Experimental Study Of Mechanical Properties Of Fibre And Multifilament Of Deep-sea Mooring Cables

With the widespread application of mooring system in the exploitation of marine resources, the design and structural stability of mooring system are increasingly concerned. With the back stiffness and small coverage, wide application of depth, etc., synthetic fibre cable has gradually become the main component of a new deep-sea mooring system. In recent years, the mechanical property of cables becomes an international research focus. The theory of mooring mechanical properties, testing and evaluation criteria has not been established. Deep-sea mooring cables by fibres, multifilaments, single small stocks, large stocks and rope. To study the mechanical properties of fibre and multifilament brings us great research value and practical significance.In order to learn the mechanical properties of deep-sea mooring lines, experimental studies involved in strength properties have been carried out in this thesis. In the fibre strength performance test, the small force-large deformation experimental device has been designed and optimized. As the fibre diameter is very small (about 40μm), microscope is chosen to measure the diameter. The intensity curve of fibre is divided into three typical phases. The yield strength, breaking strength and elastic modulus in initial stage can be calculated and the elastic modulus is basically a constant. With the increasing of loading rate, the breaking force reduces and gradually tends to stabilize. It has got the formula, breaking strength∝1 /loading rate. Tensile fracture morphology of fibre has been observed by electron microscopy. And the qualitative analysis of its causes has been carried out. Tensile speed affects tensile fracture morphology greatly. The faster tensile speed is, the greater the heat from fibre is, and the more serious the surface flexure is. It is a foundation of further study.Experimental research of fibre creep properties has been carried out. The creep can be divided into three typical stages including deceleration phase, uniform phase and acceleration phase. As stress increases, the creep rate accelerates. And the higher stress is, the more obvious this phenomena is. Besides, logarithmic forms of creep functionε=ε₀ +θ₁ lg(t) +θ₂t coming from the fitting curves provide a basis of life prediction of fibre.Prediction of multifilament performance has been carried out by establishing some formulas( k 2 =Ï€/2(?)≈0.9069). Finally, predicted values and experimental data were analyzed to study the error range of the formulas. This research work has provided an effective and necessary foundation for reckoning the performance index of deep-sea mooring cables.