European Journal of Mechanics A-Solids最新文献

Atomistic investigation of interface adherence mechanism of structural indenter nanocoining single crystal aluminum 结构压头纳米压入单晶铝的界面粘附机理的原子学研究

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-13 DOI: 10.1016/j.euromechsol.2024.105500

Zaizhen Lou , Yongda Yan , Xin Yang , Hailong Cui , Chen Li , Yanquan Geng

The utilization of nanoimprint technology has become widespread in various industries. Nanocoining, a new type of nanoimprinting technology, is essentially graphic copying. Ensuring the indenter's accuracy and the transfer's integrity is crucial. Structured tool (ST)-metal workpiece interface commonly exists in adherence phenomenon during the nanoimprint. To reduce the adherence of workpieces in ST, it is remarkable to illustrate the adhesion mechanism. The molecular dynamic simulation model for indenting aluminum with a diamond ST indenter was established, and the influence of critical process parameters on adhesion, including the indenter geometry, indenter temperature, and indenter speed, was investigated. The results demonstrate that various factors significantly influence adhesion, including the van der Waals force, surface energy, temperature, mechanical embedding, diffusion, and holding stage. The mechanism of adhesion can be composed of three parts: the mechanical embedding caused by the large range of cavity filling of the indenter, the slow thermal diffusion and thermal migration of aluminum atoms along the indenter and the combined effect of thermal-tensile stress in the demolding process. The intensity of adhesion is affected by several factors, namely the degree of plastic deformation during loading and unloading, atomic thermal migration caused by system temperature, and the magnitude of tensile stress during the demolding stage. The geometry of the indenter exerts the most significant influence on the van der Waals force, surface energy, imprinting force, and unloading force. Additionally, the omission of the holding stage during processing contributes to a reduction in adhesion. This study provides atomic-level insights into the adhesive properties of metallic materials in the nanocoining process.

纳米压印技术已在各行各业得到广泛应用。纳米压印是一种新型的纳米压印技术，其本质是图形复制。确保压头的精度和转移的完整性至关重要。在纳米压印过程中，结构工具（ST）-金属工件界面通常存在粘附现象。为了减少 ST 中工件的粘附，说明粘附机理是非常重要的。建立了用金刚石 ST 压头压入铝的分子动力学模拟模型，并研究了压头几何形状、压头温度和压头速度等关键工艺参数对附着力的影响。结果表明，范德华力、表面能、温度、机械嵌入、扩散和保持阶段等各种因素都会对附着力产生重大影响。粘附机理可由三部分组成：压头空腔填充范围大导致的机械嵌入、铝原子沿压头的缓慢热扩散和热迁移以及脱模过程中的热拉伸应力的共同作用。粘附强度受几个因素的影响，即加载和卸载过程中的塑性变形程度、系统温度引起的原子热迁移以及脱模阶段拉伸应力的大小。压头的几何形状对范德华力、表面能、压印力和卸载力的影响最大。此外，在加工过程中省略保持阶段也会导致附着力降低。这项研究从原子层面揭示了金属材料在纳米压印过程中的粘附特性。

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引用次数: 0

Research on mechanical behavior of particle/matrix interface in composite solid propellant 复合固体推进剂中颗粒/基质界面的力学行为研究

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-12 DOI: 10.1016/j.euromechsol.2024.105498

Zijie Zou , Hongfu Qiang , Fengtao Zhang , Xueren Wang , Yiyi Li

In the mesostructure of composite solid propellant, the interface formed between solid particle and matrix is a region with very special physical and chemical properties, and the mechanical behavior of the interface will directly affect the mechanical properties of the propellant. This article derived a viscoelastic cohesive constitutive model to describe the mechanical behavior of the interface. subsequently a particle/matrix interface specimen was design to measure the interface mechanical properties under different conditions. To this end, the parameters of the constitutive model were solved through a combination of experimental data fitting and inversion. It was found that the interface behavior exhibits strong rate and temperature correlations, and the cohesive constitutive model can effectively describe this characteristic.

