| 释义 |
torsion|ˈtɔːʃən|
Also 5 torcion, 6 -syon, 7 tortion.
[a. F. torsion (1314 in Littré, in sense 2 below), ad. late L. torsiōn-em (Vulg.), by-form of tortiōn-em, n. of action from L. torquēre, tort-um to twist, wring. Cf. Pr. torsio, Sp. torsion, Pg. torsão; also It. torzione, ad. L. tortiōnem.]
1. a. The action of twisting, or turning a body spirally by the operation of contrary forces acting at right angles to its axis; also the twisted condition produced by this action; twist.
angle of torsion, (a) the angle through which one end of a rod or other body is twisted while the other end is held fast; (b) Geom. the infinitesimal angle between two consecutive osculating planes of a tortuous curve. balance of torsion = torsion-balance: see 3.
1543Traheron Vigo's Chirurg. vi. i. 180 Yf the dislocation be lytle, so that the bone be not out all togyther, it is called dislocation not complete, and it is it which commonly is called torsion, or wresting. 1658Phillips, Torsion, a wresting, or wringing of any thing. 1807T. Young Lect. Nat. Phil. I. 140 Torsion, or twisting, consists in the lateral displacement, or detrusion, of the opposite parts of a solid, in opposite directions, the central particles only remaining in their natural state. Ibid. 141 The force of torsion, as it is determined by experiment, varies simply as the angle of torsion. 1814R. Buchanan Shafts Mills 24 note, Journals, or journeys, are gudgeons subject to torsion. 1834Nat. Philos. III. Hist. Astron. xxi. 105/2 (Usef. Knowl. Soc.) By means of a delicate instrument, called the balance of torsion, the attraction of a leaden sphere, eight inches in diameter, was made sensible. 1835Ure Philos. Manuf. 106 With very short filaments like those of wool, cotton, and cachemire, a thread of the greatest length may be formed by torsion. 1859J. Tomes Dental Surg. 163 Torsion, or twisting of the central incisors upon their axis, is far from rare. 1867Thomson & Tait Nat. Phil. I. i. §608 The fundamental principle that spiral springs act chiefly by torsion seems to have been first discovered by Binet in 1814.
b. A twisting of the body or a part of it; contortion, distortion. rare.
1660F. Brooke tr. Le Blanc's Trav. 89 They ejulate, weep, and lament with exotick gestures, and tortions. 1899Allbutt's Syst. Med. VII. 242 During the flexions and torsions of the vertebral column.
c. Surg. The twisting of the cut end of an artery to stop hæmorrhage.
1835–6Todd's Cycl. Anat. I. 224/2 The successful employment of torsion of the arteries as a means of suppressing hæmorrhage. 1878T. Bryant Pract. Surg. (1879) II. 5 Any bleeding taking place can usually be checked by cold styptics, or torsion.
d. Bot. The condition of being twisted spirally.
1875Bennett & Dyer Sach's Bot. 772 A distinction must be drawn between two kinds of torsion; firstly, that of erect organs; and secondly, that of organs..in a horizontal or oblique position. In the former case the torsion results from internal conditions of growth, and especially from the outer layers growing more rapidly than the inner ones.
e. Math. The degree to which a curve departs from being planar at any given point, measured by the rate of change of the angle of the osculating plane or the binormal with respect to distance along the curve; radius of torsion, the reciprocal of this.
1862G. Salmon Treat. Analytic Geom. Three Dimensions xi. 269 The angle made with each other by two consecutive osculating planes..we shall call the angle of torsion, and denote by dη. Ibid. 270 Following the analogy of the radius of curvature which is ds/dθ, the later French writers denote the quantity ds/dη by the letter r, and call it the radius of torsion. 1939Burington & Torrance Higher Math. vi. 711 Torsion is agreed to be positive when the rotation (with s increasing) of the binormal increases in the same sense as that of a right-handed screw traveling in the direction of t. 1978E. C. Young Vector & Tensor Analysis ii. 106 The torsion of a plane curve is zero, just as the curvature of a straight line is zero.
f. Zool. The twisting of the visceral hump of gastropod molluscs through 180 degrees when the embryo reaches a certain stage of development.
1888Rolleston & Jackson Forms Animal Life (ed. 2) 475 In..the Streptoneura, the posterior union of the visceral nerves..is situated dorsally to the intestine, and the loop is therefore twisted with the torsion of the visceral dome. 1930G. R. de Beer Embryol. & Evol. vii. 53 The limpet develops into a more or less symmetrical Veliger larva which suddenly undergoes a twist through 180°, the process of torsion occupying two or three minutes. 1972M. S. Gardiner Biol. of Invertebrates ii. 59/2 Torsion appears to be a reversible process, for in some genera the anus and the organs on either side of it lie posteriorly and the nerve commissures are untwisted.
g. Chem. Restricted rotation of an atom or group about a bond joining it to another atom.
