Additive manufacturing technologies have developed rapidly in recent decades, pushing the limits of known manufacturing processes. The need to study the properties of the different materials used for these processes comprehensively and in detail has become a primary goal in order to get the best out of the manufacturing itself. The widely used thermoplastic polymer material acrylonitrile butadiene styrene (ABS) was selected in the form of both filaments and ABS-like resins to investigate and compare the mechanical properties through a series of different tests. ABS-like resin material is commercially available, but it is not a sufficiently mechanically studied form of the material, which leads to the rather limited literature. Considering that ABS resin is a declared material that behaves like the ABS filament but in a different form, the objective of this study was to compare these two commercially available materials printed with three different 3D printers, namely Fused Deposition Modelling (FDM), Stereolithography (SLA) and Digital Light Processing (DLP). A total of 45 test specimens with geometries and test protocols conforming to the relevant standards were subjected to a series of tensile, three-point bending and compression tests to determine their mechanical properties. Characterization also included evaluation of morphology with 2D and 3D microscopy, dimensional accuracy of 3D scans, and Shore A hardness of each material and 3D printing process. Tensile testing results have shown that FDM toughness is 40% of the value for DLP. FDM elongation at break is 37% of DLP, while ultimate tensile stress for SLA is 27% higher than FDM value. Elastic modulus for FDM and SLA coincide. Flexure testing results indicate that value of DLP flexural modulus is 54% of the FDM value. SLA strain value is 59% of FDM, and DLP ultimate flexure stress is 77% of the value for FDM. Compression test results imply that FDM specimens absorb at least twice as much energy as vat polymerized specimens. Strain at break for SLA is 72% and strain at ultimate stress is 60% of FDM values. FDM yield stress is 32% higher than DLP value. SLA ultimate compressive stress is half of FDM, while value for DLP compressive modulus is 69% of the FDM value. The results obtained are beneficial and give a more comprehensive picture of the behavior of the ABS polymers used in different forms and different AM processes.

This study investigates the environmental aging effects on 3D-printed Acrylonitrile Butadiene Styrene (ABS) produced using Fused Deposition Modeling (FDM) and Digital Light Processing (DLP) techniques. The materials in filament (FDM) and resin (DLP) forms were exposed to UV light, humidity, and temperature fluctuations over two months. Mechanical testing via three-point bending and Fourier Transform Infrared Spectroscopy (FTIR) were employed to assess the impact of these environmental factors. Results showed notable mechanical strength and structural stability differences between the FDM-printed filament and DLP-printed resin ABS under aging conditions. The filament-based ABS exhibited superior mechanical properties, retaining its strength over time, while the resin-based ABS degraded significantly shortly after printing. Despite exposure to ambient environmental conditions, the chemical composition of both materials remained stable throughout the research period.

This paper presents theoretical and experimental aspects of Jacobian nullspace use in kinematically redundant robots for achieving kinetostatically consistent control of their compliant behavior. When the stiffness of the robot endpoint is dominantly influenced by the compliance of the robot joints, generalized stiffness matrix can be mapped into joint space using appropriate congruent transformation. Actuation stiffness matrix achieved by this transformation is generally nondiagonal. Off-diagonal elements of the actuation matrix can be generated by redundant actuation only (polyarticular actuators), but such kind of actuation is very difficult to realize practically in technical systems. The approach of solving this problem which is proposed in this paper is based on the use of kinematic redundancy and nullspace of the Jacobian matrix. Evaluation of the developed analytical model was done numerically by a minimal redundant robot with one redundant d.o.f. and experimentally by a 7 d.o.f. Yaskawa SIA 10F robot arm.

This study investigates the effects of environmental aging on the tensile properties of 3D printed specimens using Fused Deposition Modelling (FDM), Stereolithography (SLA) and Digital Light Processing (DLP) technologies. Specimens are printed from Acrylonitrile Butadiene Styrene (ABS) filament and ABS-based resin. Tensile testing is conducted on samples directly after printing and then following aging periods of one month and two months in a controlled environment (23 °C, 55 % RH). Statistical analysis is performed using ANOVA to evaluate the influence of the printing method, material type, and aging time on tensile strength, Young’s modulus, and elongation at break. The tensile performance of FDM-printed specimens generally decreases over time, which is evident from the comparative analysis. Specimens aged for two months exhibit significantly reduced tensile strength compared to both unaged and one-month aged SLA specimens. Interestingly, one-month aged specimens show a slight improvement in tensile performance com-pared to unaged samples which is an unexpected outcome. On the other hand, DLP specimens display a clear sensitivity to the aging process, with a marked degradation in performance when subjected to tensile load over time. This highlights a lack of tolerance to aging in DLP 3D printed materials under mechanical stress.