在复合固体推进剂的介观结构中，固体颗粒与基体之间形成的界面是一个具有非常特殊的物理和化学性质的区域，界面的力学行为将直接影响推进剂的力学性能。本文推导了一个粘弹性内聚构成模型来描述界面的力学行为，随后设计了一个颗粒/基质界面试样来测量不同条件下的界面力学性能。为此，通过实验数据拟合和反演相结合的方法求解了构成模型的参数。结果发现，界面行为表现出很强的速率和温度相关性，而内聚构成模型可以有效地描述这一特性。

引用次数: 0

Vibration suppression of suspended cables with three-to-one internal resonances via time-delay feedback 通过延时反馈抑制具有三比一内部共振的悬索的振动

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-10 DOI: 10.1016/j.euromechsol.2024.105487

Jian Peng , Yanan Li , Stefano Lenci , Xiangzhan Yang , Lianhua Wang

Based on the time-delay feedback control, the vibration suppression of suspended cables with three-to-one internal resonances are investigated. Initially, the nonlinear differential equation of motion for a suspended cable under time-delay feedback control is considered, and a discrete model is derived using the Galerkin method. Subsequently, the method of multiple scales is employed to perturbatively solve the discrete time-delay differential equation, determining the modulation equations around the first primary resonance. Steady-state and periodic solutions of the modulation equations are detected numerically. Numerical results indicate that the internal resonance enhances the nonlinear dynamical complexity of the controlled suspended cable. It is observed that the time delay and control gain affect the controlled system: in particular, an increase in control gain leads to a reduction in response amplitude. By adjusting the time delay and control gain, the critical excitation can be altered, an aspect that could be very useful from a practical point of view. This research sheds light on the intricate dynamics of suspended cable and provides a theoretical foundation for designing more effective control strategies in engineering applications.

基于延时反馈控制，研究了具有三比一内部共振的悬索的振动抑制问题。首先，考虑了延时反馈控制下悬索的非线性运动微分方程，并利用 Galerkin 方法推导出离散模型。随后，采用多尺度法对离散时延微分方程进行扰动求解，确定了第一个主谐振周围的调制方程。数值检测了调制方程的稳态解和周期解。数值结果表明，内部共振增强了受控悬索的非线性动力学复杂性。据观察，时间延迟和控制增益会影响受控系统：特别是，控制增益的增加会导致响应振幅的减小。通过调整时间延迟和控制增益，可以改变临界激励，这在实际应用中非常有用。这项研究揭示了悬挂缆索错综复杂的动力学特性，为在工程应用中设计更有效的控制策略奠定了理论基础。

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引用次数: 0

Vibration response of nanobeams subjected to random reactions 受随机反应影响的纳米梁的振动响应

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-09 DOI: 10.1016/j.euromechsol.2024.105489

Vu Hoa Binh , Nguyen Dong Anh , Do Van Thom , Phung Van Minh , Hoang Tien Dung

Nanobeams composed of materials exhibiting flexoelectric properties have been successfully used in advanced technological equipment, including electronic circuits and very sensitive sensors, owing to their remarkable unique effects. Therefore, it is essential to determine their mechanical behavior as a practical need. This study employs an analytical methodology to provide a precise solution to the vibration issue of nanobeams under random stationary loads. Under such circumstances, the nanobeam is influenced by both the temperature and moisture conditions simultaneously. Additionally, the beam is supported by a viscoelastic foundation that considers both the viscous resistance parameter and the elastic parameter. Analytical formulations are derived by integrating classical beam theory with nonlocal strain gradient theory in order to elucidate the impact of size effects on nanobeams. This research also demonstrates the reliability verification, which clearly validates the accuracy of the calculation formula used in this work. This study examines the impact of material parameters, viscoelastic foundation, temperature, and moisture on the displacement spectrum at the middle and entire length of the beam. The study also explores how the flexoelectric effect decreases the displacement in the nanobeam. Subsequently, we provide scientifically derived findings that have significant relevance for building practical nanobeam specifications.

