Search

The in situ inspection technology for additive manufacturing combines different types of cameras strategically placed around the part to monitor its properties during construction. The IR cameras collect accurate temperature data to validate thermal math models, while the visual cameras obtain highly detailed data at the exact location of the laser to build accurate, as-built geometric models. Furthermore, certain adopted techniques (e.g., single to grouped pixels comparison to avoid bad/biased pixels) reduce false positive readings. NASA has developed and tested prototypes in both laser-sintered plastic and metal processes. The technology detected errors due to stray powder sparking and material layer lifts. Furthermore, the technology has the potential to detect anomalies in the property profile that are caused by errors due to stress, power density issues, incomplete melting, voids, incomplete fill, and layer lift-up. Three-dimensional models of the printed parts were reconstructed using only the collected data, which demonstrates the success and potential of the technology to provide a deeper understanding of the laser-metal interactions. By monitoring the print, layer by layer, in real-time, users can pause the process and make corrections to the build as needed, reducing material, energy, and time wasted in nonconforming parts.

Friction plug welding is a process in which there is a small rotating part (plug) being spun and simultaneously pulled (forged) into a larger part to fill or repair a hole or join two pieces (functioning like a rivet). Learning from 1,500+ quality &#34known&#34 plug welds, NASA&#146s experts build a load curve that, when combined with the welders&#146 knowledge of strain size, predicts the properties of a plug weld. The software monitors load, spindle speed, torque, displacement speed and distance, and the material properties and dimensions of the sample. The software correlates changes in the process parameters to mechanical testing of ultimate tensile strength. The software works for several Aluminum alloys such as 2015, 2195, and 2219. NASA is using the technology in its current work for closing out the termination hole of some friction stir welds. FPW is also used for repairs and as a potential replacement for rivets.

The process of forming thermal insulation wafer begins with layering a photo resist pattern on an aluminum coated substrate. After the aluminum is etched, a temporary adhesive is applied to the photo resist and substrate. Next, the construction undergoes wafer scale bonding to a silicon insulator. The silicon insulator is then patterned and etched down to the buried oxide layer. The temporary adhesive is then dissolved in acetone. The acetone is diluted with non-polar solvents which are then removed via critical drying. Goddard Space Flight Center has produced multiple arrays of crystalline silicon membranes that were 450 nm thick and were isolated from a silicon support structure by thermal isolation structures that were 30 microns thick and 5 microns long. The largest membranes, among which had 100 % mechanical yield, had an aerial footprint of 1.6 mm x 1.4 mm.

Friction Pull Plug Welding (FPPW) is the process necessary to plug the hole that is left behind as a friction stir weld (FSW) joint is completed and the pin tool of the welder retracts from the joint. FPPW involves a small, rotating part (plug) being spun and simultaneously pulled (forged) into a hole in a larger part. Much work has been done to fully understand and characterize the process and its limitations. FPPW worked very well for building large rocket sections such as the circumferential welds of the upper stages of NASA's Ares rocket, and to repair the external tank. Engineers were challenged to adapt FPPW to accommodate the thicker plates new alloy combinations of the SLS. The new hybrid plug solves the issue of the plugs snapping due to the increase torsion and moment stresses when joining thicker plates. The new hybrid plug, with a steel shank, makes FPPW more practical and robust. The new plug has been used to make space-qualified parts at NASA, and the plug welds are as strong as initial welds.

This invention provides an array of nanopipette channels, formed and controlled in a metal-like material that supports anodization. The invention also permits selective first and second functionalizations, which may be the same or be different, of first and second channel surfaces so that different reactions of a multi-component fluid flowing in these channels can be evaluated simultaneously. The materials that support anodization include aluminum, magnesium, zinc, titanium, tantalum and niobium, referred to as "AN-metals." The relevant, controllable anodization parameters include applied electrical potential, current density, electrolyte concentration,solution pH, solution temperature and anodization time. The channel parameters that can be controlled include pore diameter, pore density or spacing and maximum channel length of a pore. An anodization process is initially applied to provide a plurality of adjacent nanopipette channels having inner diameters in a selected range, such as 10-50 nanometers (nm). The nanopipette array can sense the presence of a specified component(s), by production of a characteristic signal associated with the functionalized site in the presence of the specified component. Differing concentrations of the same specified component can also be estimated and controlled.

