Fast and Accurate Additive Manufacturability Analysis

This paper focuses on the design optimization of complex 3D composites structures made by additive manufacturing processes. There are commercial CAD-CAM software solutions for detailed offline path programming, but there is a growing need for innovative tools and methodologies for doing trade oil studies very early at design stage. A new innovative solution has been developed on top of the CATFIBER■ software,allowing both designers and stress engineers to quickly analyze complex double-curved geometries. It also includes a variable stiffness approach with tow-steering, and structural analysis of the manufacturing defects using Digimat■ software.

Study on the Manufacturability Evaluation Based on Double-layer Model of Manufacturing Resources

Virtual organization is a new production patter and a principal part in advanced manufacturing systems such as agile manufacturing. Manufacturability evaluation is the necessary condition to form the virtual organization. A new manufacturability evaluation approach is described in this paper, which is carried out based on every process feature under the double-layer model of manufacturing resources proposed by authors. The manufacturing resources that build up the virtual organization are selected according to the results of manufacturability evaluation.

Generative Learning in VLSI Design for Manufacturability: Current Status and Future Directions

With the continuous scaling of integrated circuit technologies,design for manufacturability(DFM)is becoming more critical,yet more challenging.Alongside,recent advances in machine learning have provided a new computing paradigm with promising applications in VLSI manufacturability.In particular,generative learning-regarded among the most interesting ideas in present-day machine learning-has demonstrated impressive capabilities in a wide range of applications.This paper surveys recent results of using generative learning in VLSI manufacturing modeling and optimization.Specifically,we examine the unique features of generative learning that have been leveraged to improve DFM efficiency in an unprecedented way;hence,paving the way to a new data-driven DFM approach.The state-of-the-art methods are presented,and challenges/opportunities are discussed.

Manufacturability and mechanical reliability study for heterogeneous integration system in display(HiSID)

In this paper,the system on display panel(SoDP)architecture,the primary stage of heterogeneous integration system in display(HiSID),is introduced for the first time.In this architecture,the driving components of display,which are supposed to be on the display flexible print circuit(FPC)in traditional architecture,are innovatively integrated onto the backside of display panel.Through the SoDP architecture,the simulated impact strain in the panel fan-out region can decrease about 30%compared to the traditional architecture,and SoDP provides more the 10 mm extra space in the in-plane Y-direction for holding a larger battery.Also,the SoDP is compatible with the current organic laser emitted diode(OLED)and system in package(SiP)processes.Besides the primary stage,this paper also presents a comprehensive and extensive analysis on the challenges of the manufacturability for the advanced stage of HiSID from four key technologies perspectives:device miniaturization,massive manufacturing,driving technology,and advanced heterogeneous integration.

Review on laser directed energy deposited aluminum alloys

Lightweight aluminum(Al)alloys have been widely used in frontier fields like aerospace and automotive industries,which attracts great interest in additive manufacturing(AM)to process high-value Al parts.As a mainstream AM technique,laser-directed energy deposition(LDED)shows good scalability to meet the requirements for large-format component manufacturing and repair.However,LDED Al alloys are highly challenging due to their inherent poor printability(e.g.low laser absorption,high oxidation sensitivity and cracking tendency).To further promote the development of LDED high-performance Al alloys,this review offers a deep understanding of the challenges and strategies to improve printability in LDED Al alloys.The porosity,cracking,distortion,inclusions,element evaporation and resultant inferior mechanical properties(worse than laser powder bed fusion)are the key challenges in LDED Al alloys.Processing parameter optimizations,in-situ alloy design,reinforcing particle addition and field assistance are the efficient approaches to improving the printability and performance of LDED Al alloys.The underlying correlations between processes,alloy innovation,characteristic microstructures,and achievable performances in LDED Al alloys are discussed.The benchmark mechanical properties and primary strengthening mechanism of LDED Al alloys are summarized.This review aims to provide a critical and in-depth evaluation of current progress in LDED Al alloys.Future opportunities and perspectives in LDED high-performance Al alloys are also outlined.

