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Design and Application of Additive Manufacturing

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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Manufacturing Processes and Systems".

Deadline for manuscript submissions: closed (10 April 2022) | Viewed by 31961

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Special Issue Editor

Prof. Dr. Rubén Paz

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Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, 35017 Las Palmas, Spain
Interests: manufacturing processes; additive manufacturing; design optimization; finite element analysis; biomaterials and natural fibre applications; additive manufacturing for tissue engineering applications
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Dear Colleagues,

Additive manufacturing (AM) is continuously improving and offering innovative alternatives to conventional manufacturing techniques. The advantages of AM (design freedom, reduction in material waste, low-cost prototyping, etc.) can be exploited in different sectors by replacing or complementing traditional manufacturing methods. For this to happen, the combination of design, materials and technology must be deeply analyzed for every specfic application. Despite the continuous progress of AM, there is still a need for further investigation in terms of design and applications to boost AM implementation in the manufacturing industry or even in other sectors where short and personalized series productions could be useful, such as the medical sector. This Special Issue aims to publish high-level research articles involving design and application of AM, including (but not limited to) innovative design approaches where AM is applied to improve conventional methods or currently used techniques, design and modeling methodologies for specific AM applications, design optimization (also driven by numerical methods such as finite element analysis) for pioneering uses of AM, and innovative design and applications of functionally graded additive manufacturing and 4D printing. The proposals must focus on the design apporach and application of AM, with the corresponding material and experimental characterization according to the specific application.

Prof. Dr. Rubén Paz
Guest Editor

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Keywords

additive manufacturing
design
innovative applications
simulation
optimization

Published Papers (13 papers)

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Editorial

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3 pages, 195 KiB

Open AccessEditorial

Special Issue “Design and Application of Additive Manufacturing”

by Rubén Paz

Materials 2022, 15(13), 4554; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15134554 - 28 Jun 2022

Viewed by 883

Abstract

Additive manufacturing (AM) is continuously improving and offering new opportunities in the manufacturing industry [...] Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

Research

Jump to: Editorial

14 pages, 7199 KiB

Open AccessArticle

Requirements for Hybrid Technology Enabling the Production of High-Precision Thin-Wall Castings

by Vladimír Krutiš, Pavel Novosad, Antonín Záděra and Václav Kaňa

Materials 2022, 15(11), 3805; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15113805 - 26 May 2022

Cited by 3 | Viewed by 1712

Abstract

Prototypes and small series production of metal thin-walled components is a field for the use of a number of additive technologies. This method has certain limits related to the size and price of the parts, productivity, or the type of requested material. On the other hand, conventional production methods encounter the limits of shape, which are currently associated with the implementation of optimization methods such as topological optimization or generative design. An effective solution is employing hybrid technology, which combines the advantages of 3D model printing and conventional casting production methods. This paper describes the design of aluminum casting using topological optimization and technological co-design for the purpose of switching to new manufacturing technology. It characterizes the requirements of hybrid technology for the material and properties of the model in relation to the production operations of the investment casting technology. Optical roughness measurement compares the surface quality in a standard wax model and a model obtained by additive manufacturing (AM) of polymethyl methacrylate (PMMA) using the binder jetting method. The surface quality results of the 3D printed model evaluated by measuring the surface roughness are lower than for the standard wax model; however, they still meet the requirements of prototype production technology. The measurements proved that the PMMA model has half the thermal expansion in the measured interval compared to the wax model, which was confirmed by minimal shape deviations in the dimensional analysis. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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20 pages, 5920 KiB

Open AccessArticle

Material Extrusion of Structural Polymer–Aluminum Joints—Examining Shear Strength, Wetting, Polymer Melt Rheology and Aging

by Stephan Bechtel, Rouven Schweitzer, Maximilian Frey, Ralf Busch and Hans-Georg Herrmann

Materials 2022, 15(9), 3120; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15093120 - 26 Apr 2022

Cited by 7 | Viewed by 1721

Abstract

Generating polymer–metal structures by means of additive manufacturing offers huge potential for customized, sustainable and lightweight solutions. However, challenges exist, primarily with regard to reliability and reproducibility of the additively generated joints. In this study, the polymers ABS, PETG and PLA, which are common in material extrusion, were joined to grit-blasted aluminum substrates. Temperature dependence of polymer melt rheology, wetting and tensile single-lap-shear strength were examined in order to obtain appropriate thermal processing conditions. Joints with high adhesive strength in the fresh state were aged for up to 100 days in two different moderate environments. For the given conditions, PETG was most suitable for generating structural joints. Contrary to PETG, ABS–aluminum joints in the fresh state as well as PLA–aluminum joints in the aged state did not meet the demands of a structural joint. For the considered polymers and processing conditions, this study implies that the suitability of a polymer and a thermal processing condition to form a polymer–aluminum joint by material extrusion can be evaluated based on the polymer’s rheological properties. Moreover, wetting experiments improved estimation of the resulting tensile single-lap-shear strength. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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10 pages, 2241 KiB

