BS EN ISO 179-2:2020 pdf download.Plastics – Determination of Charpy impact properties Part 2: Instrumented impact test.
3.11 Charpy impact strength Charpy notched impact strength a cU (a cN ) impact energy at break (3.10) relative to the initial central cross-sectional area A (A N ) of the unnotched (notched) specimen Note 1 to entry: It is expressed in kilojoules per square metre (kJ/m 2 ). Note 2 to entry: See 8.4 and ISO 179-1:2010, 3.1 and 3.2.
3.12 type of failure type of deformation behaviour of the material under test up to and including the breaking event Note 1 to entry: Failure types are: complete break (3.13), hinge break (3.14), partial break (3.15), non-break (3.16). See Figure 2. Note 2 to entry: Types t, b and s represent subgroups of the complete break C and hinge break H defined below. For these types, values of the impact energy at break W B , and thus for the Charpy impact strength, may be averaged to give a common mean value. For specimens giving a partial break P and for materials exhibiting interlaminar shear fracture, see ISO 179-1:2010, 7.7. For specimens showing more than one failure type, see ISO 179-1:2010, 7.7 and ISO 179-1:2010, Clause 10 l). Note 3 to entry: As can be seen from Figure 2, the deflection and the impact energy at maximum force are identical to the deflection and impact energy at break in the case of splintering failure (see Curve s) and brittle failure (see Curve b), where unstable cracking takes place at the maximum impact force. Note 4 to entry: Usually, complete and hinge breaks cannot be differentiated in an automatic assessment based on the force-time or force deflection-curve.
4 Principle A rod-shaped test specimen, supported near its ends as a horizontal beam, is impacted perpendicularly, with the line of impact midway between the supports, and bent at a high, nominally constant velocity. During the impact, the impact force is recorded as a function of time and/or deflection. Depending on the method of evaluation, the deflection of the specimen may be either measured directly by suitable measuring devices or, in the case of energy carriers which give a frictionless impact, calculated from the initial velocity and the force as a function of time. The force-deflection diagram obtained in these tests describes the high-bending-rate impact behaviour of the specimen from which several aspects of the material properties may be inferred.
5.1.3 Striking edge and test specimen support The striking edge and the test specimen support shall fulfil the conditions of ISO 13802:2015, Annex A. Regarding verification of these elements, ISO 13802:2015, 6.3 applies. Any material with sufficient resistance to wear and sufficiently high strength to prevent it from being deformed, as well as being capable of transmitting the forces exerted upon the specimen to the load- measuring device, can be used for the striking edge.BS EN ISO 179-2 pdf download.