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Careful note should be taken of the relationship between a hardness number and the stress-strain curve exhibited by the material. The latter, which is conventionally obtained via tensile testing , captures the full plasticity response of the material (which is in most cases a metal).
Hollomon's equation is a power law relationship between the stress and the amount of plastic strain: [10] σ = K ϵ p n {\displaystyle \sigma =K\epsilon _{p}^{n}\,\!} where σ is the stress, K is the strength index or strength coefficient, ε p is the plastic strain and n is the strain hardening exponent .
Toughness is the strength with which the material opposes rupture. One definition of material toughness is the amount of energy per unit volume that a material can absorb before rupturing . This measure of toughness is different from that used for fracture toughness , which describes the capacity of materials to resist fracture. [ 2 ]
Brinell hardness is sometimes quoted in megapascals; the Brinell hardness number is multiplied by the acceleration due to gravity, 9.80665 m/s 2, to convert it to megapascals. The Brinell hardness number can be correlated with the ultimate tensile strength (UTS), although the relationship is dependent on the material, and therefore determined ...
A variety of hardness-testing methods are available, including the Vickers, Brinell, Rockwell, Meyer and Leeb tests. Although it is impossible in many cases to give an exact conversion, it is possible to give an approximate material-specific comparison table for steels .
The strength of materials is determined using 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 ...
Contact mechanics is the study of the deformation of solids that touch each other at one or more points. [1] [2] A central distinction in contact mechanics is between stresses acting perpendicular to the contacting bodies' surfaces (known as normal stress) and frictional stresses acting tangentially between the surfaces (shear stress).
When testing metals, indentation hardness correlates roughly linearly with tensile strength, [1] but it is an imperfect correlation often limited to small ranges of strength and hardness for each indentation geometry. This relation permits economically important nondestructive testing of bulk metal deliveries with lightweight, even portable ...