This fabrication method allows for a minimalistic silicon wafer to be used as a circuit board while reducing space and increasing efficiency by depositing superconducting material on both sides. Due to the thin nature of the silicon wafer, an additional backing handle wafer is required during the fabrication of this circuitry to allow for deposition of metal thin film on a hot substrate on one side of the wafer. In addition, a metallic and polymeric sacrificial layer is used to protect the silicon substrate and superconducting metallic layers during removal of the unwanted silicon, buried oxide, and epoxy layers. This process introduces the fabrication methodology required to realize the ultra-low loss transmission lines and ultra-low crosstalk between superconducting sensors.

NASA's researchers have designed modular fixtures to address inefficiencies in time, labor, and material costs due to the need to fabricate unique, monolithic fixture bodies for different segments of the Space Launch System (SLS). Before NASA staff can configure and weld rocket sections, they must assemble modular tooling atop a large turntable with radial grooves. Supporting braces (tombstones) that form the base of the modular structure slide into radial grooves. Other extending, clamping, and joining fixtures can be variously connected to the base structure to provide circumferential support for producing conical and cylindrical structures. NASA has used the tooling to produce structures with diameters of up to 27 feet. Depending on the desired application, the base can be scaled to produce larger or smaller diameters, and the grooves can be arranged with a longitudinal arrangement for production of parts with bilateral symmetry. The development of these modular fixtures required an initial investment similar to that of a single project's tool design and fabrication costs. Once produced, only a fraction of that time/cost is required to begin all subsequent projects. NASA has used this new, adaptable tooling in the construction of several different rocket stages, proving its cost-saving capabilities.

Ultrasonic Stir Welding is a solid state stir welding process, meaning that the weld work piece does not melt during the welding process. The process uses a stir rod to stir the plasticized abutting surfaces of two pieces of metallic alloy that forms the weld joint. Heating is done using a specially designed induction coil. The control system has the capability to pulse the high-power ultrasonic (HPU) energy of the stir rod on and off at different rates from 1-second pulses to 60-millisecond pulses. This pulsing capability allows the stir rod to act as a mechanical device (moving and stirring plasticized nugget material) when the HPU energy is off, and allowing the energized stir rod to transfer HPU energy into the weld nugget (to reduce forces, increase stir rod life, etc.) when the HPU energy is on. The process can be used to join high-melting-temperature alloys such as titanium, Inconel, and steel.

Originally conceived as a method to generate pressurized pure oxygen for extravehicular activity (EVA) suits worn on the International Space Station, Glenn's technology represents a significant breakthrough. The generator is an all-solid-state device that separates oxygen from air, water, or carbon dioxide and electrochemically pumps it to a high pressure in a multi-stage process. Glenn's design features a solid oxide electrolysis (SOE) stack, based on bi-supported cell design, that is structurally supported by two electrode layers. Sandwiched between the cathode and anode sides is an oxygen-ion conducting solid-state electrolyte membrane, made of yttria-stabilized zirconia (YSZ). These membranes form the individual SOE cells within the stack, and each cell carries out a single stage of the multi-stage process, with each stage incrementally pressurizing the oxygen. A voltage (1.5 to 2 volts) is applied across the cell, and the air or other input is supplied to the cathode side, where the oxygen dissociates into oxygen ions. The YSZ membrane will conduct only the oxygen ions, producing pure, dry oxygen. The entire stack is wrapped in a glass ceramic seal, providing a pressure vessel for the device. Glenn's novel stack design allows hermetic sealing and does not require a compression sealing mechanism or other spring-loaded hardware. Each cell is wired in parallel so the voltage can be controlled across each cell to avoid electrochemical reduction of the electrolyte. In addition, each cell is electrically insulated from other cells in the stack using a non-electronically conducting, ceramic-woven cloth YSZ layer. Because Glenn's process resists fouling from water containing impurities or other debris, it does not require a high-purity water source, as do other water electrolysis technologies. The oxygen product is also sterile for medical applications because of the high temperature (in excess of 600°C) at which the process operates.