Static fatigue

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Static fatigue describes how prolonged and constant cyclic stress weakens a material until it breaks apart, which is called failure. [1] Static fatigue is sometimes called "delayed fracture". [2] The damage occurs at a lower stress level than the stress level needed to create a normal tensile fracture. [2] Static fatigue can involve plastic deformation [3] or crack growth. [4] [5] For example, repeated stress can create small cracks that grow and eventually break apart plastic, [6] glass, [7] or ceramic [8] materials. The material reaches failure faster by increasing cyclic stress. Static fatigue varies with material type and environmental factors, such as moisture presence [9] and temperature. [10] [11]

Contents

Applications

Static fatigue tests can estimate a material’s lifetime [12] and hardness to different environments [13] .  However, measuring a static fatigue limit can take a long time, and it is hard to measure a material’s true static fatigue limit with full certainty. [12]

Typical occurrence

Crack growth progression in a glass rod under cyclic stress (denoted by arrows). (1) shows the first crack. The cracks grow in (2) & (3) until the rod breaks in (4). Crack growth progression in glass rod.jpg
Crack growth progression in a glass rod under cyclic stress (denoted by arrows). (1) shows the first crack. The cracks grow in (2) & (3) until the rod breaks in (4).

Stress corrosion cracking

Stress corrosion cracking (SCC) happens when a stressed material is in a corrosive (chemically destructive) environment. [14] One example of SSC embrittlement is when moisture increases static fatigue effects in glass. [15] SCC is also seen in hydrogen embrittlement, [16] [17] embrittlement of some polymers, [18] and more.

Plastic Deformation (Plastic Flow)

Plastic deformation happens when stresses flatten, bend, or twist a material until it cannot return to its original shape. [19] This can create cracks in the material and decrease its lifetime. [3]

Examples of Static Fatigue and Stresses on Materials

Plastic pipes under water or other fluids experience hydrodynamic forces that can result in fatigue. [20] The pipes reach failure sooner as temperatures and exposure to aggressive substances increase. [20] For static fatigue tests, rotating machines apply weight on the material under study causing it to bend in different directions, which weakens the material overtime. [21]

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<span class="mw-page-title-main">Ductility</span> Degree to which a material under stress irreversibly deforms before failure

Ductility is a mechanical property commonly described as a material's amenability to drawing. In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stress before failure. Ductility is an important consideration in engineering and manufacturing. It defines a material's suitability for certain manufacturing operations and its capacity to absorb mechanical overload. Some metals that are generally described as ductile include gold and copper, while platinum is the most ductile of all metals in pure form. However, not all metals experience ductile failure as some can be characterized with brittle failure like cast iron. Polymers generally can be viewed as ductile materials as they typically allow for plastic deformation.

<span class="mw-page-title-main">Fracture</span> Split of materials or structures under stress

Fracture is the appearance of a crack or complete separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displacement develops perpendicular to the surface, it is called a normal tensile crack or simply a crack; if a displacement develops tangentially, it is called a shear crack, slip band, or dislocation.

The field of strength of materials typically refers to various methods of calculating the stresses and strains in structural members, such as beams, columns, and shafts. The methods employed to predict the response of a structure under loading and its susceptibility to various failure modes takes into account the properties of the materials such as its yield strength, ultimate strength, Young's modulus, and Poisson's ratio. In addition, the mechanical element's macroscopic properties such as its length, width, thickness, boundary constraints and abrupt changes in geometry such as holes are considered.

<span class="mw-page-title-main">Fatigue (material)</span> Initiation and propagation of cracks in a material due to cyclic loading

In materials science, fatigue is the initiation and propagation of cracks in a material due to cyclic loading. Once a fatigue crack has initiated, it grows a small amount with each loading cycle, typically producing striations on some parts of the fracture surface. The crack will continue to grow until it reaches a critical size, which occurs when the stress intensity factor of the crack exceeds the fracture toughness of the material, producing rapid propagation and typically complete fracture of the structure.

<span class="mw-page-title-main">Wear</span> Damaging, gradual removal or deformation of material at solid surfaces

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<span class="mw-page-title-main">Fracture mechanics</span> Study of propagation of cracks in materials

Fracture mechanics is the field of mechanics concerned with the study of the propagation of cracks in materials. It uses methods of analytical solid mechanics to calculate the driving force on a crack and those of experimental solid mechanics to characterize the material's resistance to fracture.

