Mechanical testing

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 (K_Ic)
  • K–R curve
  • Elastic plastic (J_Ic, 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, S., Maier, F., Chen, L., Santos, S., Pierce, D.M., Feng, B., 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, vol. 316, issue. 4, pp. G473-G481;
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 (1978), Mechanical Testing, American Society for Metals, ISBN 978-0871700131.
• 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.