【新文速递】2023年10月15日固体力学SCI期刊最新文章

今日更新：International Journal of Solids and Structures 1 篇，Journal of the Mechanics and Physics of Solids 2 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 2 篇，Thin-Walled Structures 1 篇

International Journal of Solids and Structures

Prediction and Demonstration of Periodic Tensile Cracking in Rate-Dependent Porous Cement

Lu Yunxing, Veveakis Manolis, Crandall Dustin, Bunger Andrew P.

doi:10.1016/j.ijsolstr.2023.112527

速率相关多孔水泥周期性拉伸开裂的预测与论证

Periodic tensile cracks are shown to occur when cylinder-shaped saturated cement specimens are subjected to rapid decompression, with the spacing between the cracks scaling as a power law of the decompression time. This behavior is predicted by theory, which is specified to this scenario based on prior work that was more general and applied to compaction bands. Specifically, the formation of the tensile cracks is shown to coincide with periodicity that naturally arises in the effective stress when the material follows a Terzaghi-type consolidation law, although in reverse for dilation and with material deformation described by a rate-dependent viscoplastic law. When strain rate is proportional to effective stress to a power that is greater than one, periodic regions of tensile effective stress arise through the poromechanical fluid-solid coupling. The theoretically-predicted exponent of the resulting power-law relationship between tensile cracks spacing and unloading time successfully brackets the experimental results, for which it is observed that the exponent is slightly stronger than a square-root relationship (0.28 to 0.67) at testing temperatures of 20 ℃ and 90 ℃. These results demonstrate that rapid-depressurization leads to periodic fracturing that could, on the one hand, be detrimental to the isolation provided by cement used to seal wellbores in the petroleum industry. On the other hand, the periodic tensile cracks could also be favorable to production if generated in low-permeability reservoir rocks such as shales that are targeted for petroleum production or granites that are targeted for geothermal energy.

柱状饱和水泥试样在快速减压过程中出现周期性拉伸裂缝，裂缝间距随减压时间呈幂律变化。这种行为是由理论预测的，这是基于先前的工作而指定的，这些工作更一般，并应用于压实带。具体来说，拉伸裂纹的形成与材料遵循terzaghi型固结规律时自然产生的有效应力的周期性相一致，尽管与膨胀和材料变形由速率相关的粘塑性规律描述相反。当应变率与有效应力成正比且大于1时，通过孔隙力学流固耦合会出现拉有效应力的周期性区域。拉伸裂纹间距与卸载时间幂律关系的理论预测指数与实验结果相吻合，在20℃和90℃的试验温度下，该指数略强于平方根关系(0.28 ~ 0.67)。这些结果表明，快速降压导致周期性压裂，这一方面可能不利于石油工业中用于密封井眼的水泥提供的隔离。另一方面，周期性张性裂缝如果产生于低渗透储层岩石中，如以石油生产为目标的页岩或以地热能为目标的花岗岩，也可能有利于生产。

Journal of the Mechanics and Physics of Solids

Delayed fracture caused by time-dependent damage in PDMS

Wang Jikun, Zhu Bangguo, Hui Chung-Yuen, Zehnder Alan T.

doi:10.1016/j.jmps.2023.105459

PDMS时间依赖性损伤引起的迟发性骨折

An experimental and theoretical study of delayed fracture of polydimethlsiloxane (PDMS) is presented. Previous works have demonstrated that delayed fracture in single edge notch specimens is caused by time dependent damage due to chain scission. Here we study the interactions between damage and the elastic field using different specimens and crack geometries with blunt and sharp cracks. Our experiments show that initial toughness is not well defined, as stable slow crack growth can occur over a range of applied loads. Our experiments demonstrate that there is a universal relation between crack growth rate and applied energy release rate. A model coupling the nonlinear elastic deformation and rate dependent bond scission is proposed and is in good agreement with experimental data.

