Here we report on the development of high-efficiency terminations for small-diameter synthetic-fiber tensile strength members. The principal goal of this effort was to create terminations that are as small as possible, yet nonetheless demonstrate nearly ideal efficiency. Tensile members used in test specimens were fabricated from parallel-lay aramid-fiber yarns contained within an overbraid having an outer diameter of 0.20 in. The terminations utilized are of a classic construction, consisting of a metallic fitting within which the fibers are potted in a polymer resin. Through the use of finite element analysis and extensive testing, a design was achieved which generates near-100% termination efficiency with a fitting that has an outer diameter equal to twice the strength-member diameter and a length of similar dimension. Data obtained from testing geometric variations of this design, which has an internal profile with a constant radius of curvature, provided an empirical basis for specification of optimized terminations in terms of fitting length and radius of curvature, normalized by strength-member diameter. Herein, the experimental procedures established to fabricate and test the strength-member/termination samples are explained in some detail. We summarize the finite element modeling employed to calculate maximum stresses generated within the fiber/resin composite interior of all the terminations analyzed. Test results are presented both as absolute break load and as termination efficiency, and are discussed in relation to computed stresses and the failure modes demonstrated. Parametric design rules for the optimized, constant-radius termination are formulated to allow scaling of this new class of termination for use with synthetic-fiber strength members of arbitrary size.
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