Additive manufactured osseointegrated screws with hierarchical design

Bone screws are devices used to fix implants or bones to bones.However,conventional screws are mechanically fixed with thread and often face long-term failure due to poor osseointegration.To improve osseointegration,screws are evolving from solid and smooth to porous and rough.Additive manufacturing(AM)offers a high degree of manufacturing freedom,enabling the preparation of predesigned screws that are porous and rough.This paper provides an overview of the problems currently faced by bone screws:long-term loosening and screw breakage.Next,advances in osseointegrated screws are summarized hierarchically(sub-micro,micro,and macro).At the sub-microscale level,we describe surface-modification techniques for enhancing osseointegration.At the micro level,we summarize the micro-design parameters that affect the mechanical and biological properties of porous osseointegrated screws,including porosity,pore size,and pore shape.In addition,we highlight three promising pore shapes:triply periodic minimal surface,auxetic structure with negative Poisson ratio,and the Voronoi structure.At the macro level,we outline the strategies of graded design,gradient design,and topology optimization design to improve the mechanical strength of porous osseointegrated screws.Simultaneously,this paper outlines advances in AM technology for enhancing the mechanical properties of porous osseointegrated screws.AM osseointegrated screws with hierarchical design are expected to provide excellent long-term fixation and the required mechanical strength.

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.

Impact Performance Research of Re-Entrant Octagonal Negative Poisson’s Ratio Honeycomb with Gradient Design

Based on the traditional re-entrant honeycomb,a novel re-entrant octagon honeycomb(ROH)is proposed.The deformation mode of the honeycomb under quasi-static compression is analyzed by numerical simulation,and the results are in good agreement with the experimental ones.The deformation modes,mechanical properties,and energy absorption characteristics of ROH along the impact and perpendicular directions gradient design are investigated under different velocities.The results indicated that the deformation mode of ROH is affected by gradient design along the direction of impact and impact speed.In addition,gradient design along the direction of impact can increase the initial peak stress of ROH and accelerate its densification phase.Gradient design perpendicular to the impact direction can enhance the energy absorption performance of ROH,especially for ROH,with wall thickness increasing from the inside outwards.Compared to ROH with uniform wall thickness at the same relative density,ROH with a gradient design can increase the plateau stress by over half.With the elevation of impact velocity,the plateau stress and specific energy absorption exhibit an upward trend,aligning with the dynamic performance pattern observed in conventional honeycombs.The results can be used as a reference for the design and application of honeycomb and provide a new idea for developing more efficient and reliable energy-absorbing materials.

Bionic lightweight design of limb leg units for hydraulic quadruped robots by additive manufacturing and topology optimization

Galloping cheetahs,climbing mountain goats,and load hauling horses all show desirable locomotion capability,which motivates the development of quadruped robots.Among various quadruped robots,hydraulically driven quadruped robots show great potential in unstructured environments due to their discrete landing positions and large payloads.As the most critical movement unit of a quadruped robot,the limb leg unit(LLU)directly affects movement speed and reliability,and requires a compact and lightweight design.Inspired by the dexterous skeleton–muscle systems of cheetahs and humans,this paper proposes a highly integrated bionic actuator system for a better dynamic performance of an LLU.We propose that a cylinder barrel with multiple element interfaces and internal smooth channels is realized using metal additive manufacturing,and hybrid lattice structures are introduced into the lightweight design of the piston rod.In addition,additive manufacturing and topology optimization are incorporated to reduce the redundant material of the structural parts of the LLU.The mechanical properties of the actuator system are verified by numerical simulation and experiments,and the power density of the actuators is far greater than that of cheetah muscle.The mass of the optimized LLU is reduced by 24.5%,and the optimized LLU shows better response time performance when given a step signal,and presents a good trajectory tracking ability with the increase in motion frequency.

Advancements in machine learning for material design and process optimization in the field of additive manufacturing

Additive manufacturing technology is highly regarded due to its advantages,such as high precision and the ability to address complex geometric challenges.However,the development of additive manufacturing process is constrained by issues like unclear fundamental principles,complex experimental cycles,and high costs.Machine learning,as a novel artificial intelligence technology,has the potential to deeply engage in the development of additive manufacturing process,assisting engineers in learning and developing new techniques.This paper provides a comprehensive overview of the research and applications of machine learning in the field of additive manufacturing,particularly in model design and process development.Firstly,it introduces the background and significance of machine learning-assisted design in additive manufacturing process.It then further delves into the application of machine learning in additive manufacturing,focusing on model design and process guidance.Finally,it concludes by summarizing and forecasting the development trends of machine learning technology in the field of additive manufacturing.