Open AccessArticle

Transient Phase-Driven Cyclic Deformation in Additively Manufactured 15-5 PH Steel

by Tu-Ngoc Lam, Yu-Hao Wu, Chia-Jou Liu, Hobyung Chae, Soo-Yeol Lee, Jayant Jain, Ke An and E-Wen Huang

Materials 2022, 15(3), 777; https://0-doi-org.brum.beds.ac.uk/10.3390/ma15030777 - 20 Jan 2022

Cited by 3 | Viewed by 1944

Abstract

The present work extends the examination of selective laser melting (SLM)-fabricated 15-5 PH steel with the 8%-transient-austenite-phase towards fully-reversed strain-controlled low-cycle fatigue (LCF) test. The cyclic-deformation response and microstructural evolution were investigated via in-situ neutron-diffraction measurements. The transient-austenite-phase rapidly transformed into the martensite phase in the initial cyclic-hardening stage, followed by an almost complete martensitic transformation in the cyclic-softening and steady stage. The compressive stress was much greater than the tensile stress at the same strain amplitude. The enhanced martensitic transformation associated with lower dislocation densities under compression predominantly governed such a striking tension-compression asymmetry in the SLM-built 15-5 PH. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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16 pages, 4459 KiB

Open AccessArticle

Topology Optimisation for Compliant Hip Implant Design and Reduced Strain Shielding

by Nathanael Tan and Richard J. van Arkel

Materials 2021, 14(23), 7184; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14237184 - 25 Nov 2021

Cited by 20 | Viewed by 3544

Abstract

Stiff total hip arthroplasty implants can lead to strain shielding, bone loss and complex revision surgery. The aim of this study was to develop topology optimisation techniques for more compliant hip implant design. The Solid Isotropic Material with Penalisation (SIMP) method was adapted, and two hip stems were designed and additive manufactured: (1) a stem based on a stochastic porous structure, and (2) a selectively hollowed approach. Finite element analyses and experimental measurements were conducted to measure stem stiffness and predict the reduction in stress shielding. The selectively hollowed implant increased peri-implanted femur surface strains by up to 25 percentage points compared to a solid implant without compromising predicted strength. Despite the stark differences in design, the experimentally measured stiffness results were near identical for the two optimised stems, with 39% and 40% reductions in the equivalent stiffness for the porous and selectively hollowed implants, respectively, compared to the solid implant. The selectively hollowed implant’s internal structure had a striking resemblance to the trabecular bone structures found in the femur, hinting at intrinsic congruency between nature’s design process and topology optimisation. The developed topology optimisation process enables compliant hip implant design for more natural load transfer, reduced strain shielding and improved implant survivorship. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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12 pages, 62877 KiB

Open AccessArticle

Flexible Pressure Sensor with Micro-Structure Arrays Based on PDMS and PEDOT:PSS/PUD&CNTs Composite Film with 3D Printing

by Yiwei Shao, Qi Zhang, Yulong Zhao, Xing Pang, Mingjie Liu, Dongliang Zhang and Xiaoya Liang

Materials 2021, 14(21), 6499; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216499 - 29 Oct 2021

Cited by 14 | Viewed by 2993

Abstract

Flexible pressure sensors are widely used in different fields, especially in human motion, robot monitoring and medical treatment. Herein, a flexible pressure sensor consists of the flat top plate, and the microstructured bottom plate is developed. Both plates are made of polydimethylsiloxane (PDMS) by molding from the 3D printed template. The contact surfaces of the top and bottom plates are coated with a mixture of poly (3,4-ethylenedioxythiophene) poly (styrene sulfonate) (PEDOT:PSS) and polyurethane dispersion (PUD) as stretchable film electrodes with carbon nanotubes on the electrode surface. By employing 3D printing technology, using digital light processing (DLP), the fabrication of the sensor is low-cost and fast. The sensor models with different microstructures are first analyzed by the Finite Element Method (FEM), and then the models are fabricated and tested. The sensor with 5 × 5 hemispheres has a sensitivity of 3.54 × 10⁻³ S/kPa in the range of 0–22.2 kPa. The zero-temperature coefficient is −0.0064%FS/°C. The durability test is carried out for 2000 cycles, and it remains stable during the whole test. This work represents progress in flexible pressure sensing and demonstrates the advantages of 3D printing technology in sensor processing. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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11 pages, 2861 KiB

Open AccessArticle

Double-Level Energy Absorption of 3D Printed TPMS Cellular Structures via Wall Thickness Gradient Design

by Minting Zhong, Wei Zhou, Huifeng Xi, Yingjing Liang and Zhigang Wu

Materials 2021, 14(21), 6262; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14216262 - 21 Oct 2021

