Cold Compressive Strength

High Strain Rate testing is a large subject, well known to vehicle and gas pipe designers. Strength is very dependent on strain rate, and the relationship changes markedly according to the material / alloying elements etc. See Instron.com for a wide range of "High Rate" research equipment. Specialist (and expensive) equipment is required to study the effect in detail.

dear friend, thanks for giving the information. but my real doubt is whether I should stick to the rate specified by the standard or can be liberal to the lab technician. Sometimes if they deviate from the standard, how much would be its impact on the result and what is the logic behind the deferred result ( higher or lower)? regards rajesh

ANSI and NIST (as well as a few other organizations) set out specific test methods for characterization of materials, usually based on their own testing research or that of research done at a university or other organization which does that sort of thing. When testing materials of known composition to measure and compare their properties to that of "standard" samples, the test method should be adhered to as well as possible. The results of the test should contain data which indicates the deviation of the testing method to that of the standard. When testing new materials or different alloys of existing materials, test methods have not been established yet, so different rates of load application (for example) should be recorded to provide data for characterization of such material. It is not unlikely or uncommon to find that CCS is a function of rate of load application.

Yes, our friend must believe: the speed a strain is imposed to a material does make difference in the measurements not because of the measuring machine, but the material responds differently.

Do you want an example? During WWI I guess some helmets were developed from a steel alloy with high nickel content, among other elements. This alloy was intended to greatly increase its hardness when hit by a projectile, thus, absorbing energy as much as possible while still keeping the projectile to fracture the material and get to the soldier head. When slowly deformed, it never showed the same hardness. Just a real case to illustrate the issue.

The Loading rate will be 4mm/min of ccs machine to Determination of Cold Crushing Strength (CCS).

See

http://www.precision.net.in/news.html

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