Shape recovery properties and load-carrying capacity of a 4D printed thick-walled kirigami-inspired honeycomb structure

Kirigami arts have provided a more promising method for building multiscale structures,which can shape two-dimensional(2D)sheets into three-dimensional(3D)configurations by cutting and folding.Here,we first carried out a theoretical analysis of the mechanical properties of 2D honeycomb lattice structures and experimental verification combined with finite element(FE)simulation.Furthermore,a series of thick-walled 3D kirigami-inspired honeycomb(TW3KH)structures with different mechanical properties were designed and fabricated on the exploration and optimization of geometric parameters of 2D honeycomb structures.The investigations of folding feasibility,self-expansion,and self-folding performance experimentally showed that our designed four-dimensional(4D)printing structure had good programmability and shape memory capability and a large volume change ratio during shape change.Meanwhile,research on its compression deformation behavior found that the TW3KH structures can recover load-bearing capacity very well when the angle is positive.Therefore,these TW3KH structures have great advantages in space-saving smart load-bearing equipment.

Kirigami处理下纤维素纳米纤维薄膜在智能对流散热中的应用研究

纤维素纤维薄膜是一种具有良好导电性能的复合材料,运用Kirigami技术能提升纤维素纳米纤维薄膜的导电性能和在智能散热中的热稳定性。文章探究了Kirigami技术的应用机理,分析了纤维素纳米纤维薄膜在智能对流散热中的作用,为相关领域提供借鉴。

Highly stretchable kirigami-patterned nanofiber-based nanogenerators for harvesting human motion energy to power wearable electronics

Wearable electronics are advancing towards miniaturization and flexibility.However,traditional energy supply methods have largely hindered their development.An effective solution to this problem is to convert human mechanical energy into electricity to power wearable electronic devices.Therefore,it is greatly attractive to design flexible,foldable and even stretchable energy harvesting devices.Herein,we use the electrospinning and kirigami approach to develop a type of highly stretchable kirigami-patterned nanofiber-based triboelectric nanogenerator(K-TENG).Due to its innovative structural design,the K-TENG can achieve a tensile strain of 220%,independent of the tensile properties of the material itself.When a person swings their arms,the K-TENG fixed to the clothing can convert mechanical energy from human movement into electrical energy.The produced electricity can directly drive 50 LED lights and a digital watch,or be stored in a lithium battery to charge the smartwatch and smartphone,respectively.This study employs a new method to fabricate a stretchable triboelectric nanogenerator and demonstrates its promising applications in wearable power technology.

Bioinspired multichannel colorful encryption through kirigami activating grating

Optical encryption,exploiting degrees of freedom of light as parameters to encode and decode information,plays an indispensable role in our daily life.Responsive structural color materials can give real-time visible feedback to external stimuli and provide ideal candidates for optical encryption.However,the development of existing responsive structural color materials is hindered by poor repeatability and long feedback time.Meanwhile,there are only few strategies to exploit structural colors in multichannel information encryption.Herein,bioinspired by the structural color variation due to a change in angle arising from the movement of animal’s scales or feathers,we developed a general multichannel information encryption strategy using a two-dimensional deformable kirigami arranging orientations of the grating arrays by design.The kirigami grating sheet shows rapid,repeatable,and programmable color change.This strategy utilizes the topological space deformation to guide the change of optical property,which suggests new possibilities for spatial and spectral encryption as well as mechano-sensing and camouflage.

Multiaxially-stretchable kirigami-patterned mesh design for graphene sensor devices

In wearable electronics,significant research has gone into imparting stretchability and flexibility to otherwise rigid electronic components while maintaining their electrical properties.Thus far,this has been achieved through various geometric modifications of the rigid conductive components themselves,such as with microcracked,buckled,or planar meander structures.Additionally,strategic placement of these resulting components within the overall devices,such as embedding them at the neutral plane,has been found to further enhance mechanical stability under deformation.However,these strategies are still limited in performance,failing to achieve fully strain-insensitive electrical performance under biaxial stretching,twisting,and mixed strain states.Here,we developed a new platform for wearable,motion artifact-free sensors using a graphene-based multiaxially stretchable kirigami-patterned mesh structure.The normalized resistance change of the electrodes and graphene embedded in the structure is smaller than 0.5%and 0.23%under 180°torsion and 100%biaxial strain,respectively.Moreover,the resistance change is limited to 5%under repeated stretching-releasing cycles from 0%to 100%biaxial strain.In addition,we investigated the deformation mechanisms of the structure with finite element analysis.Based on the simulation results,we derived a dimensionless geometric parameter that enables prediction of stretchability of the structure with high accuracy.Lastly,as a proof-of-concept,we demonstrated a biaxially-stretchable graphene-based sensor array capable of monitoring of temperature and glucose level with minimized motion-artifacts.