Cited by 16 | Viewed by 2700

Abstract

This paper investigates the deformation mechanism and energy absorption behaviour of 316 L triply periodic minimal surface (TPMS) structures with uniform and graded wall thicknesses fabricated by the selective laser melting technique. The uniform P-surface TPMS structure presents a single-level stress plateau for energy absorption and a localized diagonal shear cell failure. A graded strategy was employed to break such localized geometrical deformation to improve the overall energy absorption and to provide a double-level function. Two segments with different wall thicknesses separated by a barrier layer were designed along the compression direction while keeping the same relative density as the uniform structure. The results show that the crushing of the cells of the graded P-surface TPMS structure occurs first within the thin segment and then propagates to the thick segment. The stress–strain response shows apparent double stress plateaus. The stress level and length of each plateau can be adjusted by changing the wall thickness and position of the barrier layer between the two segments. The total energy absorption of the gradient TPMS structure was also found slightly higher than that of the uniform TPMS counterparts. The gradient design of TPMS structures may find applications where the energy absorption requires a double-level feature or a warning function. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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17 pages, 5645 KiB

Open AccessArticle

Manufacturing of Closed Impeller for Mechanically Pump Fluid Loop Systems Using Selective Laser Melting Additive Manufacturing Technology

by Alexandra Adiaconitei, Ionut Sebastian Vintila, Radu Mihalache, Alexandru Paraschiv, Tiberius Florian Frigioescu, Ionut Florian Popa and Laurent Pambaguian

Materials 2021, 14(20), 5908; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14205908 - 09 Oct 2021

Cited by 9 | Viewed by 2564

Abstract

In the space industry, the market demand for high-pressure mechanically pumped fluid loop (MPFL) systems has increased the interest for integrating advanced technologies in the manufacturing process of critical components with complex geometries. The conventional manufacturing process of a closed impeller encounters different technical challenges, but using additive manufacturing (AM) technology, the small component is printed, fulfilling the quality requirements. This paper presents the Laser Powder Bed Fusion (LPBF) process of a closed impeller designed for a centrifugal pump integrated in an MPFL system with the objective of defining a complete manufacturing process. A set of three closed impellers was manufactured, and each closed impeller was subjected to dimensional accuracy analysis, before and after applying an iterative finishing process for the internal surface area. One of the impellers was validated through non-destructive testing (NDT) activities, and finally, a preliminary balancing was performed for the G2.5 class. The process setup (building orientation and support structure) defined in the current study for a pre-existing geometry of the closed impeller takes full advantages of LPBF technology and represents an important step in the development of complex structural components, increasing the technological readiness level of the AM process for space applications. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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24 pages, 6030 KiB

Open AccessArticle

Comparison of CAD and Voxel-Based Modelling Methodologies for the Mechanical Simulation of Extrusion-Based 3D Printed Scaffolds

by Gisela Vega, Rubén Paz, Andrew Gleadall, Mario Monzón and María Elena Alemán-Domínguez

Materials 2021, 14(19), 5670; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195670 - 29 Sep 2021

Cited by 4 | Viewed by 2802

Abstract

Porous structures are of great importance in tissue engineering. Most scaffolds are 3D printed, but there is no single methodology to model these printed parts and to apply finite element analysis to estimate their mechanical behaviour. In this work, voxel-based and geometry-based modelling methodologies are defined and compared in terms of computational efficiency, dimensional accuracy, and mechanical behaviour prediction of printed parts. After comparing the volumes and dimensions of the models with the theoretical and experimental ones, they are more similar to the theoretical values because they do not take into account dimensional variations due to the printing temperature. This also affects the prediction of the mechanical behaviour, which is not accurate compared to reality, but it makes it possible to determine which geometry is stiffer. In terms of comparison of modelling methodologies, based on process efficiency, geometry-based modelling performs better for simple or larger parts, while voxel-based modelling is more advantageous for small and complex geometries. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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19 pages, 10582 KiB

Open AccessArticle

Novel Calibration Strategy for Validation of Finite Element Thermal Analysis of Selective Laser Melting Process Using Bayesian Optimization

by Masahiro Kusano, Houichi Kitano and Makoto Watanabe

Materials 2021, 14(17), 4948; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14174948 - 30 Aug 2021

