THE general purpose of experiment on materials is to distinguish between the fit and unfit, the suitable and unsuitable materials for the various requirements of the structural and mechanical work of the world. The special object of the engineer in testing materials is to obtain a rational basis for proportioning structures and machines so that they may sustain the straining actions to which they are subjected without fracture or prejudicial deformation, and at the same time without waste of material. Nor is there any finality in such testing, for new alloys, new heat treatments, new conditions of use are always making fresh investigation necessary. In the next place, the mechanical properties of materials desired and assumed in designing are embodied in specifications. Thence arises a second occasion for experiment. Tests of reception or inspection tests are necessary to determine whether material supplied reaches the required standard. With the widening of the sources of supply, an engineer can no longer depend merely on the reputation of the seller, but must make his own tests.
From the Thomas Hawksley Lecture delivered before the Institution of Mechanical Engineers on October 4 by Dr. W. Cawthorne Unwin, F.R.S.
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Experimental Studies of the Mechanical Properties of Materials 1 . Nature 102, 156–158 (1918). https://doi.org/10.1038/102156a0