ABSTRACT Micro-supercapacitors (MSCs) with excellent electrochemical behaviours and flexibility possess great promise for portable and wearable electronic devices. A novel type of hybrid-dimensional Fe2O3/graphene/Ag ink is developed and extruded into MSC electrodes through the direct ink writing-based three-dimensional (3D) printing. The optimal solid-state MSC device exhibits a maximum areal capacitance

ABSTRACT One common issue when implementing wearable strain sensors for health-monitoring is the limited service time when they are inevitably subjected to mechanical operation in practical applications. Therefore, integrating multi-functionality with reliable performance is a long-term pursing target. To this end, we have developed a promising strain sensor utilising a facile 3D printing technology

ABSTRACT Strength and ductility were simultaneously enhanced in the additively manufactured CoCrFeMnNi high-entropy alloy by laser powder bed fusion (LBPF) under reactive N2 atmosphere. It was found that nitrogen atoms picked up during additive manufacturing line-up to form ordered nitrogen complexes (ONCs) in the octahedral interstitial position of the HEA matrix. Dislocation multiplication is then

ABSTRACT A near-equiatomic FeCoNiCuAl High-entropy alloy (HEA) was produced using laser powder bed fusion (L-PBF) pre-alloy powder. Microstructural characteristics and tribological properties of L-PBF specimens under various volumetric energy densities (VEDs) were investigated in detail. The results showed that the phase of L-PBF specimen consisted of BCC matrix + Cu-rich B2 precipitate. The microstructure

ABSTRACT With excellent radiation resistance and high temperature strength, the oxide dispersion strengthened (ODS) nickel-based superalloys are deemed as candidate materials for advanced fission and fusion reactor. Since conventional manufacturing processes are difficult to produce components with complex shapes, additive manufacturing becomes an alternative method. In this work, ODS nickel-based

ABSTRACT Selective laser Melting (SLM), a powder bed-based additive manufacturing technology, has been developed and applied in multiple industrial fields in the last decade. However, the distortion and swelling in the SLM process resulting from thermal stress cannot be predicted subject to measurement. In this work, an in situ distortion measurement system applied to the SLM process is presented.

ABSTRACT In this paper, an automatic determination method of part build orientation for laser powder bed fusion is presented. This method includes two steps. First, an existing facet clustering-based approach is applied to automatically generate the alternative orientations of a laser powder bed fusion part. Second, support volume, volumetric error, surface roughness, build time and build cost are

ABSTRACT Surface monitoring is an essential part of quality assurance for additive manufacturing (AM). Surface defects need to be identified early in the AM process to avoid further deterioration of the part quality. In this paper, a rapid surface defect identification method for directed energy deposition (DED) is proposed. The main contribution of this work is the development of an in-situ point

ABSTRACT The current state-of-the-art metal additive manufacturing (AM) process still cannot meet the high industry requirements in terms of surface roughness. In addition, there are limited ISO/ASTM standards on the post-processing of metal AM components. Considerable efforts have been made to close these current gaps and challenges for standardization. In this review, First, all the existing ISO/ASTM

(2020). Editorial. Virtual and Physical Prototyping: Vol. 15, No. 4, pp. 371-372.

ABSTRACT This article reviews soft pneumatic actuators (SPAs) that are manufactured entirely via additive manufacturing methods. These actuators are known as four-dimensional (4D)-printed SPAs and can generate bending motions in response to either pressurised or vacuum (negative pressure) air stimulus after fabrication. They are characterised by geometrical and material factors that determine their

ABSTRACT Scaffolds are regarded as a key factor for tissue engineering as they provide a three-dimensional structural frame for host cells to attach, proliferate, and differentiate. Recently, 3D bioprinting has enabled the quick and versatile fabrication of various architectures of micro/macroscale scaffolds, but there remain obstacles to successful tissue regeneration, such as large strut diameter

ABSTRACT Biodegradable scaffolds are considered as the key component of tissue engineering which serve as temporary structural supports for tissue regeneration. The mechanical/biological properties of artificial synthetic polymeric scaffolds are highly dependent on their structural organisations. Additive manufacturing (AM) techniques have provided unprecedented opportunities to customise patient-specific

ABSTRACT After solution + artificial aging treatment (T6 heat treatment) of 2219 aluminum alloy fabricated by laser-tungsten inert gas (TIG) hybrid method, more interestingly, we found that both the strength and elongation were improved. The strengthening mechanism has been analysed in details. Results showed that each layer was divided into the arc zone (AZ) and laser zone (LZ) before and after heat

ABSTRACT The precise shape of a shift block support for the turbine blade of a hovercraft was additively manufactured using 17–4 precipitation-hardened stainless steel (STS 630) powder through laser powder bed fusion (LPBF). Subsequently, heat treatment under the H900 condition increased the yield strength and fracture strain of the shift block to 1313 MPa and 11.5%, respectively, and enhanced its

