BS ISO 4662:2017 pdf download.Rubber, vulcanized or thermoplastic – Determination of rebound resilience.
4 Principle
A test piece with plane, parallel surfaces is impacted on one surface by a linearly or circularly oscillating body, the impacting surface of which is spherical. The rebound resilience is determined by measurement of the energy of the impacting mass immediately before and after impact.
NOTE Conventionally, the input and output energies of the moving mass have been determined by observing the potential energy of the mass when at rest before moving to impact the test piece and on reaching zero velocity after rebound. The detailed descriptions of the apparatus described in this document follow this convention. However, it is equally acceptable to measure the input and output energies of the moving mass by observing its velocity immediately before and after impact and calculating the kinetic energies.
5 Pendulum method
5.1 Apparatus
5.1.1 General
The rebound resilience shall be measured by means of an apparatus consisting of a pendulum-like one- degree-of-freedom mechanical oscillatory device and a heavy and secure test piece holder.
The two items shall be suitably fixed together for rebound resilience measurements, and either item can be removed for purposes of adjustment or checking of the oscillatory device.
Means shall be provided for measuring the rebound of the pendulum, either using a calibrated scale or an electrical signal.
Various practical designs of apparatus which conform to these specifications are available (see Annex B and Annex C).
NOTE 1 The various types of apparatus designed to operate within the ranges specified for the various parameters (see below) and correctly calibrated give substantially the same values of rebound resilience.
The apparatus and impacted test piece characteristics shall be such as to fall within the following specified ranges:
— indentor diameter (D): 12,45mm to 15,05 mm;
— test piece thickness (d): (12,5 ± 0,5) mm;
— impacting mass (m): 0,25 kg to 0,35 kg;
— impact velocity (v): 1,4 rn/s to 2,0 m/s;
— apparent strain energy density (mv2/Dd2): 324 kJ/m3 to 463 kj/m3.
NOTE 2 The conditions and apparatus specified in this document involve the selection of a spherical indentor and of a flat test piece and are assumed to be essentially dependent on the fundamental parameters D, d, m and v listed above. In addition, the ratio of impact energy to an equivalent volume or “apparent strain energy density” (mv2/Dd2), which under simplifying assumptions is related to impact strain, has to be maintained within the narrow range specified.
NOTE 3 The ranges are such that they embrace the requirements for the Lüpke pendulum method (12,5 mm,
12,5 mm. 0,35 kg. 1,4 rn/s. 351 kJ/m3) and the modified Schob pendulum method (15,0 mm. 12,5 mm, 0,25 kg.
2 rn/s. 427 kJ/m3).
In addition, allowance has been made for
a) a small tolerance (±0,05 mm) to allow for mechanical imperfections of spheres of 12.5 mm and 15 mm nominal diameter;
b) an additional tolerance (27 k/m3) on mv2/Dd2 to allow for the effect of variation in test piece thickness (+0,5 mm).
5.1.2 Oscillatory device
The oscillatory device shall consist of a rigid body or hammer terminating in an indenting spherical surface, supported so as to oscillate linearly or circularly under the action of a restoring force which can be due to gravity or produced by the elastic reaction of springs or by a wire in torsion. The velocity of the indenting spherical surface at the point of impact shall be in the horizontal direction and perpendicular to the surface of the test piece.
5.1.3 System for following the motion of the hammer
The motion of the hammer shall be followed either by means of a system comprising a pointer and a fixed scale or by a system which measures the position or velocity of the hammer to furnish electrical signals.BS ISO 4662 pdf download.