High Cycle Fatigue: A Mechanics of Materials Perspective part 51. The nomenclature used in this book may differ somewhat from what is considered standard or common usage. In such instances, this has been noted in a footnote. Additionally, units of measurement are not standard in many cases. While technical publications typically adhere to SI units these days, much of the work published by the engine manufacturers in the United States is presented using English units (pounds, inches, for example), because these are the units used as standard practice in that industry. The graphs and calculations came in those units and no attempt was made to convert. | 486 Appendix A rules as may enable the Engineer and Mechanic in their respective spheres to apply the Metal with confidence and shall illustrate by theory and experiment the action which takes place under varying circumstances in Iron Railway Bridges which have been constructed . . . A report 53 summarizing the results of the investigations was published in 1849. This report was widely publicized and reprinted without the complete appendices 6 54 55 . The report contains the first systematic investigation of the effect of moving loads on railroad bridge structures and fatigue of rails. The pertinent experiments were performed by E. Hodgkinson Captain H. James and Lt. D. Galton. The commissioners 53 stated their research goals as follows The questions to be examined may be arranged under two heads namely 1. Whether the substance of metal which has been exposed for a long period to percussion and vibrations undergoes any change in the arrangement of its particles by which it becomes weakened 2. What are the mechanical effects of percussions and of the passage of heavy bodies in deflecting and fracturing the bars and beams upon which they are made to act The report 53 describes the following fatigue experiments performed by Hodgkinson on cast and wrought iron A bar of cast iron 3 inches square was placed on supports about 14 feet asunder. A heavy ball was suspended by a wire 18 feet long from the roof so as to touch the centre of the side of the bar. By drawing this bar out of the vertical position at right angles to the length of the bar in the manner of a pendulum to any required distance and suddenly releasing it it could be made to strike a horizontal blow upon the bar the magnitude of which could be adjusted at pleasure either by varying the size of the ball or the distance from which it was released. Various bars some of smaller size than the above were subjected by means of this apparatus to successions of blows numbering in most cases as many as 4 000. The .