ABSTRACT 4D printing provides a means to create dynamic structures for self-actuating devices fabricated by additive manufacturing techniques. Most existing 4D printing processes are only capable of one-way shape morphing using a single mechanism for stimulation. In the limited successful reversible 4D-printing studies, most only demonstrate 2D-to-3D shape morphing. This study introduces a contactless

ABSTRACT The fabrication quality of horizontal fluid channels without supports using SLM is low, which further affects friction loss in channels. In the paper, circular fluid channels with diameters from 2 to 14 mm were built horizontally using 316L SS. The surface roughness on the top inner channel is 50–80 μm, while the rest part is approximately 10 μm. The cylindricity is around 0.2 and circularity

ABSTRACT This paper focuses on the effect of melting modes on microstructural evolution and tribological properties of AlSi10Mg alloy fabricated by selective laser melting (SLM). The results showed that the microstructures of SLM AlSi10Mg consisted of primary α-Al surrounded by cellular Si networks (∼500 nm) when fabricated in conduction mode, but has a finer cellular-like Si phase (∼200 nm) when fabricated

Additive manufacturing is progressively paving the way for optimised lightweight components that, due to their typically complex shape, would hardly be feasible with traditional production methods. However, the peculiar mechanical properties of additively manufactured materials limit the accuracy of structural analyses. In this research, a strategy for the implementation of thickness dependent anisotropy

To overcome the mandatory requirement of nozzle conductivity in the conventional electrohydrodynamic (EHD) jet printing, this paper proposed a self-induced electric-field-driven jet printing for fabricating ultrafine silver grids. In this method, only a copper foil is mounted on an insulating glass nozzle to serve as an extraction electrode for producing an electric field with substrate by electrostatic

Biodegradable scaffolds are considered as the key component of tissue engineering which serve as temporary structural supports for tissue regeneration. The mechanical/biological properties of artificial synthetic polymeric scaffolds are highly dependent on their structural organisations. Additive manufacturing (AM) techniques have provided unprecedented opportunities to customise patient-specific scaffolds

ABSTRACT In this paper, a novel facet clustering based method is proposed to generate alternative build orientations for laser powder bed fusion. This method consists of two steps. First, a hierarchical clustering algorithm is applied to divide facets of the design model in standard tessellation language format into different clusters, each of which shares a similar normal vector. Second, alternatives

The influence of the defocusing distance on melt pool morphology, defect, microstructure and mechanical properties of the laser powder bed fusion (L-PBF) of high strength Al–Cu–Mg–Mn alloy was studied. It is found that because of the different laser energy distribution, the defocusing distance has significant effects on melt pool morphology, defects, microstructure and mechanical properties of the

Bioprinting is a relatively new and promising tissue engineering approach to solve the problem of donor shortage for organ transplantation. It is a highly-advanced biofabrication system that enables the printing of materials in the form of biomaterials, living cells and growth factors in a layer-by-layer manner to manufacture 3D tissue-engineered constructs. The current workflow involves a myriad of

While significant progress has been made in laser powder bed fusion (L-PBF) for metal additive manufacturing (AM), there is still limited large scale adoption of this advanced manufacturing technique by the industry. This paper covers the recent developments in L-PBF with discussions from the materials and process perspectives. High entropy alloys and high strength aluminium alloys have been identified

Polymeric cellular structures based on triply periodic minimal surfaces (TPMS) have been widely studied for applications in multiple disciplines due to their multifunctionality. However, there is limited acoustic application by TPMS-based structures as their acoustic properties remain largely unknown. In this paper, TPMS-based structures are fabricated by additive manufacturing and investigated as

This paper examines the relationships in laser metal additive manufacturing between part geometry and as-built part quality, including residual stresses, deformations, process induced porosity, surface roughness, and microstructural variations. A comprehensive review of these defects and their relationships with the geometric features are provided along with a brief discussion of the involved physical

Blending Polyetheretherketone (PEEK) with Polyvinyl alcohol (PVA) is promising to obtain a composite scaffold combining the excellent biomechanical properties of PEEK and the remarkable degradability of PVA. However, the weak interfacial bonding between nonpolar PEEK and polar PVA would result in poor mechanical properties. In this study, owing to its unique amphiphilic properties, graphene oxide (GO)

ABSTRACT The rapid development of additive manufacturing of cementitious materials has enabled the emergence of a new design paradigm, namely functional grading of material properties by location. Target performance parameters could be material weight and insulation value or (particularly important) ductility. A generic concept to achieve this, is through the selective addition of fibres or aggregates

