Vat Photopolymerization Additive Manufacturing of Functionally Graded Materials: A Review (original) (raw)
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Polymers
Additive manufacturing (3D printing) has significantly changed the prototyping process in terms of technology, construction, materials, and their multiphysical properties. Among the most popular 3D printing techniques is vat photopolymerization, in which ultraviolet (UV) light is deployed to form chains between molecules of liquid light-curable resin, crosslink them, and as a result, solidify the resin. In this manuscript, three photopolymerization technologies, namely, stereolithography (SLA), digital light processing (DLP), and continuous digital light processing (CDLP), are reviewed. Additionally, the after-cured mechanical properties of light-curable resin materials are listed, along with a number of case studies showing their applications in practice. The manuscript aims at providing an overview and future trend of the photopolymerization technology to inspire the readers to engage in further research in this field, especially regarding developing new materials and mathematical...
Vat Photopolymerization Additive Manufacturing Resins: Analysis and Case Study
Materials Research, 2020
Additive manufacturing processes have been developed over the last decades, especially vat photopolymerization (VP) processes, due to its simplicity and speed. The objective of this paper is to characterize commercial VP resins widely used for technical applications. Thus, test specimens were printed by Digital Light Processing and subjected to tensile, compression, flexural, hardness, and inorganic composition analyses. The resin with the highest resistance and hardness (containing 0.6 vol% of inorganics load) reached 53 MPa in tension, 110 MPa in compression, 79 MPa in bending, and 82.3 Shore D, which is comparable to injected polymers. A case study was made, replacing the injected gears of a reducer by printed ones and comparing the finite element analysis with resin properties. The characterization and case study results encourage the expansion of VP processes in the manufacturing of products in several industries and service sectors, as well as the development of new composite resins.
Cavity vat photopolymerisation for additive manufacturing of polymer-composite 3D objects
Communications Materials
Vat photopolymerisation describes resin-based additive manufacturing processes in which ultraviolet light is used to layer-wise solidify liquid resin into a desired 3D shape. If the starting resin is a dual-curing formulation the object is also thermally cured to attain its final properties, obtaining either an elastomer or a thermoset. Here, we introduce cavity vat photopolymerisation, in which one photopolymer resin produces a composite material of an elastomer and thermoset. Cavities of any geometry are purposefully designed in the solid object and then filled with liquid resin during printing due to negative pressure. Thermal curing then solidifies the resin in the cavities into an elastomer, forming a distinct interface held together by strong covalent bonds. Hybrid specimens indicate improved damping, reduced fragmentation upon fracture and increased local elasticity, and we suggest several hard-shell/soft-core applications that might benefit.
Materials
Vat photopolymerization additive manufacturing (Vat AM) technologies have found niche industrial use being able to produce personalized parts in moderate quantity. However, Vat AM lacks in its ability to produce parts of satisfactory thermal and mechanical properties for structural applications. The purpose of this investigation was to develop high-performance resins with glass transition temperatures (Tg) above 200 °C for Vat AM, evaluate the properties of the produced thermosets and establish a structure–property relationship of the thermosets produced. Herein, we have developed SLA-type resins that feature bio-derived monomer hesperetin trimethacrylate (HTM) synthesized from the flavonone hesperetin. Diluents 4-acryloyl morpholine, styrene, 4-methyl styrene and 4-tert butylstyrene (tbutylsty) were photocured with HTM as the monomer and all produced thermosets with Tg values above 200 °C. Investigations of suitable crosslinkers urethane dimethacrylate, the vinyl ester CN 151 and E...
An Overview: Different Manufacturing Techniques used for Fabricating Functionally Graded Material
Materials Today: Proceedings, 2019
The industrial applications of functionally graded material (FGM) have increased with its specific capability. This makes curiosity among the researchers how to optimize the design and manufacturing technique as well as the numerical analysis methodology in the priority basis. Contrast to composite material, the properties of the FG material can be varied through the dimension. Usually, the properties are varied along the thickness direction by power distribution formula. However, it is possible to vary the properties of FG material along longitudinal and transverse direction with better improvised technique. Present study is an overview of FGM modelling, design and various manufacturing techniques used by past researchers as well as achieved current stage industrial applications. Further, this study can show a road map to current authors for improvising fabrication techniques in their research on FGM.
A Review of Critical Issues in High-Speed Vat Photopolymerization
Polymers
Vat photopolymerization (VPP) is an effective additive manufacturing (AM) process known for its high dimensional accuracy and excellent surface finish. It employs vector scanning and mask projection techniques to cure photopolymer resin at a specific wavelength. Among the mask projection methods, digital light processing (DLP) and liquid crystal display (LCD) VPP have gained significant popularity in various industries. To upgrade DLP and LCC VPP into a high-speed process, increasing both the printing speed and projection area in terms of the volumetric print rate is crucial. However, challenges arise, such as the high separation force between the cured part and the interface and a longer resin refilling time. Additionally, the divergence of the light-emitting diode (LED) makes controlling the irradiance homogeneity of large-sized LCD panels difficult, while low transmission rates of near ultraviolet (NUV) impact the processing time of LCD VPP. Furthermore, limitations in light inte...
An overview of functionally graded additive manufacturing
Additive Manufacturing, 2018
Functionally Graded Additive Manufacturing (FGAM) is a layer-by-layer fabrication process that involves gradationally varying the material organization within a component to achieve an intended function. FGAM establishes a radical shift from contour modelling to performance modelling by having the performance-driven functionality built directly into the material by strategically controlling the density and directionality of the substance or to combine materials together to produce a seamless monolithic structure. This paper presents a state-of-art conceptual understanding of FGAM, covering an overview of current techniques that can enable the production of FGAM parts as well as identifying current technological limitations and challenges. Possible strategies for overcoming those barriers are presented and recommendations on future design opportunities are discussed.
Additive Manufacturing of Functionally Graded Objects: A Review
Volume 1A: 36th Computers and Information in Engineering Conference, 2016
Functionally graded materials (FGM) have recently attracted a lot of research attention in the wake of the recent prominence of additive manufacturing (AM) technology. The continuously varying spatial composition profile of two or more materials affords FGM object to simultaneously possess ideal properties of multiple different materials. Additionally, emerging technologies in AM domain enables one to make complex shapes with customized multifunctional material properties in an additive fashion, where laying down successive layers of material creates an object. In this paper, we focus on providing an overview of research at the intersection of AM techniques and FGM objects. We specifically discuss the FGM modeling representation schemes and outline a classification system to classify existing FGM representation methods. We also highlight the key aspects such as the part orientation, slicing, and path planning processes that are essential for fabricating a quality FGM object through ...
Processing and Application of Ceramics
Functionally graded materials (FGMs) are new materials whose properties change gradually in respect to their dimensions. This group of materials shows a tremendous improvement of previously used composite materials. FGM consists of two or more materials whose combination enables the achievement of specified properties in accordance with the desired application. The article gives an overview of different classifications, various fabrication methods and applications of the FGMs. It could also provide insight and perspective for researchers, university students and research and development teams since it has brought together diverse aspects of FGMs. As mentioned in section two, we took all FGMs fabrication methods under consideration, giving the reader an insight into how to make a product while satisfying the conditions of financial and mechanical efficiency. The classification section specifically goes over structures, types of gradients, sizes/scales, state of matter and finishes wi...