ISO 6603-2:2000 pdf download – Plastics -Determination of punctureimpact behaviour of rigid plastics —Part 2: lnstrumented impact testing.
4 Principle
The test specimen is punctured at its centre uslig a lubricated striker, perpenduIarty to the test-specimen surface and at a nominally uniform velocity. The resulting force-deflection or force-time diagram is recorded electronicaly. The test specimen may be damped in position during the test
The force-deflection diagram ob(ained in these tests records the Impact behaviour of the specimen from which several features of the behaviour of the material may be inferred.
5 Apparatus
5.1 Testing device, consisting of me following essential components:
— energy carrier, which may be inertial-mass type or hydraulic type (see 5.1.1):
— striker, which shall be lubricated;
specimen support with a recommended damping device.
The test device shall permit the test specimen to be punctured at its centre, perpendicular to its surf ace at a nominally constant velocity. The force exerted on the test specimen in the direction of impact and the deflection from the centre of the test specimen in me direction of impact shaM be derivable or measurable (see Figure 5).
5.1.1 Energy carrier, with a preferred impact velocity of (4,4 ±0,2) m/s (see 3.1 and note to 3.1). To avoid resits. which cannot be compared due to the viscoelastic behaviour of the material under impact, me decrease of velocity dursig the test shall not be greater than 20 %.
NOTE For brittle mstenals, an Impact velocity oil m/s may be found to be more appropriate because If reckices the level of vibralion and noise and inroves the ality of the force-del lection diagram see annex A).
5.1.11 Hydraulic type, consisting of a high-speed testing machine with suitable attachments.
Any deviation of the velocity of the stnker relative to the support dunng impact shall be controlled. for example by recording deflection-twile curves and checking the slope.
5.1.1.2 Inertial-mass type, which may be accelerated gravitationally. spring- or pneumatically-assisted. Suitable devices are falling-dart machines.
In the case of a gravitationally accelerated mass and neglecting frictional losses: the impact velocity v corresponds to a drop height H of the energy carrier of (1.0 0.1) m.
For all inertial-mass-type energy carriers the impact velocity shall be measured by velocity-measuring sensors placed close to the point of impact. The maximum decrease of velocity during test results in the minimum mass,
nec, of the carrier according to equations (1) and (2) (see note).
E is the highest puncture energy to be measured, expressed in joules (see 3,9);
i is the impact velocity (4.4 m/s, see 3.1).
NOTE In many cases, a weighted energy carner with a total mass mc of 20kg has been found to be sufficient for the larger Striker fld ci 5kg Or the Smailer Striker (see 51.2).
5.1.2 StrIker, preferably having a polished hemispherical striking surface of diameter (20.0 ± 02) mm. Alternatively, a (10 ± 0,1) mm diameter striking surface may be used.
NOTE I The size and nenslons of the strer and condition of the stace will affect the enpact results.
The striker shall be made of any material with sufficient resistance to wear and of sufficiently high strength to prevent plastic deformation. In practice, hardened steel or materials with lower density (i.e. titanium) have been found acceptable.
The hemispherical surface of the striker shall be lubricated to reduce any friction between the striker and the test specimen (see note 2 and annex B).
NOTE 2 Test restits obtained with a hibricated or dry striker are likely to be different Below aritieni temperatures, condensation can act as a lubncant.
The load cell shall be located within one striker diameter from the tip of the striker, i.e. mounted as dosely as possle to the tip to mirwmize all extraneous forces and sufficiently near to fulfil the frequency-response requirement (see 5.2). An example is shown in Figure 5.
5.1.3 Support ring (see Figures 5 and 6), placed on a rigid base and designed such that air can not be trapped under the test specimen, thus avoiding a possible spring effect. Below the support nng. there shall be sufflcent space for the striker to travel after total penetration of the test specimen. The recommended inside diameter of the support ring is (40 ± 2) mm, or alternatively (100±5) mm, with a minimum height of 12mm.
5.1.4 Base for test device, firmly mounted to a rigid structure so that the mass of the base (see Figure 5)ls of sufficient stiffness to minimize deflection of the specimen support.
When calculating the deflection from the kinetics of the accelerated mass, a minimum mass ratio rnim of 10 between base (mB) and energy carrier (nec) shall be used. This prevents the base from being accelerated by more than I % of the impact speed up to the end of the test. For directly measured deffections. this minimum ratio is a recommendation only. For the principles of this specification see annex B of ISO 179-2:1997.