Research On Creep And Stress Relaxation Of VECTRAN Fiber And Rope

Stratospheric airship is an important devoloping direction of the near space aircraft, and the rope is an important part of the airship's structure, which transfers load in the airship. To ensure the normal operation of the airship, the rope should have a low creep and low stress relaxation properties under the longtime load. The Vectran rope is a high-performance fiber rope with a low creep propertie, which may be able to meet the needs of the stratospheric airship. As the airship needs to stay in the stratosphere for a very long time, it is becomes necessary to study the Vectran fiber and rope's creep and stress relaxation properties in the special stratospheres environment, such as the cycle of high and low temperature environment.Vectran fiber's value of diameter and broken strength are very small, so it's difficult to measure the length of the fiber nor to load the fiber. According to these characteristics of Vectran fiber, we designed a specific experiment equipment and test method, and researched the Vectran fiber's creep behavior both in the cycle of high and low temperature environment and room temperature environment.The value of Vectran rope's broken strength is very big, but when the rope is being loaded, it's difficult to adjust the value of load. After designed an experiment equipment which can adjust the value of load, and determined the test method, we researched the stress relaxation behavior of Vectran rope in the cycle of high and low temperature environment and room temperature environment.Based on the exprimental data, we analyzed the value of stress and temperature enviroment's effccts on Vectran fiber's creep behavior and Vectran rope's stress relaxation behavior.Based on the one-dimensional creep theory and stress relaxation theory, after analyzed several creep models and stress relaxation models, we determined the creep model and stress relaxation model of Vectran fiber and rope. Based on the experimental data, we determined the parameters of the model, and obtained the creep equation of Vectran fiber and the stress relaxation equation of Vectran rope. The validation of the creep equation of Vectran fiber was verified. After determined the rule of creep rupture of Vectran fiber, we predicted the creep lifetime of Vectran fiber.