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Characterization of the mechanical properties plays an essential role in the post-processing and evaluation of the functionality of the additively manufactured metallic parts. A number of studies have been focused on the tensile properties of additively manufactured metals. However, the quasi-static compression test of the additively manufactured 316L blocks with different heat-treatment conditions and scanning strategies seems to be overlooked in the literature. This paper aims to provide a comprehensive study of compressive mechanical response in plastic deformation of SS316L fabricated by selective laser melting (SLM). The mechanical response and microstructures in compressive deformation is analyzed for three printing strategies with 0°-, 90°- and 67.5°- scanning and three heat treatment conditions (450 °C for 3 h, 1100 °C for 1 h with furnace cool and 1100 °C for 1 h with water quenching) for selective laser melted (SLMed) stainless steel 316L in comparison with wrought stainless steel 316L in this work. Alteration of mechanical properties, microstructure evolution and compressive deformation mechanism is studied. Melt pool features are not significantly affected by low-temperature heat treatment (450 °C for 3 h) but fully dissolved through high-temperature heat treatment (1100 °C for 1 h). High-temperature heat treatment provides a higher resistance to compressive plastic deformation for SLMed 316L compared with the low-temperature heat-treated and as-built samples where more twinnings are observed. The compressive plastic deformation mechanism of 90°- and 67.5°-scanning samples is similar, which mainly results from twinning-induced plasticity. For 0°-scanning samples, the strong crystallographic texture is the main cause of anisotropic deformation. Modelling and simulation have been conducted to explain the anisotropic deformation mechanism of the 0°-scanning strategy. Simulation results suggest that the morphology difference of laser-scanning tracks and melt pools, which leads to material flow along the laser scanning direction, explains the anisotropic deformation mechanism.

Being a major global carbon emitter, the manufacturing industry has been under increasing scrutiny to fabricate products that have lower carbon emissions. One of the approaches to reduce the carbon emissions of products is through the use of ecodesign in product design. This means that beyond the consideration of functionality and cost, design decision on variables such as the design's geometry and material will be made with the consideration of the product's environmental sustainability. In this work, a novel ecodesign methodology that incorporates material selection with the concept of light weighting through the use of topology optimisation is proposed to improve the environmental sustainability of structural mechanical products. The goal of this work is to generate alternative designs composed of unique material and geometry pairings that can meet the design requirements and have lower material carbon emissions as compared to the initial design. The practical application of this approach is further demonstrated in a case study of a swivel C bracket.

To abate global carbon emissions, there has been an unprecedented push for carbon transparency in the manufacturing industry. However, with products becoming increasingly complex, they contain sub-assemblies with components that have sub-components supplied by different manufacturers. This creates a multi-tier supply chain that complicates the propagation of sustainability information necessary to compute the product's carbon emission due to the lack of oversight and potential loss of information from manufacturers in the multi-tier supply chain. Blockchain technology, characterized by its immutability, visibility, and traceability, is a promising medium to propagate sustainability information. Despite the fact that many papers have proposed a system that is viable for products with a multi-tier supply chain in the literature, we have not seen its proof-of-concept yet. This work first proposes a blockchain-enabled system that enables the propagation of environmental sustainability information in a multi-tier supply chain. This paper describes the architecture of the proposed blockchain system and the data structure of each block in the blockchain. Based on the defined architecture, we implemented the proposed blockchain system with Ethereum and tested it using the pseudo-multi-tier supply chain of a torchlight.

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The effect of cold metal transfer (CMT) mode on ultra-precision machining (UPM) was investigated to explore phase transformation and potential improvements of surface integrity for a wire and arc additive manufactured (WAAMed)Ti–6Al–4V alloy part. Both CMT and CMT + Pulse (CMT + P) modes are taken into account, which is proved to be the stable methods to fabricate Ti–6Al–4V components. The calculation result shows that the heat input of the CMT + P mode is higher than that of the CMT mode. In the reheated conditions of the CMT + P mode, the α′ → α+β phase transformation occurs, which leads to a decrease in the number of acicular α′ martensite phases decreased and an increase in the size of the lamellar α+β phases. The UPM results showed that the cutting force increase with the cutting speed increases. In addition, the cutting force of the specimens fabricated in CMT mode is a little larger than that in CMT + P mode due to the higher strength and more α′ martensite phases. UPM can create a better surface finish with a reduction of surface roughness up to ∼90%. Moreover, the machine surface quality of the specimens in CMT mode is much better with the surface roughness of ∼0.1  μm at a low cutting speed.

