The Mechanism Research Of Loading Rate On The Tensile Mechanical Properties Of Mooring Synthetic Fiber

With the increase of human’s demand for resources and the depletion of land andcoastal resources, people began to enter the deep sea. Many countries have begun toattach importance to the development of deep-sea mining equipment. The mooringsystems of the deep-sea mining equipment now is more and more using the newpolyester rope, so the mechanical properties of polyester rope become the key of thedesign of the mining equipment. The mechanical properties of synthetic fiber which isthe smallest building blocks of polyester rope become the focus of the study.In this paper the heat conduction equation reduces to a one-dimensionalcylindrical coordinate system. The temperature field of the fiber during stretching wasderived by Duhamel’s principle. The results show that the temperature field has arelationship with the fiber tensile rate, initial temperature, fiber radius, fiber originallength. Based on the equation we derived the temperature field of polypropylenefibers at different strain or of different loading rate. The temperature along the fiberdirection is reduced by the parabolic way. The larger the strain or loading rate, thehigher the temperature.We derived the effect of loading rate to the mechanical properties of fiber tensile.The results show that temperature has a large influence on the fibers’ constitutiverelations, and the temperature and the constitutive model present inverse relationship.The temperature of the fiber is affected by the loading rate, so the innate character ofthe different mechanical properties of fibers at different loading rate is thetemperature difference.We derived the constitutive model of necking segment. when the fiber get intothe necking segment the temperature increased fast and it will reach a higher value.The stress-strain curve has a greater change in the necking segment. With theincreasing strain the stress at first increase fast, but when the stress reach the highestpoint it begin to reduce. That is because the high temperature makes the fibersoftening. And when the stress reaches a point it decreases gradually until the fiberbroken.Based on the temperature of necking segment we derived the temperature fieldwhen the fiber fractures. The results show that the temperature field is an integrated function of time and radius. Along the direction of the fiber radius the temperature isreduce as the parabolic manner. When the fiber broken, the surface’s thermal isconduct with the external environment, so the temperature of the surface is lower.Then the core is conduct with the adjacent areas, the temperature of the core is higher.During to the temperature contrast, when the surface reaches the room temperature thecore’s temperature is still high. So with the decrease of the core’s temperature, thecore gives a pressure to the surface. When the pressure reaches a certain level, thesurface occur fold. Grater pressure will cause buckling. Different stretching rate of thefiber has different temperature, and different temperature will cause different pressure,the fracture morphology of the fiber will be different.