Mechanics of engineeringComprising statics and dynamics of solids: and the mechanics of the materials of constructions, or strength and elasticity of beams, columns, arches, shafts, etc . ed with a heavy pendulum carrying a pen-cil free to move axially. By a continuous slow motion ofthe handle the pendulum is gradually deviated more andmore from the vertical, through the intervention of thetest-piece, which is thus subjected to an increasing tor-sional moment. The axis of the test-piece lies in the axisof motion. This motion of the pendulum by means of aproperly curved guide, WR, causes an axi
Mechanics of engineeringComprising statics and dynamics of solids: and the mechanics of the materials of constructions, or strength and elasticity of beams, columns, arches, shafts, etc . ed with a heavy pendulum carrying a pen-cil free to move axially. By a continuous slow motion ofthe handle the pendulum is gradually deviated more andmore from the vertical, through the intervention of thetest-piece, which is thus subjected to an increasing tor-sional moment. The axis of the test-piece lies in the axisof motion. This motion of the pendulum by means of aproperly curved guide, WR, causes an axial (, parallelto axis of test-piece) motion of the pencil A, as well as anangular deviation /9 equal to that of the pendulum, andthis axial distance CF,=sT, of the pencil from its initialposition measures the moment of torsion=JPa=JPe sin the piece twists, the drum and paper move relativelyto the pencil through an angle sUo equal to the angle TORSION. 241 of torsion a so far attained. The abscissa so and ordinatesT of the curve thns marked on the paper, measure,when the paper is unrolled, the values of a and Pa throughall the stages of the torsion. Fig. 218 shows typical. curves thus obtained. Many valuable indications aregiven by these strain diagrams as to homogeneousness ofcomposition, ductility, etc., etc. On relaxing the strainat any stage within the elastic limit, the pencil retracesits path; but if beyond that limit, a new path is takencalled an elasticity-line, in general parallel to the firstpart of the line, and showing the amount of angular re-covery, BC, and the permanent angular set, OB. m® MB 223. Examples in Torsion.âThe modulus of safe shearingstrength, S, as given in § 221, is expressed in pounds persquare inch; hence these two units should be adoptedthroughout in any numerical examples where one of theabove values for S is used. The same statement appliesto the modulus of shearing elasticity, USJ in the table of§ 210. rj Example 1.âFig. 21
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectenginee, bookyear1888
