Mechanics of Materials最新文献_第2页

Deformation localization of superhard amorphous carbons under nanoindentation accompanied by sp3-to-sp2 rehybridization 纳米压痕下sp3-to-sp2再杂化的超硬非晶碳变形局部化

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-12 DOI: 10.1016/j.mechmat.2026.105608

Xin Li, ZhongTing Zhang, HengAn Wu, YinBo Zhu

Tetrahedral amorphous carbons (ta-Cs) represent a class of atomically disordered diamonds with excellent mechanical properties and promising applications. In recent experiments, several high-density superhard ta-Cs have been synthesized under high-pressure and high-temperature conditions, in which the hardness of atomically disordered diamonds is larger than single-crystal diamond. It is essential to understand the origin of ultrahigh hardness and associated deformation mechanisms for guiding experimental synthesis and future applications. Through large-scale molecular dynamics simulations, we investigated the nanoindentation of three representative ta-Cs, including amorphous diamond (a-D), paracrystalline diamond (p-D), and nano-polycrystalline diamond (NPD). A distinctive deformation localization was revealed to accompanied by the sp³-to-sp² rehybridization, with the mechanical performance of ta-Cs strongly dependent on the size and proportion of paracrystallite and crystallinity. During nanoindentation, the paracrystalline/crystalline grains in p-D and NPD evolved into sp²/sp³ mixed amorphous domains, while the disordered matrix in ta-Cs maintained disordered, which led to occurrence of the sp³-to-sp² rehybridization. The short exponential attenuation length indicates the confined indentation response within a small region and notabe deformation localization. Our study provides atomic-scale insights into the mechanical behavior and microstructure destruction of ta-Cs, inspiring their potential applications and opening up new perspectives for investigating other amorphous carbons.

四面体无定形碳（ta-Cs）是一类具有优异力学性能的原子无序金刚石，具有广阔的应用前景。在最近的实验中，在高压和高温条件下合成了几种高密度的超硬ta-Cs，其中原子无序金刚石的硬度大于单晶金刚石。了解超高硬度材料的起源及其变形机制对指导实验合成和未来应用具有重要意义。通过大规模分子动力学模拟，我们研究了三种具有代表性的ta-Cs的纳米压痕，包括非晶金刚石（a-D）、准晶金刚石（p-D）和纳米聚晶金刚石（NPD）。在sp3-to-sp2再杂化过程中，ta-Cs发生了明显的形变局部化，其力学性能与副晶的大小、比例和结晶度密切相关。在纳米压痕过程中，p-D和NPD中的准晶/晶态晶粒演化为sp2/sp3混合非晶畴，而ta-Cs中的无序基体保持无序状态，导致sp3-to-sp2再杂化的发生。较短的指数衰减长度表明在小范围内的受限压痕响应和明显的变形局部化。我们的研究为ta-Cs的力学行为和微观结构破坏提供了原子尺度的见解，激发了它们的潜在应用，并为研究其他非晶碳开辟了新的视角。

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引用次数: 0

Compressive collapse modes of hyperelastic origami honeycombs 超弹性折纸蜂窝的压缩崩塌模式

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-08 DOI: 10.1016/j.mechmat.2026.105600

Antonio Schiavone, Graham McShane

Mechanical metamaterials are currently redefining the scope of achievable material properties through the use of micro-architecture. Origami-inspired metamaterials represent one avenue for design and optimisation of these materials, offering a large geometric design space with a range of unique and highly tunable properties. In this investigation, we consider the mechanics of flexible, elastic origami honeycombs with the “symmetric diamond Miura-ori” cell geometry. Potential applications for these materials include biomedical devices, wave attenuation, blast protection, energy absorption, soft robotics, deployable and reconfigurable structures, and many more. In this investigation, we develop insights into the large strain elastic compressive collapse mechanisms of these materials. A key question is to what extent the compressive collapse of these materials follows origami “rigid facet” folding kinematics to large strains, and whether or not that adherence is desirable for a given application. To answer this question, two modelling approaches are used. An analytical model is derived that predicts the large strain response adhering to folding kinematics, while a finite element (FE) model captures additional collapse mechanisms. Together, these modelling approaches are used to identify different regimes of collapse within the geometric design space, and create a design map quantifying this. The comparison also validates the analytical model within its regime of applicability, and provides an understanding of its accuracy outside of this. Following this, the new design map is applied to two case studies: the application of these materials as soft robotic actuators (where folding kinematics is desirable to large strains) and elastic energy absorbers (where departures from folding kinematics are shown to be advantageous). For the former regime, the hyperelastic analytical model derived here provides an accurate and computationally efficient route to exploit the rich material design space.

