Proceedings of the Engineers' Society of Western Pennsylvania Volume 9-10

Proceedings of the Engineers' Society of Western Pennsylvania Volume 9-10

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1893 edition. Excerpt: ...but the whole of it. The formula of the text-books assumes that the load is gradually applied, starting from 0, and that the mean load only should be used. But each successive increment of load produces its corresponding increment of stretch, and it requires the whole load to produce the whole stretch. The stretch will be the same if the whole load is applied in one lump, and not r'y successive increments. The half load can only produce one-hall the stretch, and the work of the whole load cannot be measured by the half of it. It is unfortunate that the Professor, in seeking to defend the " cause of a true understanding of the properties of engineering materials," should have hit upon a formula of the text-books that is itself a blunder. The analysis of the action of suddenly-applied loads to which the Professor refers me, Unwin, 1888, p. 89, is simply a copy of Col. Maitland's results, to which the Professor had already referred. The apparatus used by Col. Maitland, and which Prof. Johnson says was similar to mine, consisted of" a test-specimen screwed into two blocks, one above and one below, so that, on falling a certain distance, the top block was arrested and the weight of the lower one subjected the specimen to sudden tensile strain." The reduced length of the specimen was 2 inches. "The elastic limit may be some 40,000 pounds per square inch, yet the resilience or capacity for absorbing energy without taking a set is, for one of the rounds, almost nil." Is this difference in obtaining the same result (a permanent set) a property of the material? Prof. Johnson must admit that there is some difference between "almost nil " and 40,000 pounds per square inch. I have defined the more

Product details

  • Paperback | 202 pages
  • 189 x 246 x 11mm | 372g
  • United States
  • English
  • black & white illustrations
  • 1236892259
  • 9781236892256