ASTM F2650-17

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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