Battery/Ultracapacitor (UC) Hybrid Energy Storage Systems (HESS) for Electric Vehicles (EVs) have been frequently proposed in the literature to increase battery cycle life. The HESS consists of a Power Management Strategy (PMS) and an Energy Management Strategy (EMS). Existing EMS are quite empirical, such as setting constant target UC energy levels regardless of load. This work presents an improved complete HESS management strategy. The EMS involves a more comprehensive method of setting the target UC energy level using a speed-dependent band. This allows the UC to achieve two goals – contain sufficient energy for future accelerations and have sufficient space for capturing energy from future regenerative braking – without knowledge of the future drive profile. The PMS involves a speed-dependent battery power limit, which also achieves two goals – better UC utilization and allowing the battery to supply the steady state power. Simulations show existing works cannot achieve the four goals simultaneously unless their UCs are sized twice as large compared to the proposed rule-based HESS. In addition, the proposed HESS extends battery cycle life by up to 42% compared to a battery-only system. Lastly, a reduced-scale experiment was built to show that the proposed HESS is able to run in real-time.

Overhangs are usually inevitable in Additive Manufacturing (AM). Moreover, making their downward surfaces reach higher accuracy after printing has an imperative impact on improving the accuracy of them and their corresponding as-printed parts. Although extensive studies have been devoted to improving the accuracy of as-printed parts, the effective, general, reliable, and less-consumption (in time and material) approach to make an overhang (especially on its downward surfaces) reach its ideal accuracy is still rare. Hence, a new machine-leaning-based geometric compensation approach is proposed in this study. First, based on the Taguchi method, a series of (overhang) benchmarks are designed and printed to collect the (geometric) deviations of the downward surfaces. With these data, a new deviation predictor is established based on the gaussian process regression model. The predictor can effectively predict the deviation(s) (as well as its corresponding quantified uncertainty) of each downward surface (after printing) by using a pointwise manner. Meanwhile, to make the downward surface of an overhang meet its ideal accuracy (after printing) with high confidence, a specific stochastic chance-constrained programming problem is first formulated to evaluate the new and suitable overhang height of each point on the downward surface. Based on the above-mentioned predictor, the programming problem gets solved by developing a new overhang-height optimization method that integrates the Monte Carlo simulation with the particle swarm optimization. After that, a support structure-associated compensation method is presented to make a pointwise compensation (according to the above-evaluated overhang height) on the downward surface and determine the support structures’ optimized number and anchor positions. Finally, experiments on several representative overhangs are also implemented based on a typical material extrusion machine to validate the effectiveness of the proposed approach. The results show that the proposed approach reduces the deviations of the downward surface by up to 63.92% on average, saving up to 40% of material (less support structures). In addition, methodological comparisons with state-of-the-art approaches are also implemented. The comparisons show that the proposed approach has the great potential to reliably improve the accuracy of the overhang’s downward surface(s) after printing in a less-consumption manner.

Among different treatments of critical-sized bone defects, bone tissue engineering (BTE) is a fast-developing strategy centering around the fabrication of scaffolds that can stimulate tissue regeneration and provide mechanical support at the same time. This area has seen an extensive application of bioceramics, such as calcium phosphate, for their bioactivity and resemblance to the composition of natural bones. Moreover, recent advances in additive manufacturing (AM) have unleashed enormous potential in the fabrication of BTE scaffolds with tailored porous structures as well as desired biological and mechanical properties. Robocasting is an AM technique that has been widely applied to fabricate calcium phosphate scaffolds, but most of these scaffolds do not meet the mechanical requirements for load-bearing BTE scaffolds. In light of this challenge, various approaches have been utilized to mechanically strengthen the scaffolds. In this review, the current state of knowledge and existing research on robocasting of calcium phosphate scaffolds are presented. Applying the Gibson-Ashby model, this review provides a meta-analysis from the published literature of the compressive strength of robocast calcium phosphate scaffolds. Furthermore, this review evaluates different approaches to the mechanical strengthening of robocast calcium phosphate scaffolds. The aim of this review is to provide insightful data and analysis for future research on mechanical strengthening of robocast calcium phosphate scaffolds and ultimately for their clinical applications.

