Abstract: A drive shaft which includes a first tube body having one or more first body channels defined through a wall thickness thereof. The one or more channels are configured to increase bending and/or axial flexibility of the first tube body while only allowing for a less than proportional reduction in torsional stiffness of the first tube body. A second tube body can be concentrically disposed relative to the first tube body and connected to the first tube body at a first end portion and a second end portion. The second tube body can include one or more second body channels defined through a wall thickness thereof. The one or more channels are configured to increase bending and/or axial flexibility of the second tube body while only allowing for a less than proportional reduction in torsional stiffness of the second tube body.

Abstract: In accordance with at least one aspect of this disclosure, a composite shaft includes a plurality of composite elements arranged about an axis to form a hollow shaft with at least one undulation. The plurality of composite elements incudes a first group of the composite elements arranged about the axis offset by an angle +? and a second group of the composite elements arranged about the axis offset by an angle ?? to form a web with the first group of composite elements. The first and second groups of the plurality of composite elements are configured to cooperate with one another to allow the hollow shaft to be flexible under axial load and stiff under rotational load.

Abstract: A flexible coupling includes a first flange and a second flange, wherein in a relaxed state the first flange and the second flange are each aligned along a longitudinal axis. A plurality of first coupling members extends from the first flange. Each first coupling member includes a first and second driving beam meeting at a first node to form a topologically triangular truss. A plurality of second coupling members extend from the second flange. Each second coupling member includes a first and second driven beam extending from the second flange and meeting at a second node to form a topologically triangular truss. The first node of each of the first coupling members is connected to the second node of a respective one of the second coupling members.

Abstract: A polymer-matrix fiber-reinforced composite structure includes a plurality of polymer composite layers having at least one polymer composite layer that includes a first polymer-matrix and a first fluorescent agent interspersed through the first polymer-matrix. Damage to the polymer composite structure results in a change in fluorescence at the point of damage. A method for detecting damage in the polymer composite structure described above including the steps of applying light having a wavelength selected to induce fluorescence in the first fluorescent agent to the polymer composite structure, detecting a detected fluorescence pattern, and comparing the detected fluorescence pattern to a predetermined normal fluorescence pattern.

Abstract: A drive shaft has a tubular member extending between axial ends and being hollow. The tubular member is formed of a thermoplastic matrix with embedded fibers. At least one ring member is positioned radially of the tubular member. A method is also disclosed.

Abstract: A drive shaft for transferring torque including a tubular insert extending along an axis and defining a first layer of the drive shaft including at least one straight portion and at least one undulation, wherein the tubular insert includes a first material having a first deformation temperature, and a polymeric tubular covering defining a second layer of the drive shaft surrounding the tubular insert including a second material having a deformation temperature lower than the deformation temperature of the first material, wherein the covering includes at least one straight portion adjacent to the straight portion of the tubular insert and at least one undulation adjacent to the at least one undulation of the tubular insert.

Abstract: A composite shaft includes a shaft body formed from a plurality of polymer impregnated fiber-reinforced material layers having an annular outer surface and an annular inner surface defining a passage. A plurality of internal support members extend along the passage. Each of the plurality of internal support members includes a support body formed from molded plastic having an outer surface that abuts the annular inner surface of the support body, a first end, an opposing second end, and a circular end wall arranged at one of the first end and the opposing second end.

Abstract: A drive shaft extending along a central axis is configured to operate under dominant unidirectional torsional load. The drive shaft has an asymmetrically-structured composite body which is configured to have a greater torque-carrying capability in a first torsional direction than in a second torsional direction that is opposite the first torsional direction.

Abstract: A drive shaft has a central tubular portion formed of a polymer composite with imbedded fibers. It extends between a first end and a second end. The central tubular portion has an outer peripheral surface. There is at least one ring on the outer peripheral surface of the central tubular portion. A method of repairing a composite material tube includes the steps of (a) identifying a damaged area on a composite tube, and (b) placing a patch on a surface of the tube and over the damaged area.

Abstract: A flexible coupling includes a first flange having an outer edge, a first surface, a second surface opposite the first surface, and a first plurality of passages. A second flange including an outer edge section, a first surface section, a second surface section opposite the first surface section, and a second plurality of passages. A connecting element extends between and connecting the first flange and the second flange through one of the first plurality of passages and one of the second plurality passages. The connecting element includes a connecting member having a first stop element and a second stop element. A compliant component is arranged on the connecting element. The compliant component is positioned on the connecting member between one of: the first stop element and the first surface; the second stop element and the second surface section; and between the second surface and the first surface section.

