cracking and eventual failure of materials under a constant, sustained stress.{{Cite book |last=Suresh |first=S. |title=Fatigue of materials |date=1998 |publisher=Cambridge University Press |isbn=978-0-521-57046-6 |edition=2nd |location=Cambridge; New York}} (It is different from fatigue, which refers to the deformation and eventual failure of materials subjected to cyclical stresses.) With static fatigue materials experience damage or failure under stress levels that are lower than their normal ultimate tensile strengths.{{Cite book |last=Pelleg |first=Josh |url=https://link.springer.com/chapter/10.1007/978-3-030-86118-6_15 |title=Cyclic Deformation in Oxides, Carbides, and Nitrides |publisher=Springer |year=2021 |isbn=978-3-030-86118-6 |volume=22 |pages=495–511 |doi=10.1007/978-3-030-86118-6_15 |s2cid=244421914}} The exact details vary with the material type and environmental factors, such as moisture presence{{Cite book |last1=Laughton |first1=M.J. |url=https://doi.org/10.1016/B978-075064637-6/50037-X |title=Optical Fibres in Power Systems |last2=Warne |first2=D.J. |last3=Tricker |first3=R. |publisher=Newnes |year=2003 |isbn=978-0-7506-4637-6 |edition=16 |pages=37-1, 37-3-37-17 |doi=10.1016/B978-075064637-6/50037-X}} and temperature.{{Cite book |last=Kingery |first=W.D. |url=https://archive.org/details/introductiontoce0000king |title=Introduction to ceramics |publisher=Wiley |year=1976 |isbn=978-0471478607 |location=New York |pages= |url-access=registration}}{{Cite journal |last1=Ebel |first1=A. |last2=Caty |first2=O. |last3=Rebillat |first3=F. |date=2022 |title=Effect of temperature on static fatigue behavior of self-healing CMC in humid air |journal=Composites Part A: Applied Science and Manufacturing |volume=157 |page=106899 |doi=10.1016/j.compositesa.2022.106899 |s2cid=247148726 |doi-access=free}} This phenomenon is closely related to stress corrosion cracking.
Typical occurrence
= Stress corrosion cracking =
{{Main|Stress corrosion cracking}}Stress corrosion cracking (SCC) happens when a stressed material is in a corrosive (chemically destructive) environment.{{Cite book |last1=Raja |first1=V.S. |url=https://doi.org/10.1533/9780857093769.3.245 |title=Stress Corrosion Cracking |last2=Tetsuo |first2=Shoji |publisher=Woodhead Publishing |year=2011 |isbn=978-1-84569-673-3 |pages=245–272|doi=10.1533/9780857093769.3.245 }} One example of SSC embrittlement is when moisture increases static fatigue degradation of glass.{{Cite journal |last1=Wiederhorn |first1=S. M. |last2=Bolz |first2=L. H. |date=1970-10-01 |title=Stress Corrosion and Static Fatigue of Glass |journal=Journal of the American Ceramic Society |language=en |volume=53 |issue=10 |pages=543–548 |doi=10.1111/j.1151-2916.1970.tb15962.x |issn=1551-2916}} SCC is also seen in hydrogen embrittlement{{Cite web |last=Lou than |first=M.R. |title=Hydrogen Embrittlement - Office of Scientific and Technical Information |url=http://sti.srs.gov/fulltext/WSRC-STI-2008-00062.pdf}}{{Cite journal |last1=Murakami |first1=Y. |last2=Kanezaki |first2=T. |last3=Matsuoka |first3=S. |date=2008 |title=Hydrogen Embrittlement Mechanism in Fatigue of Austenitic Stainless Steels |journal=Metallurgical and Materials Transactions A |volume=39 |issue=6 |pages=1327–1339 |doi=10.1007/s11661-008-9506-5 |bibcode=2008MMTA...39.1327M |s2cid=137234625 |doi-access=free }} and embrittlement of some polymers.{{Cite book |last1=Brown |first1=Norman |title=Recent Advances in Science and Technology of Materials |last2=Parrish |first2=Mark F. |date=1974 |publisher=Springer US |isbn=9781461345404 |editor-last=Bishay |editor-first=Adli |pages=1–13 |language=en |doi=10.1007/978-1-4613-4538-1_1}}
= Plastic Deformation (Plastic Flow) =
Plastic deformation happens when stresses flatten, bend, or twist a material until it cannot return to its original shape.{{Cite book |chapter-url=https://www.sciencedirect.com/science/article/pii/B9780750682879000069 |title=Materials Enabled Designs |chapter=Chapter 6 - Degradation and Reliability of Materials |publisher=Butterworth Heinemann |year=2009 |isbn=978-0-7506-8287-9 |pages=161–187 |doi=10.1016/B978-0-7506-8287-9.00006-9 |via=Science Direct |last1=Pfeifer |first1=Michael }} This can create cracks in the material and decrease its lifetime.{{Cite journal |last1=Wang |first1=G.S. |last2=Blom |first2=A.F. |title=Effect of Large Local Plastic Flow on the Fatigue Life of Metallic Materials |url=https://www.gruppofrattura.it/ocs/index.php/ICF/ICF11/paper/viewFile/9810/9226 |journal=Aeronautics Division |via=The Swedish Defence Research Agency}}
Testing
Static fatigue tests can be used to determine the lifespan of a material with different loads and environmental conditions.{{Cite journal |last1=Wilkins |first1=B.J. |last2=Dutton |first2=R. |date=March 1976 |title=Static Fatigue Limit with Particular Reference to Glass |url=https://doi.org/10.1111/j.1151-2916.1976.tb09442.x |journal=Journal of the American Ceramic Society |volume=59 |issue=3–4 |pages=108–112 |doi=10.1111/j.1151-2916.1976.tb09442.x}}{{Cite book |last1=Kelly |first1=A. |url=https://doi.org/10.1016/B0-08-042993-9/00181-9 |title=Comprehensive Composite Materials (2.05 - Glass Fiber Reinforced Plastics—Properties) |last2=Zweben |first2=C. |last3=Sims |first3=G.D. |last4=Broughton |first4=W.R. |publisher=Pergamon |year=2000 |isbn=978-0-08-042993-9 |volume=2 |pages=151–197 |doi=10.1016/B0-08-042993-9/00181-9}} However, accurately assessing a material's true static fatigue life presents challenges, as these tests often require an extended duration and there is significant variability in the results.
Examples of Static Fatigue and Stresses on Materials
Plastic pipes under water or other fluids experience hydrodynamic forces that can result in fatigue.{{Citation |last=Farshad |first=Mehdi |title=7 - Fatigue, corrosion, and wear |date=2006-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9781856174961500082 |work=Plastic Pipe Systems |pages=153–165 |editor-last=Farshad |editor-first=Mehdi |access-date=2023-04-15 |place=Oxford |publisher=Elsevier Science |language=en |isbn=978-1-85617-496-1}} The pipes reach failure sooner as temperatures and exposure to aggressive substances increase.