由具有柔电特性的材料组成的纳米梁由于其显著的独特效果，已成功应用于先进的技术设备中，包括电子电路和非常灵敏的传感器。因此，根据实际需要确定其机械行为至关重要。本研究采用分析方法为纳米梁在随机静态负载下的振动问题提供了精确的解决方案。在这种情况下，纳米梁会同时受到温度和湿度条件的影响。此外，横梁由粘弹性地基支撑，该地基同时考虑了粘滞阻力参数和弹性参数。通过将经典梁理论与非局部应变梯度理论相结合，得出了分析公式，以阐明尺寸效应对纳米梁的影响。本研究还进行了可靠性验证，明确验证了本工作中使用的计算公式的准确性。本研究探讨了材料参数、粘弹性基础、温度和湿度对梁中部和全长位移谱的影响。研究还探讨了挠电效应如何减小纳米梁的位移。随后，我们提供了科学的研究结果，这些结果对制定实用的纳米梁规格具有重要意义。

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引用次数: 0

Determination of material constants of piezoceramics using genetic algorithm 利用遗传算法确定压电陶瓷的材料常数

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-09 DOI: 10.1016/j.euromechsol.2024.105490

Bo-Yen Sun, Shiou-Yi Chang, Yu-Hsi Huang

This study seeks to accurately determine the piezoelectric material constants of piezoceramic disks from the resonant frequencies of the disks using a genetic algorithm programmed according to the principles of plate theory. Mindlin's plate theory is judged to be most suitable for approximating the relationship between the in-plane and out-of-plane resonant frequencies and the material constants of a disk-shaped piezoceramic thick plate, which was programmed into a genetic algorithm in order to obtain all relevant piezoelectric material constants from measured resonant frequencies of sample piezoceramic disks through inverse calculation. To verify the accuracy of the material constants, finite element method was employed to derive the theoretical resonant frequencies along with the corresponding mode shapes, which were then compared with the actual resonant frequencies measured using amplitude-fluctuation electronic speckle pattern interferometry. The comparison shows that the genetic algorithm can successfully determine all desired material constants of piezoceramic disks from the measured resonant frequencies in a single operation, and that the resonant frequency values modeled using the constants more accurately correspond to the experimentally measured frequencies than those derived from material constants obtained using conventional methods.

本研究试图利用根据平板理论原理编程的遗传算法，从压电陶瓷圆盘的谐振频率准确确定其压电材料常数。根据判断，Mindlin 的平板理论最适合用于近似计算盘形压电陶瓷厚板的平面内和平面外谐振频率与材料常数之间的关系，因此将该理论编程到遗传算法中，以便通过逆计算从测量的样本压电陶瓷盘谐振频率中获得所有相关的压电材料常数。为验证材料常数的准确性，采用有限元法推导出理论共振频率和相应的模态振型，然后将其与使用振幅波动电子斑点图干涉仪测量的实际共振频率进行比较。比较结果表明，遗传算法可以在一次操作中根据测量到的共振频率成功确定压电陶瓷盘的所有所需材料常数，而且与使用传统方法获得的材料常数相比，使用这些常数建模的共振频率值更准确地对应于实验测量频率。

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引用次数: 0

Controllably ultrawide bandgap of a metamaterial beam based on inertial amplification and magnetorheological elastomer 基于惯性放大和磁流变弹性体的可控超宽带隙超材料光束

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-09 DOI: 10.1016/j.euromechsol.2024.105494

