Generalized requirements and decompositions for the design of test parts for micro additive manufacturing research

AbstractThe design of experimental test parts to characterize micro additive manufacturing (AM) processes is challenging due to the influence of the manufacturing and metrology processes. This work builds on the lessons learned from a case study in the literature to derive generalized requirements and high level decompositions for the design of test parts and the design of experiments to characterize micro additive manufacturing processes. While the test parts and the experiments described are still work in progress, the generic requirements derived from them can serve as a starting point for the design of other micro additive manufacturing related studies and their decompositions can help structure future work

Additive manufacturing with vat polymerization method for precision polymer micro components production

The direct fabrication of miniaturized polymer components by Additive Manufacturing (AM) processes is a remarkable method at the micro dimensional scale. However, the measurement of complex micro products and the evaluation of the related uncertainty are still particularly challenging and necessary in the micro AM field. In the DTU, a proprietary Vat Photopolymerization machine able to produce micro features has been designed, built and validated. This study evaluates the capability of the machine in terms of printed dimensions and the corresponding uncertainty assessment. For this purpose, two test parts with micro features of different geometries and dimensions have been designed and five samples of each test part have been printed. The dimensions of the micro features have been evaluated for quality control capability assessment and to stablish procedures for verification of AM machines

Impact of beam shape on print accuracy in digital light processing additive manufacture

Photopolymerization-based additive manufacturing requires selectively exposing a feedstock resin to ultraviolet (UV) light, which in digital light processing is achieved either using a digital micromirror device or a digital mask. The minimum tolerances and resolution for a multilayer process are separate for resolution through the Z-axis, looking through the thickness of a printed part, and resolution in the XY-axes, in the plane of the printed layer. The former depends wholly on the rate of attenuation of the incident UV light through the material relative to the mechanical motion of the build layer, while the latter is determined by a two-dimensional pattern of irradiance on the resin formed by the digital micromirror device or the digital mask. The size or the spacing of elements or pixels of this digital mask is frequently given by manufacturers as the “resolution” of the device, however, in practice the achievable resolution is first determined by the beam distribution from each pixel. The beam distribution is, as standard, modeled as a two-parameter Gaussian distribution but the key parameters of peak intensity and standard deviation of the beam are hidden to the user and difficult to measure directly. The ability of models based on the Gaussian distribution to correctly predict the polymerization of printed features in the microscale is also typically poor. In this study, we demonstrate an alternative model of beam distribution based on a heavy-tailed Lorentzian model, which is able to more accurately predict small build areas for both positive and negative features. We show a simple calibration method to derive the key space parameters of the beam distribution from measurements of a single-layer printed model. We propose that the standard Gaussian model is insufficient to accurately predict a print outcome as it neglects higher-order terms, such as beam skew and kurtosis, and in particular failing to account for the relatively heavy tails of the beam distribution. Our results demonstrate how the amendments to the beam distribution can avoid errors in microchannel formation, and better estimates of the true XY-axes resolution of the printer. The results can be used as the basis for voxel-based models of print solidification that allow software prediction of the photopolymerization process

Design of Test Parts to Characterize Micro Additive Manufacturing Processes

AbstractThe minimum feature size and obtainable tolerances of additive manufacturing processes are linked to the smallest volumetric elements (voxels) that can be created. This work presents the iterative design of a test part to investigate the resolution of AM processes with voxel sizes at the micro scale. Each design iteration reduces the test part size, increases the number of test features, improves functionality, and decreases coupling in the part. The final design is a set of three test parts that are easy to orient and measure, and that provide useful information about micro additive manufacturing processes

Anàlisi de resultats d'una campanya experimental d'assaigs realitzada sobre provetes fabricades per impressió 3D-DLP

En aquest projecte es valora una possible actualització a l’ANSYS Workbench d’aquelles assignatures impartides a l’Escola Tècnica Superior d’Enginyeria Industrial de Barcelona on s’utilitza el mètode dels elements finits i l’ANSYS APDL i se’n facilita la transició mitjançant l’elaboració d’un manual, adaptació de guions procedimentals i estructuració d’un curs d’introducció al programa.D’una banda, un estudi previ mitjançant una enquesta a estudiants de grau i màster de l’Escola mostra un cert descontentament sobre la situació actual de les pràctiques i l’ús de l’ANSYS APDL i, alhora, indica que els estudiants valorarien positivament un possible canvi a la versió renovada del programari que alguns ja coneixen. Segons ells, sembla que el Workbench millora enintuïtivitat i en certes funcionalitats com l’acoblament de diferents sistemes d’anàlisi (estructurals, tèrmics, etc.) o la interacció amb la geometria, fet que en facilita l’aprenentatge.D’altra banda, s’analitza el mercat de programari disponible de simulació numèrica aplicada a la mecànica estructural i se’n seleccionen dos alternatives: el Salome-Meca i l’ANSYS, una de programari lliure i una versió educativa de programari comercial. Tot i considerar que actualment és més interessant l’ANSYS, de cara al futur es proposa valorar l’opció de programari lliure Salome-Meca.Finalment, després de la realització del projecte es conclou que, en conjunt, l’ANSYS Workbench millora les prestacions que ofereix l’ANSYS APDL i, per això, es creujustificada la transició al nou programa

Direct Ink Writing of Mineral Materials: A review

This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this recordDue to the intrinsically limited mechanical properties, functionalities and structures of mineral material composites (MMCs) made through traditional fabrication approaches, there is a critical need to develop novel three dimensional (3D) forming techniques that can construct mineral material composites (MMCs) and structures with high performance and functionalities. The direct ink writing (DIW), as a slurry deposition based additive manufacturing approach for MMCs, offers many advantages in terms of high precision, complex geometry, multi-material capability, cost effectiveness and environmental friendliness. This review gives a comprehensive overview on the state-of-art of DIW fabricated MMCs, including material classification, formulation and processing. It presents the key aspects of material processing and their effects on the properties and performance of DIW formed mineral materials. In addition, it illustrates the applications of DIW in the fields of architecture, tissue engineering, functional micro parts and geological engineering modelling.National Natural Science Foundation of ChinaChina Scholarship Counci

Gaming in Action

The «Gaming in Action» project, which brought the publicaion of this book, involved institutions from different countries that deal with adult education. For almost three years, the partners worked with teachers and trainers who applied innovative pedagogical scenarios of game-based learning and gamification, all oriented from a rigorous pedagogical perspective. The project's main goal was to increase the acquisition of pedagogical innovation skills in these models and incorporate them into their pedagogical practices. The project searched to highlight the need for quality pedagogical training in a new, technologically digital, era: in this, education has less to do with reproducing information passively and has more to do with the development of creativity, critical thinking, problem- solving and decision-making.Erasmus Plus "Gaming in Action – engaging adult learners with games and gamification" Project number: 2018-1-TR01-KA204-05931

Improving the Isotropy of Additively Manufactured Parts by Fused Deposition Modeling: From Polymeric Self-Assembly to Reactive Processing

This dissertation focuses on understanding how the interfacial segregation of low molecular weight polymeric species in a polymer blend impacts the interlayer adhesion and mechanical isotropy of objects prepared by fused deposition modeling (FDM), a widely used additive manufacturing technique. The molecular weight, architecture, and chemical identity of the low molecular weight polymer in the blend dramatically impacts the formation of a robust interlayer interface. Additional modification of the low molecular weight component presents opportunities for reactive processing. The impact of covalent bonds between interfacial layers on the interlayer adhesion and overall isotropy of an FDM printed object is examined