ASTM F2650-17e1

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
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Designation: F2650 − 17 An American National Standard
Standard Terminology Relating to
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Impact Testing of Sports Surfaces and Equipment
This standard is issued under the fixed designation F2650; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
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ε NOTE—Editorially corrected ‘standard gravity’ in November 2017.
1. Scope assisted impact test, n—an impact test in which the missile is
accelerated by means other than gravity alone, for example,
1.1 This terminology covers terms related to impact test
by an actuator.
methods and impact attenuation specifications of sports equip-
ment and surfaces.
drop height (h), n—height from which a missile is dropped
during a gravity-driven impact test, measured as the vertical
1.2 This terminology is appropriate for use in the develop-
distancebetweenthelowestpointoftheelevatedmissileand
ment of standards that describe gravity-driven impact test
its first point of contact with the impacted surface or anvil.
methodsorspecifyimpactattenuationperformancecriteriaand
which fall under the jurisdiction of ASTM Committee F08 on theoretical drop height, n—drop height (h) that, under
Sports Equipment and Facilities. standardconditions,wouldresultinanimpactvelocityequalto
a missile’s measured impact velocity (V ).
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1.3 This terminology defines common terms that are appli-
DISCUSSION—The “standard conditions” assume standard gravity and
cable to many sports-related impact tests including those used
that friction and air resistance do not affect the fall of the missile. In a
in the context of sports surfaces, athletic footwear, protective
free-fall impact test the actual drop height will approximate the
equipment and padding. The use of a common terminology
theoretical drop height. In a guided impact test, the theoretical drop
will promote greater consistency among standards and reduce
height will be less than the actual drop height, due to the effects of
friction in the guidance mechanism.
the risk of misinterpretation.
1.4 The values stated in SI units are to be regarded as the g, n—(pronounced “gee”) a unit of acceleration equal to
standard. The values given in parentheses are for information standard gravity. Missile accelerations expressed in ‘g’units
only. are the ratio of the missile acceleration to standard gravity
and are hence dimensionless.
1.5 This international standard was developed in accor-
DISCUSSION—The symbol g is properly written in lowercase and
dance with internationally recognized principles on standard-
italic, to distinguish it from the symbol G (uppercase, used to indicate
ization established in the Decision on Principles for the
the gravitational constant) and g (not italicized) which is an abbrevia-
Development of International Standards, Guides and Recom-
tion of the gram unit.
mendations issued by the World Trade Organization Technical
g-max, n—maximum acceleration magnitude recorded during
Barriers to Trade (TBT) Committee.
a single impact, expressed in ‘g’ units.
2. Terminology
average g-max, n—arithmetic average of a specified set of
g-max values.
2.1 Definitions:
acceleration, n—rate of change of velocity with time.
gravity-driven impact test, n—an impact test in which the
DISCUSSION—Acceleration is a vector quantity, having both magni-
missile is accelerated by gravity alone, during a period of
tude and direction. Acceleration magnitude is expressed in units of
free-fall.
−2 −2
m/s (ft/s ) and direction is defined relative to a Cartesian coordinate
system or other spatial reference frame.
head injury criterion (HIC), n—weighted impulse criterion
calculated from a head impact acceleration-time profile and
used to quantify head impact severity. The HIC calculation
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results in a severity index that is weighted by both impact
This terminology is under the jurisdiction ofASTM Committee F08 on Sports
Equipment, Playing Surfaces, and Facilities and is the direct responsibility of
acceleration magnitude and by the time for which high
Subcommittee F08.80 on Common Terminology, Methods and Laboratory Prac-
magnitude accelerations persist.
tices.
DISCUSSION—HIC scores can only be directly referenced to the head
Current edition approved Sept. 15, 2017. Published October 2017. Originally
injury risk data on which the criterion is based if the impact
approved in 2007. Last previous edition approved in 2013 as F2650 – 13. DOI:
10.1520/F2650-17E01. acceleration-time profile is recorded using a human head or a
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