A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.

A method of forming a gas turbine engine component, the method including forming a plurality of cooling apertures in a preform structure of the component, the plurality of cooling apertures of the preform structure comprising a first cooling aperture and a second cooling aperture, wherein cross-sectional shapes of the first and second cooling apertures of the preform structure are different from one another, as measured in a same relative plane; and applying a coating to at least a portion of the preform structure to form the component, wherein a cross-sectional shape of the first and second cooling apertures of the component are approximately the same as one another, as measured in the same relative plane.

A rotor blade for a gas turbine engine is provided. The rotor blade includes a blade body formed of a first material; and a spar within a portion of the blade body, the spar formed of a second material that is different than the first material, the spar having an elongate body including a notch. The notch, weakened geometric feature, or other reduction in cross-section defines a frangible portion of the spar that is used to control a fracture of a rotor blade.

A propeller includes a rotatable hub and at least two propeller blades coupled to the rotatable hub. Each of the propeller blades is formed from a combination of a first material having a negative Poisson's ratio (NPR) and a second material having a positive Poisson's ratio (PPR). The first material and the second material can be layered or can be formed as a matrix with one of the first or second material embedded in the other. In a layered configuration, a layer of the first material is positioned between adjacent layers of the second material, and the layers can be connected by tabs of NPR material. The combination of the NPR and PPR materials improve the strength and impact resilience of the propeller blades compared to conventional materials.

A gear reduction reduces a speed of a fan rotor relative to a speed of a fan drive turbine. A rigid connection between a fan case and an inner core housing includes a plurality of A-frames connected at a connection point to the fan case. Legs in the A-frames extend away from the connection point in opposed circumferential directions to be connected to a compressor wall of the inner core housing. The rigid connection also includes a plurality of fan exit guide vanes rigidly connected to the fan case. A lateral stiffness ratio of the lateral stiffness of the plurality of fan exit guide vanes and a lateral stiffness of a combination of the plurality of A-frame, the compressor wall, and a fan intermediate case which is forward of the low pressure compressor being greater than or equal to 0.6 and less than or equal to 2.0.

A method for manufacturing a metallic component is disclosed. The method includes forming a metallic component with a support structure using an additive manufacturing process. The support structure includes support walls arranged to form flow passages with a predetermined cross-sectional area. The method also includes placing the metallic component with the support structure into a chamber and sealing the chamber. The method further includes introducing a fuel mixture into the chamber after sealing the chamber. The method still further includes igniting the fuel mixture in the chamber to remove one or more of the support walls of the support structure from the metallic component.

A method for producing a vibration-damping structure combination for damping vibrations for movable masses, having a first structure and a further structure, the further structure movable within a stop surface defined by a first structure surface of the first structure. The method includes a) providing the first structure, having the first structure surface and which defines a coating surface of a coating at least in some sections; b) coating the first structure surface of the first structure with the coating, the coating surface of the coating being applied such that a cavity is formed; c) filling the cavity with the filler; d) curing the filler until the further structure having a further structure surface is formed, which lies against the coating surface; and e) removing the coating, the further structure thus being movable relative to the first structure within the stop surface defined by the first structure surface.

A method of forming a gas turbine engine component, the method including forming a plurality of cooling apertures in a preform structure of the component, the plurality of cooling apertures of the preform structure comprising a first cooling aperture and a second cooling aperture, wherein cross-sectional shapes of the first and second cooling apertures of the preform structure are different from one another, as measured in a same relative plane; and applying a coating to at least a portion of the preform structure to form the component, wherein a cross-sectional shape of the first and second cooling apertures of the component are approximately the same as one another, as measured in the same relative plane.

A construction system for mechanical metamaterials based on discrete assembly of a finite set of modular, mass-produced parts. A modular construction scheme enables a range of mechanical metamaterial properties to be achieved, including rigid, compliant, auxetic and chiral, all of which are assembled with a consistent process across part types, thereby expanding the functionality and accessibility of this approach. The incremental nature of discrete assembly enables mechanical metamaterials to be produced efficiently and at low cost, beyond the scale of the 3D printer. Additionally, a lattice structure constructed of two or more rigid, compliant, auxetic and chiral part types enable the creation of heterogenous macroscopic metamaterial structures.

An acoustic liner that may be for a turbofan engine may comprise a first sidewall, a second sidewall, wherein the first sidewall and the second sidewall define a plurality of cells disposed therebetween, and a pre-cut septum ribbon comprising a plurality of permeable septum coupled together via a plurality of connecting members, with each one of the plurality of permeable septum being generally in a respective one of the plurality of cells.