机械超材料目前正在通过使用微结构重新定义可实现的材料特性的范围。折纸启发的超材料代表了设计和优化这些材料的一种途径，提供了具有一系列独特和高度可调特性的大型几何设计空间。在这项研究中，我们考虑具有“对称钻石三浦里”细胞几何的柔性弹性折纸蜂窝的力学。这些材料的潜在应用包括生物医学设备、波衰减、爆炸防护、能量吸收、软机器人、可部署和可重构结构等等。在这项研究中，我们深入了解了这些材料的大应变弹性压缩坍塌机制。一个关键的问题是，这些材料的压缩坍塌在多大程度上遵循折纸“刚性面”折叠运动学到大应变，以及这种依从性是否适合给定的应用。为了回答这个问题，使用了两种建模方法。推导了一个解析模型，预测了遵循折叠运动学的大应变响应，而有限元（FE）模型捕获了额外的崩溃机制。总之，这些建模方法被用来识别几何设计空间内不同的崩溃制度，并创建一个量化的设计地图。比较还验证了其适用性范围内的分析模型，并提供了其准确性之外的理解。在此之后，新的设计地图应用于两个案例研究：将这些材料应用于软机器人执行器（其中折叠运动学对大应变是可取的）和弹性能量吸收器（其中偏离折叠运动学被证明是有利的）。对于前一种情况，本文推导的超弹性分析模型为利用丰富的材料设计空间提供了一条精确且计算效率高的途径。

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引用次数: 0

Effective elastic modulus of 3D printed plastic 2D and 3D infill patterns 3D打印塑料2D和3D填充图案的有效弹性模量

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-08 DOI: 10.1016/j.mechmat.2026.105601

Bo Zhang , Andrea Carolina Oña Vera , Ticho Ooms , Yaxin Tao , Yuming Qi , Wouter De Corte , Roman Wan-Wendner

3D printing creates complex structures by precisely depositing material layer by layer. This allows materials to be placed only where needed (based on stress analysis), producing lightweight yet rigid structures. In this study, plastic cylindrical domains filled with rectangular and gyroid infill patterns incorporating various design parameters, such as infill density, unit cell size, and inclination angle (for rectangular infills), are printed. The infill patterns are supported during printing by a thin outer skin layer, allowing for measurements by means of digital image correlation. Uniaxial compression tests are conducted on the cylinders, and the effective elastic modulus of the infill patterns is evaluated by accounting for load eccentricities and removing the influence of the outer shell. The results reveal that the relations between infill density and effective elastic modulus are linear for the rectangular 2D infill patterns and follow a power law for the gyroid 3D infill patterns, corresponding to stretching-dominated and bending-dominated deformation modes, respectively. The unit cell size minimally influences the effective elastic modulus. Inclination negatively impacts the effective elastic modulus of the rectangular infill pattern by inducing shear stress along the inclined extrusion axis, which weakens both interlayer and interfilamentous interfaces. Furthermore, the relationships between inclination angles, infill density, and effective elastic modulus follow power law functions. This study investigated the impact of infill pattern design parameters on the effective elastic modulus, establishing functional relationships between these parameters and the elastic modulus, and providing valuable insights for structural optimization, ultimately leading to lightweight and stiff structures.

