Repository: UIHistories Project: Book - First Years of Engineering Experiment Station (1906) [PAGE 7]

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ILLINOIS ENGINEERING EXPERIMENT STATION

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that up to the breaking point in tension the modulus of elasticity for tension is practically equal to t h a t for compression, instead of being one-half as great, as had generally been assumed by writers on this subject. In- reinforced concrete beams, the action of the steel and concrete during flexure was studied. I t was shown that the concrete failed in tension at its usual breaking limit instead.of carrying stress to ten times that limit, as had been claimed by some experimenters, and the added stretch in the steel at this point was clearly shown on the diagrams. Among the results brought out by this investigation were the following: the.stages of action during flexure; the accurate determination of the position of the neutral axis; a basis of calculation of resisting moment of beam based upon tension in the steel; t h e value of an experimental determination of the position of the neutral axis and of the percentage of steel suitable for a given concrete; the effect of elastic limit of steel and of form of bar upon strength of beam. The tests also opened up the field for further experimentation. The publication of the results was received with much interest by the engineering press and the engineering profession. The comments made gave testimony to the thoroughness of the work and to the great interest and value attached to the investigation, as throwing new light on a subject very much in need of scientific data. Bequests for Bulletin No. 1 have come from all parts of the world. The investigation of reinforced concrete beams is being continued and experiments on reinforced concrete columns have been started. Circular No. 1, High-Speed Tool Steels, by L. P. Breckenridge, was issued April 15, 1905. In this circular is given a brief review of the results of experiments made by different engineers with this new tool steel. Experiments with high-speed tool steels on cast iron have been in progress at the shops of the mechanical engineering department of the University during the last year. These tests have been carried on by H. B. Dirks, M. E., and constituted the basis for his graduate work. Bulletin No. 2, Tests of High-Speed Tool Steels on Cast Iron, by L. P. Breckenridge and H. B. Dirks, giving the results of these experiments, was published in January, 1906. These tests were made with eight different brands of tool steel on cast-iron test pieces of varying hardness. The hardness of these test pieces was obtained by the use of a twist drill weighted to a known pres-