Method of manufacturing a honey comb structure of thermostructural composite material

A method of manufacturing a honeycomb structure of thermostructural composite material comprising a fiber reinforcing fabric densified by a matrix, the fibers of the reinforcing fabric and the matrix being of a material selected from the group consisting of carbon and ceramics, the method comprising the steps of:

• making a three-dimensional fiber fabric (41) by superposing two-dimensional plies (40) that are bonded together by fibers passing through the plies;
• making slit-shaped cuts (42) in a staggered configuration through the plies and through the entire thickness of the fabric;
• stretching the cut fabric in a single plane to form cells (46) whose walls are constituted by the lips of the cuts (42);
• and
• while the cut fabric is held in the stretched state, densifying it using the matrix to obtain a rigid honeycomb structure (48) of thermostructural material;
• the two-dimensional plies (40) of the three-dimensional fabric (41) comprising one of:
• layers of woven cloth;
• or single-directional sheets whose directions are inclined relative to one another;
• the cuts (42) being one of:
• made parallel to the warp thread direction of the layers of the cloth;
• made parallel to the weft thread direction of the layers of cloth;
• made in a direction that is inclined relative to the warp thread direction of the layers of the cloth;
• or made in a direction that is inclined relative to the weft thread direction of the layers of cloth;
• the bonding between the plies (40) of the three-dimensional fabric being provided by needling;
• the cuts (42) being one of:
• made perpendicularly to the plies;
• or made in planes that are inclined relative to the normal to the plies;
• the cut and stretched fabric (47) being densified by chemical vapor infiltration while being held in the stretched state by means of a jig (50, 52);
• the cut and stretched fabric (47) being provided with at least one fiber layer (54, 55) on each of its faces parallel to the plies of the fabric, and the assembly formed by the stretched fabric and the fiber layers being densified to obtain a panel (58) comprising a rigid honeycomb core covered by a rigid skin on each face with the fiber layer placed on each face of the fabric bonded thereby by needling;
• and
• the cuts (42) being made in one of:
• a plane fabric (41) and a cylindrical fabric (61) with the cuts (62) one of:
• made in meridian planes and the fabric stretched circumferentially;
• or made in planes perpendicular to the axis of the fabric and the fabric is stretched parallel to its axis.