对聚二甲基硅氧烷(PDMS)的延迟断裂进行了实验和理论研究。以往的研究表明，单刃缺口试样的延迟断裂是由链断裂引起的时间依赖性损伤引起的。本文采用不同的试样和裂纹几何形状研究了损伤与弹性场之间的相互作用。我们的实验表明，初始韧性不是很好地定义，因为稳定的缓慢裂纹扩展可以在一定范围内发生。实验表明，裂纹扩展速率与外加能释放速率之间存在普遍的关系。提出了一个耦合非线性弹性变形和速率相关键断的模型，该模型与实验数据吻合较好。

A phase-field formulation for cohesive fracture based on the Park-Paulino-Roesler (PPR) cohesive fracture model

Giraldo-Londoño Oliver, Muñetón-López Rogelio A.

doi:10.1016/j.jmps.2023.105460

基于Park-Paulino-Roesler (PPR)黏性断裂模型的黏性断裂相场公式

Unlike most cohesive zone models (CZMs), the Park-Paulino-Roesler (PPR) cohesive fracture model has the inherent ability to control the softening shape of the traction-separation relationships, which makes it suitable to model fracture for a wide variety of materials. Like other CZMs, the PPR model is well-suited for problems where the crack path is known a priori but its implementation may become complex in situations where the crack path is not known beforehand. To overcome this limitation, we recast the PPR model within the framework of the phase field method, which enables the modeling of crack propagation problems with complex crack topologies using a straightforward multi-field finite element implementation. We use constitutive functions (i.e., crack geometric function and degradation function) consistent with the PPR model for the case of mode-I fracture, such that equivalent traction-separation relationships from the phase-field model approximate those from the original PPR model. Our choice of geometric and degradation functions is based upon those proposed by Wu (2017). We present several numerical examples to demonstrate the ability of the model to capture fracture of problems with different materials, geometries, and boundary conditions. Also, we show that the results from our model converge to those obtained with the original PPR model for problems where the crack path is known a priori. Being crucial in engineering design, we finally show that the model can capture size and boundary effects with satisfactory accuracy.

与大多数黏结带模型(CZMs)不同，Park-Paulino-Roesler (PPR)黏结断裂模型具有固有的控制牵引-分离关系软化形状的能力，这使得它适用于各种材料的断裂模型。与其他czm一样，PPR模型非常适合于裂纹路径先验已知的问题，但在裂纹路径事先未知的情况下，其实现可能会变得复杂。为了克服这一限制，我们在相场方法的框架内重新构建了PPR模型，这使得能够使用简单的多场有限元实现对具有复杂裂纹拓扑结构的裂纹扩展问题进行建模。对于i型断裂，我们使用了与PPR模型一致的本构函数(即裂纹几何函数和退化函数)，使得相场模型的等效牵引-分离关系近似于原始PPR模型。我们对几何函数和退化函数的选择是基于Wu(2017)提出的。我们提出了几个数值例子来证明该模型能够捕获具有不同材料，几何形状和边界条件的断裂问题。此外，我们还表明，对于已知先验裂纹路径的问题，我们的模型的结果收敛于原始PPR模型的结果。在工程设计中至关重要的是，我们最终证明了该模型能够以令人满意的精度捕获尺寸和边界效应。

Mechanics of Materials

Modelling the effect of layer strength distribution on the brick-and-mortar failure regimes and properties

Hunter Georgia, Djumas Lee, Molotnikov Andrey, Brassart Laurence

doi:10.1016/j.mechmat.2023.104820

模拟了层间强度分布对砂浆破坏形态和性能的影响

Brick-and-Mortar structures are of high interest because their staggered multi-material arrangement can result in a remarkable combination of high strength and high toughness. Synthetic replication of these structures with high geometric control has been made possible recently with the advances in multi-material Additive Manufacturing (AM). However, very little is known on how inherent material variation in the constituent materials, which can be significant in AM, affects the structure response. In this work, we use a semi-analytical model to theoretically show that a variation in the strength of the layers in a Brick-and-Mortar structure has a significant effect on the failure response of the structure. It can lead to changes in failure regimes and negatively impact the mechanical properties, such as decrease the strain to failure or decrease the yield stress. This is particularly pronounced when the material behaviour is situated close to the transition point between failure regimes. We then present an experimental method to capture strength variability in the layer material and demonstrate that the incorporation of this variability into the semi-analytical model improves our prediction of the failure response of the structure, as compared to experiments.

