ISO 37-2017 pdf free.Rubber, vulcanized or thermoplastic — Determination oftensile stress-strain properties.
This document specifies a method for the determination of the tensile stress-strain properties ofvulcanized and thermoplastic rubbers.
The properties which can be determined are tensile strength, elongation at break, stress at a givenelongation, elongation at a given stress, stress at yield and elongation at yield.The measurement ofstress and strain at yield applies only to some thermoplastic rubbers and certain other compounds.
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document.For dated references, only the edition cited applies. Forundated references, the latest edition of the referenced document (including any amendments) applies.ISO 5893,Rubber and plastics test equipment —Tensile, flexural and compression types (constant rate oftraverse)-Specification.
ISO 23529:2016,Rubber — General procedures for preparing and conditioning test pieces for physicaltest methods.
Standard test pieces, either dumb-bells or rings, are stretched in a tensile-testing machine at a constantrate of traverse of the driven grip or pulley.Readings of force and elongation are taken as requiredduring the uninterrupted stretching of the test piece and when it breaks.
Dumb-belland ring test pieces do not necessarily give the same values for their respective stress-strainproperties. This is mainly because in stretched rings, the stress is not uniform over the cross-section.A second factor is in the existence of “grain”which might cause dumb-bells to give different valuesdepending on whether their length is parallel or at right angles to the grain.
The main points to be noted in choosing between rings and dumb-bells are as follows.a) Tensile strength
Dumb-bells are preferable for determination of tensile strength.Rings give lower, sometimes muchlower, values than dumb-bells.
b) Elongation at break Rings give approximately the same values as dumb-bells, provided that
1) the elongation of rings is calculated as a percentage of the initial internal circumference, and
2) dumb-bells are cut at right angles to the grain if this is present to a significant degree.
Dumb-bells shall be used if it is required to study grain effects, as rings are not suitable for thispurpose.
c)Elongation at a given stress and stress at a given elongation
The larger dumb-bells (types 1, 2 and 1A) are generally preferred.
Rings and dumb-bells give approximately the same values provided that
1) the elongation of rings is calculated as a percentage of the initial mean circumference, and
2) the average value is taken for dumb-bells cut parallel and at right angles to the grain if this is present to a significant degree.
Rings might be preferred in automated testing, due to the ease of handling of the test pieces, and inthe determination of stress at a given strain.ISO 37 pdf download.