Multipurpose Test Specimen

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Multipurpose test specimen

Fundamentals

The multipurpose test specimen used for the polymer testing is standardised by ISO 3167 [1].

The figure 1 shows the specified geometries for the multipurpose test specimen of type 1A and 1B as well as permissible specimen's forms according to ISO 527 [2].

Fig. 1:

Multipurpose test specimen type 1A and other specimens for the tensile test

A characteristic dimension for the multiple purposed specimen is the length l₁, which allows in the case of the type 1A specimen the manufacturing of three-point bending specimen or SENB – (Single-Edge-Notched Bend) with the following dimensions:

• width W = 10 mm (= b₁),
• thickness B = 4 mm (= h),
• length L = 80 mm (= l₁),

The important advantage of this method is, that for the tensile test, the bend test, the impact test or the notched flexural impact test, an identical inner condition can be observed.
For the realisation of tensile tests, the use of proportional minimised specimens is permissible, which is necessary in that case, if only a small amount of the material is available or rather the removal from construction elements for its characterisation is needed.
The shouldered test bar results from a sufficient clamping in the test equipment of the universal test machine and the generation of a homogeneous uni-axial stress condition in sufficient distance from the clamps.

Realisation of different tests

Independent of the type of shaping process (mostly the injection moulding), the multipurpose test specimen type 1A according to ISO 3167 represent is the preferred specimen for thermoplastic moulding materials. Beside the tensile test, the plane-parallel part in the middle of the specimen can used for different mechanical, electrical or thermal tests (figure 2). The advantage is that in these tests a uniform status relating to orientations and residual stresses (internal state) as well as an identical thickness and width (exterior state) exist.

On the necessity of preparing specimens from moulded component parts, there is mostly no possibility to take out specimen's lengths of 170 mm. In this case, proportional minimised specimen can be cutted. Here it is to consider that the testing velocity and the extensometer length have to be scaled with it.

Fig. 2:

Multipurpose test specimen according to ISO 3167 and from this fabricated specimens for realising of different tests [3]

Variety of definitions

Beside the multiple purpose specimen, a numerous other specimens for mechanical or fracture-mechanical tests exists, also for the execution of fatigue tests and for special specimens for new manufacture technologies such as the laser-sintering.

References

[1]	ISO 3167 (2014-08): Plastics – Multipurpose Test Specimens
[2]	ISO 527-2 (2012-02): Plastics – Determination of Tensile Properties – Part 2: Test Conditions for Moulding and Extrusion Plastics
[3]	Bierögel, C.: Specimen Preparation. In: Grellmann, W., Seidler, S. (Eds.): Polymer Testing. Carl Hanser Munich (2022) 3rd Edition, p. 18, (ISBN 978-1-56990-807-8; ePub ISBN 978-1-56990-808-2; see AMK-Library under A 22)