3D打印通过一层一层地精确沉积材料来创建复杂的结构。这使得材料只放置在需要的地方（基于应力分析），产生轻质但刚性的结构。在这项研究中，塑料圆柱域填充矩形和旋转填充图案，结合各种设计参数，如填充密度、单元格大小和倾角（用于矩形填充），被打印出来。在印刷过程中，填充图案由薄的外层皮肤层支撑，允许通过数字图像相关方法进行测量。对圆柱体进行了单轴压缩试验，在考虑载荷偏心和去除外壳影响的情况下，对填充模式的有效弹性模量进行了计算。结果表明：二维矩形填充模式下填充密度与有效弹性模量呈线性关系，三维回转线填充模式下填充密度与有效弹性模量呈幂律关系，分别对应拉伸为主和弯曲为主的变形模式；单胞尺寸对有效弹性模量的影响最小。倾斜沿倾斜挤压轴方向产生剪切应力，对矩形充填模式的有效弹性模量产生负向影响，使层间和丝间界面均减弱。此外，倾角、填充密度和有效弹性模量之间的关系遵循幂律函数。本研究探讨了填充模式设计参数对有效弹性模量的影响，建立了这些参数与弹性模量之间的函数关系，为结构优化提供了有价值的见解，最终实现了轻量化和刚性结构。

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引用次数: 0

Local chemistry-driven intragranular stress redistribution during dwell fatigue of a near-alpha titanium alloy 近α钛合金停留疲劳过程中局部化学驱动的晶内应力重分布

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-08 DOI: 10.1016/j.mechmat.2026.105605

K.U. Yazar , Sureddy Tejanath Reddy , Amit Bhattacharjee , Marc De Graef , Satyam Suwas

Dwell fatigue is a critical issue in titanium alloys, posing serious challenges to their reliability in aerospace and defense applications. It manifests as accelerated accumulation of damage due to localized stress redistributions, particularly in regions of unfavorable grain orientations. In the present study, local compositional variations and their effects on dwell fatigue of a near-alpha titanium alloy, IMI 834, with a bimodal microstructure were investigated. To date, stress redistributions during the ‘dwell period’ have primarily been linked to grain orientations, with limited investigations into other contributing factors. However, a unique phenomenon related to elemental segregation in primary alpha (

α_{p}

) grains and the consequent deformation heterogeneities, revealed through correlative use of compositional mapping and electron backscatter diffraction combined with dictionary indexing of diffraction patterns, is reported in the present study Aluminium segregation during the duplex annealing stage results in a core-shell structure in the

α_{p}

grains. Higher aluminium concentration in the core reduces the ratio of the initial slip system strength of basal to prismatic <a> slip and thereby promoting basal slip. Full-field crystal plasticity simulations using a phenomenological power law model, accounting for these local compositional variations, reveal the resulting stress redistribution within

α_{p}

grains, in contrast to a case without segregation. These results highlight the importance of incorporating local chemistry-driven effects in such predictive models for dwell fatigue, underscoring the value of correlative microscopy in characterizing chemistry-induced micromechanical heterogeneity at the individual grain scale.

居住疲劳是钛合金的一个关键问题，对其在航空航天和国防应用中的可靠性提出了严峻的挑战。它表现为局部应力重分布导致的损伤加速积累，特别是在不利晶粒取向的区域。本文研究了具有双峰组织的近α钛合金imi834的局部成分变化及其对驻留疲劳的影响。迄今为止，“停留期”的应力重分布主要与晶粒取向有关，对其他影响因素的调查有限。然而，本文报道了一种与α (αp)初生晶粒元素偏析及其变形非均质性相关的独特现象，该现象是通过成分映射和电子背散射衍射相结合结合衍射图字典索引发现的。较高的铝浓度降低了基底滑移与柱状滑移的初始滑移体系强度之比，从而促进了基底滑移。利用现象学幂律模型对αp晶粒的全场塑性进行了模拟，计算了这些局部成分的变化，揭示了αp晶粒内部的应力重新分布，与没有偏析的情况形成对比。这些结果强调了在此类居住疲劳预测模型中纳入局部化学驱动效应的重要性，强调了相关显微镜在表征单个晶粒尺度上化学诱导的微观力学非均质性方面的价值。

