ASTM F779-12

Standard Test Method for Torsion Characteristic of Alpine Skis

SIGNIFICANCE AND USE
This test method provides a means for determining the torsional stiffness of Alpine skis. It is not intended to evaluate the data with regard to the quality of the ski.
SCOPE
1.1 This test method covers the measurement of ski forebody torsion and ski afterbody torsion of adult Alpine skis.
1.2 No limitation to ski size is proposed. This test method is applicable to all Alpine skis.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 29-Feb-2012
• ICS: 97.220.20 - Winter sports equipment
• Technical Committee: F27 - Snow and Water Sports
• Drafting Committee: F27.30 - Skiing and Snowboarding Equipment

Relations

• Replaces: ASTM F779-93(2006) - Standard Test Method for Torsion Characteristic of Alpine Skis
• Effective Date: 01-Mar-2012
• Replaced By: ASTM F779-12(2018) - Standard Test Method for Torsion Characteristic of Alpine Skis
• Effective Date: 01-Jul-2018
• Referred By: ASTM F504-05(2022) - Standard Test Method for Measuring the Quasi-Static Release Moments of Alpine Ski Bindings
• Effective Date: 01-Mar-2012

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F779 − 12
Standard Test Method for
1
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
the data with regard to the quality of the ski.
1.2 No limitation to ski size is proposed.This test method is
applicable to all Alpine skis.
4. Apparatus
1.3 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 Clamping Fixture, to grip the ski as a vise with a flat,
responsibility of the user of this standard to establish appro-
rigid jaw and three clamps with at least 150 +50, −0 mm
priate safety and health practices and determine the applica-
spacing between them. One clamp is located at each end of the
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, θ —that angle, in degrees, to
A
ment (≤0.2 N·m) and quasistatic loading system having a
whichtherunningsurfaceisrotatedatPoint Awhenamoment,
clamping fixture described in 4.1. Common devices for this
M, is applied at Point A as shown in Fig. 1.
t
loading system are a weight on a cable wrapped around the
2.1.2 afterbody torsional spring constant, C —the moment
A
head, or a weight on a lever arm rigidly attached to the head.
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
M
should be in the same plane as the clamping fixture (that is,
t
C ~N·m/deg! 5
A
θ camber forced out of ski in clamped position).
A
2.1.3 forebody torsion angle, θ —that angle, in degrees, to
F
4.3 Scale, to measure the torsion angle with an accuracy of
whichtherunningsurfaceisrotatedatPoint Fwhenamoment,
0.5°.
M, is applied at Point F as shown in Fig. 1.
t
2.1.4 forebody torsional spring constant, C —the moment
TS 5. Procedure
per degree of rotation of the ski forebody when the ski is
5.1 Test skis at room temperature (23 6 5°C) without
clamped in accordance with Fig. 1 and the moment applied in
specificpreconditioning.Torsionheadandclampingfixtureare
accordance with Fig. 2.
adjusted such that the distance between them is C/2 62mm
M
t
shown in Fig. 1. If the ski geometry does not allow point A or
C ~N·m/deg! 5
F
θ
F
point F, or both, to be used as shown in Fig. 1, move the
2.1.5 moment of torsion, M—the moment in newton-metres
t location of point A or point F, or both, toward the center of the
applied to rotate the ski about its longitudinal axis when the ski
ski; points A and F should be moved the minimum distance
is clamped according
...

This document is not anASTM standard and is intended only to provide the user of anASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:F779–93 (Reapproved 2006) Designation: F779 – 12
Standard Test Method for
1
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
1.1 This test method covers the measurement of ski forebody torsion and ski afterbody torsion of adult Alpine skis.
1.2 No limitation to ski size is proposed. This test method is applicable to all Alpine skis.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Terminology
2.1 Definitions of Terms Specific to This Standard:
2.1.1 afterbody torsion angle, u —that angle, in degrees, to which the running surface is rotated at Point A when a moment,
A
M, is applied at Point A as shown in Fig. 1.
t
2.1.2 afterbody torsional spring constant, C —the moment per degree of rotation of the ski afterbody when the ski is clamped
A
in accordance with Fig. 1 and the moment applied in accordance with Fig. 2.
M
t
C ~N · m/deg!5
A
u
A
F0779-12_1
2.1.3 forebody torsion angle, u —that angle, in degrees, to which the running surface is rotated at Point F when a moment, M
F
t, is applied at Point F as shown in Fig. 1.
2.1.4 forebody torsional spring constant, C —the moment per degree of rotation of the ski forebody when the ski is clamped
TS
in accordance with Fig. 1 and the moment applied in accordance with Fig. 2.
F0779-12_2
2.1.5 moment of torsion, M—the moment in newton-metres applied to rotate the ski about its longitudinal axis when the ski
t
is clamped according to Fig. 1 and the moment is applied according to Fig. 2.
3. Significance and Use
3.1 This test method provides a means for determining the torsional stiffness of Alpine skis. It is not intended to evaluate the
data with regard to the quality of the ski.
4. Apparatus
4.1 Clamping Fixture, to grip the ski as a vise with a flat, rigid jaw and three clamps with at least 150 +50, −0 mm spacing
between them. One clamp is located at each end of the 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 ski.
4.2 Torsion Head, shown in Fig. 2, with low-friction moment (#0.2 N·m) and quasistatic loading system having a clamping
fixture described in 4.1. Common devices for this loading system are a weight on a cable wrapped around the head, or a weight
on a lever arm rigidly attached to the head. The torsion head clamping fixture should have a width of 10 6 1 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 base should be in 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 of 0.5°.
5. Procedure
5.1 Test skis at room temperature (23 6 5°C) without specific preconditioning. Torsion head and clamping fixture are adjusted
1
This test method is under the jurisdiction of ASTM Committee F27 on Snow Skiing and is the direct responsibility of F27.30 on Skis and Boots.
Current edition approved Oct.March 1, 2006.2012. Published December 2006.March 2012. Originally approved in 1982. Last previous edition approved in 19982006 as
F779 – 93 (1998).(2006). DOI: 10.1520/F0779-93R06.10.1520/F0779-12.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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F779 – 12
FIG. 1 Clamping Fixture
FIG. 2 Torsion Head Fixture
such that the distance between them is C/2 6 2 mm shown in Fig. 1. Mount the ski to the clamping fixture so that the ski forebody
or ski afterbody can rotate freely about Point . If the ski geometry does not allow point A or point F, or both, to be used as shown
in Fig. 1, move the location of point A or point F, or both, toward the center of the ski; points A and F should be moved the
minimum distance necessary. Mount the ski to the clamping fixture so that the ski forebody or ski afterbody can rotate freely about
Point M. The torsion head is attached to the ski at Point A or F 6 2 mm such that the longit
...