ASTM F779-93(2006)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F779–93 (Reapproved 2006)
Standard Test Method for
Torsion Characteristic of Alpine Skis
ThisstandardisissuedunderthefixeddesignationF779;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Significance and Use
1.1 This test method covers the measurement of ski fore- 3.1 This test method provides a means for determining the
body torsion and ski afterbody torsion of adult Alpine skis. torsional stiffness of Alpine skis. It is not intended to evaluate
1.2 No limitation to ski size is proposed.This test method is the data with regard to the quality of the ski.
applicable to all Alpine skis.
4. Apparatus
1.3 This standard does not purport to address all of the
4.1 Clamping Fixture, to grip the ski as a vise with a flat,
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- rigid jaw and three clamps with at least 150 +50, −0 mm
spacing between them. One clamp is located at each end of the
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. fixture and one in the center as illustrated in Fig. 1.The clamps
should be at least 30 mm wide and cover the full width of the
2. Terminology
ski.
2.1 Definitions of Terms Specific to This Standard: 4.2 Torsion Head, shown in Fig. 2, with low-friction mo-
2.1.1 afterbody torsion angle, u —that angle, in degrees, to ment (#0.2 N·m) and quasistatic loading system having a
A
whichtherunningsurfaceisrotatedatPoint Awhenamoment, clamping fixture described in 4.1. Common devices for this
M, is applied at Point A as shown in Fig. 1. loading system are a weight on a cable wrapped around the
t
2.1.2 afterbody torsional spring constant, C —the moment head, or a weight on a lever arm rigidly attached to the head.
A
per degree of rotation of the ski afterbody when the ski is The torsion head clamping fixture should have a width of 10 6
clamped in accordance with Fig. 1 and the moment applied in 1 mm and a length equal to or greater than the width of the ski.
accordance with Fig. 2. The base surface of the torsion head fixture to the ski base
should be in the same plane as the clamping fixture (that is,
M
t
C ~N · m/deg!5
A camber forced out of ski in clamped position).
u
A
4.3 Scale, to measure the torsion angle with an accuracy of
2.1.3 forebody torsion angle, u —that angle, in degrees, to
F
0.5°.
whichtherunningsurfaceisrotatedatPoint Fwhenamoment,
M, is applied at Point F as shown in Fig. 1.
t 5. Procedure
2.1.4 forebody torsional spring constant, C —the moment
TS
5.1 Test skis at room temperature (23 6 5°C) without
per degree of rotation of the ski forebody when the ski is
specificpreconditioning.Torsionheadandclampingfixtureare
clamped in accordance with Fig. 1 and the moment applied in
adjusted such that the distance between them is C/2 62mm
accordance with Fig. 2.
shown in Fig. 1. Mount the ski to the clamping fixture so that
M
t the ski forebody or ski afterbody can rotate freely about Point
C ~N · m/deg!5
F
u
F
M. The
...