This standard describes a method for determining the fatigue resistance of vulcanized rubber under repeated tensile deformation. When the sample size and cycle frequency are basically unchanged or no temperature rise occurs, defects will cause cracks to grow and eventually break the sample. This method stipulates that during repeated deformation, the specimen relaxes to zero strain in each cycle. For some rubbers, under static deformation, a similar fatigue process can occur without relaxing to zero strain during repeated deformation, but this standard does not adopt this condition. This method is suitable for rubber with stable stress-strain properties, which does not show excessive stress softening or permanent deformation, or a high viscosity state, at least after a certain cycle of circulation. For materials that cannot meet the above conditions, there may be considerable difficulties in experimental and theoretical explanations. For example, a rubber shows large permanent deformation during a fatigue test. Under the conditions of constant maximum load and maximum elongation, the test strain is difficult to determine, and the fatigue life may have different values. How the test results for this rubber are interpreted, or how they compare to other rubbers, remains to be determined by basic research work. Generally speaking, if the permanent deformation of a rubber exceeds 10% as measured in accordance with 8.5 and 9.2, it belongs to this type of material. Therefore, this method is not applicable to most thermoplastic elastomers. Similar considerations apply to other changes involving elastic aspects during the trial. This fatigue test is different from the flexure test described in GB/T 15584. In the latter, fatigue fracture occurs under the simultaneous action of stress and temperature. This test is superior to the Demecia type flex crack and cut growth test (see GB/T 13934). Its advantage is that it can obtain automatically recorded quantitative results without relying on the operator's analysis and interpretation; it can accurately determine the initial Deformable and easily changed to suit different uses. When using standard test results to perform correlation analysis on actual application effects, special attention needs to be paid because the fatigue resistance test results of different vulcanized rubbers are different, related to the test conditions used and the content and method of comparison of test results. Appendix A gives instructions for selecting test conditions and interpreting test results.
ISO 6943:2007 history
2017ISO 6943:2017 Rubber, vulcanized — Determination of tension fatigue
2011ISO 6943:2011 Rubber, vulcanized - Determination of tension fatigue
2007ISO 6943:2007 Rubber, vulcanized - Determination of tension fatigue
1984ISO 6943:1984 Rubber, vulcanized; Determination of tension fatigue