Acoustic septum cap honeycomb

A method for making a precursor structure for use in making an acoustic structure that is adapted to be located near a source of noise, said method comprising the steps of:

• providing a honeycomb comprising a first edge to be located nearest said source of noise and a second edge, said honeycomb further comprising a plurality of walls that extend between said first and second edges, said walls defining a plurality of cells wherein each of said cells has a cross-sectional area measured perpendicular to said walls and a depth defined by the distance between said first and second edges;
• providing at least one sheet of acoustic material that has a thickness and a perimeter;
• forming said sheet of acoustic material into a septum cap, said septum cap having a resonator portion that extends transversely across said cells and which has an outer edge to be located at said walls and a flange portion that is located between said outer edge of said resonator portion and the perimeter of said sheet of acoustic material, said flange portion extending parallel to said walls and comprising an anchoring surface, said anchoring surface having a width wherein the width of said anchoring surface is substantially greater than the thickness of said sheet of acoustic material and wherein said acoustic material comprises an open mesh fabric that comprises monofilament fibers;
• inserting said septum cap into said cell such that said anchoring surface is friction fit against said walls and wherein the width of said anchoring surface is sufficient to provide an adequate friction force between said anchoring surface and said walls to retain said septum cap within said cell.