•A 3D printed scaffold/hydrogel composite was fabricated to provide the topological cue and compliance cue at the same time for cell guidance•The larger pore size and bigger directed fiber number of 3D scaffold lead to a more uniform cell orientation (topotaxis)•The cells in collagen can still sense the scaffold topological cue and migrate along it (durotaxis)

A dual-networked distribution of the reinforcements holds promise for achieving a balance between high-strength and moderate plasticity in titanium matrix composites (TMCs). Unfortunately, achieving this improvement in TMCs via additive manufacturing (AM) methods, presents significant challenges. Those challenges arise from the inherent differences in chemical and physical properties, which often led to agglomeration of the reinforcement and cracks caused by the high thermal residual stresses. To overcome those issues, this study focuses on the development of Ti-6Al-4V (Ti64) alloys incorporated with 0.5 wt%graphene nanosheets (GNSs) constructing a dual quasi-continued TiC network structure via powder bed fusion. The results exhibited a super-high tensile yield strength (1307 MPa), accompanied by a moderated elongation of 2.6% with reduced residual stress. The microstructure, phase contents, and mechanical performance were thoroughly investigated. A thermo-metallurgical-mechanical coupling model was developed, considering factors such as laser absorption effects and laser scanning strategy. Finally, a reasonable dual-network model was built to elucidate the contribution of various strengthening factors. Overall, this study illustrates that the strength of GNS/Ti64 composites is affected by the factors of GNS distribution, quasi-continue network in-situ TiC particles, temperature and residual stress field, offering a reference for fabricating high-strength nanocarbon/Ti64 composites by AM methods.

The rapid development of additive manufacturing technology provides a more flexible and efficient manufacturing solution for the high value-added parts with a complex topology. However, the poor surface finish poses a major obstacle for the wide application of the additively manufactured components when their functionality and tolerance are benchmarked with those produced by the conventional process. In selective laser melting, visible pattern and texture of the printed layers and unmolten particles cannot be avoided although research works have been conducted to improve the surface finish by optimising the selective laser melting strategy and process parameters. Therefore, a dedicated post-processing technique is generally required to improve the surface finish of the additively manufactured products in terms of various levels of geometric complexity. In this study, a vibration-assisted conformal polishing tool is developed to finish a representative v-groove structure fabricated by selective laser melting. Experiments are conducted to investigate the effects of abrasive size and polishing time on the improvement in surface roughness. The developed technique in this paper can be applied to finish the additively manufactured internal structures such as honeycomb structure and irregular holes that have linear projection along a single axis.

Designing metallic cellular structures with triply periodic minimal surface (TPMS) sheet cores is a novel approach for lightweight and multi-functional structural applications. Different from current honeycombs and lattices, TPMS sheet structures are composed of continuous and smooth shells, allowing for large surface areas and continuous internal channels. In this paper, we investigate the mechanical properties and energy absorption abilities of three types of TPMS sheet structures (Primitive, Diamond, and Gyroid) fabricated by selective laser melting (SLM) with 316 L stainless steel under compression loading and classify their failure mechanisms and printing accuracy with the help of numerical analysis. Experimental results reveal the superior stiffness, plateau stress and energy absorption ability of TPMS sheet structures compared to body-centred cubic lattices, with Diamond-type sheet structures performing best. Nonlinear finite element simulation results also show that Diamond and Gyroid sheet structures display relatively uniform stress distributions across all lattice cells under compression, leading to stable collapse mechanisms and desired energy absorption performance. In contrast, Primitive-type structures display rapid diagonal shear band development followed by localized wall buckling. Lastly, an energy absorption diagram is developed to facilitate a systematic way to select optimal densities of TPMS structures for energy absorbing applications.

Abstract

Biomimicry is a desirable quality of tissue engineering scaffolds. While most of the scaffolds reported in the literature contain a single pore size or porosity, the native biological tissues such as cartilage and skin have a layered architecture with zone-specific pore size and mechanical properties. Thus, there is a need for functionally graded scaffolds (FGS). EHD-jet 3D printing is a high-resolution process and a variety of polymer solutions can be processed into 3D porous scaffolds at ease, overcoming the limitations of other 3D printing methods (SLS, stereolithography, and FDM) in terms of resolution and limited material choice. In this paper, a novel proof of concept study on fabrication of porous polycaprolactone-based FGS by using EHD-jet 3D printing technology is presented. Organomorphic scaffolds, multiculture systems, interfacial tissue engineering, and in vitro cancer metastasis models are some of the futuristic applications of these polymeric FGS.

Biocompatible tissue engineering (TE) scaffolds were used to closure the leakage area in gastro intestinal (GI) tract as patches; they could induce the regeneration of defected tissue and degraded steadily. However, some disadvantages, such as small and uncontrolled pore size, hinder the application of existed TE scaffolds. In this study, PCL/F127 composite scaffolds were fabricated through electrohydrodynamic jetting (E-jetting) technique. And the E-jetted scaffolds were cultured with esophageal fibroblast cells (the most important cell type in wound healing process) to evaluate their biocompatibility. The results show that E-jetted PCL/F127 scaffold has potential to be an alternative GI tract regeneration tool.