Yu Xue , Biliu Zhou , Jinqiang Li , Wei Zhang

This paper presents the design of a metamaterial beam for controllably ultrawide bandgap (36.3Hz–218.6Hz) and low-frequency vibration attenuation, achieved by a lever-based inertial amplification and a variable stiffness of a magnetorheological elastomer (MRE) modulated by an external magnetic field. The metamaterial is formed by periodical mass-lever inertial amplifier and spring-MRE resonators connected to a base beam. The Galerkin method is employed to theoretically investigate the controllably ultrawide tunability of a low-frequency bandgap in terms of the MRE properties, the mass-lever inertial amplification and the geometric nonlinearity conditions. The results obtained are validated through numerical simulations. The study further extends to lightweight design of metamaterials, where the target frequency that depends on controllably ultrawide bandgap is introduced. With the same target frequency of bandgap, the proposed system exhibits a lighter resonator mass than the traditional metamaterials. Finally, a target frequency-based bandgap control strategy is developed, enabling real-time tunability of the bandgap within a low-frequency wideband range without changing the mass of the resonator or reconstructing the structure. Compared to typical "mass-spring" metamaterials, the proposed system shows superiority in achieving ultrawide bandgaps. This metamaterial offers a promising solution for creating controllably ultrawide vibration-attenuating structures, making it highly suitable for practical applications.

本文介绍了一种超材料横梁的设计，通过基于杠杆的惯性放大和磁流变弹性体（MRE）在外部磁场调制下的可变刚度，实现可控的超宽带隙（36.3Hz-218.6Hz）和低频振动衰减。超材料由周期性质量杠杆惯性放大器和弹簧-磁流变弹性体谐振器组成，并与基梁相连。本文采用伽勒金方法，从 MRE 特性、质量杠杆惯性放大和几何非线性条件等方面，对低频带隙的可控超宽可调性进行了理论研究。数值模拟验证了所获得的结果。研究进一步扩展到超材料的轻量化设计，引入了取决于可控超宽带隙的目标频率。在带隙目标频率相同的情况下，与传统超材料相比，所提出的系统具有更轻的谐振器质量。最后，还开发了一种基于目标频率的带隙控制策略，可在低频宽带范围内实现带隙的实时可调，而无需改变谐振器的质量或重建结构。与典型的 "质量弹簧 "超材料相比，所提出的系统在实现超宽带隙方面表现出了优越性。这种超材料为创建可控的超宽振动衰减结构提供了一种有前途的解决方案，因此非常适合实际应用。

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引用次数: 0

Nonlinear combined resonance of magneto-electro-elastic plates 磁电弹性板的非线性组合共振

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-08 DOI: 10.1016/j.euromechsol.2024.105492

Lei-Lei Gan, Gui-Lin She

The existing articles on the nonlinear resonances of magneto-electro-elastic (MEE) structures are mainly devoted to the parametric resonance and primary resonance, neglecting the coupling effect between parametric and forced excitations. To reveal this issue, the coupled longitudinal and transverse excitations are considered to investigate the combined resonance of MEE plates, in which the simply supported ends is considered. The expressions of magnetic-, electric- and displacement-fields are determined using the Maxwell's equation and first order shear deformation theory (FSDT). Applying the Galerkin method, the nonlinear ordinary differential equations are derived. The combined resonance problem of MEE plates with simply supported ends is solved by developing the method of varying amplitude (MVA). And the resonance trajectory is depicted by amplitude-frequency diagram in the follow-up analysis, in which the complicated dynamical phenomena with jump, hysteresis and multi-stable solution can be observed. To reveal the dynamic mechanism, comprehensive numerical analyses including electric potential, magnetic potential, excitations, temperature variation and other factors are conducted, the bifurcation and chaotic dynamic behaviors are also analyzed. The results elucidate that these parameters under discussion play significant roles.

现有关于磁电弹性（MEE）结构非线性共振的文章主要关注参数共振和主共振，忽略了参数激励和强迫激励之间的耦合效应。为了揭示这个问题，我们考虑了纵向和横向耦合激励，研究了 MEE 板的组合共振，其中考虑了简单支撑的两端。利用麦克斯韦方程和一阶剪切变形理论（FSDT）确定了磁场、电场和位移场的表达式。应用 Galerkin 方法推导出了非线性常微分方程。通过开发变幅法（MVA），解决了具有简单支撑端部的 MEE 板的组合共振问题。在后续分析中，通过幅频图描述了共振轨迹，观察到了具有跳跃、滞后和多稳解的复杂动力学现象。为揭示其动力学机理，还进行了包括电动势、磁势、激励、温度变化等因素在内的综合数值分析，并对分岔和混沌动力学行为进行了分析。结果表明，这些参数发挥了重要作用。

