Dynamic tensile properties of polyethylene terephthalate fiber bundle with large deformability

In this paper, strain rate effects on the tensile mechanical properties of Polyethylene Terephthalate (PET) fiber bundles at room temperate were studied. First of all, an MTS load frame together with an Instron drop-weight impact system were used to carry out the tensile test under the quasi-static (1/600s-1) and the dynamic loadings (40, 80, 120 and 160s-1), respectively. The dynamic mechanical properties, consisting of the tensile strength, peak strain, elastic modulus and toughness, were analyzed based on the test data. It was concluded that the tensile strength increases with strain rate while the peak strain and toughness decrease with the strain rate. The initial elastic modulus remains almost unchanged at the low strain rate (no more than 40s-1) and starts to grow when the strain rate is beyond 40s-1. The second-stage elastic modulus rises continuously with the strain rate from 1/600 to 160s-1. Afterwards, the dynamic tensile strength of a PET fiber bundle was statistically analyzed by using the two-parameter Weibull distribution model that can help to quantify the scatter of the dynamic tensile strength. The corresponding parameters can be added into a numerical simulation in future to reflect the different tensile strength caused by defects.