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引用次数: 0

On the evaluation of in-situ mechanical properties of an additively manufactured BCC lattice 增材制造BCC晶格的原位力学性能评价

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-07 DOI: 10.1016/j.mechmat.2026.105602

Malo Valmalle , Benjamin Smaniotto , Junhe Lian , Luc St-Pierre , François Hild

Additive manufacturing enables for the fabrication of complex lattice materials with superior strength-to-weight ratios. These lattice structures are made from small struts that are difficult to test individually and whose responses may be size-dependent. In the present work, the mechanical response of a BCC lattice was studied when subjected to in-situ compression, i.e., monitored via Digital Volume Correlation (DVC). Backtracking was implemented in the DVC procedure to account for geometric imperfections generated by the manufacturing process. Displacement fields were measured via DVC and then employed in a Finite Element Model Updating (FEMU) procedure to calibrate the parameters of the constitutive law. Numerical simulations with the calibrated parameters were found to be in good agreement with experiments. The lattice material had a lower strength than that reported in the literature and measured with ex-situ tensile tests. This difference is attributed to size effects; this work demonstrates that they can be accounted for and that a single in-situ test is sufficient to calibrate such material properties.

增材制造能够制造具有优越强度重量比的复杂晶格材料。这些晶格结构由难以单独测试的小支柱构成，其响应可能与尺寸有关。在目前的工作中，研究了BCC晶格在受到原位压缩时的力学响应，即通过数字体积相关（DVC）进行监测。回溯在DVC程序中实现，以解释由制造过程产生的几何缺陷。通过DVC测量位移场，然后采用有限元模型更新（FEMU）程序校准本构律参数。数值模拟结果与实验结果吻合较好。晶格材料的强度低于文献报道的强度，并通过非原位拉伸试验测量。这种差异归因于尺寸效应；这项工作表明，它们可以被解释，并且单个原位测试足以校准此类材料的性能。

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引用次数: 0

The role of chain stretch heterogeneity on the uniaxial failure response of rubbery networks 链拉伸非均质性对橡胶网络单轴破坏响应的影响

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-07 DOI: 10.1016/j.mechmat.2026.105599

Lucas Mangas Araujo, Laurence Brassart

The macroscopic failure response of rubbery networks such as elastomers and hydrogels involves the scission of individual polymer chains, mediated by the network topology. However, the precise mechanisms by which individual chain scission events result in macroscopic failure remain poorly understood. In this work, we use Discrete Network (DN) simulations to investigate failure mechanisms in model random networks in uniaxial tension. Our DN simulation results suggest that macroscopic failure, characterised by a sharp drop in the macroscopic stress–stretch response, only requires the scission of a small fraction of chains in a localised region of the network, even in perfect monodisperse networks. Localised failure is triggered by pre-existing heterogeneities in the chain stretch and is further modulated by network parameters such as the chain length or chain strength. Simple micromechanical models of rubber elasticity, such as the three-chain and eight-chain models, fail to capture the onset of damage because they do not capture the chain stretch heterogeneity. More sophisticated microsphere theories in their affine and non-affine versions only partially address this shortcoming. Overall, our results provide new insights into failure mechanisms of rubbery networks, while providing reference results useful for the validation of improved constitutive theories.

橡胶网络（如弹性体和水凝胶）的宏观失效响应涉及单个聚合物链的断裂，由网络拓扑结构介导。然而，单个链断裂事件导致宏观失效的确切机制仍然知之甚少。在这项工作中，我们使用离散网络（DN）模拟来研究模型随机网络在单轴拉伸下的失效机制。我们的DN模拟结果表明，以宏观应力-拉伸响应急剧下降为特征的宏观破坏，即使在完美的单分散网络中，也只需要在网络的局部区域中切断一小部分链。局部失效是由链拉伸中预先存在的异质性触发的，并进一步受到链长度或链强度等网络参数的调节。橡胶弹性的简单微观力学模型，如三链和八链模型，无法捕捉到损伤的开始，因为它们没有捕捉到链拉伸的异质性。更复杂的微球理论在它们的仿射和非仿射版本中只能部分地解决这个缺点。总的来说，我们的研究结果为橡胶网络的破坏机制提供了新的见解，同时为改进的本构理论的验证提供了有用的参考结果。