<span class="mw-page-title-main">Hydrogen embrittlement</span> Reduction in ductility of a metal exposed to hydrogen

Hydrogen embrittlement (HE), also known as hydrogen-assisted cracking or hydrogen-induced cracking (HIC), is a reduction in the ductility of a metal due to absorbed hydrogen. Hydrogen atoms are small and can permeate solid metals. Once absorbed, hydrogen lowers the stress required for cracks in the metal to initiate and propagate, resulting in embrittlement. Hydrogen embrittlement occurs most notably in steels, as well as in iron, nickel, titanium, cobalt, and their alloys. Copper, aluminium, and stainless steels are less susceptible to hydrogen embrittlement.

<span class="mw-page-title-main">Intergranular fracture</span>

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<span class="mw-page-title-main">Embrittlement</span> Loss of ductility of a material, making it brittle

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<span class="mw-page-title-main">Filler (materials)</span> Particles added to improve its properties

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<span class="mw-page-title-main">Environmental stress cracking</span> Brittle failure of thermoplastic polymers

Environmental Stress Cracking (ESC) is one of the most common causes of unexpected brittle failure of thermoplastic polymers known at present. According to ASTM D883, stress cracking is defined as "an external or internal crack in a plastic caused by tensile stresses less than its short-term mechanical strength". This type of cracking typically involves brittle cracking, with little or no ductile drawing of the material from its adjacent failure surfaces. Environmental stress cracking may account for around 15-30% of all plastic component failures in service. This behavior is especially prevalent in glassy, amorphous thermoplastics. Amorphous polymers exhibit ESC because of their loose structure which makes it easier for the fluid to permeate into the polymer. Amorphous polymers are more prone to ESC at temperature higher than their glass transition temperature (Tg) due to the increased free volume. When Tg is approached, more fluid can permeate into the polymer chains.

Anti-scratch coating is a type of protective coating or film applied to an object's surface for mitigation against scratches. Scratches are small surface-level cuts left on a surface following interaction with a sharper object. Anti-scratch coatings provide scratch resistances by containing tiny microscopic materials with scratch-resistant properties. Scratch resistance materials come in the form of additives, filters, and binders. Besides materials, scratch resistances is impacted by coating formation techniques. Scratch resistance is measured using the Scratch-hardness test. Commercially, anti-scratch coatings are used in the automotive, optical, photographic, and electronics industries, where resale and/or functionality is impaired by scratches. Anti-scratch coatings are of growing importance as traditional scratch resistance materials like metals and glass are replaced with low-scratch resistant plastics.

<span class="mw-page-title-main">Ceramic matrix composite</span> Composite material consisting of ceramic fibers in a ceramic matrix

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<span class="mw-page-title-main">475 °C embrittlement</span> Loss of plasticity in ferritic stainless steel

