| 摘要 |
<p>Fibrous preforms for producing annular parts from a composite material are made by winding stacked layers of a spiral or helical fabric strip (10) including substantially helical warp yarns and substantially radial weft yarns. The mass per unit area of the helical fabric warp increases from the inner to the outer diameter thereof, and the layers of the fabric strip are needled so that they are bonded together by fibres drawn from the fabric yarns. The increase in the mass per unit area of the warp at least approximately compensates, as far as the volume density of the preform is concerned, for the decrease in the weft density between the inner diameter and the outer diameter.</p> |
