The International Hardness test is based on measurement of the penetration of a rigid ball into the rubber specimen under specified conditions. The measured penetration is converted into IRHD, the scale of degrees being so chosen that 0 represents a material having an elastic modulus of zero, and 100 represents a material of infinite elastic modulus.
The scale also fulfills the following conditions over most of the normal range of hardness: one IRHD (International Rubber Hardness Degree) range represents approximately the same proportionate difference in Young's modulus, and for rubber vulcanizates in the usual range of resilience, readings in IRHD are comparable with those given by a Type A durometer (Test Method D2240) when testing standard specimens.
The term “usual range of resilience” is used to exclude those compounds that have unusually high rates of stress relaxation or deformational hysteresis. For such compounds, differences in the dwell time in the two hardness tests (Test Methods D2240 and D1415) result in differences in hardness values. Readings may not be comparable when testing curved or irregularly shaped test specimens.
Let see the testing video as per DIN ISO 48, ASTM D 1415, JIS K 6253, DIN 53519, BS903 Part A26, NFT 46-003:
The scale also fulfills the following conditions over most of the normal range of hardness: one IRHD (International Rubber Hardness Degree) range represents approximately the same proportionate difference in Young's modulus, and for rubber vulcanizates in the usual range of resilience, readings in IRHD are comparable with those given by a Type A durometer (Test Method D2240) when testing standard specimens.
The term “usual range of resilience” is used to exclude those compounds that have unusually high rates of stress relaxation or deformational hysteresis. For such compounds, differences in the dwell time in the two hardness tests (Test Methods D2240 and D1415) result in differences in hardness values. Readings may not be comparable when testing curved or irregularly shaped test specimens.
Let see the testing video as per DIN ISO 48, ASTM D 1415, JIS K 6253, DIN 53519, BS903 Part A26, NFT 46-003:
Nice blog, thanks for sharing Hardness test block
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