A facile strategy for tuning the density of surface-grafted biomolecules for melt extrusion-based additive manufacturing applications

Melt extrusion-based additive manufacturing(ME-AM)is a promising technique to fabricate porous scaffolds for tissue engi-neering applications.However,most synthetic semicrystalline polymers do not possess the intrinsic biological activity required to control cell fate.Grafting of biomolecules on polymeric surfaces of AM scaffolds enhances the bioactivity of a construct;however,there are limited strategies available to control the surface density.Here,we report a strategy to tune the surface density of bioactive groups by blending a low molecular weight poly(ε-caprolactone)5k(PCL5k)containing orthogonally reactive azide groups with an unfunctionalized high molecular weight PCL75k at different ratios.Stable porous three-dimensional(3D)scaf-folds were then fabricated using a high weight percentage(75 wt.%)of the low molecular weight PCL 5k.As a proof-of-concept test,we prepared films of three different mass ratios of low and high molecular weight polymers with a thermopress and reacted with an alkynated fluorescent model compound on the surface,yielding a density of 201-561 pmol/cm^(2).Subsequently,a bone morphogenetic protein 2(BMP-2)-derived peptide was grafted onto the films comprising different blend compositions,and the effect of peptide surface density on the osteogenic differentiation of human mesenchymal stromal cells(hMSCs)was assessed.After two weeks of culturing in a basic medium,cells expressed higher levels of BMP receptor II(BMPRII)on films with the conjugated peptide.In addition,we found that alkaline phosphatase activity was only significantly enhanced on films contain-ing the highest peptide density(i.e.,561 pmol/cm^(2)),indicating the importance of the surface density.Taken together,these results emphasize that the density of surface peptides on cell differentiation must be considered at the cell-material interface.Moreover,we have presented a viable strategy for ME-AM community that desires to tune the bulk and surface functionality via blending of(modified)polymers.Furthermore,the use of alkyne-azide“click”chemistry enables spatial control over bioconjugation of many tissue-specific moieties,making this approach a versatile strategy for tissue engineering applications.

An identification method for enclosed voids restriction in manufacturability design for additive manufacturing structures

Additive manufacturing （AM） technologies, such as selective laser sintering （SLS） and fused deposition modeling （FDM）, have become the powerful tools for direct manufacturing of complex parts. This breakthrough in manufacturing technology makes the fabrication of new geometrical features and multiple materials possible. Past researches on designs and design methods often focused on how to obtain desired functional performance of the structures or parts, specific manufacturing capabilities as well as manufacturing constraints of AM were neglected. However, the inherent constraints in AM processes should be taken into account in design process. In this paper, the enclosed voids, one type of manufacturing constraints of AM, are investigated. In mathematics, enclosed voids restriction expressed as the solid structure is simply- connected. We propose an equivalent description of simply-connected constraint for avoiding enclosed voids in structures, named as virtual temperature method （VTM）. In this method, suppose that the voids in structure are filled with a virtual heating material with high heat conductivity and solid areas are filled with another virtual material with low heat conductivity. Once the enclosed voids exist in structure, the maximum temperature value of structure will be very high. Based upon this method, the simplyconnected constraint is equivalent to maximum temperature constraint. And this method can be easily used to formulate the simply-connected constraint in topology optimization. The effectiveness of this description method is illustrated by several examples. Based upon topology optimization, an example of 3D cantilever beam is used to illustrate the trade-off between manufacturability and functionality. Moreover, the three optimized structures are fabricated by FDM technology to indicate further the necessity of considering the simply-connected constraint in design phase for AM.

Repositioning fertilizer manufacturing subsidies for improving food security and reducing greenhouse gas emissions in China

China removed fertilizer manufacturing subsidies from 2015 to 2018 to bolster market-oriented reforms and foster environmentally sustainable practices.However,the impact of this policy reform on food security and the environment remains inadequately evaluated.Moreover,although green and low-carbon technologies offer environmental advantages,their widespread adoption is hindered by prohibitively high costs.This study analyzes the impact of removing fertilizer manufacturing subsidies and explores the potential feasibility of redirecting fertilizer manufacturing subsidies to invest in the diffusion of these technologies.Utilizing the China Agricultural University Agri-food Systems model,we analyzed the potential for achieving mutually beneficial outcomes regarding food security and environmental sustainability.The findings indicate that removing fertilizer manufacturing subsidies has reduced greenhouse gas(GHG)emissions from agricultural activities by 3.88 million metric tons,with minimal impact on food production.Redirecting fertilizer manufacturing subsidies to invest in green and low-carbon technologies,including slow and controlled-release fertilizer,organic-inorganic compound fertilizers,and machine deep placement of fertilizer,emerges as a strategy to concurrently curtail GHG emissions,ensure food security,and secure robust economic returns.Finally,we propose a comprehensive set of government interventions,including subsidies,field guidance,and improved extension systems,to promote the widespread adoption of these technologies.