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引用次数: 0

Nonlinear simultaneous resonance behaviors of a shallow arch model under the moving load 移动荷载下浅拱模型的非线性同步共振行为

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-08 DOI: 10.1016/j.euromechsol.2024.105493

Xiaoyang Su , Houjun Kang , Wei Zhang , Yunyue Cong , Yuewu Wang , Chaoran Liu

By applying a moving load with the uniform velocity, this paper investigates nonlinear behaviors of a shallow arch model allowing for describing the effects of the initial configuration of the structure. Two different cases are taken into account, namely, simultaneous primary resonances of the first and third modes; simultaneous resonances of the first mode for two-term excitations. First, nonlinear ordinary differential equations (ODEs) of the shallow arch are derived by using Galerkin method. Through introducing different time scales, the ODEs are solved based on the widely utilized method of multiple time scales (MMTS). In this way, the modulation equations for the two cases are derived, on the basis of which the steady state frequency- and force-response curves are obtained. Meanwhile, phase portraits, power spectra and two-parameter bifurcation diagram are also given to assist in analysis on nonlinear behaviors. The results show that the large vibration of the shallow arch under the moving load may occur and primary resonance peaks of the different modes are located in distinct positions.

通过施加匀速运动载荷，本文研究了浅拱模型的非线性行为，以描述结构初始配置的影响。本文考虑了两种不同的情况，即第一和第三模态同时发生主共振；第一模态在两期激励下同时发生共振。首先，利用 Galerkin 方法推导出浅拱的非线性常微分方程（ODE）。通过引入不同的时间尺度，利用广泛使用的多时间尺度法（MMTS）求解 ODE。这样，就得出了两种情况下的调制方程，并在此基础上得到了稳态频率和力响应曲线。同时，还给出了相位肖像、功率谱和双参数分岔图，以帮助分析非线性行为。结果表明，浅拱在移动荷载作用下可能发生较大振动，不同模态的主共振峰位于不同位置。

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引用次数: 0

Understanding adhesive sliding nanocontact mechanics in an exponentially graded coating–substrate structure 了解指数分级涂层-基底结构中的粘合滑动纳米接触力学原理

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-07 DOI: 10.1016/j.euromechsol.2024.105482

Youxue Ban , Jie Yan , Zhiqiang Li , Changwen Mi

The objective of this study is to investigate the frictionally adhesive nanocontact characteristics between a sliding rigid cylinder and an exponentially graded coating–substrate structure. Adhesive forces are modeled using the Maugis–Dugdale adhesive theory, while the Steigmann–Ogden surface mechanical theory describes the surface effects of the graded coating. Within the contact region, normal and tangential tractions adhere to the extended Amontons’ friction law. The governing equations and boundary conditions of the nanocontact problem are reformulated into Fredholm integral equations, which are solved numerically using Gauss–Jacobi quadratures and a self-designed iterative algorithm. Validation against existing literature results demonstrates the accuracy and reliability of the proposed solution method and numerical algorithm. Extensive parametric studies are conducted to investigate the effects of various parameters, including surface material properties, coefficient of friction, Tabor’s parameter, inhomogeneity index of the exponentially graded coating, and external loads. Results reveal that sliding friction significantly influences adhesive nanocontact, affecting nanocontact boundaries, contact traction distribution, and adhesive region boundaries. Additionally, surface effects play a crucial role, leading to smaller nanocontact length and maximum pressure but larger adhesive zone. Furthermore, the interplay between sliding friction, surface effects, and adhesion is underscored, emphasizing the importance of considering these factors in the analysis of sliding nanocontact problems involving graded materials. Ultimately, this work provides a comprehensive solution framework for addressing such complex nanocontact scenarios, offering insights valuable to the field of materials science and engineering.

