Fused filament fabrication (FFF) is a widely used additive manufacturing process that is increasingly adopted for prototyping and is growing in popularity for manufacturing. Simultaneously, there is increasing consideration of material lifecycles in choosing and designing materials and material processing techniques. One approach to extending material lifetimes is enabling the recovery of material properties after damage through an autonomous self-healing behavior. Here, we investigate the microcapsule-solvent-based self-healing of high-impact polystyrene (HIPS), a common thermoplastic polymer, toward increasing FFF three-dimensional (3D) printed specimen lifetimes and improving material sustainability by fabricating robust materials. Double-walled self-healing microcapsules filled with an environmentally friendly ethyl phenylacetate solvent are synthesized using in situ interfacial emulsion polymerization and coated on polymer filaments prior to FFF 3D printing. The ability of these microcapsules to sustain the FFF 3D printing process is demonstrated, and the self-healing performance of FFF 3D printed HIPS composites is evaluated via quantification of mechanical properties and healing efficiency (up to 81% healing efficiency is achieved).

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Standards dealing with power quality disturbances and emission limits for equipment and installations are constantly evolving as additional knowledge is gained. Often, each type of disturbance, such as harmonics, is considered individually and without regard for the possible effects of other types of disturbances, such as unbalance. The interdependencies between the disturbance phenomena are often disregarded. The work reported in this paper is focused on quantifying and correlating the effect of supply system unbalance on the harmonic emissions of the most basic harmonic-producing converter, the uncontrolled six-pulse rectifier. Six-pulse rectifiers with different loading conditions are supplied by sources with varying levels of unbalance to determine the effect of the unbalance on harmonic emissions via simulation. Different unbalanced supply conditions, all within credible levels, are considered and the effects on the harmonic emissions of the six-pulse rectifier are evaluated. The results of these simulations show that as source unbalance increases, THD and triplen harmonics also increase in a nearly-linear pattern. This type of relationship may be appropriate for consideration in the ongoing efforts in standardization related to both harmonics and unbalance so that more coordinated decisions can be made.

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