Abstract:
Methods are disclosed to render a wide range of titanium alloys superplastic at temperatures so low that oxidation is not a problem. Alpha beta alloys are vapor deposited to a particular microstructure which is superplastic. Alpha alloys and beta alloys are coevaporated with stabilizing particles.
Abstract:
An aircraft duplex hinge assembly (10 or 10') configured for use in aircraft, especially helicopters, having a compound curvature airframe (130) configuration wherein the edges of access panels (100) and the corresponding airframe apertures have a beveled configuration. The duplex hinge assembly (10 or 10') includes dual hinge mechanisms (20) and a latching mechanism (50) to deactivate the duplex hinge mechanism (10) with the access panel (100) in the closed position. The dual hinge mechanisms (20) include a primary mounting bracket (22) secured in combination with the airframe (130), a secondary mounting bracket (24) secured in combination with the access panel (100), and an interconnecting member (26) having a straight segment (30), an arcuate segment (32), and a protective flat segment (34). The straight and protective flat segments (30, 34) are mounted in rotatable combination with the primary and secondary mounting brackets (22, 24), respectively, and the protective flat segment (34) protects the access panel (100) from damage during opening and closing. One embodiment of the duplex hinge assembly (10) further includes an aft locking subassembly (40) that functions as the primary means for maintaining the access panel (100) in the closed position. Another embodiment of the duplex hinge assembly (10') includes a stabilizing member (60) secured in combination with the interconnecting members (26) and operative to stabilize the hinge mechanisms (20) and the access panel during opening and closing sequencing. Optionally, either embodiment of the duplex hinge assembly (10 or 10') may include a panel support assembly (70) that is operative to support and maintain the access panel (100) in a partially or fully open position.
Abstract:
A multiple beam laser sintering device includes a sintering beam (64) having a focal point at a powder bed (68) and at least one defocussed laser beam (116) incident on a region near the focal point of the focussed beam (64). The sintering beam (64) raises the temperature of the powder (84) to the sintering temperature. The defocussed beam (116) raises the temperature of the material surrounding the sintering beam (64) to a level below the sintering temperature, thereby reducing the temperature gradient between the sintering location and the surrounding material. Thermal radiation may be measured from one or both beams and used to control the power of one or both beams and the power of one or both beams may be controlled to maintain the temperature at a desired level. Alternatively, a plurality of defocussed beams may be used to provide either a plurality of thermal gradient steps, or to control the temperature of each region around the sintering point independently.
Abstract:
A temperature-controlled laser sintering system includes a laser beam (12) which is focussed onto a sintering bed (38) by a focussing mirror (26) and a set of scanning mirrors (32, 34). Thermal radiation (114) emitted from the sintering bed (38) are imaged to the scanning mirrors and to a dichroic beamsplitter (110) which reflects such radiation but passes the wavelength of the laser beam (12). The radiation (118) is focussed onto an optical detector (126) which provides a signal on a line (128) to a power control circuit (104). The power control circuit (104) controls a modulator (100) which modulates the power of the laser beam (112) so as to maintain the thermal radiation emission (114) (and thus the temperature at the sintering location) at a substantially constant level.
Abstract:
The recirculating flow in the vaned passage (32) in the case (44) surrounding the tips of the fan blades (43) of a turbo fan engine (10) or ducted fan propulsor is modified or blocked off during certain engine or aircraft operating modes. In one embodiment an aneroid valve (30) closes off the vaned passage (32) upon attaining a given altitude and fails open to assure that the safe stall margin is retained during take off. The active VPCT (32, 31, 30) serves to increase fan efficiency and engine thrust while maintaining stall margin at the required safety level. The vaned passage (24) in another embodiment is utilized to abate or preclude the stall precursor waves manifested by the rotor blade (43) by modulating (50, 58) the recirculating flow as a function of time.