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引用次数: 0

Strengthening mechanism of CoCrFeMnNi high-entropy alloys with dual-gradient nanostructures: Grain size and twin boundary spacing 双梯度纳米结构CoCrFeMnNi高熵合金的强化机理：晶粒尺寸和孪晶界间距

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-07 DOI: 10.1016/j.mechmat.2026.105603

Xingguo Yang , Shuaijun Li , Yuxuan Yi , Chao Song , Fei Yin

Both a grain size gradient and twinning-induced plasticity can achieve a synergistic effect of high strength and plasticity in metals/alloys. To investigate whether this effect is still produced at the nanoscale, a series of CoCrFeMnNi high-entropy alloy (HEA) atomic models with equiatomic ratios was designed, including homogeneous nanostructured (HNS), single-gradient nanostructured (SGNS), and dual-gradient nanostructured (DGNS) models, and others. The mechanical response of the CoCrFeMnNi HEA under uniaxial tensile loading was simulated by molecular dynamics (MD). Research has shown that, compared to the HNS samples, the mechanical properties of both the HEA samples with SGNS and DGNS are significantly improved, with DGNS producing better strengthening. The grain size gradient yields a certain stress/strain and dislocation density gradient distribution, stimulating the deformation potential of almost all the grains. Furthermore, it also suppresses mechanically driven grain boundary (GB) migration and grain rotation, promotes grain growth, weakens strain softening, and enhances the strengthening effect of GBs, all of which improve the mechanical properties of nanocrystalline HEAs. Twinning also weakens strain softening, and a reasonable twin boundary (TB) spacing and gradient can increase the number of dislocations and affect the direction and resistance to dislocation motion to achieve higher strength. The MD simulation shows that the DGNS improves the mechanical properties of nanocrystalline HEA on the basis of the SGNS, and the combination of a larger grain size gradient and smaller TB spacing gradient has the best strengthening effect.

晶粒尺寸梯度和孪晶诱导塑性都可以在金属/合金中实现高强塑性的协同效应。为了研究这种效应在纳米尺度上是否仍然会产生，我们设计了一系列具有等原子比的CoCrFeMnNi高熵合金（HEA）原子模型，包括均相纳米结构（HNS）、单梯度纳米结构（SGNS）和双梯度纳米结构（DGNS）模型等。采用分子动力学方法模拟了CoCrFeMnNi HEA在单轴拉伸载荷下的力学响应。研究表明，与HNS相比，添加SGNS和DGNS的HEA样品的力学性能都有显著提高，其中DGNS的强化效果更好。晶粒尺寸梯度产生一定的应力应变和位错密度梯度分布，激发了几乎所有晶粒的变形潜力。抑制机械驱动晶界（GB）迁移和晶粒旋转，促进晶粒长大，减弱应变软化，增强GB的强化效果，从而改善纳米晶HEAs的力学性能。孪晶还可以减弱应变软化，合理的孪晶边界（TB）间距和梯度可以增加位错数量，影响位错运动的方向和阻力，从而达到更高的强度。MD模拟结果表明，DGNS在SGNS的基础上改善了纳米晶HEA的力学性能，较大的晶粒尺寸梯度和较小的TB间距梯度组合的强化效果最好。

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引用次数: 0

Plasticity and fracture properties of laser powder bed fusion fabricated 316L stainless steel - Experimental and numerical investigations 激光粉末床熔合制备316L不锈钢的塑性和断裂性能-实验和数值研究

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-06 DOI: 10.1016/j.mechmat.2026.105597