Controlling the laser induction and cutting process on polyimide films for kirigami-inspired supercapacitor applications

The recently emerging laser-induced graphene(LIG)technology,with one-step processing and designable features,has been widely used in the fabrication of wearable/portable electronics.Herein,by taking inspiration from kirigami,we designed a stretchable supercapacitor(SC)step by step through controlling laser induction and cutting process on the polyimide(PI)film,with the use of one single CO_(2) laser source.Firstly,the carbonized basic geometric units of lines were produced on PI films to investigate the processing-structure relationships.Then,the complex photothermal conversion and heat transfer progress involved in the carbonized process were simulated by a photothermal model.Both experimental and theoretical results suggested that the laser power,scan rate and focus condition have great influence on the size,shape and morphology of the carbonized lines.Finally,we optimized the parameters of laser induction and cutting process to fabricate the kirigami-inspired SCs with reliable electrochemical properties and editable mechanical flexibility,showing great potential in the field of flexible electronics.

Notch Flexure as Kirigami Cut for Tunable Mechanical Stretchability towards Metamaterial Application

Kirigami is an art of paper cutting,which can be used in mechanical metamaterials,actuators,and energy absorption based on its deployable and load-deflection characteristics.Traditional cuts with zero width produce undesirable plastic deformation or even tear fracture due to stress concentration in stretching.This study proposes to enlarge the cut width into a notch flexure,which is applied to an orthogonality-cutted kirigami sheet,which buckles out of plane into a 3D configuration patterns under uniaxial tension.The use of compliant beam as the notch makes the stress distribution around the cuts more uniform in both elastic and elastoplastic regime.The experimental and numerical results show that by tuning the geometric parameters of cuts and material properties of the sheets,the trigger condition of 3D patterns can be adjusted.Potential capability of tunable phononic wave propagation in this kirigami-inspired metamaterial is demonstrated.This design methodology offers a theoretical guide for kirigami-based structures.

Critical transitions in the shape morphing of kirigami metallic glass

Kirigami, the ancient Japanese paper cutting technique, has been applied to achieve high stretchability and low energy loss of designed metallic glass. Despite the exploration of the underlying deformation mechanism of kirigami-inspired structures from the energy point of view, the morphable responses of the kirigami patterns and the origin of the kirigami response are yet to be fully understood. This study reveals the mechanical driven-forms of the kirigami structure with the corresponding deformation stages. Based on the beam deflection theory, the elastic buckling behavior of kirigami metallic glass is manifested and a critical force prediction model is developed. Moreover, a force concentration parameter is introduced in the rigid-plastic deformation stage, predicting the nominal ultimate force. The kirigami-inspired facture force is firstly proposed. The findings of these models are in good agreement with the experimental sizedependent kirigami responses, and expected to provide significant insights into the understanding of the deformation behavior and the design of kirigami metallic glasses.

Configuration-dependent stretchable all-solid-state supercapacitors and hybrid supercapacitors

Given the rise in the popularity of wearable electronics that are able to deform into desirable configurations while maintaining electrochemical functionality,stretchable and flexible(hybrid)supercapacitors(SCs)have become increasingly of interest as innovative energy storage devices.Their outstanding power density,long lifetime with low capacitance loss,and appropriate energy density,in particular in hybrid cases make them ideal candidates for flexible electronics.The aim of this review paper is to provide an in-depth discussion of these stretchable and flexible SCs ranging from fabrication to electro-mechanical properties.This review paper begins with a short overview of the fundamentals of charge storage mechanisms and different types of multivalent metal-ion hybrid SCs.The research methods leading up to the current state of these stretchable and flexible SCs are then presented.This is followed by an in-depth presentation of the challenges associated with the fabrication methods for different configurations.Proposed novel strategies to maximize the elastic and electrochemical properties of stretchable/flexible or quasi-solid-state SCs are classified and the pros and cons associated with each are shown.The advances in mechanical properties and the expected advancements for the future of these SCs are discussed in the last section.