Porous solids are widely utilized in natural and engineering systems due to their exceptional specific mechanical response and customizable properties. However, lightweight cellular solids often undergo severe localized deformation, resulting in catastrophic failure. This limitation undermines their damage resistance, thereby limiting their use primarily within small strain regimes. To address this issue, we drew inspiration from the unique structural features and damage-tolerant characteristics of the knobby starfish, leading us to the design of hierarchical diamond–triply periodic minimal surface (TPMS) lattices on two levels. We carried out a thorough examination of their mechanical behaviors, energy absorption, and damage tolerance using both experimental methods and finite element models. The designed hierarchical diamond lattices displayed stable elastoplastic-like deformation across large strain, along with excellent damage resistance, maintaining a stiffness and strength of over 57% of the initial value after four cycles of compression. Simulations aligned well with experimental results, showing a progressive transition in the deformation behavior of the designed lattices from bending-dominated to stretching-dominated as the thickness of the micro-lattice increased. However, there are no significant changes in the deformation behavior for the shear modulus. Overall, the designed hierarchical diamond lattices demonstrated superior specific energy absorption of 2.62J/g and remarkable damage tolerance compared to state-of-the-art lattices. This study aims to provide new insights into the design of hierarchically structured cellular materials.

The representation and archiving of design information play an essential role in product conceptual design by enabling the design teams to reuse existing solutions. However, most existing studies on information management of conceptual design focus mainly on the systematization of function-related design knowledge, while few studies are related to the aesthetic aspect of design information. The challenge lies in acquiring and quantifying the aesthetic information involved in conceptual design activities. It is also difficult to represent and archive the relationships and hierarchies of aesthetic information in conceptual design. In this context, this study proposes a method to facilitate the searching and retrieval of existing design solutions with effective representation and archiving of both functional and aesthetic information in conceptual design. First, to address the challenge of acquiring and quantifying the aesthetic information, Kansei adjectives and aesthetic design principles were applied to quantify the aesthetic design information. Second, a model using knowledge-based information representation and an approach for archiving conceptual design information was proposed to represent and archive the aesthetic information in hierarchal relationships. The proposed approach was illustrated by a case study of digital camera design. A system prototype with a domain-driven vocabulary to represent and archive aesthetic information for digital camera design was successfully developed to show the feasibility of the proposed approach.

This paper proposes concept to decide end-of-life (EoL) product recovery option, followed by methods to quantify product condition. A case study is presented using refrigerator crankshaft to illustrate the implication of product condition on product recovery decision making. The product condition comprises wear-out life of the product, change of dimension and cleanliness level. The advantage from the proposed concept is twofold - firstly, knowledge learned and embedded resources from EoL products able to get back to the product life cycle chain as a closed loop and, secondly, the most favourable EoL product recovery option can be made wisely. With thorough understanding of EoL product condition, it enables original equipment manufacturers (OEMs) to make quick and informed decision.

Based on compute analysis engineering (CAE), the performances of acoustic and fluent for muffler comprehensively were analyzed and optimized in the paper. First, aiming at the heavy exhaust noise of diesel engine, bench experiments of measuring independently were designed and carried out, the frequency spectrum of exhaust noise was achieved, combining with simulation analysis of the finite element, acoustic and fluid performances of the original muffler and respective muffling cavities were analyzed, whose shortage such as transmission loss, pressure loss and flow regeneration noise were achieved, the muffler would be re-designed by CAE. Simulation shows the performances of improved mufflers were better than the original one. Eventually, insertion loss of experiment for new muffler is more 10dB(A) above than the original one, and power loss met requirement.

For the relatively strong vibration caused by a three-wheeled motorcycle exhaust system and raised the level of the noise in the whole motorcycle, this paper combines the experimental modal analysis method and finite element analysis (FEA) method, establishes finite model of the exhaust system, finishes the experimental modal analysis and transient response analysis based on Hyperworks software and laboratory equipment, and obtains six natural frequencies and mode shapes. Comparison has been made between acceleration RMS changes before and after the mounting points changed with the transient excitations. At the end, the document also verifies better results after the improvement and found the basement of reducing noise in the next step.

