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In this paper, an analysis of the flexible printed circuit board (FPCB) windings is performed. A one-dimensional model of the flex-wire winding is introduced and an equation for the FPCB ac winding resistance is derived. Experimental verification of derived equations is performed, i.e., impedance and power loss measurements.
This feasibility study demonstrates the ability to additively manufacture 3D parts from reactive metal alloys using robotically controlled wire arc additive manufacturing (WAAM). Experiments consisted of developing WAAM welding parameters and performing robotic welding inside a controlled atmosphere purge box that was specifically built for this project. Purge atmospheres with varying levels of oxygen were created to determine minimum purge requirements for WAAM builds in order to build components without significant uptake of oxygen or nitrogen. Weld parameters were successfully developed for a titanium alloy (Ti-6-4) and tantalum, both being very sensitive to atmospheric contamination during welding. WAAM builds were made from Ti-6-4, Ta, and also 308L stainless steel to relate back to previous results for 308L WAAM studies performed in air. Oxygen purge levels varied from 1000 ppm to 1 ppm, and were further compared to builds made at atmospheric levels of O 2 (21%). Results showed significant uptake of oxygen and nitrogen for all three metals for WAAM parts built outside the inert atmosphere box, where only shielding gas from the welding torch was used as protection. However, considerable reduction of oxygen and nitrogen uptake, in all three metals, was observed even for moderate purge levels of 1000 ppm O 2 in the box. Additional purging reduced oxygen and nitrogen uptake further and was shown to be metal dependent where Ta and Ti-6-4 were more sensitive to nitrogen uptake than oxygen uptake. Guidelines for the measured O 2 content of WAAM purge atmospheres were created as follows: 900 ppm for 308L SS, 130 ppm for Ti-6-4, and 40 ppm for Ta. These purge levels produced nitrogen and oxygen contents of the build similar to the wire composition and within the allowable specifications for these metals.
Simple circuit provides interface between normally incompatible voicecommunication lines. Circuit maintains 40 dB of isolation between input and output halves of four-wire line permitting two-wire line to be connected. Balancing potentiometer, Rg, adjusts gain of IC2 to null feed through from input to output. Adjustment is done on workbench just after assembly.
The objective of this program is to address safety and reliability issues of complete wiring systems. The plans for carrying out the objective include the following: determine the wiring system design factors; investigate circuit protection technologies; and address manufacturing and maintenance procedures.
Large-scale additive manufacturing (AM) is of interest in the manufacturing industry to produce components of dimensions on the order of hundreds of millimeters to meters in scale. Wire-arc AM (WAAM) of Ti-6Al-4V (Ti64) is an attractive technique for large-scale AM in the aerospace industry, give the high strength-to-weight ratio of the material and high deposition rate of the process. However, due to the large scale, significant distortion and residual stresses are developed in the material during deposition and cooling, potentially leading to part failure. WAAM of a prototypical large-scale Ti64 machine tool component is studied in this work via finite element analysis (FEA). Element activation/deactivation technique is employed to simulate deposition and the resulting distortion and residual stress (RS) predictions are analyzed to evaluate the possibility of crack formation. Significant distortion (∼10 mm) and RS (>1300 MPa) is predicted, suggesting the formation of cracks and possible crack propagation into the build region. Incorporation of fillets significantly reduces RS concentration regions, thus reducing the possibility of part failure. Material deposition sequence also affects the RS pattern in the build.
The performance of a constant-temperature normal hot-wire in a supersonic flow is critically examined. It is shown that this instrument is inherently unsuitable for measuring turbulent temperature correlations because of the highly nonlinear response to temperature fluctuations, particularly at low overheat ratios. The instrument is therefore limited to measurements of mean and fluctuating mass-flow rates. Suitable calibration procedures, as well as the limits on spatial and temporal resolution are discussed, and corrections for mean stagnation temperature changes are suggested.
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