Toward understanding the microstructure characteristics,phase selection and magnetic properties of laser additive manufactured Nd-Fe-B permanent magnets

Nd-Fe-B permanent magnets play a crucial role in energy conversion and electronic devices.The essential magnetic properties of Nd-Fe-B magnets,particularly coercivity and remanent magnetization,are significantly infuenced by the phase characteristics and microstructure.In this work,Nd-Fe-B magnets were manufactured using vacuum induction melting(VIM),laser directed energy deposition(LDED)and laser powder bed fusion(LPBF)technologies.Themicrostructure evolution and phase selection of Nd-Fe-B magnets were then clarified in detail.The results indicated that the solidification velocity(V)and cooling rate(R)are key factors in the phase selection.In terms of the VIM-casting Nd-Fe-B magnet,a large volume fraction of theα-Fe soft magnetic phase(39.7 vol.%)and Nd2Fe17Bxmetastable phase(34.7 vol.%)areformed due to the low R(2.3×10-1?C s-1),whereas only a minor fraction of the Nd2Fe14B hard magnetic phase(5.15 vol.%)is presented.For the LDED-processed Nd-Fe-B deposit,although the Nd2Fe14B hard magnetic phase also had a low value(3.4 vol.%)as the values of V(<10-2m s-1)and R(5.06×103?C s-1)increased,part of theα-Fe soft magnetic phase(31.7vol.%)is suppressed,and a higher volume of Nd2Fe17Bxmetastable phases(47.5 vol.%)areformed.As a result,both the VIM-casting and LDED-processed Nd-Fe-B deposits exhibited poor magnetic properties.In contrast,employing the high values of V(>10-2m s-1)and R(1.45×106?C s-1)in the LPBF process resulted in the substantial formation of the Nd2Fe14B hard magnetic phase(55.8 vol.%)directly from the liquid,while theα-Fe soft magnetic phase and Nd2Fe17Bxmetastable phase precipitation are suppressed in the LPBF-processed Nd-Fe-B magnet.Additionally,crystallographic texture analysis reveals that the LPBF-processedNd-Fe-B magnets exhibit isotropic magnetic characteristics.Consequently,the LPBF-processed Nd-Fe-B deposit,exhibiting a coercivity of 656 k A m-1,remanence of 0.79 T and maximum energy product of 71.5 k J m-3,achieved an acceptable magnetic performance,comparable to other additive manufacturing processed Nd-Fe-B magnets from MQP(Nd-lean)Nd-Fe-Bpowder.

Microstructure and thermal properties of dissimilar M300–CuCr1Zr alloys by multi-material laser-based powder bed fusion

Multi-material laser-based powder bed fusion (PBF-LB) allows manufacturing of parts with 3-dimensional gradient and additional functionality in a single step. This research focuses on the combination of thermally-conductive CuCr1Zr with hard M300 tool steel.Two interface configurations of M300 on CuCr1Zr and CuCr1Zr on M300 were investigated. Ultra-fine grains form at the interface due to the low mutual solubility of Cu and steel. The material mixing zone size is dependent on the configurations and tunable in the range of0.1–0.3 mm by introducing a separate set of parameters for the interface layers. Microcracks and pores mainly occur in the transition zone.Regardless of these defects, the thermal diffusivity of bimetallic parts with 50vol% of CuCr1Zr significantly increases by 70%–150%compared to pure M300. The thermal diffusivity of CuCr1Zr and the hardness of M300 steel can be enhanced simultaneously by applying the aging heat treatment.