1932Physical Rev. XL. 445 (heading) The torsion oscillator-rotator in the quantum mechanics. 1978Nature 14 Dec. 674/1 Although in some cases, rotation of a rigid molecular structure cannot lead to superposition, this may be possible as a result of torsion about certain bonds.
†2. Path. A wringing or griping of the bowels; tormina. Obs. (The earliest sense in Eng.)
c1425tr. Arderne's Treat. Fistula 78 It availeþ..to euery inflacion of þe wombe, and to ventosite of it, and torcions, i.[e.] gryndyng. 1543Traheron Vigo's Chirurg. iii. Wounds i. ii. 100 Knowen by the greate payne, and torsyon or grypynge of the bellie. 1626Bacon Sylva §39 All Purgers have in them a raw Spirit, or Winde; which is the principall Cause of Tortion in the Stomach, & Belly. 1689Moyle Sea Chyrurg. iii. vii. 109 Sometimes there is..intolerable tortion of the Bowels.
3. attrib. and Comb., as torsion arm, torsion axis, torsion circle, torsion pendulum, torsion screw, torsion spring; torsion-balance, an instrument for measuring minute horizontal forces, consisting of a wire or filament having a horizontal arm to the end of which the force is applied so as to make it revolve and twist the wire, etc., through an angle proportional to the twisting moment of the force; torsion bar, a bar that is subject to torque; spec. one in the suspension of some motor vehicles, fixed to the frame at one end and the wheel assembly at the other so that up-and-down motion of the latter tends to twist the bar and is thereby absorbed; torsion-basin Geol., a basin formed by torsion of the earth's crust in any region; torsion-curve, a curve caused by torsion; torsion electrometer, an electrometer that measures by means of a torsion-balance; torsionmeter, torsion meter, an instrument which measures the torsion in a rotating shaft, thus providing information about the power output of the engine driving it; torsion test Engin., a test in which a material is subjected to torsion (see quot. 1936).
1831Holland Manuf. Metal I. 199 It does not appear that these torsion nails have ever found much favour. 1837Brewster Magnet. 15 The torsion balance, for measuring small forces. 1873Maxwell Electr. & Magn. §38 The torsion-balance was devised by Michell for the determination of the force of gravitation between small bodies, and was used by Cavendish for this purpose. Ibid. §215 The angle through which the electrical force twisted the torsion-arm. Ibid. §725 The torsion-screw, which turns the torsion-head round a vertical axis. 1884F. J. Britten Watch & Clockm. 265 Small clocks..are made with torsion pendulums. 1891W. G. Kircaldy Strength & Properties of Materials vii. 196 Some examples of Twisting, or torsion, tests have been given to show in a graphic way the behaviour of different metals. 1899Mar. M. Ogilvie-Gordon in Nature 7 Sept. 445/1 Two great internal torsion-basins, within the Alpine systems of southern Europe, are the Hungarian and the west Mediterranean. 1901― Ibid. 24 Jan. 294/1, I wrote my paper on the ‘Torsion-structure of the Dolomites’ in 1898. Ibid. 295 The torsion-curves round the northern periphery of the Adriatic crust-basin. 1905Engineering 7 Apr. 440 (heading) Denny and Johnson's torsion meter. 1936P. F. Foster Mech. Testing of Metals & Alloys vii. 115 Torsion tests are carried out to determine the modulus of rigidity of a material..or to ascertain its ultimate torsional strength. 1937Daily Herald 15 Jan. 16/6 The action of the torsion-bar controlled shock-absorbers preventing roll and pitch. 1969Divakaran & Garg Strength of Materials i. 27 In a torsion test on the same specimen the angle of twist was found to be 0.43°. 1978L. Pryor Viper viii. 150 He'd nodded and set to work ordering adjustments to the tires, wings and torsion bars. 1983Sci. Amer. Jan. 120/2 The strength of the gravitational force is measured from the magnetic force that is required to prevent the rotation of a torsion bar when an additional mass is brought close to it. 1970Jrnl. Physics E III. 105/1 The only practicable way to measure the power [of a ship's main engine] is by the use of a torsionmeter, ie an instrument that measures the twist put in the propeller shaft by the torque it transmits.
Hence ˈtorsionless a., not subject to torsion.
1858Herschel Outl. Astron. i. iv. (ed. 5) 160 A metallic arc..supported from its middle..by a torsionless suspension. |