Abstract: A drive shaft has a central tubular portion formed of a polymer composite with imbedded fibers. It extends between a first end and a second end. The central tubular portion has an outer peripheral surface. There is at least one ring on the outer peripheral surface of the central tubular portion. A method of repairing a composite material tube includes the steps of (a) identifying a damaged area on a composite tube, and (b) placing a patch on a surface of the tube and over the damaged area.

Abstract: A mechanical part configured to be placed under torque. The mechanical part includes an inner tube having, a corrugated web, and an outer shell. The inner tube has an outer tube circumference, a tube axial direction, and a tube length. The corrugated web has a plurality of peaks and a plurality of troughs, a height measured as a difference between one of the peaks and one of the troughs, and a web length perpendicular to the height and in the tube axial direction. The outer shell has an inner shell circumference, an outer shell circumference, and a shell length. The plurality of troughs is affixed to the outer circumference of the inner tube. The plurality of peaks is affixed to the inner shell circumference of the outer shell. The web length is aligned with the tube length and the shell length.

Abstract: A drive shaft has a tubular member extending between axial ends and being hollow. The tubular member is formed of a thermoplastic matrix with embedded fibers. At least one ring member is positioned radially of the tubular member. A method is also disclosed.

Abstract: In accordance with at least one aspect of this disclosure, a composite structure can be formed of or including a plurality of composite strips. The plurality of composite strips include one or more filler strips which can have at least one filler edge having a filler edge geometry between a first surface and second surface, the second surface being opposite the first surface. The filler edge geometry can be configured to prevent formation of one or more gaps between one or more adjacent composite strips.

Abstract: In accordance with at least one aspect of this disclosure, a composite structure can be formed of or including a plurality of composite strips. The plurality of composite strips include one or more filler strips which can have at least one filler edge having a filler edge geometry between a first surface and second surface, the second surface being opposite the first surface. The filler edge geometry can be configured to prevent formation of one or more gaps between one or more adjacent composite strips.

Abstract: In accordance with at least one aspect of this disclosure, a drive shaft includes, a first tube body having one or more first body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the first tube body while only allowing for a less than proportional reduction in torsional stiffness of the first tube body. A second tube body can be concentrically disposed relative to the first tube body and connected to the first tube body at a first end portion and a second end portion. The second tube body can include one or more second body channels defined through a wall thickness thereof, the one or more channels configured to increase bending and/or axial flexibility of the second tube body while only allowing for a less than proportional reduction in torsional stiffness of the second tube body.

Abstract: A drive shaft extends between axial ends and has at least one portion through which an outer diameter of the drive shaft changes through an infinite number of diameters, with the at least one portion extending across at least 15% of an axial distance between the axial ends of the drive shaft. A drive shaft with a generally spiral undulation at its outer periphery is also disclosed.

Abstract: An aircraft drive shaft including an outer shaft having a first diameter configured to couple a first gearbox and a second gearbox to provide power transfer between the two gearboxes, an inner shaft concentric with the outer shaft and having a second diameter configured to provide structural support to the outer shaft, a gap defined between an outer peripheral surface of the inner shaft and an inner peripheral surface of the outer shaft, wherein the gap is sized according to a ballistic projectile cross-section size that the aircraft is considered to encounter on an upcoming mission, and a sleeve located at least at first end of the outer shaft connecting the outer shaft to the inner shaft.

Abstract: A drive shaft is for selectively connecting a drive input to an output. The drive shaft has a tubular portion, a first diaphragm member, and a second diaphragm member displaced axially along the shaft from the first diaphragm member. The first and second diaphragm members each are formed with two axial ends. At least one undulation extends radially of the ends. The tubular portion connects the first and second diaphragm members. The first and second diaphragm members and the tubular portion are formed of fiber-reinforced polymer matrix composites. The first and second diaphragm members are connected to first and second axial ends of the tubular portion through a mechanical connection at joints. There is also a method of forming a drive shaft.

Abstract: A drive shaft body extends between axial ends and has an outer peripheral surface with undulations extending between relatively greater and smaller outer diameters. The undulations extend along a non-zero angle relative to a circumferential direction defined relative to a drive axis of the drive shaft. The undulations extend along a spiral. The drive shaft body is formed of a fiber-reinforced composite material.