3D Concrete Printing (3DCP) has been gaining popularity in the past few years. Due to the nature of line-by-line printing and the slump of the material deposition in each extruded line, 3D printed structures exhibit obvious lines or marks at the layer interface, which affects surface finish quality and potentially affect bonding strength between layers. This makes it necessary to control the extrudate

ABSTRACT Lightweight and high-strength polymer-derived SiOC ceramics with varied lattice structures have been successfully produced using different polysiloxanes as preceramic polymers (PCPs) via photopolymerisation-based digital-light-processing 3D printing and pyrolysis. Photocurable precursor resins were prepared by simple mixing of polysiloxanes with photosensitive acrylate monomers, achieving

In recent years, additive manufacturing technology has been highly focused on its strong capability in complex geometry manufacturing and great suitability for customised product fabrication. Researchers have recognised the key role of additive manufacturing in leading the next-generation manufacturing, and have conducted extensive research from different aspects, including product design, process

ABSTRACT Additive manufacturing (AM) of co-fired low temperature ceramics offers a unique route for fabrication of novel 3D radio frequency (RF) and microwave communication components, embedded electronics and sensors. This paper describes the first-ever direct 3D printing of low temperature co-fired ceramics/floating electrode 3D structures. Slurry-based AM and selective laser burnout (SLB) were used

(2020). Editorial. Virtual and Physical Prototyping: Vol. 15, No. 2, pp. 131-132.

Metal-doped polymer derived ceramics (PDCs) exhibits multifunctional properties due to the introduction of special metal element; however as one of the cheapest metal element carriers, metal inorganic salts have rarely been reported for the fabrication of metal-doped PDCs. In this article, a novel hydrophilic photosensitive γ-methacryloxypropyl trimethoxy modified polyhydroxymethylsiloxane preceramic

Magnesium (Mg) alloy shows great potential as bone implant owing to its favourable biocompatibility and degradability. In the present work, bioglass-reinforced Mg-based composite was manufactured via laser additive manufacturing. The results showed that too low a volumetric energy density (Ev ) resulted in the appearance of open pores on the surface, which significantly deteriorated the densification

Metamaterials that exhibit negative Poisson’s ratio (NPR) are known as auxetics. They laterally expand or contract when they are axially tensioned or compressed. A re–entrant chiral auxetic structure (RCA) is a recently developed structure, which combines the topological features of re–entrant and chiral honeycombs. Comparative study between the RCA structure and popular benchmarks subjected to uniaxial

This paper aims to explore the effects of optimisation parameters (the filter radius, mesh size, and target volume fraction) on the compliance and manufacturability of smooth self-supporting topologies for additive manufacturing (AM); and conduct manufacturability experiments of selected simulation results with the Selective Laser Melting (SLM) technology. In this study, smooth self-supporting topologies

This paper presents a numerical study on stress-constrained shell-lattice infill structural optimisation. This problem is inherently challenging for several reasons: (i) different stress measures have to be used for the solid shell and the porous lattice infill, and the two types of stress constraints make the problem extremely complex to solve and (ii) involvement of the shell layer further complicates

Among the various Additive Manufacturing (AM) technologies available for metal part production, powder bed processes are the most promising for industrial mass production. However, one obstacle to the widespread adoption of AM technologies is the effect of the residual stress state on the integrity and lifetime of parts. The residual stress state is influenced to a great extent by the geometry and

A solution-based electrohydrodynamic (EHD) printing strategy was developed to fabricate sub-microscale biopolymeric fibres to mimic the tiny architectures of native extracellular matrix (ECM) for enhanced cellular performance. It was found that when the working voltage was significantly reduced to 500 V, sub-microscale fibres as well as user-specific patterns with an average fibre size of 193 ± 51 nm

This work presents a comprehensive failure mechanism study of the bi-directionally corrugated panel (DCP) structures inspired by the telson of mantis shrimp. The DCP structures were fabricated by selective laser melting (SLM) with AlSi10Mg powder. The influence of key structural parameters, namely wave number (N), on the compressive behaviours, stress distribution, deformation modes and fracture mechanism

The microstructure of metals depends on the additive manufacturing (AM) process and the process parameters. However, experimentation on different process parameters for different materials is costly and time-consuming. To overcome these challenges, numerical simulations provide insights that allow prediction of microstructure formed under different process parameters. Microstructure modelling requires

Multi-objective optimisation of the bio-inspired lightweight structure is developed by response surface methodology (RSM) and non-dominated sorting genetic algorithm II (NSGA-II) for future applications in the aerospace and military fields. Multilayer bio-inspired sandwich structures of Ti6Al4V alloy are designed and fabricated by selective laser melting (SLM). Results show that the bio-inspired sandwich