3D打印形状记忆智能剪纸结构

目的探究不同切口及不同打印角度形状记忆剪纸结构的拉伸力学性能及形状记忆恢复性能,获得具有较好变形能力和形状记忆恢复能力的智能化剪纸结构。方法使用FDM打印不同角度的剪纸结构样件,并利用激光切割机获得具有方形切口和圆形切口的样件。对打印角度为0°/90°、±45°的方形切口和圆形切口样件进行常温拉伸实验。为探究温度的影响,进行高温缓慢拉伸实验和高温快速拉伸实验;对比方形切口件和圆形切口件在不同初始应变下的形状记忆恢复能力。结果在常温下,打印角度为0°/90°的方形切口样件的拉伸距离为1.75mm,圆形切口样件的拉伸距离为2.50mm;±45°打印角度的方形切口样件的拉伸距离为3.25mm,圆形切口样件的拉伸距离为3.00mm。在高温下,材料进入高弹态,2种切口样件在200%拉伸应变下均未断裂;提高拉伸速率后,方形切口样件的拉伸应变为243.8%,圆形切口样件的拉伸应变为337.5%。结论将打印角度从0°/90°改为±45°后,方形切口和圆形切口剪纸结构的变形能力均增强。相比于方形切口,圆形切口剪纸结构具有更好的变形能力。高温下剪纸结构的变形能力大大增强;圆形切口剪纸结构样件的形状记忆恢复能力强于方形切口样件的。

纳米银-聚合物菱形剪纸薄膜应变传感特性的研究

采用银镜制备法和激光切割技术获得了纳米银颗粒/聚二甲基硅氧烷剪纸结构薄膜,并系统地研究了薄膜作为柔性应变传感器的力学及压阻特性。将数值模拟与实验相结合,测量了传感薄膜的应变比γ、压阻滞回特性、线性度及压阻敏感性,重点探讨了薄膜制备工艺、结构参数与上述薄膜传感特性的定量关系。结果表明,在给定结构下,结构薄膜整体与结构单元的应变比γ为常数,反映了结构薄膜的变形特性,是理想的力学性能表征参数。菱形剪纸结构薄膜具有量级可达200的大应变比,即在大应变下,材料的实际应变很小。这一特点极大地提升了薄膜的应变测量范围、压阻稳定性、线性度,并保持了合理的压阻灵敏度。

蓝印花布发展现状分析及其创新设计研究

分析了中国传统蓝印花布当前的发展处境,理清概念,革新观念,权衡蓝印花布"产业化"发展与"原生态"保护的利弊。提出了借鉴剪纸艺术等相关工艺及纹样的成功经验,从蓝印花布的最直观标志性符号和工艺中,求寻创新设计的思路与方法,针对不同目标市场多元化发展,打破目前传统蓝印花布传承发展相对被动的生存局面。

折纸结构及其特性的工程应用策略

在过去的十年中,随着折痕设计、力学建模和可展开制造技术的发展进步,各类折纸/剪纸结构及其应用迅速出现:应用于航空航天领域的可展天线、钻杆、太阳翼等,其折展比更优、质量体积比更小;应用于医疗技术领域的人造血管支架、微型抓手,实现了跨越空间进行手术的目标;将折纸结构应用于致动器,其可弯曲性能会承受或减轻一定的应力,可以用于穿戴辅助设备、电子设备;应用于能量吸收装置,可以提高装置承受破坏性负载时的能量吸收能力,如用于减轻汽车撞击、地震等伤害的各种装置。近期,折纸/剪纸结构及其特性在一些新兴技术设备的构造中有了新的突破:如在切割、折叠和屈曲中的应用,在可伸缩/可变形电子器件、机械/光学超材料、微米/纳米级生物传感器和执行器中的应用,更为显著的进展是将功能材料(单晶硅、形状记忆聚合物、储能材料、石墨烯等)部署到3D微纳米级折纸结构中。本文首先概述了折纸基础知识——常见的折痕图案和数学定理,然后重点介绍了基于折纸/剪纸结构诸多特性的工程应用策略,最后探讨了其潜在研究方向及未来所要面临的挑战。

石墨烯剪纸的大变形拉伸力学行为研究

将传统宏观剪纸技术应用于纳观尺度,通过引入圆角矩形切口图案构建了石墨烯剪纸.采用分子动力学方法研究了单层与双层石墨烯剪纸的大变形拉伸力学行为和变形破坏机制,并系统地研究了关于切口图案的3个无量纲几何参数对单层石墨烯剪纸的力学性能和变形破坏机制的影响规律.研究发现,通过引入规则切口,可以有效地大幅度提高石墨烯的延展性,其断裂应变可达到完美石墨烯的5—6倍.通过控制3个几何参数,可以有效地调控石墨烯的延展性和力学行为.研究结果表明,古老的剪纸技术为提高二维纳米材料延展性、实现光电纳米器件可延展柔性化提供了一种新的解决方案.