Abstract:
A composite sandwich structure which includes upper and lower skin structures (20, 22), first and second honeycomb core structures (24, 26), and an intermediate portion disposed between the first and second honeycomb core structures. The intermediate portion comprises a composite laminate (30), a barrier member (32) and a foaming adhesive layer (34) disposed between the composite laminate and the barrier member. The foaming adhesive layer is of a type designed to expand when exposed to an elevated temperature. The composite laminate and the barrier member operate to limit the expansion of the foaming adhesive layer into the open cells of the first and second honeycomb core structures. The foaming adhesive layer, upon expansion, applies pressure against the composite laminate. This pressure, acting concomitantly with the applied curing pressure and the elevated temperature, cures the laminate. Furthermore, the expansion of the foaming adhesive urges the composite laminate and the barrier member apart so as to fill any core discrepancies, i.e., mistrimmed or damaged core, thay may exist in the honeycomb core structures.
Abstract:
A manipulator (26) for controlling force and position of a retained device (22) is disclosed. Various construction details are disclosed that provide a manipulator (26) which is back driveable and which provides planar control of both force and position of the device relative to an object being worked on. In a particular embodiment, the manipulator (26) includes an actuator assembly (46) having two pairs of voice coils (58, 59), a housing (56) gimbaled to a frame (45) and engaged with the actuator assembly (46) through a universal joint (54), and a tool (22) retained in a distal end of the housing (56). Excitation of the voice coils (58, 59) produces a planar force on the joint (54). Movement of the joint (54) results in pivoting of the housing (56) about the gimbal (76) and spherical motion of the device. In a further embodiment, the manipulator (26) includes a body (57) gimbaled to the housing (56) and a plurality of force transducers (82) disposed about the body (57) and between the body (57) and housing (56). Forces on the device may be measured by the response of the transducers (82). In another embodiment, the manipulator (26) includes a plurality of position sensors (114, 116) disposed about the gimbal (76) and between the housing (56) and frame (45). The plurality of position sensors (114, 116) respond to pivoting motion of the housing (56) such that the position of the device (22) may be monitored.
Abstract:
The flywheel containment device (2) includes a shaft (4), defining an axis of rotation, and a flywheel (6) having an annular shaped cross section perpendicular to the axis of rotation. The flywheel (6) is connected to the shaft (4) and has an outer diameter (5) and an inner diameter (3). The containment device (2) also comprises an annular shaped honeycomb structure (8) with an annular shaped honeycomb layer (10) having an outer diameter and an inner diameter greater than the outer diameter of the flywheel (6). The honeycomb layer (10) comprises a plurality of pores (11) that are open on the inner diameter of the honeycomb layer (10) to trap dust created if the flywheel (6) fails. The honeycomb layer (10) is positioned around the outer diameter of the flywheel (6) such that the honeycomb structure (8) is independent from the flywheel (6). The device (2) further includes means for supporting the honeycomb structure (8) such that the honeycomb structure (8) is capable of rotating independently from the flywheel (6). A containment vessel (18) is also positioned around the outer diameter of the honeycomb structure (8).
Abstract:
A method of repairing a combustion chamber assembly (32) from an axial flow gas turbine engine (20) is disclosed. Various details are developped which facilitate repair of the combustion chamber assembly of the engine. In one detailed embodiment, a laser beam (80) separates the bulkhead of the combustion chamber assembly from the remainder of the assembly to allow independent repair of the bulkhead and the remainder of the assembly.
Abstract:
A split tubular elastomer damper (20) has a pair of co-axial aligned elastomer members (29, 30) located in a split housing (21, 22), each member located in a respective, separate co-axially aligned housing with each having a lug (24, 27). A common independent shaft (34) attaches the members to each other such that strain induced displacements are split between the members. This maximizes the displacement capacity of the tubular elastomer damper, particularly in high stroking applications. Essentially, the amount of elastomer required to tolerate a designated strain is half that of a conventional damper, substantially reducing size and weight requirements while maintaining full functional properties.