Hardness - Revision history

Bbreer6: /* Sensitivity Coefficient */

2019-06-01T20:47:59Z

Sensitivity Coefficient

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	These tests can be improved by the introduction of a sensitivity coefficient. Sensitivity coefficients are used to determine the factor that different parameters, such as force, diameter, and depth have on hardness.		These tests can be improved by the introduction of a sensitivity coefficient. Sensitivity coefficients are used to determine the factor that different parameters, such as force, diameter, and depth have on hardness.

	The Sensitivity coefficient ci, is defined as the change in hardness H, over the input parameter xi:		The Sensitivity coefficient <math>c_{i}</math>, is defined as the change in hardness H, over the input parameter <math>x_{i}</math>:

	<math> c_{i} = \frac{\Delta H}{\Delta x_{i}} </math>		<math> c_{i} = \frac{\Delta H}{\Delta x_{i}} </math>

2019-06-01T20:47:02Z

Sensitivity Coefficient

← Older revision		Revision as of 16:47, 1 June 2019
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	The Sensitivity coefficient ci, is defined as the change in hardness H, over the input parameter xi:		The Sensitivity coefficient ci, is defined as the change in hardness H, over the input parameter xi:

	ci = ΔH/~~Δxi~~		<math> c_{i} = \frac{\Delta H}{\Delta x_{i}} </math>

	==Examples and History==		==Examples and History==

2019-06-01T20:45:53Z

Calculating Hardness

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	==Calculating Hardness==		==Calculating Hardness==

	~~There~~ is no one way of calculating hardness. In fact, there are many hardness tests, such as Brinell, Knoop, Rockwell, and Vickers.		Contrary to many physical properties, there is no one way of calculating hardness. In fact, there are many hardness tests, such as the Brinell, Knoop, Rockwell, and Vickers tests, that aim to obtain approximations of hardness of one material relative to other materials.

	===Brinell Scale===		===Brinell Scale===

2018-11-17T04:16:06Z

← Older revision		Revision as of 00:16, 17 November 2018
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	~~'''Dalton Lewis (Fall 2018)'''~~

	Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.		Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.

2018-11-17T03:43:09Z

← Older revision		Revision as of 23:43, 16 November 2018
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			'''Dalton Lewis (Fall 2018)'''

	Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.		Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.

2017-04-10T03:55:17Z

Same as before, just wanted to save

← Older revision		Revision as of 23:55, 9 April 2017
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	===Knoop Scale===		===Knoop Scale===
			The Knoop hardness test is typically used for thin sheets or particularly brittle materials, where a large indentation would damage the testing material too much. In this test, a small pyramidal diamond point is pressed into a generally fixed amount of material. Because the pointed tip of the indenter is standard, the depth does not have to be measured; rather, the length of the indentation is measured (it is approximately 30 times the size of the depth). The Knoop Hardness (HK) is calculated in the following way:
			HK = P/Cp*L^2
			where:
			L = length of indentation along its long axis
			Cp = correction factor related to the shape of the indenter, ideally 0.070279
			P = load
			(HK values are typically in the range from 100 to 1000.)

	===Rockwell Scale===		===Rockwell Scale===
			The Rockwell scale is another indentation method to measure the hardness of a material. This test compares an indent made by a light load to one that is made by a larger load. Measuring the differences in depth of penetration yields the hardness factor. The Rockwell Hardness (HR) is calculated in the following way:
	==~~=Vickers Scale===~~		HR = N - d/s
			where:
			d = depth from zero load point
			and N/s are both scale factors dependent on which variation is being used

	===Sensitivity Coefficient===		===Sensitivity Coefficient===

2017-04-10T03:39:35Z

This is my edit for the bucket points. I described the different tests out there to measure hardness.

← Older revision		Revision as of 23:39, 9 April 2017
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	There is no one way of calculating hardness. In fact, there are many hardness tests, such as Brinell, Knoop, Rockwell, and Vickers.		There is no one way of calculating hardness. In fact, there are many hardness tests, such as Brinell, Knoop, Rockwell, and Vickers.

			===Brinell Scale===
			The Brinell Scale was the first widely-used and standardized scale to determine the hardness of a material. It used an indentation method to measure hardness, ultimately limiting its usefulness due to possible damage to the test-pieces. The test typically involves a steel rod ( of a 10mm diameter) used as an indenter with a constant force of 3,000 kgf. With particularly soft/hard substances, changes are made to the force and material of the rod. The BHN (Brinell Hardness Number) is calculating in the following way:
			BHN = 2P/piD(D-sqrt(D^2-d^2))
			where:
			BHN = Brinell Hardness Number (kgf/mm2)
			d = diameter of indentation (mm)
			P = applied load in kilogram-force (kgf)
			D = diameter of indenter (mm)

			===Knoop Scale===

			===Rockwell Scale===

			===Vickers Scale===

	===Sensitivity Coefficient===		===Sensitivity Coefficient===

2016-11-08T22:50:36Z

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	~~CLAIMED BY ANTHONY CHAWKI~~
	Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.		Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.

2016-11-08T22:25:50Z

← Older revision		Revision as of 18:25, 8 November 2016
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			CLAIMED BY ANTHONY CHAWKI
	Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.		Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.

2015-12-06T05:08:19Z

← Older revision		Revision as of 01:08, 6 December 2015
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	~~Claimed by sgould8~~
	Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.		Hardness is the measure of how well a solid object can resist shape change when being exposed to compressive forces.

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	== See also ==		== See also ==
			https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

	http://www.npl.co.uk/upload/pdf/brinell_hardness_co.pdf		http://www.npl.co.uk/upload/pdf/brinell_hardness_co.pdf
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	http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter		http://chemwiki.ucdavis.edu/Analytical_Chemistry/Chemical_Reactions/Properties_of_Matter

			https://en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness

	https://en.wikipedia.org/wiki/File:Stress-strain1.svg		https://en.wikipedia.org/wiki/File:Stress-strain1.svg
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	[[Category:Properties of Matter]]		[[Category:Properties of Matter]]

			Sarah Gould