Experimental study for small diameter flexible lines

For a class of flexible lines structures such as fibers, strands, cords, composites, biological structures, etc. a number of mechanical properties are difficult to evaluate. Often, experimental measurements are required, especially for developing new products. The problem is complicated for very flexible lines made of more than one material when no direct correlation among properties can be precisely established, especially from small displacement theory and at very low loads. The solution is farther complicated by the anisotropic (usually transversely isotropic) nature of the line structure and its viscoelastic behavior. This paper presents novel procedures and apparatus for studying bending stiffness, fatigue, and wear and friction characteristics of small diameter flexible lines. Detailed experimental results are presented for lines made of various braided or solid cores embedded in a polymeric jacket. The evaluation of experimental results is based on certain classical analytical solutions. Time dependent and environmental effects are easily incorporated in the experiment. This research provides background for the development of an analytical model for predicting mechanical properties for flexible lines.