ABSTRACT
When an engineer designs some structure or machine, he must know the effects which the application of forces may have on the material before he can use it. Various mechanical tests have been devised over the years to determine such effects. Thus, for example, in a tensile test we measure the force required to stretch a specimen of the metal until it breaks, whilst in various hardness tests we produce a small dent in the surface by means of using a compressive force and take the force used divided by the surface area of the impression produced by it as a measure of hardness.