Additively manufactured Ti–Ta–Cu alloys for the next-generation load-bearing implants

Bacterial colonization of orthopedic implants is one of the leading causes of failure and clinical complexities for load-bearing metallic implants. Topical or systemic administration of antibiotics may not offer the most efficient defense against colonization, especially in the case of secondary infection, leading to surgical removal of implants and in some cases even limbs. In this study, laser powder bed fusion was implemented to fabricate Ti3Al2V alloy by a 1:1 weight mixture of CpTi and Ti6Al4V powders. Ti-Tantalum(Ta)–Copper(Cu) alloys were further analyzed by the addition of Ta and Cu into the Ti3Al2V custom alloy. The biological,mechanical, and tribo-biocorrosion properties of Ti3Al2V alloy were evaluated. A 10 wt.% Ta(10Ta) and 3 wt.% Cu(3Cu) were added to the Ti3Al2V alloy to enhance biocompatibility and impart inherent bacterial resistance. Additively manufactured implants were investigated for resistance against Pseudomonas aeruginosa and Staphylococcus aureus strains of bacteria for up to 48 h. A 3 wt.% Cu addition to Ti3Al2V displayed improved antibacterial efficacy, i.e.78%–86% with respect to CpTi. Mechanical properties for Ti3Al2V–10Ta–3Cu alloy were evaluated, demonstrating excellent fatigue resistance, exceptional shear strength, and improved tribological and tribo-biocorrosion characteristics when compared to Ti6Al4V. In vivo studies using a rat distal femur model revealed improved early-stage osseointegration for alloys with10 wt.% Ta addition compared to CpTi and Ti6Al4V. The 3 wt.% Cu-added compositions displayed biocompatibility and no adverse infammatory response in vivo. Our results establish the Ti3Al2V–10Ta–3Cu alloy’s synergistic effect on improving both in vivo biocompatibility and microbial resistance for the next generation of load-bearing metallic implants.

Full-IC manufacturability check based on dense silicon imaging

With the increased design complexities brought in by applying different Reticle Enhancement Technologies (RETs) in nanometer-scale IC manufacturing process, post-RET sign-off verification is quickly becoming necessary. By introducing innovative algorithms for lithographic modeling, silicon imaging and yield problem locating, this paper describes a new methodology of IC manufacturability verification based on Dense Silicon Imaging (DSI). Necessity of imaging based verification is analyzed. Existing post-RET verification methods are reviewed and compared to the new methodology. Due to the greatly improved computational efficiency produced by algorithms such as the ~16*log2N/log2M times faster Specialized FFT, DSI based manufacturability checks on full IC scale, which were impractical for applications before, are now realized. Real verification example has been demonstrated and studied as well.

Effect of fabrication temperature on the manufacturability of lateral ZnO nanowire array UV sensor

Fabrication temperature is an important factor affecting the manufacturability of electronic devices,especially for the bottom-up self-assembled nano-device.In this study,we used a lateral-bridged zinc oxide(ZnO)nanowire array UV sensor as a model to investigate the influence of temperature on device performance over the entire manufacturing process,from sensor fabrication to packaging.We found that annealing of the SiO2 substrate would make ZnO seed layer on top of it more compact and uniform,and hence improve the lateral orientation and uniformity of ZnO nanowires grown from the seed layer.With the annealed substrate,the light-to-dark current ratio increased by two orders of magnitude.On the contrary,annealing the ZnO seed layer would deteriorate the light-to-dark current ratio of the sensor,because annealing caused most of the grains in the seed layer to become vertically aligned,which in turn affected the lateral growth of ZnO nanowire arrays.During the packaging process,the surface structure of ZnO nanowires would change if the chip welded at a temperature of 230℃for 2 min,resulting in a decrease of light-to-dark current ratio by three orders of magnitude.

Optimizing product manufacturability in 3D printing

3D printing has become a promising technique for industry production. This paper presents a research on the manufacturability optimization of discrete products un- der the influence of 3D printing technology. For this, we first model the problem using a tree structure, and then formulate it as a linear integer programming, where the total production time is to be minimized with the production cost constraint. To solve the problem, a differential evolution （DE） algorithm is developed, which automatically determines whether tra- ditionai manufacturing methods or 3D printing technology should be used for each part of the production. The algorithm is further quantitatively evaluated on a synthetic dataset, com- pared with the exhaustive search and alternating optimization solutions. Simulation results show that the proposed algo- rithm can well combine the traditional manufacturing meth- ods and 3D printing technology in production, which is help- ful to attain optimized product design and process planning concerning manufacture time. Therefore, it is beneficial to provide reference of the widely application and further in- dustrialization of the 3D printing technology.