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References

  1. ↑ In Materials, Woodhead Publishing (2010). Guedes, Rui Miranda (ed.). Creep and Fatigue in Polymer Matrix Composites (1st ed.). Woodhead Publishing. ISBN   9780081014585.
  2. 1 2 Pelleg, Josh (2021). Cyclic Deformation in Oxides, Carbides, and Nitrides. Vol. 22. Springer. pp. 495–511. doi:10.1007/978-3-030-86118-6_15. ISBN   978-3-030-86118-6. S2CID   244421914.
  3. 1 2 Wang, G.S.; Blom, A.F. "Effect of Large Local Plastic Flow on the Fatigue Life of Metallic Materials". Aeronautics Division– via The Swedish Defence Research Agency.
  4. ↑ Courtney, Thomas H. (2005-12-16). Mechanical Behavior of Materials: Second Edition. Waveland Press. ISBN   9781478608387.
  5. ↑ Furmanski, J.; Rimnac, C.M. (2011). "Crack Propagation Resistance Is Similar Under Static and Cyclic Loading in Crosslinked UHMWPE: A Pilot Study". Clinical Orthopaedics and Related Research. 469 (8): 2302–2307. doi:10.1007/s11999-010-1712-y. PMC   3126950 . PMID   21128033.
  6. ↑ Crawford, Roy. J. (1998). Plastics Engineering (Chapter 1 - General Properties of Plastics) (1 ed.). Matthew Deans. pp. 1–40. ISBN   9780081007099.
  7. ↑ Grutzik, S.J.; Strong, K.T.; Rimsza, J.M. (December 2022). "Kinetic model for prediction of subcritical crack growth, crack tip relaxation, and static fatigue threshold in silicate glass". Journal of Non-Crystalline Solids: X. 16 (100134): 100134. Bibcode:2022JNCSX..1600134G. doi: 10.1016/j.nocx.2022.100134 . S2CID   254308009.
  8. ↑ Ruys, Andrew (2019). Processing, structure, and properties of alumina ceramics. Woodhead Publishing. pp. 71–121. doi:10.1016/C2017-0-01189-8. ISBN   978-0-08-102442-3.
  9. ↑ Laughton, M.J.; Warne, D.J.; Tricker, R. (2003). Optical Fibres in Power Systems (16 ed.). Newnes. pp. 37–1, 37-3–37-17. doi:10.1016/B978-075064637-6/50037-X. ISBN   978-0-7506-4637-6.
  10. ↑ Kingery, W.D. (1976). Introduction to ceramics . New York: Wiley. ISBN   978-0471478607.
  11. ↑ Ebel, A.; Caty, O.; Rebillat, F. (2022). "Effect of temperature on static fatigue behavior of self-healing CMC in humid air". Composites Part A: Applied Science and Manufacturing. 157: 106899. doi: 10.1016/j.compositesa.2022.106899 . S2CID   247148726 – via Elsevier Science Direct.
  12. 1 2 Wilkins, B.J.; Dutton, R. (March 1976). "Static Fatigue Limit with Particular Reference to Glass". Journal of the American Ceramic Society. 59 (3–4): 108–112. doi:10.1111/j.1151-2916.1976.tb09442.x.
  13. ↑ Kelly, A.; Zweben, C.; Sims, G.D.; Broughton, W.R. (2000). Comprehensive Composite Materials (2.05 - Glass Fiber Reinforced Plastics—Properties). Vol. 2. Pergamon. pp. 151–197. doi:10.1016/B0-08-042993-9/00181-9. ISBN   978-0-08-042993-9.
  14. ↑ Raja, V.S.; Tetsuo, Shoji (2011). Stress Corrosion Cracking. Woodhead Publishing. pp. 245–272. doi:10.1533/9780857093769.3.245. ISBN   978-1-84569-673-3.
  15. ↑ Wiederhorn, S. M.; Bolz, L. H. (1970-10-01). "Stress Corrosion and Static Fatigue of Glass". Journal of the American Ceramic Society. 53 (10): 543–548. doi:10.1111/j.1151-2916.1970.tb15962.x. ISSN   1551-2916.
  16. ↑ Lou than, M.R. "Hydrogen Embrittlement - Office of Scientific and Technical Information" (PDF).
  17. ↑ Murakami, Y.; Kanezaki, T.; Matsuoka, S. (2008). "Hydrogen Embrittlement Mechanism in Fatigue of Austenitic Stainless Steels". Metallurgical and Materials Transactions A. 39 (6): 1327–1339. Bibcode:2008MMTA...39.1327M. doi: 10.1007/s11661-008-9506-5 . S2CID   137234625.
  18. ↑ Brown, Norman; Parrish, Mark F. (1974). Bishay, Adli (ed.). Recent Advances in Science and Technology of Materials. Springer US. pp. 1–13. doi:10.1007/978-1-4613-4538-1_1. ISBN   9781461345404.
  19. ↑ Pfeifer, Michael (2009). "Chapter 6 - Degradation and Reliability of Materials". Materials Enabled Designs. Butterworth Heinemann. pp. 161–187. doi:10.1016/B978-0-7506-8287-9.00006-9. ISBN   978-0-7506-8287-9 – via Science Direct.
  20. 1 2 Farshad, Mehdi (2006-01-01), Farshad, Mehdi (ed.), "7 - Fatigue, corrosion, and wear", Plastic Pipe Systems, Oxford: Elsevier Science, pp. 153–165, ISBN   978-1-85617-496-1 , retrieved 2023-04-15
  21. ↑ Goodman, Soderberg (2022), "Fatigue", MET 301: Design for Cyclic Loading (PDF), New Jersey Institute of Technology, p. 1
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