Architectural Design and Additive Manufacturing of Mechanical Metamaterials:A Review

Mechanical metamaterials can be defined as a class of architected materials that exhibit unprecedented mechanical properties derived from designed artificial architectures rather than their constituent materials.While macroscale and simple layouts can be realized by conventional top-down manufacturing approaches,many of the sophisticated designs at various length scales remain elusive,due to the lack of adequate manufacturing methods.Recent progress in additive manufacturing(AM)has led to the realization of a myriad of novel metamaterial concepts.AM methods capable of fabricating microscale architectures with high resolution,arbitrary complexity,and high feature fidelity have enabled the rapid development of architected meta materials and drastically reduced the design-computation and experimental-validation cycle.This paper first provides a detailed review of various topologies based on the desired mechanical properties,including stiff,strong,and auxetic(negative Poisson’s ratio)metamaterials,followed by a discussion of the AM technologies capable of fabricating these metamaterials.Finally,we discuss current challenges and recommend future directions for AM and mechanical metamaterials.

Practice Teaching Reform of Mechanical Design and Manufacture and Its Automation Specialty under Transformation and Development

With the development of the times, undergraduate colleges and universities begin to transform and develop to adapt to the changing society, and put forward new requirements for practical teaching strategies, especially for applied undergraduate colleges. The reform of practical teaching is particularly important. Under the development of education transformation, the reform of mechanical design and manufacture and the practice teaching of automation specialty also occupy a very important position. Through the understanding of the reform of the practical teaching of this specialty, the effect of the reform is observed, and a reasonable teaching scheme is put forward to promote the steps of the transformation of the practical teaching.

Microstructures and mechanical properties of Ti−Al−V−Nb alloys with cluster formula manufactured by laser additive manufacturing

Ti−Al−V−Nb alloys with the cluster formula,12[Al−Ti_(12)](AlTi_(2))+5[Al−Ti1_(4)](V,Nb)2Ti,were designed by replacing V with Nb based on the Ti−6Al−4V alloy.Single-track cladding layers and bulk samples of the alloys with Nb contents ranging from 0 to 6.96 wt.%were prepared by laser additive manufacturing to examine their formability,microstructure,and mechanical properties.For single-track cladding layers,the addition of Nb increased the surface roughness slightly and decreased the molten pool height to improve its spreadability.The alloy,Ti−5.96Al−1.94V−3.54Nb(wt.%),exhibited better geometrical accuracy than the other alloys because its molten pool height was consistent with the spread layer thickness of the powder.The microstructures of the bulk samples contained similar columnar β-phase grains,regardless of Nb content.These grains grew epitaxially from the Ti substrate along the deposition direction,with basket-weaveα-phase laths within the columnar grains.Theα-phase size increased with increasing Nb contents,but its uniformity decreased.Along the deposition direction,the Vickers hardness increased from the substrate to the surface.The Ti−5.96Al−1.94V−3.54Nb alloy exhibited the highest Vickers hardness regardless of deposition position because of the optimal matching relationship between theα-phase size and its content among the designed alloys.

The design, manufacture and application of multistable mechanical metamaterials-a state-of-the-art review

Multistable mechanical metamaterials are a type of mechanical metamaterials with special features,such as reusability,energy storage and absorption capabilities,rapid deformation,and amplified output forces.These metamaterials are usually realized by series and/or parallel of bistable units.They can exhibit multiple stable configurations under external loads and can be switched reversely among each other,thereby realizing the reusability of mechanical metamaterials and offering broad engineering applications.This paper reviews the latest research progress in the design strategy,manufacture and application of multistable mechanical metamaterials.We divide bistable structures into three categories based on their basic element types and provide the criterion of their bistability.Various manufacturing techniques to fabricate these multistable mechanical metamaterials are introduced,including mold casting,cutting,folding and three-dimensional/4D printing.Furthermore,the prospects of multistable mechanical metamaterials for applications in soft driving,mechanical computing,energy absorption and wave controlling are discussed.Finally,this paper highlights possible challenges and opportunities for future investigations.The review aims to provide insights into the research and development of multistable mechanical metamaterials.

