This research used a discrete event simulation to create data on a shipment receiving process instead of using historical records on the process. The simulation was used to create records with different inputs and operating conditions and the resulting overall elapsed time for the overall process. The resulting records were used to create a set of predictive artificial neural network models that predicted elapsed time based on the process characteristics. Then, the connection weight approach was used to determine the relative importance of the input variables. The connection weight approach was applied in three different steps: (1) on all input variables to identify predictive and non-predictive inputs, (2) on all predictive inputs, and (3) after removal of a dominating predictive input. This produced a clearer picture of the relative importance of input variables on the outcome variable than applying the connection weight approach once.

Fused Granular Fabrication Additive Manufacturing (FGF AM) has the capability to create tooling that is lower cost than conventionally manufactured tooling and still has sufficient properties for many applications. A vacuum infusion (VI) mold was printed from fiberglass-acrylonitrile butadiene styrene (ABS) and evaluated for wear and suitability for small VI runs. The mold was designed to accentuate high wear as a “worst case” scenario. The mold was able to produce 10 parts successfully before any noticeable change occurred to the surface finish. By 14 parts, the surface finish had roughened sufficiently that demolding was difficult and resulted in damage to the part. Profilometry measurements showed a 7 × increase in roughness over the run. No significant tool wear or change in geometry was detected. Even longer life would be expected for typical tooling designs since the test mold was deliberately designed to accentuate wear and demolding issues. Based on these results, similar FGF molds are a feasible option for short run VI production for prototyping or low-volume composites manufacturing, possibly at lower cost and quicker turnaround time than machined aluminum molds.

Metal powder bed fusion (PBF) additive manufacturing (AM) builds metal parts layer by layer upon a substrate material. The strength of this interface between the substrate and the printed material is important to characterize, especially in applications where the substrate is retained and included in the finished part. Ensuring that this interface between the original and the printed material has adequate material properties enables the use of this PBF AM process to repair existing structures and create new parts using both AM and conventional manufacturing. This paper studies the tensile and torsional shear strengths of wrought and PBF-built SS316L specimens and compares them to specimens that are composed of half wrought material and half PBF material. These specimens were created by building new material via PBF onto existing wrought SS316L blocks, then cutting the specimens to include both materials. The specimens are also examined using optical microscopy and electron backscatter diffraction (EBSD). The PBF specimens consistently exhibited higher strength and lower ductility than the wrought specimens. The hybrid PBF/wrought specimens performed similarly to the wrought material. In none of the specimens did any failure appear to occur at or near the interface between the wrought substrate and the PBF material. In addition, most of the deformation in the PBF/wrought specimens appeared to be limited to the wrought portion of the specimens. These results are consistent with optical microscopy and EBSD showing smaller grain size in the PBF material, which correlates to increased strength in SS316L due to the Hall–Petch relationship. With the strength at the interface meeting or exceeding the strength of the original wrought material, this process shows great promise as a method for adding additional features or repairing existing structures using metal PBF AM.

Metal powder bed fusion (PBF) additive manufacturing (AM) builds metal parts layer by layer upon a substrate material. The strength of this interface between substrate and printed material is important to characterize, especially in applications where the substrate is retained and included in the finished part. This paper studied the tensile and torsional strengths of wrought and additively manufactured (through PBF) SS316L and compared them to specimens composed of half wrought material and half PBF material. The PBF specimens consistently exhibited higher strength and lower ductility than the wrought specimens. The hybrid PBF/wrought specimens performed similarly to the wrought material. In no specimens did any failure appear to occur at or near the interface between wrought substrate and PBF material. In addition, most of the deformation in the PBF/wrought specimens appeared to be limited to the wrought portion of the specimens. These results are consistent with microscopy showing smaller grain size in the PBF material, which often leads to increased strength in SS316L due to the Hall-Petch relationship.

In designing for a system’s lifecycle considerations, long-term energy needs often become an important limiting factor. Shifting from conventional energy sources (e.g. fossil fuels) toward renewable sources (e.g. wind and solar) has become a popular means for focusing on the lifecycle of large-scale systems like automobiles and the national electrical grid. This same shift in small, low-power systems such as sensors has the additional advantage of potentially increasing the operational life of the systems. This paper introduces a methodology for determining the feasibility of in situ energy harvesting as a viable power source for a given low-power system. The method is demonstrated by considering a wireless sensor node and the specific application of monitoring the fatigue life of highway bridges, with a target operational life of ten years for the sensor node. Peak and average power requirements for wireless sensor nodes are calculated and compared to the power density available from solar, wind, and vibration energy. Energy storage is also discussed, including both disposable batteries (as the status quo with which to compare energy harvesting) and rechargeable systems (as a necessary component of the energy harvesting system). Solar, wind, and vibration energy are all found to be feasible sources of power for this particular application. Vibration harvesting has lower power density than solar and wind harvesting, but has the advantage of being less dependent on location, more self-contained, and largely maintenance free. Energy harvesting in general only becomes attractive for projected life cycles exceeding the life of disposable batteries, which for this particular application is estimated at 4–6 years. Thus, energy harvesting is an excellent way to extend the lifespan of low-power systems where power availability is the limiting factor.