Study of the effect of temperature and relaxation time on the force‐strain characteristics of textile yarns upon tensile loading

Abstract The textile materials can be used in many technical applications in various fields, such as automotive. Depending on the application areas, the textile or fiber‐based materials have to meet certain predetermined requirements. Textile yarns can be used as reinforcing cords in composites in which an elastomeric matrix is used. The basic mechanical tensile test at standard temperature does not provide all the information required for obtaining the material parameters. The tests are also necessary to be performed at reduced temperatures, depending on the following application. Furthermore, it is necessary to consider stress relaxation in specific tests for the practical use. In this work, there is the experimental investigation of the effect of the selected temperatures (20 °C and 120 °C) and the relaxation times (60 s and 120 s) on the mechanical properties of the selected textile yarns from polyamide 6.6 under the uniaxial tensile tests. The results reveal that the relaxation time for the first 20 seconds is interesting because there is a significant decrease in the force while holding the strain. A final method is proposed, and it can be used for any other applications, and it guarantees the repeatability of measurements in the relatively fast measured time.