Abstract: A check valve is disclosed that includes a base having a porous first surface, a keeper coupled to the base, and a flexible leaf with a first section that is fixedly coupled between the keeper and the base and a second section that is cantilevered from the first section. The leaf has a first position when the leaf is fully in contact with the base and a second position when the leaf is fully in contact with the keeper. The leaf is configured to sealingly cover the porous first surface when the leaf is in the first position. The leaf is in an unstressed configuration when in the first position, and a maximum stress in the leaf is less than the yield stress when the leaf is in the second position. The check valve is particularly suited for use with cryogenic fluids such as liquid hydrogen and liquid oxygen.

Abstract: A powder delivery system for a laser-based additive manufacturing process includes a hopper adapted to contain a powder and continuously feed the powder through an output of the hopper, a rotatable disk having a top surface that is substantially flat, the top surface adapted to receive the powder continuously fed through the output of the hopper, the top surface being disposed below the output of the hopper by a prescribed gap, and a vacuum powder removal device operable to remove the powder from the top surface via a vacuum.

Abstract: According to one embodiment of the invention, a system for fabricating a part includes a computer operable to control the fabrication of a three-dimensional part using a solid CAD model, a deposition station operable to deposit successive two-dimensional layers of material to fabricate the three-dimensional part, and a machining station operable to remove at least a portion of one or more of the deposited two-dimensional layers of material. The deposition station includes a substrate on which to fabricate the three-dimensional part, a welding-based deposition system having a welding torch, a laser-based deposition system having a laser head, a plasma powder cladding system having a plasma torch, and a multi-axis robot operable to, when directed by the computer, utilize one of the welding-based deposition system, laser-based deposition system, and plasma powder cladding system to deposit any of the two-dimensional layers of material.

Abstract: According to one embodiment of the invention, a method for controlling the size of the molten pool in a laser based additive manufacturing process includes coaxially aligning an imaging device with a laser nozzle and imaging a molten pool, created by a laser, on a substrate with the imaging device. The method further includes comparing at least one characteristic of the molten pool with a respective characteristic of a target molten pool, and adjusting, in substantially real-time, a laser power of the laser based on the comparison in order to correlate the characteristic of the molten pool with the respective characteristic of the target molten pool.

Abstract: According to one embodiment of the invention, a method for controlling operational weld parameters of a welding-based deposition process includes generating a solid model representing a three-dimensional part on a computer, electronically slicing the solid model into a plurality of electronic two-dimensional layers, identifying a path of material deposition based on the electronic two-dimensional layers, the path comprising a plurality of deposition points, and determining a geometrical factor for each deposition point. The geometrical factor is defined by a ratio of an actual volume of material around each deposition point to a theoretical volume of material around each deposition point. The method further includes automatically adjusting, during material deposition for a respective deposition point, one or more parameters of the welding-based deposition process based on the geometrical factor for the respective deposition point.