Mechanical testing

Application of forces or torques to a material or structure to determine its mechanical properties

Mechanical testing covers a wide range of tests, which can be divided broadly into two types:

  1. those that aim to determine a material's mechanical properties, independent of geometry.[1]
  2. those that determine the response of a structure to a given action, e.g. testing of composite beams, aircraft structures to destruction, etc.

Mechanical testing of materials

Tensile test. A standard specimen is subjected to a gradually increasing load (force) until failure occurs. The resultant load-displacement behaviour is used to determine a stress–strain curve, from which a number of mechanical properties can be measured.

There exists a large number of tests, many of which are standardized, to determine the various mechanical properties of materials. In general, such tests set out to obtain geometry-independent properties; i.e. those intrinsic to the bulk material. In practice this is not always feasible, since even in tensile tests, certain properties can be influenced by specimen size and/or geometry. Here is a listing of some of the most common tests:[2]

  • Hardness Testing
    • Vickers hardness test (HV), which has one of the widest scales
    • Brinell hardness test (HB)
    • Knoop hardness test (HK), for measurement over small areas
    • Janka hardness test, for wood
    • Meyer hardness test
    • Rockwell hardness test (HR), principally used in the USA
    • Shore durometer hardness, used for polymers
    • Barcol hardness test, for composite materials
  • Tensile testing, used to obtain the stress-strain curve for a material, and from there, properties such as Young modulus, yield (or proof) stress, tensile stress and % elongation to failure.
  • Impact testing
    • Izod test
    • Charpy test
  • Fracture toughness testing
    • Linear-elastic (KIc)
    • K–R curve
    • Elastic plastic (JIc, CTOD)
  • Creep Testing, for the mechanical behaviour of materials at high temperatures (relative to their melting point)
  • Fatigue Testing, for the behaviour of materials under cyclic loading
    • Load-controlled smooth specimen tests
    • Strain-controlled smooth specimen tests
    • Fatigue crack growth testing
  • Non-Destructive Testing

References

  1. ^ Siri, Saeed; Maier, Franz; Chen, Longtu; Santos, Stephany; Pierce, David M.; Feng, Bin (2019). "Differential biomechanical properties of mouse distal colon and rectum innervated by the splanchnic and pelvic afferents". American Journal of Physiology. Gastrointestinal and Liver Physiology. 316 (4): G473–G481. doi:10.1152/ajpgi.00324.2018. PMC 6483024. PMID 30702901.
  2. ^ Ed. Gale, W.F.; Totemeier, T.C. (2004), Smithells Metals Reference Book (8th Edition), Elsevier

General references

  • Foster, P. Field (2007), The Mechanical Testing of Metals and Alloys, Read Books, ISBN 978-1406734799.
  • American Society for Metals (2000), ASM Handbook Volume 8: Mechanical Testing and Evaluation, American Society for Metals, ISBN 978-0871703897.
  • Fenner, Arthur J. (1965), Mechanical Testing of Materials (International monographs on materials science and technology), Newnes, ASIN B0000CMMOM.
  • Foster, P. Field (2007), The Mechanical Testing of Metals and Alloys, Read Books, ISBN 978-1406734799.
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