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The objectives of this work are threefold: (1) quantify the effects that certain print parameters have on the mechanical performance of parts produced by Low Force Stereolithography (LFS), (2) demonstrate the relative impact that certain print parameters have on the mechanical performance of LFS parts and (3) propose theoretical parameter schemas to optimize LFS prints. This work presents the mechanical properties of LFS parts with respect to distinct LFS print parameters, namely print orientation (PO), print layer thickness (LT), post-print cure time (CM) and post-print cure temperature (CT) at three (3) levels apiece. To date, LFS has been largely unstudied; however, as a novel approach with unique engineering material availability, it is important to quantify its overall performance. Using D638-22 to analyze this additive method, it was found that the Segment Modulus (SE), Ultimate Strength (US), percent elongation (%e), Poisson's ratio (ν) and Toughness (T) all varied greatly across the nine (9) distinct sample types designed for the study. Specifically, SE, US, %e, ν and T achieved a minimum/maximum of 331/463 ksi, 4.39/9.07 ksi, 1.20/3.55%, 0.377/.450 and 0.033/.200 ksi, respectively, depending on the parameters chosen. This wide range of property data must be coupled to LFS print parameters if the technology is to be implemented as a viable approach to manufacture end-use or provisional tooling. Furthermore, it is essential to understand the relationship between a given property and a specific parameter. S/N plots were used to quantify both of these relationships. The results indicate that all print parameters influence the mechanical performance of LFS parts.

This work presents W-band (75–110 GHz) dielectric characterization of commercially available photoresins in their neat state, as well as in polymer matrix composite (PMC) mixtures with various loading concentrations of the paraelectric barium strontium titanate (BST). Due to difficulties 3D printing the BST-loaded PMC resins detailed within, a custom curing and casting process was used to fabricate testable PMC samples, which were synthesized to demonstrate the dielectric functionalization of the underlying polymer matrix. Dielectric characterization of the PMCs confirmed the functionalization of our composites when compared to the commercial photoresins. For example, a volumetric loading concentration of 25 vol % BST increased the dielectric permittivity (εr) from 2.78 to 9.60 and the loss tangent (tanδ) from 0.022 to 0.114. These results indicate that the realization of UV-cured photoresins with “designer-dielectric” functionalization based on vol % of filler are strong candidates for use in stereolithography (SLA) 3D printing applications. To accomplish this, and with a special interest for radio/microwave/terahertz (RF/MW/THz) applications, we highlight the need for both (a) better photoresin matrix materials with lower intrinsic tanδ and (b) selection criteria related to the size/geometry and electronic properties of potential filler materials to maintain the printability of PMC photoresins in SLA systems.