Design,Manufacture and Maintenance of Pressure Equipment Based on Accidents Survey

Most of the important units of pressure equipment have been manufactured successfully in China related to the national key construction projects,such as 10 million tons/year oil refinery,million tons/year ethylene,large coal chemical,etc.However,some of them failed to operate shortly after their putting into service.Some suffered severe damage even during the previous period of manufacture and installation.In this paper,cases of accident survey and failure analysis are given for some typical pressure vessels.It is found that many accidents are related to insufficient consideration of the design and manufacture of the equipment.These accidents occur fundamentally because of the Chinese design standards codes for pressure equipment without risk or life concepts and the support from a database for potential risk existing in their dynamic service.Most designers and manufacturers are unable to make correct design,materials selection and manufacturing process all due to a lack of engineering experience.In order to avoid the repetition of the accidents and improve the safety,reliability and economy of pressure equipment,a platform is suggested for design,manufacture and maintenance of pressure equipment in China based on accidents survey.In other words,some effective precautionary measures are taken at the design and manufacture stage,and the design methodology has to be based on service life requirement and desirable risk level.At the service stage some reasonable inspection/monitoring approaches should be utilized to control risks and ensure the equipment operating safely until its desired lifespan.Finally,the basic scheme and some key technologies are briefly given for the platform construction.The concept of risk and life based design,manufacture and maintenance proposed herein has important significance for improving and perfecting the codes and standards for design,manufacture and maintenance of Chinese pressure-bearing equipment,enhancing the life and reliability of Chinese pressure-bearing equipment and promoting the development of in-service maintenance technology that combines safety and economy.

Study in the design and manufacture process of the elastic cable anchor box in steel box girder of Taizhou Bridge

Taizhou Yangtze River Highway Bridge is a large span suspension bridge with three pylons. The elastic cables are installed to connect the steel tower and the steel box girder. The constraints can increase the safety coefficient of the middle saddle, and improve the stress conditions of the middle pylon and decrease the deflection in the middle of the main girder, as well as the longitudinal displacement of the main girder caused by live loads. The anchorage boxes of the elastic cable are installed in the wind fairing outside the vertical web plate of the box girder. Two anchor boxes form a pair and are arranged parallelly. Eight anchor boxes are installed in the bridge. In this paper, the design scheme and the technical difficulties in manufacturing are briefly discussed with the precision control techniques.

A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy designed using cluster-plus-glue-atom model for laser additive manufacturing

A novel Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy was designed using the cluster formula approach(cluster-plus-glue-atom model)and prepared by laser melting deposition(LMD).Its composition formula 12[Al-Ti_(12)](AlTi_(2))+5[Al_(0.8)Si_(0.2)-Ti_(12)Zr_(2)](V_(0.8)Mo_(0.2)Nb_(1)Ti)features an enhancedβ-Ti via co-alloying of Zr,V,Mo,Nb and Si.The experimental results show that the cluster formula ofαandβphases in the novel alloy are respectivelyα-[Al-Ti_(11.5)Zr_(0.5)](Al_(1)Ti_(2))andβ-[Al_(0.8)Si_(0.2)-Ti_(13.2)Zr_(0.8)](V_(1)Mo_(0.4)Nb_(1.6)),both containing Zr elements.The fitted composition via the α andβphase cluster formulas has little difference with the actual alloy composition,suggesting that the validity of cluster-plus-glue-atom model in the alloy composition design.After hot isostatic pressing(HIP),both the Ti-6Al-4V and the novel alloy by LMD are characterized by prior-βcolumnar grains,while the typical<100>texture disappears.Compared with Ti-6Al-4V,Ti-5.55Al-6.70Zr-1.50V-0.70Mo-3.41Nb-0.21Si alloy exhibits a combination of higher strength(1,056 MPa)and higher ductility(14%)at room temperature and higher strength(580 MPa)at 550℃ after HIP,and can potentially serves as LMD materials.

Design-Manufacture Interface Relationship Management in Supply Chain

As firms come under greater market pressure, the management of the inter-functional design/manufacture relationship becomes a more important competitive variable. The characteristics of the design-manufacture interface were analyzed, and several methods of the design-manufacture interface relationship management were compared. Based on theories concerned and enterprise practice, how to manage the relationship of design-manufacture interface to reduce the product cost and shorten the time-to-market was demonstrated, finally the competitive advantage was improved.

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.

Design and In Situ Additive Manufacturing of Multifunctional Structures

Multifunctional structures(MFSs)integrate diverse functions to achieve superior properties.However,conventional design and manufacturing methods—which generally lack quality control and largely depend on complex equipment with multiple stations to achieve the integration of distinct materials and devices—are unable to satisfy the requirements of MFS applications in emerging industries such as aerospace engineering.Motivated by the concept of design for manufacturing,we adopt a layer regulation method with an established optimization model to design typical MFSs with load-bearing,electric,heat-conduction,and radiation-shielding functions.A high-temperature in situ additive manufacturing(AM)technology is developed to print various metallic wires or carbon fiber-reinforced high-meltingpoint polyetheretherketone(PEEK)composites.It is found that the MFS,despite its low mass,exceeds the stiffness of the PEEK substrate by 21.5%.The embedded electrics remain functional after the elastic deformation stage.Compared with those of the PEEK substrate,the equivalent thermal conductivity of the MFS beneath the central heat source area is enhanced by 568.0%,and the radiation shielding is improved by 27.9%.Moreover,a satellite prototype with diverse MFSs is rapidly constructed as an illustration.This work provides a systematic approach for high-performance design and advanced manufacturing,which exhibits considerable prospects for both the function expansion and performance enhancement of industrial equipment.

