Research on building method of measuring the allowable slippage coefficient to serve the design of non-geodesic wound filamentary composite shell of revolution

Abstract

Composite structures obtained by winding methods (cylinder, sphere, torus, etc.) are used in many fields. To form the structure, the fibers are impregnated with resin and spread onto the mandrel in a geodesic or non-geodetic trajectory. The non-geodetic trajectory of the fiber is an unbalanced trajectory, i.e., the fiber has a tendency to slip transversely. The slippage tendency of fiber is assessed by the slippage coefficient (l), which is the ratio between the geodesic (k_g) and the normal curvature (k_n), l = k_g/k_n. When the value of l is bigger than the allowable value ([l]), the fiber will be slipped. In this paper, from the fiber trajectory theory, a method of measuring the allowable slippage coefficient is built, and at the same time, the error prediction is due to the influence of the fiber width. Since then, the winding mandrel has been designed and made of POM plastic for experiments. Experiments were carried out on the winding machine MQC-01CT, the winding material is glass fiber with a width of 6 mm wetted with epoxy resin. The results show the average allowable slippage coefficient [l] = 0,195 with error Dλ = 0,063%. The results are the basis for determining the allowable slippage coefficient in different cases of composite and mandrel materials. At the same time, the measured values are the basis for calculating the structure and technology of winding the corresponding composite materials.