Jian Liu , Guobin Li , Cunyi Li , Chuanqiang Li , Jianguang Fang

To understand the complex mechanical behaviour of Laser Powder Bed Fusion (LPBF) fabricated 316L stainless steel (LPBF-316L), its anisotropic plasticity and ductile fracture are systematically investigated under various stress states and strain rates in this study. For comparison, tensile tests are also conducted on traditionally rolled 316L stainless steel (TR-316L) samples. Based on the experimental results, the transversely isotropic Hill-48 yield criterion and a modified Johnson-Cook (J-C) plasticity model are calibrated to describe the dynamic and anisotropic plastic response. Scanning electron microscopy reveals that fracture morphology is strongly influenced by stress state, strain rate, and build orientation, with void coalescence and dimple formation indicative of ductile failure, alongside manufacturing-induced defects. Additionally, a modified Mohr-Coulomb criterion (MMC) is proposed to characterise both anisotropic fracture initiation and strain rate sensitivity. A combination of experimental and numerical approaches is employed to capture the evolution of stress and strain fields during deformation. Finally, a comparative analysis of the three-dimensional fracture envelopes of TR-316L and LPBF-316L samples is performed. It is found that LPBF-316L exhibits lower sensitivity to the average normalised Lode angle than TR-316L. This study offers critical insight into the mechanical performance of additively manufactured metallic materials and informs the development of predictive models for advanced structural applications.

为了了解激光粉末床熔合（LPBF）制备的316L不锈钢（LPBF-316L）的复杂力学行为，本研究系统地研究了其在不同应力状态和应变速率下的各向异性塑性和韧性断裂。为了进行比较，还对传统轧制的316L不锈钢（TR-316L）样品进行了拉伸试验。基于试验结果，标定了横向各向同性的Hill-48屈服准则和修正的Johnson-Cook （J-C）塑性模型来描述动态和各向异性的塑性响应。扫描电镜显示，断裂形态受应力状态、应变速率和构建方向的强烈影响，伴随着制造缺陷，孔洞合并和韧窝形成表明韧性破坏。此外，提出了一种改进的Mohr-Coulomb准则（MMC）来表征各向异性断裂起裂和应变速率敏感性。采用实验与数值相结合的方法来捕捉变形过程中应力场和应变场的演变过程。最后，对TR-316L和LPBF-316L试样的三维断口包络进行了对比分析。结果表明，LPBF-316L对平均归一化Lode角的灵敏度低于TR-316L。这项研究为增材制造金属材料的机械性能提供了关键的见解，并为先进结构应用的预测模型的发展提供了信息。

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引用次数: 0

Brittle failure in residually stressed soft materials — Modeling, initiation and propagation of failure, and experimental simulations 残余应力软材料的脆性破坏。破坏的建模、开始和扩展以及实验模拟

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-05 DOI: 10.1016/j.mechmat.2026.105598

Soumya Mukherjee , Paritosh Mahata , Saksham Raj

This paper presents a framework to model semi-brittle (gradual) to fully brittle catastrophic failure of residually stressed soft materials. We consider a virtual stress-free configuration that follows the Volokh failure model, where Neo-Hookean or Yeoh models are embedded in the incomplete Gamma function. Using inverse analysis, two failure models are developed accurately for residually stressed bodies. The first developed model is used to investigate the initiation and propagation of failure in a residually stressed hollow thick sphere subjected to internal pressure — a problem equivalent to cavitation instability and void growth. In the presence of residual stress, a cavity need not necessarily grow outward starting from the inner surface Instead, the initiation and propagation of failure show intricate patterns, mechanisms, and staging, influenced by different types of residual stress fields. Failure can initiate at the outer surface, at an intermediate point, or simultaneously at multiple locations and propagate both inward and outward. Among several other cases, compound spheres (a specific type of residually stressed spheres) exhibit an intriguing pattern and a clear staging in failure propagation. The residually stressed Yeoh model with Volokh failure is used to simulate the failure of initially stressed natural rubber under biaxial extension, based on experimental results on the failure of natural rubber. Diverse shapes of the failure envelope demonstrate the initial stress-driven anisotropic response of natural rubber. The current constitutive framework applies to predicting the failure of any other residually stressed soft structures. This model is further simplified to create a residually stressed Yeoh model that can be useful for various applications.

