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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.
Meyer's law is often used to relate hardness values based on the fact that if the weight is quartered, the diameter of the indenter is halved. For instance, the hardness values are the same for a test load of 3000 kgf with a 10 mm indenter and for a test load of 750 kgf with a 5 mm diameter indenter.
After time, the indenter on a Rockwell scale can become inaccurate as well and need replacing to ensure accurate and precise hardness measurements. [14] The equation for Rockwell Hardness is =, where d is the depth in mm (from the zero load point), and N and h are scale factors that depend on the scale of the test being used (see following ...
The principle behind the test is that the mean pressure required to test the material is the measurement of the hardness of the material. Units of megapascals (MPa) are frequently used for reporting Meyer hardness, but any unit of pressure can be used. [2]
Use of SPT data for direct prediction of liquefaction potential suffers from roughness of correlations and from the need to "normalize" SPT data to account for overburden pressure, sampling technique, and other factors. [4] Additionally, the method cannot collect accurate data for weak soil layers for several reasons:
The equation based definition of hardness is the pressure applied over the contact area between the indenter and the material being tested. As a result hardness values are typically reported in units of pressure, although this is only a "true" pressure if the indenter and surface interface is perfectly flat. [citation needed]
Newmark's Influence Chart is an illustration used to determine the vertical pressure at any point below a uniformly loaded flexible area of soil of any shape. This method, like others, was derived by integration of Boussinesq's equation for a point load.
Hardness scales may also refer to: Methods of measuring the deposit formation by hard water. The scale of Pencil hardness This page was last edited on 11 ...