As with the resin socket, it is vital to ensure the the yarns are straight on the spike and are evenly distributed round it. Typically, the included angle of the barrel interior cone is 6o. It uses the wedge action of the spike against the fibres and the body of the barrel to develop holding power. The barrel & spike is often used with parallel yarn constructions. It is important to ensure that the rope yarns are evenly distributed in the socket and that they are thoroughly wetted by the resin. Generally they are filled with a 2 component cold cure polyester resin. Wire rope sockets can be used to good effect on fibre ropes. The findings from the research and tests developed by TTI over the years and computer modeling were instrumental in the ability to develop this splice in such a short length. This was achieved by splicing within the strand, rather than splicing through the rope. A typical example includes a novel splice in a 1200tonne break load Kevlar rope that was only 1.5m long compared to the industry standard method 4m long. TTI has developed high tensile and fatigue efficienct splices for Parallel Yarn, wire rope construction and Parallel Strand Ropes. Research by TTI has identified the key parameters that affect splice performance as follows This shows that this particular splice would continue to slip with cycles and would eventually pull out. A graph below shows the slip between strands at various positions along the length. This technique can also be used to develop the optimum splice length. Pressure variation along length of spliceĪnother development by TTI is the methodology to determine the stability of the splice to prevent splice under varying cyclic load conditions. Measurements of inter-strand pressure in a splice Iii) Radial contact pressure continues to fall off in the taper region at a slower rate, thus it is essential to have a sufficiently long taper region otherwise tensile or fatigue failure can occur in the splice. Ii) At each end of the splice, there are transitional zones where more slip occurs during bedding-in because the radial contact pressure is lower. (During the initial bedding-in, there may be a few slips while tensions equalise between the sub-ropes.)
SPLICE A ROPE FULL
I) At the midpoint of the full tuck region and when the optimum contact pressure is provided by the correct splice design, the spliced strands should be locked under conditions of continuous cycling. From this we can deduce that there are three critical zones along the length of a splice:. Maximum pressure occurs at about the midpoint of the full tuck region and diminishes in each direction to a much lower value. The radial pressure trend along the splice length is shown below. Tests developed and conducted by TTI with miniature pressure transducers inserted between the spliced strands measured the radial pressure along the full length of a splice. TTI has developed a splice model for the US Navy which includes contact pressure and slip modes and can be used to study mechanical properties of a splice. There is no common formal process of ‘designing’ to determine the number of tucks, angles and dimensions, and there are no formal, independently monitored standards for designer qualifications. For example, the splice must not be a site for accelerated fatigue and must not loosen with rope rotation.Ĭlassical named splice designs, such as Admiralty, Liverpool and Australian have proven over the centuries that they can be efficient but they were developed for application to natural and steel fibre ropes, and were recently adapted for synthetic fibre ropes. The splice design must take into account the rope application. Splicing is routinely carried out on Braided, 3 or 4 Strand Ropes and Wire Rope Constructions. Knotting, which is also used, develops approximately 50% of the rope strength. The following notes are intended to give an overview of the main termination types used in fibre ropes. Specification of termination for engineered systems.Leech paper on modeling terminations The analysis of splices used in large synthetic ropes)
Modeling mechanical and fatigue properties (see Dr.
TTI can provide design and engineering services as follows TTI provides a complete termination design service in all types of terminations
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