本文提出了一个框架来模拟残余应力软材料的半脆性（逐渐）到完全脆性突变破坏。我们考虑遵循Volokh失效模型的虚拟无应力配置，其中Neo-Hookean或Yeoh模型嵌入在不完全Gamma函数中。利用逆分析方法，准确地建立了残余受力体的两种破坏模型。第一个建立的模型用于研究内压作用下残余应力空心厚球破坏的开始和扩展，这是一个相当于空化不稳定和空洞生长的问题。在残余应力存在的情况下，空腔不一定从内表面开始向外生长，相反，受不同类型残余应力场的影响，破坏的发生和扩展表现出复杂的模式、机制和阶段。破坏可以在外表面、中间点或同时在多个位置开始，并向内和向外传播。在其他几种情况中，复合球（一种特殊类型的残余应力球）在破坏传播中表现出一种有趣的模式和明确的阶段。基于天然橡胶破坏的实验结果，采用残余应力Yeoh模型和Volokh破坏模型，模拟了初始应力天然橡胶在双轴拉伸下的破坏。不同形状的破坏包络表明天然橡胶的初始应力驱动的各向异性响应。目前的本构框架适用于预测任何其他残余应力软结构的破坏。该模型进一步简化，以创建可用于各种应用程序的残余压力杨氏模型。

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引用次数: 0

Modeling solvent diffusion in amorphous polymers spanning glass transition region 模拟溶剂在非晶态聚合物中跨越玻璃过渡区的扩散

IF 4.1 3区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

Mechanics of Materials

Pub Date : 2026-01-02 DOI: 10.1016/j.mechmat.2025.105584

Junwei Xu , Kunquan Wang , Rui Xiao , Lu Dai

Diffusion of solvent molecules into amorphous networks exhibits distinct behaviors based on polymer states. The diffusion behavior of solvents in elastomers or rubber-like polymers is classified as Case I diffusion, also known as Fickian diffusion. In contrast, diffusion of solvent molecules in glassy polymers differs significantly from that in rubbery polymers, characterized by a distinct boundary between a swollen region and a non-swollen region. This type of diffusion is termed Case II diffusion. In this study, a model is developed to simultaneously characterize both Fickian and non-Fickian diffusion behaviors. The free energy comprises three components: an equilibrium component arising from entropic elasticity due to network deformation of the polymer chains, a non-equilibrium component due to the viscoelastic contribution, and the free energy associated with the mixing of solvents and polymer chains. The free volume theory is introduced to describe the influence of glass transition on solvent diffusion and viscosity. Specifically, as free volume increases, the solvent diffusion rate rises rapidly, while viscosity decreases significantly. Finite element simulations are further performed to investigate the effects of various parameters on diffusion behavior, with a particular focus on revealing the central mechanisms related with the Case II diffusion. This work enhances the understanding of complex diffusion behaviors in amorphous polymers across the glass transition region.

溶剂分子在非晶网络中的扩散表现出基于聚合物状态的不同行为。溶剂在弹性体或类橡胶聚合物中的扩散行为被归类为案例I扩散，也称为菲克扩散。相反，溶剂分子在玻璃聚合物中的扩散与橡胶聚合物中的扩散有很大不同，其特征是肿胀区域和非肿胀区域之间有明显的边界。这种扩散称为情形II扩散。在本研究中，建立了一个同时表征菲克式和非菲克式扩散行为的模型。自由能包括三个组成部分：由聚合物链的网络变形引起的熵弹性产生的平衡分量，由粘弹性贡献引起的非平衡分量，以及与溶剂和聚合物链混合有关的自由能。引入自由体积理论，描述了玻璃化转变对溶剂扩散和粘度的影响。具体来说，随着自由体积的增加，溶剂扩散速率迅速上升，而粘度明显下降。进一步进行了有限元模拟，以研究各种参数对扩散行为的影响，特别侧重于揭示与案例II扩散相关的核心机制。这项工作增强了对非晶聚合物在玻璃过渡区的复杂扩散行为的理解。

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