砖和砂浆结构是高度感兴趣的，因为它们交错的多材料排列可以导致高强度和高韧性的显着组合。近年来，随着多材料增材制造(AM)技术的进步，具有高度几何控制的这些结构的合成复 制成为可能。然而，对于组成材料的固有材料变化如何影响结构响应知之甚少，这在AM中可能很重要。在这项工作中，我们使用半解析模型从理论上表明，砖混结构中各层强度的变化对结构的破坏响应有显著影响。它可以导致失效状态的改变，并对力学性能产生负面影响，例如降低失效应变或降低屈服应力。当材料行为接近失效状态之间的过渡点时，这一点尤为明显。然后，我们提出了一种实验方法来捕获层材料中的强度变异性，并证明与实验相比，将这种变异性纳入半解析模型可以提高我们对结构破坏响应的预测。

International Journal of Plasticity

Transformation Induced Plasticity in Ferritic Steels: New Experiments and Updated Modeling

Taleb Lakhdar, Duchaussoy Amandine, Jimenez Jose

doi:10.1016/j.ijplas.2023.103775

铁素体钢的相变诱发塑性:新的实验和更新的模型

In this work, we first experimentally investigated transformation-induced plasticity (TRIP) in the martensitic transformation of 36NiCrMo steel. The objective was to study some loading conditions encountered in industrial applications such as quenching and multi-pass welding. In addition to the classical case where the applied loading was maintained constant during the transformation, original TRIP experiments were performed with more complex applied loading: cyclic, multi-axial, proportional, nonproportional, applied during only a part of the transformation, high up to the yield stress of the austenitic phase. The test results showed a dissymmetry between the TRIP responses under tension and compression and reveal the existence of TRIP backstress. Finally, we have found an approximation of the maximum amount of TRIP which may be obtained for the transformation in the material under question (about 1.1% in our case). This result suggests that for a first approximation, the amount of final TRIP may be considered proportional to the norm of the applied stress as long as the latter does not exceed the yield stress. Some microstructural investigations have been performed in order to quantify the phase constituents and study the effect of the TRIP test conditions on the microstructure. The next step of the work was devoted to TRIP modeling where the model of Leblond (1989) and its extension by Taleb and Sidoroff (2003) have been considered. From the simulation of the classical TRIP tests described above, it was found that this model generally overestimates the TRIP strain and contrary to experiments, it predicts the same TRIP norm under tension and equivalent compression. Thus, maintaining the practicality of the original version and its ease of use, a new version of the model is proposed having the capabilities to describe the phenomena observed experimentally. Namely, the general overestimation of TRIP has been corrected by the introduction of the TRIP backstress effects, while the dissymmetry tension-compression was corrected through the introduction of a function of the first invariant applied stress tensor. The new version of the model shows excellent capabilities in simulating the experimental data base performed in this work. Nevertheless, further research considering other steels and other transformations is warranted.

在这项工作中，我们首先实验研究了36NiCrMo钢马氏体相变中的相变诱导塑性(TRIP)。目的是研究工业应用中遇到的一些加载条件，如淬火和多道次焊接。除了在转变过程中施加恒定载荷的经典情况外，原始TRIP实验还进行了更复杂的施加载荷:循环，多轴，比例，非比例，仅在转变的一部分施加载荷，高至奥氏体相的屈服应力。试验结果表明，拉伸和压缩作用下的TRIP响应不对称，表明TRIP背应力的存在。最后，我们已经找到了在所讨论的材料中可能获得的最大TRIP量的近似值(在我们的情况下约为1.1%)。这一结果表明，对于第一个近似，最终的TRIP量可以被认为与施加应力的规范成正比，只要后者不超过屈服应力。为了量化相组成和研究TRIP试验条件对微观组织的影响，进行了一些显微组织研究。下一步的工作是致力于TRIP建模，其中考虑了Leblond(1989)的模型及其Taleb和Sidoroff(2003)的扩展。通过对上述经典TRIP试验的模拟发现，该模型普遍高估了TRIP应变，与实验相反，它预测的是相同的拉伸和等效压缩下的TRIP范数。因此，在保持原始版本的实用性和易用性的基础上，提出了一个能够描述实验观察到的现象的新版本模型。即，通过引入TRIP背应力效应纠正了TRIP的一般高估，而通过引入第一个不变施加应力张量的函数纠正了不对称的张压。新版本的模型在模拟本工作的实验数据库方面表现出优异的能力。然而，进一步的研究考虑其他钢和其他转化是必要的。

Void nucleation at dislocation boundaries aided by the synergy of multiple dislocation pile-ups