The main sound source of motorcycle noise is engine exhaust noise in the paper. Installing muffler can effectively reduce the exhaust noise, in the other word, if the acoustic performance of muffler can be improved, exhaust noise of engine will effectively be suppressed. Based on the FEM, establishing the acoustic simulation model, the performance of muffler relates to acoustic is studied. Based on muffling theory, the optimal projects of the interior structure for muffler are proposed. Through doing experiments of insertion loss for muffler and the pass-by noise for motorcycle, these confirmed that the improved muffler can reduce the motorcycle’s noise.

The manufacturing industry is facing unprecedented challenges in this dynamic economy and social environment. Factors like incorporation of quality services, environmental sustainability and the successful effective leveraging of industrial informatics for virtual enterprises are new determinants for a manufacturing enterprise to stay competitive. Among these, the environmental problems related to electronic waste have prompted the electronic products manufacturers to innovate and adopt new initiatives such as take back system and after-sales service network. A concept with a holistic approach to integrate manufacturing and services with the considerations for environmental sustainability is being introduced here. Based on this, the service stage is discussed and a software infrastructure framework for this stage will be proposed. Finally, a case scenario for the use of computer in manufacturing environment is elaborated.

The role of angiogenesis in health and disease have gained considerable momentum in recent years. Visualizing angiogenic patterns and associated events of surrounding vascular beds in response to therapeutic and laboratory-grade biomolecules have become a commonplace in regenerative medicine and the biosciences. To aid imaging investigations in angiogenesis, the two-photon excitation fluorescence microscopy (2PEF), or multiphoton fluorescence microscopy is increasingly utilized in scientific investigations. The 2PEF microscope confers several distinct imaging advantages over other fluorescence excitation microscopy techniques – for the observation of in-depth, three-dimensional vascularity in a variety of tissue formats, including fixed tissue specimens and in vivo vasculature in live specimens. Understanding morphological and subcellular changes that occur in cells and tissues during angiogenesis will provide insights to behavioral responses in diseased states, advance the engineering of physiologically-relevant tissue models and provide biochemical clues for the design of therapeutic strategies. We review the applicability and limitations of the 2PEF microscope on the biophysical and molecular-level signatures of angiogenesis in various tissue models. Imaging techniques and strategies for best practices in 2PEF microscopy will be reviewed.

Selective laser melting processes deposit and join metal powders to near net shape in a layer-by-layer manner. The process of melting and re-solidification of several layers of deposited material can result in geometric deviations, and the impact is particularly significant for sub-millimetre structures oriented at a wide range of overhang angles with respect to the building platform. This paper assesses and benchmarks the capabilities of a neural network-based geometric compensation approach for truss lattice structures with circular cross-sections. The neural network method is capable to generate free-form cross-sections with enhanced geometric freedom for compensation compared to more established analytical compensation approaches limited to predefined geometric shapes. For neural network training, lattice dome structures composed of trusses with different overhang angles were designed and printed by selective laser melting and measured via X-ray computed tomography, resulting in point cloud data sets containing more than 20,000 data points for each overhang angle. For experimental validation, neural network-compensated dome structures were benchmarked against dome structures with elliptical parameter compensation. Results show that the neural network compensated lattice trusses achieve higher printing dimensional accuracy compared to the uncompensated structures and those compensated based on elliptical parameter estimates.

In tissue engineering, cell-laden scaffold has gradually replaced cell-less scaffold due to better biological performance. However, manual pipetting, the traditional cell seeding for cell-laden scaffold, leads to an imprecise and inhomogeneous cell distribution. As an alternative, micro-extrusion of cell-laden hydrogel achieves homogenous cell distribution, but causes high shear stress which is harmful to cells. To address this challenge, the objective of this study is to print cells on porous scaffold precisely without causing high shear stress to produce homogeneous cell-laden hybrid scaffold. Porous polycaprolactone scaffold fabricated through electro-hydrodynamic jetting was used as a representation. To improve scaffold hydrophilicity for better cell adhesion, 6% (w/w) Pluronic F127 was blended with polycaprolactone. HeLa cells, as a demonstration, were ejected on the scaffold fibers through piezoelectric inkjet printing. As a result, inkjet printing showed a more precise and homogeneous cell distribution and enhanced cell proliferation compared to manual pipetting (1.34- fold increase after 7 days). Furthermore, due to the low viscosity of cell solution, the average shear stress caused during inkjet printing was 1.79 kPa as opposed to 18 kPa of micro-extrusion, which is friendly to cells. In summary, through inkjet printing, homogeneous cell-laden hybrid scaffold could be fabricated with lower shear stress.