ISO 6943:2017
Rubber, vulcanized — Determination of tension fatigue
Rubber, vulcanized — Determination of tension fatigue
- Статус документа:
- Действующий
- Формат:
- Электронный (PDF)
- Количество страниц:
- 18
- Дата публикации:
- 9 августа 2017 г.
- Издание:
- ISO IS 6943 edition 4 version 1
- ICS:
- 83.060
ISO 6943:2017 specifies a method for the determination of the resistance of vulcanized rubbers to fatigue under repeated tensile deformations, the test piece size and frequency of cycling being such that there is little or no temperature rise. Under these conditions, failure results from the growth of a crack that ultimately severs the test piece. The method is restricted to repeated deformations in which the test piece is relaxed to zero strain for part of each cycle. Analogous fatigue processes can occur under repeated deformations which do not pass through zero strain and also, in certain rubbers, under static deformation, but this document does not apply to these conditions. The method is believed to be suitable for rubbers that have reasonably stable stress-strain properties, at least after a period of cycling, and that do not show undue stress softening or set, or highly viscous behaviour. Materials that do not meet these criteria might present considerable difficulties from the points of view of both experiment and interpretation. For example, for a rubber that develops a large amount of set during the fatigue test, the test strain will be ill-defined and the fatigue life is likely to differ markedly under constant maximum load and constant maximum extension conditions; how the results for such a rubber should be interpreted or compared with those for other rubbers, has not been established by basic work. As a general guide, a rubber for which the set determined in accordance with 9.5 and 10.2 exceeds 10 % is likely to fall into this category. For this reason, the method is not considered suitable for most thermoplastic elastomers. Similar considerations apply with regard to other changes in elasticity behaviour during testing. This fatigue test is distinct from the flexometer tests described in the various parts of ISO 4666, where fatigue breakdown occurs under the simultaneous action of stress and temperature. Advantages over the De Mattia flex cracking and cut growth test (see ISO 132) include the following: - the test yields quantitative results which do not depend on operator interpretation and which can be recorded automatically; - the initial deformation is clearly defined and can readily be varied to suit different applications. Great caution is necessary in attempting to relate standard test results to service performance since the comparative fatigue resistance of different vulcanizates can vary according to the test conditions used and to the basis by which the results are compared. Guidance on the selection of test conditions and on the interpretation of results is given in Annex A.
Abstract
Overview - ISO 6943:2017 (Rubber, vulcanized - Determination of tension fatigue)
ISO 6943:2017 specifies a laboratory method for measuring the tension fatigue resistance of vulcanized rubber under repeated tensile deformation. The test quantifies fatigue life (number of cycles to failure) using dumb‑bell or ring test pieces cycled at frequencies (normally 1–5 Hz) and sizes that avoid significant temperature rise. The method applies where the specimen is relaxed to zero strain for part of each cycle and is intended for rubbers with reasonably stable stress–strain behaviour (not for most thermoplastic elastomers).
Key topics and technical requirements
- Test principle: repetitive extension of dumb‑bell or ring specimens until crack growth severs the specimen; fatigue life recorded as cycles to break.
- Test pieces: dimensions and preparation rules for dumb‑bell and ring test pieces; cutting tools must be sharp and maintained per ISO 23529.
- Apparatus: a fatigue‑testing machine providing reciprocating motion (1–5 Hz), clamps or roller fixtures for secure gripping, and means to count cycles and measure load if required.
- Measurements: fatigue life, set after cycling, maximum strain, maximum stress and strain energy density; guidance for measurement instruments (micrometers, calipers, graduated cones).
- Calibration and conditioning: calibration requirements referenced to ISO 18899 and specimen conditioning per ISO 23529; Annex B contains calibration schedule.
- Limitations: not applicable to tests that don’t relax to zero strain, to rubbers showing excessive set (>~10% as a guide), severe stress softening or highly viscous behaviour. Results may not directly predict in‑service performance; Annex A provides guidance on selecting test conditions and interpreting results.
Applications - who uses ISO 6943:2017
- Rubber product manufacturers (hoses, seals, belts, vibration isolators) for material selection and quality control.
- R&D and materials laboratories evaluating vulcanizate formulations and compounding changes.
- Third‑party testing labs providing standardized fatigue data for specifications and supplier comparisons.
- Design engineers seeking comparative fatigue data to inform component lifetime assessments (with caution about translating lab fatigue to field performance).
Related standards
- ISO 18899 - calibration of test equipment (normative reference).
- ISO 23529 - specimen preparation and conditioning (normative reference).
- ISO 4666 (flexometer tests) - for combined stress + temperature fatigue (different method).
- ISO 132 (De Mattia flex cracking) - alternative comparative test; ISO 6943 offers quantitative, automatable results.
Use keywords: ISO 6943:2017, tension fatigue testing, vulcanized rubber fatigue life, dumb‑bell and ring test pieces, fatigue‑testing machine, strain energy density, rubber testing standards.
Технические детали
- Технический комитет
- ISO/TC 45/SC 2 - Testing and analysis
- SKU
- ISO 6943:2017
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