本研究的目的是研究滑动刚性圆柱体与指数分级涂层-基底结构之间的摩擦粘附纳米接触特性。粘附力使用 Maugis-Dugdale 粘附理论建模，而 Steigmann-Ogden 表面力学理论则描述了分级涂层的表面效应。在接触区域内，法向和切向牵引力遵循扩展的阿蒙顿摩擦定律。纳米接触问题的控制方程和边界条件被重新表述为弗雷德霍姆积分方程，并使用高斯-雅各比四元数和自行设计的迭代算法对其进行数值求解。根据现有的文献结果进行验证，证明了所提出的求解方法和数值算法的准确性和可靠性。通过广泛的参数研究，考察了各种参数的影响，包括表面材料特性、摩擦系数、Tabor 参数、指数分级涂层的不均匀指数以及外部载荷。结果表明，滑动摩擦对纳米粘合接触有显著影响，会影响纳米接触边界、接触牵引力分布和粘合区域边界。此外，表面效应也起着关键作用，导致纳米接触长度和最大压力变小，但粘合区域变大。此外，研究还强调了滑动摩擦、表面效应和粘附之间的相互作用，强调了在分析涉及分级材料的滑动纳米接触问题时考虑这些因素的重要性。最终，这项研究为解决此类复杂的纳米接触问题提供了一个全面的解决方案框架，为材料科学与工程领域提供了宝贵的见解。

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引用次数: 0

A graded elastic modulus concept to eliminate stress or strain energy density singularity at sharp notches and cracks, with consequent elimination of size-scale effect on strength 分级弹性模量概念可消除尖锐缺口和裂缝处的应力或应变能量密度奇异性，从而消除尺寸尺度对强度的影响

IF 4.4 2区工程技术 Q1 MECHANICS

European Journal of Mechanics A-Solids

Pub Date : 2024-11-07 DOI: 10.1016/j.euromechsol.2024.105477

M. Ciavarella

It has been recently suggested by the author that in the classical problem of a sharp wedge or crack loaded in plane (mode I and/or mode II), the stress singularity can be removed by grading the elastic properties of the underlying material from the notch tip by using a power law,

E \sim r^{β}

. While the treatment is extended to the case of mode III (antiplane shear) which permits closed form results, we also discuss two ways to deal with the likely effect of material’s grading on strength. In one, already explored in the previous paper, the strength is a power law of the modulus, and we suggest an “optimal” design by keeping the dominant stress constantly equal to the strength. In a second method, we propose to cancel the singularity in the strain energy density, which requires a much stronger grading, and we also possibly take into account that the critical strain energy density is a power law of the modulus. Noticing that only in the presence of a singularity a length scale can be defined experimentally by testing a very large notch and a very small one, according to the Theory of Critical Distances (TCD), the effect of cancelling singularity also implies independence on size/scale and constant strength. It is concluded that the technique is much more powerful than drilling a hole or rounding the tip of the notch/crack. Moreover, if a “smart” material could be designed to damage itself as to reduce its modulus when near a high stress concentration according to our prescriptions, it would naturally self-heal, opening up interesting applications.

作者最近提出，在平面加载（模式 I 和/或模式 II）的尖锐楔形或裂缝的经典问题中，可以通过使用幂律 E∼rβ 对缺口顶端的底层材料的弹性特性进行分级来消除应力奇异性。虽然处理方法扩展到了模式 III（反平面剪切）的情况，从而可以得到封闭形式的结果，但我们也讨论了处理材料分级对强度可能产生的影响的两种方法。其中一种方法已在前一篇论文中探讨过，即强度是模量的幂律，我们建议采用一种 "最优 "设计，使主要应力始终等于强度。在第二种方法中，我们建议消除应变能密度中的奇异点，这需要更强的分级，我们还可能考虑到临界应变能密度是模量的幂律。根据临界距离理论（TCD），只有在存在奇异点的情况下，才能通过测试一个非常大的凹口和一个非常小的凹口来实验定义长度尺度，因此取消奇异点的效果也意味着尺寸/尺度的独立性和强度的恒定性。结论是，该技术比钻孔或将缺口/裂缝顶端修圆要强大得多。此外，如果一种 "智能 "材料能根据我们的规定，在接近高应力集中时自我损坏以降低模量，那么它自然会自我修复，从而开辟出有趣的应用领域。

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引用次数: 0