کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5205918 | 1502943 | 2015 | 6 صفحه PDF | دانلود رایگان |
The free retraction of vulcanised strips of natural rubber released from simple uniaxial deformation is studied using high speed cinematography in the context of a simple momentum theory. Good agreement between the theory and experiment is observed when vulcanisates are released from stresses below 1Â MPa, which corresponds to tensile strains rates below 1Â ÃÂ 103Â sâ1. Above this critical stress and corresponding strain rate value, an increasing dispersion is observed in the form of slowing down of the characteristic retraction pulse, and also by a relaxation of strain ahead of the pulse front (a dispersion of the pulse). Holding samples at high strains for an extended period of time prior to releasing results in a further, significant retardation of the retraction pulse velocity. These effects are related to the increasing non-linearity of high strain rate retraction stress-strain behaviour. Energy balance arguments show that the dispersion of the retraction pulse is a prerequisite for pulse propagation, and that its magnitude underpins the deviation from the momentum model outlined in this paper.
Journal: Polymer Testing - Volume 47, October 2015, Pages 36-41