Design for Ti-Al-V-Mo-Nb alloys for laser additive manufacturing based on a cluster model and on their microstructure and properties

In this study,α+βTi-Al-V-Mo-Nb alloys with the addition of multiple elements that are suitable for laser additive manufacturing(LAM)were designed according to a Ti-6Al-4V cluster formula.This formula can be expressed as 12[Al-Ti12](AlTi2)+5[Al-Ti14]((Mo,V,Nb)2Ti),in which Mo and Nb were added into the alloys partially instead of V to give alloys with nominal compositions of Ti-6.01Al-3.13V-1.43Nb,Ti-5.97Al-2.33V-2.93Mo,and Ti-5.97Al-2.33V-2.20Mo-0.71Nb(wt.%).The microstructures and mechanical properties of the as-deposited and heat-treated samples prepared via LAM were examined.The sizes of theβcolumnar grains andαlaths in the Nb-containing samples are found to be larger than those of the Ti-6Al-4V alloy,whereas Mo-or Mo/Nb-added alloys contain finer grains.It indicates that Nb gives rise to coarsenedβcolumnar grains andαlaths,while Mo significantly refines them.Furthermore,the single addition of Nb improves the elongation,whereas the single addition of Mo enhances the strength of the alloys.The simultaneous addition of Mo/Nb significantly improves the comprehensive mechanical properties of the alloys,leading to the best properties with an ultimate tensile strength of 1,070 MPa,a yield strength of 1,004 MPa,an elongation of 9%,and micro-hardness of 355 HV.The fracture modes of all the alloys are ductile-brittle mixed fracture.

Automatic Virtual Entity Simulation of Conceptual Design Results—Part Ⅰ:Symbolic Scheme Generation and Identification

The development of new products of high quality, low unit cost, and short lead time to market are the key elements required for any enterprise to obtain a competitive advantage. For shorting the lead time to market and improving the creativity and performances of the product, a rule-based conceptual design approach and a methodology to simulate the conceptual design results generated in conceptual design process in automatical virtual entity form are presented in this paper. This part of paper presents a rule-based conceptual design method for generating creative conceptual design schemes of mechanisms based on Yan＇s kinematic chain regeneration creative design method. The design rules are adopted to describe the design requirements of the functional characteristics, the connection relationships and topological characteristics among mechanisms. Through the graphs-based reasoning process, the conceptual design space is expanded extremely, and the potential creative conceptual design results are then dug out. By refining the design rules, the solution exploration problem is avioded, and the tendentious conceptual design schemes are generated. Since mechanical, electrical and hydraulic subsystems can be transformed into general mechansims, the conceptual design method presented in this paper can also be applied in the conceptual design problem of complex mechatronic systems. And then the method to identify conceptual design schemes is given.

Practical Analysis of Mechanical Automation Technology in Automobile Manufacturing

In today’s rapidly developing modern society,automobiles,as an important part of transportation and industrial fields,play a pivotal role.With the improvement of people’s living standards and the increase in traffic demand,the automobile manufacturing industry has been continuously developing and growing globally.However,to cope with increasingly fierce market competition and ever-changing consumer demands,the automobile manufacturing industry is also facing the challenges of improving production efficiency,reducing costs,and improving product quality.In this context,automation technology has gradually become a major trend in the automobile manufacturing industry.As an important support of modern industry,automation technology has shown great application potential in many fields.From industrial production to daily life,automation technology can be seen everywhere.In the field of manufacturing,especially in automobile manufacturing,the application of automation technology is getting more and more attention.Automated production lines,intelligent robots,and automated warehousing systems have all changed the face of automobile manufacturing to varying degrees,bringing companies higher efficiency,more stable quality,and greater competitive advantages.The application trend of this automation technology in various fields not only meets the needs of modern industry for efficient,precise,and sustainable development but also provides new ideas and paths for the future development of the automobile manufacturing industry.

Anti⁃icing/De⁃icing Mechanism and Application Progress of Bio⁃inspired Surface for Aircraft

Icing on the surface of aircraft will not only aggravate its quality and affect flight control,but even cause safety accidents,which is one of the important factors restricting all-weather flight.Bio-inspired anti-icing surfaces have gained great attention recently due to their low-hysteresis,non-stick properties,slow nucleation rate and low ice adhesion strength.These bio-inspired anti-icing surfaces,such as superhydrophobic surfaces,slippery liquid-infused porous surfaces and quasi-liquid film surfaces,have realized excellent anti-icing performance at various stages of icing.However,for harsh environment,there are still many problems and challenges.From the perspective of bioinspiration,the mechanism of icing nucleation,liquid bounce and ice adhesion has been reviewed together with the application progress and bottleneck issues about anti-icing in view of the process of icing.Subsequently,the reliability and development prospect of active,passive and active-passive integrated anti-icing technology are discussed,respectively.

Adaptive enhancement design of triply periodic minimal surface lattice structure based on non-uniform stress distribution

The Schwarz primitive triply periodic minimal surface(P-type TPMS)lattice structures are widely used.However,these lattice structures have weak load-bearing capacity compared with other cellular structures.In this paper,an adaptive enhancement design method based on the non-uniform stress distribution in structures with uniform thickness is proposed to design the P-type TPMS lattice structures with higher mechanical properties.Two types of structures are designed by adjusting the adaptive thickness distribution in the TPMS.One keeps the same relative density,and the other keeps the same of non-enhanced region thickness.Compared with the uniform lattice structure,the elastic modulus for the structure with the same relative density increases by more than 17%,and the yield strength increases by more than 10.2%.Three kinds of TPMS lattice structures are fabricated by laser powder bed fusion(L-PBF)with 316L stainless steel to verify the proposed enhanced design.The manufacture-induced geometric deviation between the as-design and as-printed models is measured by micro X-ray computed tomography(μ-CT)scans.The quasi-static compression experimental results of P-type TPMS lattice structures show that the reinforced structures have stronger elastic moduli,ultimate strengths,and energy absorption capabilities than the homogeneous P-TPMS lattice structure.

