A composite sucker rod assembly is provided for use in down-hole wells. The sucker rod assembly includes a plurality of wound fiber strength elements that are drawn into an in-situ mold tube or clamshell and resin-infused in conjunction with creating a conical wedge terminus connection for at least one end-fitting. Each terminus fitting has a tapered cavity with a proximal opening to receive the composite material. The cavity is tapered so as to flare outwardly from said cavity's proximal opening toward the cavity's distal end. A two-piece cruciform or single piece pin insert interlocks with the wound fiber elements and the terminus fitting to form a high strength connection. The assembly is tensioned prior to infusing and curing the resin matrix for the composite. The mid-span of the sucker rod or tension member can be molded in an oval, elliptical or airfoil shape by various means.

The purpose of the present invention is to provide a lightweight composite material structure while suppressing a drop in strength. In a composite material structure, which is configured as a fiber-reinforced plastic composite material extending in one direction and having a plurality of holes (5) formed at intervals in a row in the one direction and which is subjected to a tensile load and/or a compressive load in the one direction, a peripheral region (3a) around the holes (5) comprises a first area (10) obtained by bending composite material, which is reinforced using continuous fibers that have been made even in the longitudinal direction, so that the center line of the width (W) of the composite material weaves between adjacent holes (5) and zigzags in the one direction. The tensile rigidity and/or compressive rigidity in the one direction of the peripheral region (3a) around the holes (5) is lower than the tensile rigidity and/or the compressive rigidity in the one direction of the other regions (3b) that surround the peripheral regions (3a).

A carbon-fiber-reinforced resin cylinder for propeller shafts includes a first-carbon-fiber-reinforced resin layer having a first carbon fiber, and a second-carbon-fiber-reinforced resin layer having a second carbon fiber and being higher in strength and lower in elastic modulus than the first-carbon-fiber-reinforced resin layer. The first carbon fiber is arranged so as to extend along a longitudinal direction of the cylinder.