Yang Ping, Zhao Pengyang

doi:10.1016/j.ijplas.2023.103779

在多个位错堆积的协同作用下，位错边界处的空洞成核

Void nucleation is of great significance in understanding ductile fracture. Recent experiments have shown that voids are nucleated via vacancy condensation and dislocation boundaries are the main nucleation sites. However, it is unclear what role is played exactly by dislocation boundaries in promoting void nucleation. Here we propose a new mechanism for dislocation boundary-induced void nucleation and develop a corresponding model based on the classical nucleation theory and vacancy diffusion theory. The model suggests that void nucleation is mainly influenced by hydrostatic stress, temperature, and relative vacancy concentration, whose contributions are systematically studied. It is also suggested that the vacancy formation energy and the interaction energy of hydrostatic stress and vacancy, which are absent in the previous models and introduced in ours, exhibit a clear tendency to lower the activation free energy barrier. Analysis of the nucleation kinetic suggests that the growth rate of void depends on the vacancy diffusion coefficient and vacancy concentration; the higher the values of these parameters, the faster the growth rate of the void. The kinetic feasibility of the newly proposed mechanism is examined using three-dimensional discrete dislocation dynamics simulations. The results predict that the size of incipient voids nucleated at the dislocation boundary is ∼35 nm, which is consistent with the experimental characterization value of ∼50 nm. Finally, when the relaxation of the dislocation boundary is considered, the synergistic effect is weakened.

空洞成核对认识韧性断裂具有重要意义。最近的实验表明，孔洞通过空位凝聚成核，位错边界是主要的成核位置。然而，目前还不清楚位错边界在促进空洞成核过程中究竟起着怎样的作用。本文在经典成核理论和空位扩散理论的基础上，提出了位错边界诱导空洞成核的新机制，并建立了相应的模型。该模型表明，孔隙成核主要受静水应力、温度和相对空位浓度的影响，并对其贡献进行了系统研究。此外，本文还引入了前人模型中所没有的空位形成能和静水应力与空位的相互作用能，它们具有明显的降低激活自由能垒的趋势。成核动力学分析表明，空穴的生长速率取决于空位扩散系数和空位浓度;这些参数的值越高，孔隙的生长速度越快。采用三维离散位错动力学模拟验证了新提出的机理的动力学可行性。结果预测，在位错边界处初始孔洞的成核尺寸为~ 35 nm，与实验表征值~ 50 nm一致。最后，当考虑位错边界松弛时，协同效应减弱。

Thin-Walled Structures

Thermal and mechanical damage to carbon fibre reinforced composites with metallic fasteners under lightning strike

Kuang Chengzhao, Zhou Yuchen, Zhu Huixin, Shi Qizhen, Fu Kunkun, Li Yan

doi:10.1016/j.tws.2023.111280

带有金属紧固件的碳纤维增强复合材料在雷击下的热损伤和机械损伤

In this study, lightning strike (LS) damage to carbon fibre reinforced composites (CFRCs) with metallic fasteners was investigated by simulated LS tests and finite element (FE) model. First, the LS damage mode and mechanism of a single-lap composite joint and a CFRC laminate with a metallic rivet were studied. Resin pyrolysis was found on the surface but severe delamination was evident inside the composites due to a gas explosion caused by the sudden burn-off of polymer matrices and thermal expansion inside the laminate. Then, the effect of rivet spacing on the LS damage to CFRCs was examined. The results showed that the damaged area was significantly reduced because the surrounding rivets effectively suppressed impact-induced delamination and consumed more electrical energy. The results also showed that large-area delamination across the rivets was achieved due to high potential at the surrounding rivets when the spacing was short but dynamic deflection was confined by the surrounding rivets. In contrast, delamination was only concentrated at the central rivet when the spacing was large, which can be ascribed to fewer currents flowing into the surrounding rivets, and the confinement of the adjacent rivets was less significant.

采用模拟雷击试验和有限元模型研究了金属紧固件碳纤维增强复合材料的雷击损伤。首先，研究了单搭接复合材料节点和金属铆钉CFRC层合板的LS损伤模式和机理。表面发现了树脂热解，但由于聚合物基体突然燃烧和层合板内部热膨胀引起的气体爆炸，复合材料内部明显存在严重的分层现象。然后，研究了铆钉间距对CFRCs的LS损伤的影响。结果表明，由于周围铆钉有效地抑制了冲击引起的分层，并且消耗了更多的电能，因此损伤面积显著减小。结果还表明，当铆钉间距较短但动态挠度受到周围铆钉的限制时，由于周围铆钉的高电位，铆钉之间会发生大面积的分层。相反，当间距较大时，分层只集中在中心铆钉上，这可以归因于流入周围铆钉的电流较少，相邻铆钉的限制不太明显。