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VOSI
V41.23 PUBLIC SAFETY UNIVERSAL
SPECIFICATION/TEST METHOD
FOR
FOOTWEAR HEEL ATTACHMENT STRENGTH
1. SCOPE
1.1 To establish a
test method (tensile test) for measuring the breaking strength
of footwear heels.
1.2 To establish
minimum strength requirements regardless of heel height.
2. REFERENCED DOCUMENTS
2.1 ASTM F694, Heel
Attachment Strength Test for Womens Shoes.
2.2. Proposed
Standard Test Method for Heel Attaching Strength of
Footwear, (ASTM Subcommittee F13.2 on Biomechanics and Footwear
Construction, 11-2000).
2.3 SATRA PM113,
Heel Attachment Strength (SATRA Technology Center, Ketering,
Northhamptonshire, NN169JH, UK, admin@satra.co.uk).
3. TERMINOLOGY
3.1 Heel
Breast the front
face of the shoe heel.
3.2 Heel
Height the
perpendicular distance from the top back edge of the heel to
the plane of the tread (wear) surface.
3.3 Outsole
The bottom (sole) of the shoe: including the surface that
is exposed to wear.
3.4 Top
Piece (toplift)
the bottom layer of a heel usually made of leather, rubber,
plastic, etc.
4. TEST METHOD
4.1 Use a tensile
testing machine with a 2-in/min (5 cm/min) traverse rate (ref.
2.2) and autographic recorder.
4.2 Drill a 3/16
in (4.76 mm) diameter hole 3/8 of an inch above the top piece
wear surface and midway between the breast and the rear
surface of the heel (through the side of the heel).
4.3 Use a
suitable U-shaped strap and push a #10 machine screw (0.190-in. diam.)
through both the strap and the heel and secure with a nut and
washer.
4.4 Connect the
strap to the upper jaw of the tensile testing machine.
4.5 Clamp the
front of the shoe in the lower jaw, and determine the breaking
strength.
4.6 Minimum required breaking strength 125-lb. (556N)
(ref. 2.3: 500N (112 lb.))
5. SIGNIFICANCE & USE
5.1 The high and
often narrow heel of womens shoes frequently break and cause
women to fall and become injured.
5.2 This test
method will establish a minimum required breaking strength for
womens heels to minimize the number of injuries caused by
heels that fail during walking.
5.3
Footwear manufacturers must use a
heel/outsole attachment method that will resist the heel
attachment torque produced by the 500 Newton breaking strength
times the distance of the heel height minus the 3/8-inch heel
tensile test attachment distance.
5.4 Users of the ref. 2.1 test
method, which applies a torque to break the heel/insole
attachment, have a 250 in. lb. minimum torque requirement. This
is equivalent to the 125-lb. (556N) minimum tensile test
breaking force applied to a 2" high heel. Heel heights
greater than 2" require the same breaking force, therefore
the required torque is greater than the ref. 2.1 250 in lbs.
5.5 Footwear manufacturers must be
able to provide minimum heel breaking test certification for
womens
shoes (per V41.23) having heel heights greater than l" (2.5
cm)
6. KEYWORDS
6.1 Womens Heels,
Tensile Test, Heel Breaking Strength, Heel Attachment Torque
This Universal
Specification/Test Method is under the jurisdiction of Voices of
Safety International (VOSI) Committee V41.20 on "Pedestrian
Slip Resistance Requirements for Walkways & Footwear".
Copies are
available from VOSI, 264 Park Ave., N. Caldwell, NJ 07006, PH
(973) 228-2258, Fax 0276, e-mail: dcmeserlian@voicesofsafety.com
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