Robust isogeometric topology optimization for piezoelectric actuators with uniform manufacturability

Piezoelectric actuators have received substantial attention among the industry and academia due to quick responses, such as high output force, high stiffness, high accuracy, and precision. However, the design of piezoelectric actuators always suffers from the emergence of several localized hinges with only one-node connection, which have difficulty satisfying manufacturing and machining requirements (from the over- or under-etching devices). The main purpose of the current paper is to propose a robust isogeometric topology optimization (RITO) method for the design of piezoelectric actuators, which can effectively remove the critical issue induced by one-node connected hinges and simultaneously maintain uniform manufacturability in the optimized topologies. In RITO, the isogeometric analysis replacing the conventional finite element method is applied to compute the unknown electro elastic fields in piezoelectric materials, which can improve numerical accuracy and then enhance iterative stability. The erode–dilate operator is introduced in topology representation to construct the eroded, intermediate, and dilated density distribution functions by non-uniform rational B-splines. Finally, the RITO formulation for the design of piezoelectric materials is developed, and several numerical examples are performed to test the effectiveness and efficiency of the proposed RITO method.

Challenges and opportunities in the production of magnesium parts by directed energy deposition processes

Mg-alloys have gained considerable attention in recent years for their outstanding properties such as lightweight,high specific strength,and corrosion resistance,making them attractive for applications in medical,aerospace,automotive,and other transport industries.However,their widespread application is hindered by their low formability at room temperature due to limited slip systems.Cast Mg-alloys have low mechanical properties due to the presence of casting defects such as porosity and anisotropy in addition to the high scrap.While casting methods benefit from established process optimization techniques for these problems,additive manufacturing methods are increasingly replacing casting methods in Mg alloys as they provide more precise control over the microstructure and allow specific grain orientations,potentially enabling easier optimization of anisotropy properties in certain applications.Although metal additive manufacturing(MAM)technology also results in some manufacturing defects such as inhomogeneous microstructural evolution and porosity and additively manufactured Mg alloy parts exhibit lower properties than the wrought parts,they in general exhibit superior properties than the cast counterparts.Thus,MAM is a promising technique to produce Mg alloy parts.Directed energy deposition processes,particularly wire arc directed energy deposition(WA-DED),have emerged as an advantageous additive manufacturing(AM)technique for metallic materials including magnesium alloys,offering advantages such as high deposition rates,improved material efficiency,and reduced production costs compared to subtractive processes.However,the inherent challenges associated with magnesium,such as its high reactivity and susceptibility to oxidation,pose unique hurdles in the application of this technology.This review paper delves into the progress made in the application of DED technology to Mg-alloys,its challenges,and prospects.Furthermore,the predominant imperfections,notably inhomogeneous microstructure evolution and porosity,observed in Mg-alloy components manufactured through DED are discussed.Additionally,the preventive measures implemented to counteract the formation of these defects are explored.

An overview of additively manufactured metal matrix composites:preparation,performance,and challenge

Metal matrix composites(MMCs)are frequently employed in various advanced industries due to their high modulus and strength,favorable wear and corrosion resistance,and other good properties at elevated temperatures.In recent decades,additive manufacturing(AM)technology has garnered attention as a potential way for fabricating MMCs.This article provides a comprehensive review of recent endeavors and progress in AM of MMCs,encompassing available AM technologies,types of reinforcements,feedstock preparation,synthesis principles during the AM process,typical AM-produced MMCs,strengthening mechanisms,challenges,and future interests.Compared to conventionally manufactured MMCs,AM-produced MMCs exhibit more uniformly distributed reinforcements and refined microstructure,resulting in comparable or even better mechanical properties.In addition,AM technology can produce bulk MMCs with significantly low porosity and fabricate geometrically complex MMC components and MMC lattice structures.As reviewed,many AM-produced MMCs,such as Al matrix composites,Ti matrix composites,nickel matrix composites,Fe matrix composites,etc,have been successfully produced.The types and contents of reinforcements strongly influence the properties of AM-produced MMCs,the choice of AM technology,and the applied processing parameters.In these MMCs,four primary strengthening mechanisms have been identified:Hall–Petch strengthening,dislocation strengthening,load transfer strengthening,and Orowan strengthening.AM technologies offer advantages that enhance the properties of MMCs when compared with traditional fabrication methods.Despite the advantages above,further challenges of AM-produced MMCs are still faced,such as new methods and new technologies for investigating AM-produced MMCs,the intrinsic nature of MMCs coupled with AM technologies,and challenges in the AM processes.Therefore,the article concludes by discussing the challenges and future interests of AM of MMCs.