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.

The Next-Generation Dow XLA^(TM) Fiber Brings Fashion and Choice to Denim Designers and Manufacturers

Shanghai, China. August 29, 2008-Cutting edge fashion and design, advanced textile technology and innovative industry partnerships were brought together in Shanghai at the launch of XLA? Denim Fashion Show to introduce the next-generation XLATM stretch fiber for denim application.

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。

机械设计与低温锂电池全流程数字化智能制造的联系及应用

随着现代制造技术、信息技术和数字化技术的飞速发展,低温锂电池生产迎来了技术升级。对此本文综述了机械设计与低温锂电池数字化智能制造的联系以及技术优化进展。首先分析了低温锂电池产业数字化、智能化的发展流程,包括低温锂电池数字化制造和二阶段的智能化制造;然后重点探讨了机械设计为低温锂电池数字化智能制造产业带来的优化变革。从产业发展角度来看,与机械设计技术深度融合,可以从多个方面优化现有的低温锂电池数字化智能制造技术,对后者的产业结构调整和技术升级具有重要的指导作用。

面向增材制造的非均匀点阵结构综述

受益于增材制造技术的发展,多孔结构、拓扑优化结构、生物仿生结构等具有高度复杂度结构的制造难度得以降低,促进了高度复杂结构的研究进展。点阵结构作为一种典型多孔结构,性能优异和可设计性好,其研究成果已应用于航空航天、生物医疗、汽车制造等诸多领域。其中非均匀点阵结构相较于均匀点阵结构,更能发挥出结构和材料的潜能,因此更具有实际应用价值。本文对非均匀点阵结构的设计方法和制造方式的研究现状和发展动向进行梳理,对非均匀点阵结构进行了详细地综述,指出当前研究存在的挑战,并展望了点阵结构今后的研究方向。

新工科背景下“正/逆向设计加工”课程实践体系的探索与实践

阐述了长安大学现代工程训练中心建立的“正/逆向设计加工”课程实践体系的主要内容和实施效果。体系以教学融合+创新实践的方法进行构建,融合“CAD”“3D打印”“逆向工程”“CNC数控加工”等知识内容,采用递进式教学打破课程孤岛,鼓励学生自主创造,坚持全贯穿式教学实践环境。为培养新工科背景下的智能制造复合型人才提供了新型教学思路,对推动高校工程训练教学改革具有一定的借鉴意义。

多组分多层级3D打印材料研究进展

多组分多层级3D打印材料(McMl3DPMs)是一种新兴的先进材料,源于多孔材料、复合材料和增材制造的融合。由于增材制造赋予了Mc Ml3DPMs三维架构跨越广泛组分构成和结构类型的能力,Mc Ml3DPMs拥有杰出的机械性能,甚至是通常被认为相互排斥的性能(例如高强度和高韧性)。本文重点介绍为了实现高性能结构用Mc Ml3DPMs所必须解决的科学挑战以及最近研究工作对此做出的努力,将从结构设计、制造过程建模、缺陷表征和性能评价3个方面对相关案例进行回顾。最后,本文指出了当前研究的不足之处,并展望了Mc Ml3DPMs的未来发展,包括讨论了进一步推进这一新兴领域发展的几个可能的研究方向。

工程认证背景下基于智能制造的汽车制造技术课程设计教学改革

汽车制造技术课程设计是汽车类专业非常重要的一门核心实践课程。随着智能制造技术的不断发展以及工程认证的广泛实施,汽车制造技术课程设计的内容、评价体系等需要相应的完善。该文从教学内容更新、师资力量培训以及评价体系完善3个方面进行了分析并提出改革措施。新措施的实施更有利于学生接触智能制造相关知识,课程评价体系的细化不仅成绩更加公平,而且可为后续教学过程持续改进提供数据基础。

粤港澳大湾区工业设计赋能制造业高质量发展:机制、短板与路径优化

工业设计作为高附加值生产性服务业,不仅是产业技术创新的重要一环,更是推动制造业延链提质、深度转型升级、加快形成新质生产力的有力手段,能够从研发端、生产端和需求端赋能制造业全链路高质量发展,并在优化产品质量、塑造品牌形象、加深产业融合等领域发挥关键作用。粤港澳大湾区是我国工业设计产业发展的桥头堡,在赋能区域制造业高质量发展上率先起步,取得了显著成效,但对标国际领先地区仍存在内部发展不平衡、链群发展不充分、龙头企业引领力偏弱等突出问题。结合新时代背景下工业设计数智化发展新趋势,粤港澳大湾区亟待从优化产业政策生态、强化高端创新载体建设、突出数字赋能效应、重视设计人才引培等方面进一步发力提升。