F型画面的美在剪纸艺术中的运用

剪纸艺术作为我国的传统艺术,构图形式多种多样,F型画面作为其中的一种,具有独特的艺术魅力。文章以剪纸的构图入手,阐明剪纸艺术符合F型的比例,并从环境、材料和生产工艺上阐明造成这种构图形式的原因,对传统的剪纸艺术进行分割,证明F矩形画面的美,以及F矩形中蕴含的分割比例在剪纸艺术设计中的应用价值。

探析剪纸艺术在现代设计中的发展路径

目的研究剪纸艺术对现代设计的启示及其发展。方法对比剪纸艺术与现代设计的相互影响,梳理剪纸艺术在现代设计中的设计要素,从文化与产业的并重、人文与经济的融和、剪纸"时尚化"的演绎3个方面进行研究分析,并在教学及团队研究中作了有益的探索。结论剪纸艺术在现代设计中的发展首先要加强剪纸在文创类产品的开发,其次需推动民间艺术与旅游纪念品的设计与发展,最后通过剪纸"时尚化"的定义,将其衍变为现代"剪纸",成为营造装饰氛围的主力军。剪纸艺术之于现代设计不仅要有情感,而且更要具备一定的功能性与装饰性,其价值才能真正实现。

辐射对称金字塔型剪纸的力学行为

通过在弹性薄板上引入切口,构建了多边形辐射对称金字塔型剪纸结构.利用伽辽金法求解的悬臂梁形变公式和悬臂梁组合的方法,创建了用于解释形变过程的"梁模型",得到n个模块的正N边形金字塔结构的弹性系数与结构参数的关系公式,并求出弹性系数线性阈值的表达式,解释了该结构产生平面外扭曲的原因.利用推导的"梁模型"公式,并通过有限元仿真和实验的方法,系统研究了辐射对称金字塔型剪纸结构的力学响应特征,验证模型的准确性,并用于已有报道的石墨烯剪纸结构的力学特征分析.这项工作系统解释了竖直拉伸的金字塔型剪纸结构的力学响应.

基于文学意境视阈下的民间剪纸艺术

民间剪纸艺术在多元文化存在的今天,发挥着重要的文化载体角色,从不同角度传承着本源文化,本文从文学意境角度出发,来讨论民间剪纸艺术结构中的文学特性,诠释来自于民间朦胧的文学意识向往,探讨来自民间厚重的文化积淀,通过本文的阐述,有助于我们认识民间剪纸艺术并加深对其艺术形态特征的理解和整个民族美术的把握,加强理论研究的根基,从而推动民间剪纸艺术的传承与发展。

基于聚焦离子束纳米剪纸/折纸形变的三维微纳制造技术及其光学应用

高精度的三维微纳制造技术是现代光电子学和微纳光子学发展的重要基础之一,是实现下一代微纳光子集成器件的重要前提.纳米尺度的剪纸和折纸技术由于能够实现丰富的三维形变,正发展成为一门新兴的研究领域.本文系统地介绍了一种新型的片上三维微纳加工方法基于聚焦离子束的纳米剪纸/折纸技术.该技术利用聚焦离子束辐照具有不同拓扑形貌的自支撑膜片,可实现优于50 nm精度、前所未见的三维形状变换,包括片上、实时的多向折叠、弯曲、扭曲等形变.提出了“树型”纳米剪纸和“闭环”纳米剪纸两种类型的加工方法,并针对不同类型的工艺特性和优缺点进行分析对比.利用全局扫描纳米剪纸技术制备的闭环纳米结构实现了独特的光学效应,包括超光学手性、超构表面衍射、相位和偏振调控以及光子自旋霍尔效应等.研究结果表明,纳米剪纸/折纸形变技术在保持结构复杂性和功能性的同时,可实现高精度、原位、片上、一步成型的三维微纳加工,可望为三维微纳光子器件的设计、制备和应用提供一类新的设计方法和技术途径,乃至为相关微纳光学、微电子、微机电系统、生物医学等领域的发展提供新颖的加工平台.

剪纸艺术之审美意蕴及其在现代平面设计的运用

剪纸艺术是一株灿烂的民族艺术之花,是活态的生活文化史,具有深厚而丰赡的审美意蕴。文章通过分析剪纸艺术的风格特征,将其与现代平面设计相结合。重点从传统与现代、传承与创新、图形与设计三个方面,论述了剪纸艺术在现代平面设计中的新理念。通过实例分析可知,二者的巧妙结合,是借鉴其形式特点,保留其形式遗风,借用、延伸其寓意,并结合现代设计理念和表现手法,对其进行再设计,赋予其时代气息和新的生命力。