Automatic Virtual Entity Simulation of Conceptual Design Results—Part Ⅱ:Symbolic Scheme Simulation

The development of new products of high quality, low unit cost, and short lead time to market are the key elements required for any enterprise to obtain a competitive advantage. This part of the paper presents a methodology to automatically simulate the conceptual design results in the virtual entity form. To the identified basic mechanisms, their kinematic analysis is carried out by matching basic Barranov trusses, and their virtual entities are modeled based on feature-based technique and encapsulated as one design object. Based on the structures of the basic mechanisms and their connections, a space layout to the mechanical system corresponding to the symbolic scheme is then fulfilled. With the preset-assembly approach, all parts in the mechanical system are put onto proper positions where the constraint equations are met according to the space layout results. In this way, the virtual entity assembly model of the mechanical system relative to the symbolic scheme is set up. The approach presented in this paper can not only obtain innovative conceptual conceptual design results, but also can evaluate their performances under 3-D enviroment efficently.

口腔种植修复中钛基底氧化锆基台的制作和力学性能

背景:随着计算机辅助设计和计算机辅助制造技术的发展,钛基底氧化锆基台因具备良好的应用优势被广泛运用于临床,但仍存在一些问题,尚缺乏共识性的设计标准。目的:综述钛基底氧化锆基台的制作方法及基台连接、穿龈设计、基台角度和粘接对钛基底氧化锆基台各类力学性能的影响。方法:检索Pub Med数据库和中国知网2010-2023年发表的相关文献,检索词为“zirconia abutment,titanium base;氧化锆基台,钛基底”,部分经典文献延长检索时间限制,通过纳入和排除标准获取相关文献,对57篇符合标准的文献进行综述。结果与结论:建议临床医生尽量选择具有抗旋结构的基台连接或是具有莫氏锥度的非抗旋连接,当运用钛基底氧化锆基台时,种植体应放置在正确的轴向角度(植体轴向向唇侧倾斜角度不超过15°或略向腭侧倾斜);当植体轴向向唇侧倾斜角度≥30°时,应当适当降低咬合力,以降低种植体、基台及修复体机械并发症和生物并发症的风险;应尽可能选择穿龈高度较高的钛基底,并且其穿龈角度不应超过40°。Multilink Hybrid Abutment可以作为氧化锆基台与钛基底口外粘结的首选粘接剂。

Additive manufacturing of tungsten,tungsten-based alloys,and tungsten matrix composites

Tungsten(W) materials are gaining more and more attention due to the extended applications of metallic systems in the extreme environments.Given W’s unique characteristics like room-temperature brittleness,additive manufacturing(AM)techniques could give them a higher design flexibility and manufacturability.With the growing focus and thriving development of W-faced AM techniques,since the mechanical performance of additively manufactured W parts is still unsatisfactory,a critical review to further explore the possibilities of combining W and AM processes is urgently needed.In this review,we systematically explain the fundamentals of AM processes for W materials.Following the traditional classification,we further discuss the widely used AM processes including wire arc additive manufacturing(WAAM),electron beam melting(EBM),laser powder bed fusion(LPBF),laser direct energy deposition(laser DED),and other modified yet emergent AM techniques.Accordingly,since additively manufacturing W materials is processing parameter-sensitive,we illustrated the effects of various important processing parameters on the AM process control and final parts’ quality.With this detailed understanding,various categories of AM-compatible W materials(i.e.,pure W,W alloys,and W composites) were presented,and their general mechanical performance,distinct role(particularly the role of different alloying elements and added secondary-phase particles in W),and application-oriented benefits have been summarized.After clarifying the current status,main challenges,and triumphant successes for additively manufacturing W materials,we further provide a concise prospect into the development of additively manufactured(AMed) W materials by integrating potential fabrication,measurement,alloy design,and application’s considerations.In summary,this critical review investigates the fundamental and practical problems crucially limiting the applications of AMed W materials,and the comprehensive discussion concentrates the history of the development and combination between AM techniques and W design.All the understanding is of great importance to achieving foreseeable successful future applications of AMed W materials.