Digital Twin Modeling Enabled Machine Tool Intelligence:A Review

Machine tools,often referred to as the“mother machines”of the manufacturing industry,are crucial in developing smart manufacturing and are increasingly becoming more intelligent.Digital twin technology can promote machine tool intelligence and has attracted considerable research interest.However,there is a lack of clear and systematic analyses on how the digital twin technology enables machine tool intelligence.Herein,digital twin modeling was identified as an enabling technology for machine tool intelligence based on a comparative study of the characteristics of machine tool intelligence and digital twin.The review then delves into state-of-the-art digital twin modelingenabled machine tool intelligence,examining it from the aspects of data-based modeling and mechanism-data dual-driven modeling.Additionally,it highlights three bottleneck issues facing the field.Considering these problems,the architecture of a digital twin machine tool(DTMT)is proposed,and three key technologies are expounded in detail:Data perception and fusion technology,mechanism-data-knowledge hybrid-driven digital twin modeling and virtual-real synchronization technology,and dynamic optimization and collaborative control technology for multilevel parameters.Finally,future research directions for the DTMT are discussed.This work can provide a foundation basis for the research and implementation of digital-twin modeling-enabled machine tool intelligence,making it significant for developing intelligent machine tools.

Advances and challenges in direct additive manufacturing of dense ceramic oxides

Ceramic oxides,renowned for their exceptional combination of mechanical,thermal,and chemical properties,are indispensable in numerous crucial applications across diverse engineering fields.However,conventional manufacturing methods frequently grapple with limitations,such as challenges in shaping intricate geometries,extended processing durations,elevated porosity,and substantial shrinkage deformations.Direct additive manufacturing(dAM)technology stands out as a state-of-the-art solution for ceramic oxides production.It facilitates the one-step fabrication of high-performance,intricately designed components characterized by dense structures.Importantly,dAM eliminates the necessity for post-heat treatments,streamlining the manufacturing process and enhancing overall efficiency.This study undertakes a comprehensive review of recent developments in dAM for ceramic oxides,with a specific emphasis on the laser powder bed fusion and laser directed energy deposition techniques.A thorough investigation is conducted into the shaping quality,microstructure,and properties of diverse ceramic oxides produced through dAM.Critical examination is given to key aspects including feedstock preparation,laser-material coupling,formation and control of defects,in-situ monitoring and simulation.This paper concludes by outlining future trends and potential breakthrough directions,taking into account current gaps in this rapidly evolving field.

Role of inclination angle on columnar-to-equiaxed transition in the eutectic Al-5Mg-2Si alloy fabricated by laser powder bed fusion

In this study,the effect of inclination angles relative to the building direction in the additively manufactured eutectic Al-5Mg-2Si alloy was investigated through the laser powder bed fusion(LPBF).The microstructures and mechanical properties of the Al-5Mg-2Si alloy manufactured with different inclination angles(0°,30°,45°,60°and 90°)were reported and discussed.It is found that the“semicircular”melt pool(MP)in the load bearing face of 0°sample was eventually transformed into“stripe-like”MP in the 90°sample,accompanied by an increased fraction of melt pool boundaries(MPBs).Moreover,the microstructural analysis revealed that the columnar-to-equiaxed transition(CET)of theα-Al grains and eutectic Mg2Si was completed in the 90°sample,which were significantly refined with the average size of 10.6μm and 0.44μm,respectively.It is also found that the 90°sample exhibited good combination of strength and elongation(i.e.yield strength of 393 MPa,ultimate tensile strength of 483 MPa and elongation of 8.1%).The anisotropic mechanical properties were highly associated with the refined microstructures,thermal stress,and density of MPBs.Additionally,the CET driven by inclination angles was attributed to the variation of thermal conditions inside the local MPs.