1、Designation: F779 12 (Reapproved 2018)Standard Test Method forTorsion Characteristic of Alpine Skis1This standard is issued under the fixed designation F779; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision
2、. A number in parentheses indicates the year of last reapproval. A superscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the measurement of ski fore-body torsion and ski afterbody torsion of adult Alpine skis.1.2 No limitation t
3、o ski size is proposed. This test method isapplicable to all Alpine skis.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practice
4、s and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Re
5、com-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 afterbody torsion angle, Athat angle, in degrees, towhich the running surface is rotated at Point A when a moment,Mt, is applied at
6、Point A as shown in Fig. 1.2.1.2 afterbody torsional spring constant, CAthe momentper degree of rotation of the ski afterbody when the ski isclamped in accordance with Fig. 1 and the moment applied inaccordance with Fig. 2.CANm/deg! 5MtA2.1.3 forebody torsion angle, Fthat angle, in degrees, towhich
7、the running surface is rotated at Point F when a moment,Mt, is applied at Point F as shown in Fig. 1.2.1.4 forebody torsional spring constant, CTSthe momentper degree of rotation of the ski forebody when the ski isclamped in accordance with Fig. 1 and the moment applied inaccordance with Fig. 2.CFNm
8、/deg! 5MtF2.1.5 moment of torsion, Mtthe moment in newton-metresapplied to rotate the ski about its longitudinal axis when the skiis clamped according to Fig. 1 and the moment is appliedaccording to Fig. 2.3. Significance and Use3.1 This test method provides a means for determining thetorsional stif
9、fness of Alpine skis. It is not intended to evaluatethe data with regard to the quality of the ski.4. Apparatus4.1 Clamping Fixture, to grip the ski as a vise with a flat,rigid jaw and three clamps with at least 150 +50, 0 mmspacing between them. One clamp is located at each end of thefixture and on
10、e in the center as illustrated in Fig. 1. The clampsshould be at least 30 mm wide and cover the full width of theski.4.2 Torsion Head, shown in Fig. 2, with low-friction mo-ment (0.2 Nm) and quasistatic loading system having aclamping fixture described in 4.1. Common devices for thisloading system a
11、re a weight on a cable wrapped around thehead, or a weight on a lever arm rigidly attached to the head.The torsion head clamping fixture should have a width of 10 61 mm and a length equal to or greater than the width of the ski.The base surface of the torsion head fixture to the ski baseshould be in
12、 the same plane as the clamping fixture (that is,camber forced out of ski in clamped position).4.3 Scale, to measure the torsion angle with an accuracy of0.5.5. Procedure5.1 Test skis at room temperature (23 6 5C) withoutspecific preconditioning. Torsion head and clamping fixture areadjusted such th
13、at the distance between them is C/2 6 2mmshown in Fig. 1. If the ski geometry does not allow point A orpoint F, or both, to be used as shown in Fig. 1, move thelocation of point A or point F, or both, toward the center of theski; points A and F should be moved the minimum distancenecessary. Mount th
14、e ski to the clamping fixture so that the skiforebody or ski afterbody can rotate freely about Point M. Thetorsion head is attached to the ski at Point A or F 6 2 mm such1This test method is under the jurisdiction of ASTM Committee F27 on Snowand Water Sports and is the direct responsibility of F27.
15、30 on Skiing andSnowboarding Equipment.Current edition approved July 1, 2018. Published August 2018. Originallyapproved in 1982. Last previous edition approved in 2012 as F779 12. DOI:10.1520/F0779-12R18.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
16、59. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical
17、Barriers to Trade (TBT) Committee.1that the longitudinal axis of the ski is in the center of the torsionhead. Apply a moment, Mt,of206 0.2 Nm. (The momentshould be applied quasistatically.) The torsion angle must beread within 2 to 5 s after the torsion moment, Mt, is initiallyapplied.6. Calculation
18、6.1 Calculate the afterbody torsional spring constant, CA,innewton-metres per degree, in accordance with the followingequation:CA5MtA(1)6.2 Calculate the forebody torsional spring constant, CF,innewton-metres per degree, in accordance with the followingequation:CF5MtB(2)7. Report7.1 Report the follo
19、wing information:7.1.1 ASTM F779,7.1.2 Brand, model designation, manufacturers registrationnumber, size of ski, and the locations of points A and F relativeto the tip and tail of the ski, respectively,7.1.3 Afterbody torsional spring constant, forebody tor-sional spring constant, and7.1.4 Any deviat
20、ions from this standard with explanations.8. Precision and Bias8.1 PrecisionThe precision of this test method is currentlybeing determined.8.2 BiasThe procedure in this test method has no biasbecause the values for torsion characteristics of Alpine skis aredefined only in terms of the test method.FI
21、G. 1 Clamping FixtureFIG. 2 Torsion Head FixtureF779 12 (2018)29. Keywords9.1 Alpine skis; torsion characteristicsASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly adv
22、ised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either
23、 reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. I
24、f you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Indivi
25、dual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the Copyright Clearance Center, 222Rosewood Drive, Danvers, MA 01923, Tel: (978) 646-2600; http:/ 12 (2018)3