Analysis of Efficient 32 Bit Adder Using Tree Grafting Technique

Adder with high efficiency and accuracy is the major requirement for electronic circuit design.Here the optical logic gate based adder circuit is designed for better performance analysis of optical input signals varied with the wavelength.Efficiency of the adder can be improved by increasing the speed of operation,reducing the complexity and power consumption.To maintain the high efficiency with accuracy,a new combination of adder has been proposed and tested in this work.A new adder by combining the logics of Brent Kung,Sklansky and Kogge Stone adders by Tree Grafting Technique(BSKTGT)has been tested along with individual Brent Kung,Sklansky,Kogge Stone,Knowles,Han Carlson and Ladner Fischer adders.All the existing and proposed adders have been designed and tested for efficiency with the help of Cadence platform with 45 nm technology.Efficiency in terms of Size reduction,Power reduction,Power Delay Product(PDP)and accuracy in adding 8 bit,16 bit and 32 bit values had been tested for all the adders and found that the 32 bit BSKTGT adder performed well in all aspects and have produced better efficiency with the power consumption of 52.512426μW with 3.16%of power saving over Brent Kung adder,utilised an area of 631.191 with 8.55%reduction over Kogge Stone Adder,has the cell count of 132 which is 10.61%reduction over Brent Kung Adder and PDP value of 122.6695 J,which is 0.46%less than that of the Han Carlson Adder.

The Part Count Tool (PaCT) for Design Concept Selection

This paper presents a part count tool that predicts the part count for a particular product concept during the conceptual design phase. The part count tool will also aid in ranking the design concepts by the criterion of number of components for a product. This tool utilizes existing automated concept generation algorithms to generate the design concepts. It extracts the available data from the Design Engineering Lab Design Repository to determine an average number of parts per component type in the repository and then calculates an average part count for new concepts. The part count tool also uses an algorithm to determine how to connect two non-compatible components through the addition of mutually compatible components. While emphasis is placed on the average parts per product in evaluating designs, the overall functional requirement of the product is also considered.

Integration of Strain Sensors on Additively Manufactured Implantable Devices

The development of personalized healthcare is rapidly growing thanks to the support of low-power electronics,advanced fabrication processes and secured data transmission protocols.Long-acting drug delivery systems able to sustain the release of therapeutics in a controllable manner can provide several advantages in the treatment of chronic diseases.Various systems under development control drug release from an implantable reservoir via concentration driven diffusion through nanofluidic membranes.Given the high drug concentration in the reservoir,an inward osmotic fluid transport occurs across the membrane,which counters the outward diffusion of drugs.The resulting osmotic pressure buildup may be sufficient to cause the failure of implants with associated risks to patients.Confidently assessing the osmotic pressure buildup requires testing in vivo.Here,using metal and polymer AM(additive manufacturing)processes,we designed and developed implantable drug reservoirs with embedded strain sensors to directly measure the osmotic pressure in drug delivery implants in vitro and in vivo.

基于OBE和迭代创新的机械制造及自动化专业人才培养模式改革与实践研究

针对国家对高素质技能人才培养的需求,对基于OBE理念和迭代创新的人才培养模式进行改革,并以机械制造及自动化(模具方向)专业为例,从人才培养目标和核心能力指标、专业课程体系和课程内容、教学模式和教学方法、教学评价体系和教师队伍的培养等方面提出改革设想并进行了教学实践,取得了一定的成效。

机械制造装备设计中翻转课堂教学方法的应用

翻转课堂教学模式遵循“以学生为中心”的理念,可以有效提高学生学习的积极性,培养学生的团队协作能力、自主学习能力、分析和解决问题能力及表达能力等。基于翻转课堂教学模式对大学机械工程专业必修课程——机械制造装备设计课程进行了研究,分析了课程教学现状及教学中存在的问题,探讨了机械制造装备设计课程采用翻转课堂教学模式的教学设计,指出了开展翻转课堂教学过程中出现的问题并提出了持续改进建议。

智能制造背景下的机械自动化技术的创新与应用

机械自动化技术的创新与应用已成为推动制造业转型升级的重要驱动力,在智能制造的驱动下,通过融合信息技术、自动化技术和人工智能等新兴技术,能够有效提高生产效率、降低成本、提升产品质量。为促进机械自动化技术深度应用,分析了智能制造的技术背景,论述了机械自动化技术与智能制造融合创新关键方向,总结了先进智能制造背景下的机械自动化先进技术的应用情况,说明了现阶段技术发展的阻碍及发展建议。

机械设计制造及其自动化技术在智能制造领域的应用

结合机械设计制造及其自动化技术的基本情况,主要对其在智能制造领域的应用进行分析,确保机械设计制造及其自动化技术能发挥相应作用,让机械设计制造及其自动化技术能满足智能制造领域的工作需求,在分析时,主要对机械设计制造及其自动化技术的优势进行研究,再分析其在智能制造领域的应用进行研究,推动智能制造领域的稳健发展。