Three-dimensional (3D) printed Sc-modified Al alloy by powder bed fusion (PBF) provides significant strength and ductility without hot tearing during the process. This kind of 3D-printable high specific strength materials exhibits great potential in lightweight applications. Due to the lesser design limitation through the 3D printing process, the degree of lightweight is greatly affected by the specific

Flexible electronics are attractive because of flexibility and portability. The circuits are printed on flexible substrates, which are delicate and heat-sensitive. Traditional photolithography, which uses high temperatures and corrosive chemicals, easily causes damages in flexible substrates. Here, we develop a low-cost nanoparticle based laser patterning process for fabrication of flexible electronics

To evaluate specimen size dependence on the tensile properties of additively manufactured (AM) components, various rectangular specimens, ranging from miniaturised to ASTM standard specimens, are machined from electron beam melted Ti-6Al-4V and used for the tensile testing. It is found that the elongation is strongly related to the sample size while the yield and ultimate tensile strengths exhibit

(2019). Editorial. Virtual and Physical Prototyping: Vol. 14, No. 4, pp. 307-307.

Incorporating additive manufacturing (AM) constraints in topology optimisation can lead to performance optimality while ensuring manufacturability of designs. Numerical techniques have been previously proposed to obtain support-free designs in AM, however, few works have verified the manufacturability of their solutions. Physical verification of manufacturability becomes more critical recalling that

Hydraulic valve spools can be produced with hollow structures using SLM to increase dynamic response. The contact between the valve spool and body is crucial and relates to the performance of a hydraulic valve, which has not been studied. This paper investigates the reciprocating contact of an SLM-fabricated spool valve from a tribological aspect. By varying the process parameters, porous and standard

Al2O3-based composite ceramics have excellent high temperature performance and are ideal materials for preparing hot end components. However, poor fracture toughness and thermal shock resistance limit its applications. Based on the excellent low thermal expansion characteristics and thermal shock resistance of Al2TiO5 ceramic, different composition ratios of Al2O3/Al2TiO5 composite ceramics were prepared

In this research, the effects of Selective Laser Melting (SLM) process parameters comprising laser power, scan speed, hatch space and scan pattern angle on the formation of porosity and subsequently density have been analysed. To improve the mechanical properties, post-processes (heat treatment) must be performed. Therefore, heat treatment was added to the design of experiment to analyse the effect

Compressive behaviour of Triply Periodic Minimal Surface type Neovius structure is investigated. The structure was manufactured by Fused Deposition Modelling (FDM) Additive Manufacturing technology in ABS material. The Neovius cellular structures with four different unit cell sizes of 8, 10, 12 and 14 mm with the volume fractions of 15%, 20% and 25% were investigated. Morphology of the samples was

The potentiality of the Fused Deposition Modeling (FDM) process for multi-material printing has not yet been thoroughly explored in the literature. That is a limitation considering the wide diffusion of dual extruders printers and the possibility of increasing the number of these extruders. An exploratory study, based on tensile tests and performed on double-material butt-joined bars, was thus conceived;

Ceramic matrix composites (CMCs) are materials that can be engineered for high-temperature applications in various fields including aerospace, marine, etc. It is very difficult to fabricate CMCs using traditional moulding methods due to their brittleness and high hardness. Additive manufacture (AM) technology, a digital manufacturing technology, provides multiple advantages over traditional manufacturing

3D food printing, or the use of food materials in additive manufacturing, has been a topic of interest to the commercial sector for the past decade. Recently, there has also been increased attention from the academic field, with a considerable volume of research being published. Most of these studies have focused on developing food inks for extrusion-based printing beyond conventional materials such

This paper performs a combined numerical and experimental study to explore the role of minimum length scale constraints in multi-scale topology optimisation. Multi-scale topology optimisation is generally performed without considering the actual unit cell size, while an arbitrary value considerably smaller than the part is selected afterwards. However, this procedure would be problematic if including

This investigation developed selective laser melting (SLM) processing parameters for the in situ fabrication of an Al-Cu12 alloy from pure elemental blends of aluminium and copper powders. Use of elevated pre-heat temperatures (400°C) created a coarser dendritic cell microstructure consisting of supersaturated Al-rich with a uniform Al2Cu phase granular microstructure compared to non-pre-heated samples

Additive manufacturing (AM) is becoming increasingly popular because of its unique advantages. However, AM still suffers from support material waste during the fabrication process when overhanging features exist. Plenty of research has been carried out for minimising support usage. However, former studies only focused on the optimisation for a single part fabrication. In this paper, a four-step strategy

Lattice and trabecular structures are excellent candidates for energy absorbing applications such as personal protective equipment or any sort of bumper. Additive manufacturing technologies allow more freedom in the design of new topologies such as trabecular and lattice structures overcoming the limitation of the traditional manufacturing processes. In the present research, an investigation on the