Slots and pre-weakened region in 3D woven components

A method of forming a ceramic matrix composite, the method comprising:

• forming a preform by:
• weaving a plurality of warp tows with a plurality of weft tows, wherein weaving the plurality of warp tows comprises redirecting a subset of the plurality of warp tows around a region of the preform such that the region is free of the plurality of warp tows;
• weaving a plurality of fugitive yarns into the region of the preform in at least one of a warp position or weft position, wherein weaving the plurality of warp tows, the plurality of weft tows, and the plurality of fugitive yarns comprises a three-dimensional weaving technique and wherein redirecting the subset of the plurality of warp tows comprises routing the subset of the plurality of warp tows along a border of the region to provide a reinforced area along a periphery of the region;
• subsequently, decomposing the fugitive yarns to transform the region into a pre-weakened region, the pre-weakened region having a higher porosity than a remainder of the preform;
• densifying the preform with a ceramic matrix;
• and
• machining the pre-weakened region to form a slot in the ceramic matrix composite.