Cited by 7 | Viewed by 1929

Abstract

Selective laser melting (SLM) produces a near-net-shaped product by scanning a concentrated high-power laser beam over a thin layer of metal powder to melt and solidify it. During the SLM process, the material temperature cyclically and sharply rises and falls. Thermal analyses using the finite element method help to understand such a complex thermal history to affect the microstructure, material properties, and performance. This paper proposes a novel calibration strategy for the heat source model to validate the thermal analysis. First, in-situ temperature measurement by high-speed thermography was conducted for the absorptivity calibration. Then, the accurate simulation error was defined by processing the cross-sectional bead shape images by the experimental observations and simulations. In order to minimize the error, the optimal shape parameters of the heat source model were efficiently found by using Bayesian optimization. Bayesian optimization allowed us to find the optimal parameters with an error of less than 4% within 50 iterations of the thermal simulations. It demonstrated that our novel calibration strategy with Bayesian optimization can be effective to improve the accuracy of predicting the temperature field during the SLM process and to save the computational costs for the heat source model optimization. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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12 pages, 4772 KiB

Open AccessArticle

A New Method for Automatic Detection of Defects in Selective Laser Melting Based on Machine Vision

by Zhenqiang Lin, Yiwen Lai, Taotao Pan, Wang Zhang, Jun Zheng, Xiaohong Ge and Yuangang Liu

Materials 2021, 14(15), 4175; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14154175 - 27 Jul 2021

Cited by 15 | Viewed by 2163

Abstract

Selective laser melting (SLM) is a forming technology in the field of metal additive manufacturing. In order to improve the quality of formed parts, it is necessary to monitor the selective laser melting forming process. At present, most of the research on the monitoring of the selective laser melting forming process focuses on the monitoring of the melting pool, but the quality of forming parts cannot be controlled in real-time. As an indispensable link in the SLM forming process, the quality of powder spreading directly affects the quality of the formed parts. Therefore, this paper proposes a detection method for SLM powder spreading defects, mainly using industrial cameras to collect SLM powder spreading surfaces, designing corresponding image processing algorithms to extract three common powder spreading defects, and establishing appropriate classifiers to distinguish different types of powder spreading defects. It is determined that the multilayer perceptron (MLP) is the most accurate classifier. This detection method has high recognition rate and fast detection speed, which cannot only meet the SLM forming efficiency, but also improve the quality of the formed parts through feedback control. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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14 pages, 6709 KiB

Open AccessArticle

The Influence of Laser Defocusing in Selective Laser Melted IN 625

by Alexandru Paraschiv, Gheorghe Matache, Mihaela Raluca Condruz, Tiberius Florian Frigioescu and Ion Ionică

Materials 2021, 14(13), 3447; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14133447 - 22 Jun 2021

Cited by 13 | Viewed by 1868

Abstract

Laser defocusing was investigated to assess the influence on the surface quality, melt pool shape, tensile properties, and densification of selective laser melted (SLMed) IN 625. Negative (−0.5 mm, −0.3 mm), positive (+0.3 mm, +0.5 mm), and 0 mm defocusing distances were used to produce specimens, while the other process parameters remained unchanged. The scanning electron microscopy (SEM) images of the melt pools generated by different defocusing amounts were used to assess the influence on the morphology and melt pool size. The mechanical properties were evaluated by tensile testing, and the bulk density of the parts was measured by Archimedes’ method. It was observed that the melt pool morphology and melting mode are directly related to the defocusing distances. The melting height increases while the melting depth decreases from positive to negative defocusing. The use of negative defocusing distances generates the conduction melting mode of the SLMed IN 625, and the alloy (as-built) has the maximum density and ultimate tensile strength. Conversely, the use of positive distances generates keyhole mode melting accompanied by a decrease of density and mechanical strength due to the increase in porosity and is therefore not suitable for the SLM process. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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16 pages, 20735 KiB

Open AccessArticle

The Influence of Shape Changing Behaviors from 4D Printing through Material Extrusion Print Patterns and Infill Densities

by Seokwoo Nam and Eujin Pei

Materials 2020, 13(17), 3754; https://0-doi-org.brum.beds.ac.uk/10.3390/ma13173754 - 25 Aug 2020

Cited by 16 | Viewed by 3448

Abstract

Four-dimensional printing (4DP) is an approach of using Shape Memory Materials (SMMs) with additive manufacturing (AM) processes to produce printed parts that can deform over a determined amount of time. This research examines how Polylactic Acid (PLA), as a Shape Memory Polymer (SMP), can be programmed by manipulating the build parameters of material extrusion. In this research, a water bath experiment was used to show the results of the shape-recovery of bending and shape-recovery speed of the printed parts, according to the influence of the print pattern, infill density and recovery temperature (Tr). In terms of the influence of the print pattern, the ‘Quarter-cubic’ pattern with a 100% infill density showed the best recovery result; and the ‘Line’ pattern with a 20% infill density showed the worst recovery result. The ‘Cubic-subdivision’ pattern with a 20% infill density demonstrated the shortest recovery time; and the ‘Concentric’ pattern with a 100% infill density demonstrated the longest recovery time. The results also showed that a high temperature and high infill density provided better recovery, and a low temperature and low infill density resulted in poor recovery. Full article

(This article belongs to the Special Issue Design and Application of Additive Manufacturing)

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