Abstract: Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

Abstract: Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

Abstract: Embodiments of reinforced composite structures for aircrafts and methods for making such reinforced composite structures are provided herein. A reinforced composite structure for an aircraft comprises a fiber reinforced composite stringer. The fiber reinforced composite stringer comprises a beam body portion and a runout portion that extends from the beam body portion in a first direction. The beam body and runout portions are defined by projection of a variable I-shaped cross-section in the first direction along at least a portion of an entire combined length of the beam body and runout portions. The variable I-shaped cross-section has a cap section, a foot section, and a web section that extends between the cap and foot sections. The variable I-shaped cross-section is configured such that a height of the web section tapers in the first direction along at least a portion of an entire length of the runout portion.

Abstract: Embodiments of reinforced composite structures for aircrafts and methods for making such reinforced composite structures are provided herein. A reinforced composite structure for an aircraft comprises a fiber reinforced composite stringer. The fiber reinforced composite stringer comprises a beam body portion and a runout portion that extends from the beam body portion in a first direction. The beam body and runout portions are defined by projection of a variable I-shaped cross-section in the first direction along at least a portion of an entire combined length of the beam body and runout portions. The variable I-shaped cross-section has a cap section, a foot section, and a web section that extends between the cap and foot sections. The variable I-shaped cross-section is configured such that a height of the web section tapers in the first direction along at least a portion of an entire length of the runout portion.

Abstract: Embodiments of thermal-acoustic sections for an aircraft for reducing noise along an acoustic path produced from an acoustic source are provided herein. The thermal-acoustic section comprises a first porous layer having a first characteristic acoustic impedance. A second porous layer is disposed adjacent to the first porous layer and has a second characteristic acoustic impedance that is greater than the first characteristic acoustic impedance. The thermal-acoustic section is configured to be positioned along the acoustic path such that at least a portion of the noise from the acoustic source is directed through the first porous layer to the second porous layer to promote absorption of the noise.

Abstract: A liner assembly for a fan case includes a noise attenuation layer covered by a face sheet. The face sheet includes openings to the underlying noise attenuation layer. The face sheet and noise attenuation layer include acoustically transparent joints. The noise attenuation layer includes a first side joined to a second side at a seam by an adhesive strip. The adhesive strip bonds the first side to the second side without filling any chambers. The face sheet includes a joint filled with an adhesive providing the desired uninterrupted surface within the fan case. Openings are formed through the joint and the adhesive to communicate with the underlying noise attenuation layer. The joint and seam become essentially transparent acoustically to improve noise attenuation performance.

Abstract: A composite structure having improved ballistic toughness and suitable for use in a fan containment case is provided. The composite structure includes a plurality of core layers, a plurality of inner plies position between adjacent ones of the core layers, each of the inner plies being formed from an organic matrix composite, an inner skin located adjacent an innermost one of the core layers, and an outer skin located adjacent an outermost one of the core layers. In a preferred embodiment, the core layers are formed from a honeycomb material made from aluminum or an aluminum alloy.

Abstract: A liner assembly for a fan case includes a noise attenuation layer covered by a face sheet. The face sheet includes openings to the underlying noise attenuation layer. The face sheet and noise attenuation layer include acoustically transparent joints. The noise attenuation layer includes a first side joined to a second side at a seam by an adhesive strip. The adhesive strip bonds the first side to the second side without filling any chambers. The face sheet includes a joint filled with an adhesive providing the desired uninterrupted surface within the fan case. Openings are formed through the joint and the adhesive to communicate with the underlying noise attenuation layer. The joint and seam become essentially transparent acoustically to improve noise attenuation performance.