今日更新：International Journal of Solids and Structures 4 篇，Journal of the Mechanics and Physics of Solids 2 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 6 篇International Journal of Solids and StructuresInstabilities and cavitation in cylindrical wavy line contact: A Maugis analysisJan Steven Van Dokkum, Francesc Pérez-Ràfols, Lucia Nicoladoi:10.1016/j.ijsolstr.2024.113008圆柱波线接触中的不稳定性和空化:毛吉分析The Maugis analysis is applied to adhesive contact between a cylinder with various wave profiles and a semi-infinite, elastic half-plane. We extend the analysis of Waters, Lee and Guduru, who consider the adhesive contact of a Hertzian indenter on a semi-infinite, elastic half-space with axi-symmetric, wave profiles. This work gives the closed-form contact mechanical solution for continuous, line contact without the need for any approximation. The resulting semi-analytical model serves to complement existing (numerical) models of adhesive line contact with the static load-area response as a reference. Herewith we analyse adhesion-induced loading-unloading hysteresis and contrast semi-analytical and numerical result to asses the limit of the former analysis. We confirm that roughness-induced dissipation vanishes with increasing wave roughness and decreasing Maugis parameter due to an increase in the range of adhesion and cavitation. Instability and cavitation are mutually exclusive at a given load-area locus yet occur successively in the same contact. An interesting result is that the Johnson parameter, that is known to govern the amplification of adhesion in the JKR-limit, bounds the load-area envelope irrespective of Maugis parameter. However, the Johnson parameter does not control the occurrence of roughness-induced dissipation and thus interface toughening.毛吉斯分析应用于具有不同波型的圆柱体与半无限弹性半平面之间的粘着接触。我们扩展了Waters, Lee和Guduru的分析，他们考虑了半无限弹性半空间中具有轴对称波剖面的赫兹压头的粘接接触。这项工作给出了连续直线接触的闭式接触力学解，而不需要任何近似。所得到的半解析模型补充了现有的黏着线接触(数值)模型，并作为静态载荷-区域响应的参考。在此基础上，我们分析了粘着引起的加载-卸载迟滞现象，并将半解析结果与数值结果进行了对比，以评估前者分析的局限性。我们证实，由于附着力和空化范围的增加，粗糙度引起的耗散随着波粗糙度的增加和毛吉斯参数的减小而消失。在给定的载荷区域轨迹上，失稳和空化是相互排斥的，但在同一接触中却依次发生。一个有趣的结果是，约翰逊参数，这是已知的，以控制在jkr限制粘附的放大，边界的载荷面积包线，不管毛吉参数。然而，Johnson参数并不能控制粗糙度引起的耗散和界面增韧的发生。On plasticity-enhanced interfacial toughness in bonded jointsE.D. Reedy, F.W. DelRio, B.D. Clarke, S.J. Grutzikdoi:10.1016/j.ijsolstr.2024.113011塑性增强粘结接头界面韧性的研究The performance and reliability of many structures and components depend on the integrity of interfaces between dissimilar materials. Interfacial toughness Γ is the key material parameter that characterizes resistance to interfacial crack growth, and Γ is known to depend on many factors including temperature. For example, previous work showed that the toughness of an epoxy/aluminum interface decreased 40 % as the test temperature was increased from −60 °C to room temperature (RT). Interfacial integrity at elevated temperatures is of considerable practical importance. Recent measurements show that instead of continuing to decrease with increasing temperature, Γ increases when test temperature is above RT. Cohesive zone finite element calculations of an adhesively bonded, asymmetric double cantilever beam specimen of the type used to measure Γ suggest that this increase in toughness may be a result of R-curve behavior generated by plasticity-enhanced toughening during stable subcritical crack growth with interfacial toughness defined as the critical steady-state limit value. In these calculations, which used an elastic-perfectly plastic epoxy model with a temperature-dependent yield strength, the plasticity-enhanced increase in Γ above its intrinsic value Γo depended on the ratio of interfacial strength σ* to the yield strength σyb of the bond material. There is a nonlinear relationship between Γ/Γo and σ*/σyb with the value Γ/Γo increasing rapidly above a threshold value of σ*/σyb. The predicted increase in toughness can be significant. For example, there is nearly a factor of two predicted increase in Γ/Γo during micrometer-scale crack-growth when σ*/σyb = 2 (a reasonable choice for σ*/σyb). Furthermore, contrary to other reported results, plasticity-enhanced toughening can occur prior to crack advance as the cohesive zone forms and the peak stress at the tip of the original crack tip translates to the tip of the fully formed cohesive zone. These results suggest that plasticity-enhanced toughening should be considered when modeling interfaces at elevated temperatures.许多结构和部件的性能和可靠性取决于不同材料之间界面的完整性。界面韧性Γ是表征界面裂纹扩展的关键材料参数，而Γ取决于包括温度在内的许多因素。例如，先前的研究表明，当测试温度从- 60 °C升高到室温(RT)时，环氧树脂/铝界面的韧性降低了40 %。高温下的界面完整性具有相当重要的实际意义。最近的测量表明，当测试温度高于rt时，Γ不是随着温度的升高而继续降低，而是增加。黏结区的有限元计算用于测量Γ的非对称双悬臂梁试件表明，韧性的增加可能是稳定亚临界裂纹扩展过程中塑性增强增韧所产生的r曲线行为的结果，界面韧性定义为临界稳态极限值。在这些计算中，使用具有温度依赖屈服强度的完美弹塑性环氧树脂模型，塑性增强的Γ高于其固有值Γo取决于粘结材料的界面强度σ与屈服强度σyb的比值。Γ/Γo与σ/σyb呈非线性关系，当达到σ*/σyb阈值后，Γ/Γo迅速增大。预测的韧性增加可能是显著的。例如，当σ*/σyb = 2 (σ*/σyb的合理选择)时，在微米级裂纹扩展过程中，Γ/Γo的预测增量接近2倍。此外，与其他报道的结果相反，塑性增强的增韧可以在裂纹推进之前发生，因为黏聚区形成，原始裂纹尖端的峰值应力转化为完全形成的黏聚区尖端。这些结果表明，在高温下模拟界面时应考虑塑性增强增韧。Enhanced energy absorption in high entropy alloys with octet lattice nanostructuresVan-Lam Nguyen, Minh-Quan Doan, Ha Thi Dang, Dang Thi Hong Hue, Tinh Quoc Bui, Kyoungdoc Kim, Van-Hai Dinh, Le Van Lichdoi:10.1016/j.ijsolstr.2024.113013八元晶格纳米结构高熵合金的能量吸收增强The work focuses on the numerical investigation of compressive mechanical behaviors and energy absorption properties of high entropy alloys (HEAs) with stochastic bicontinuous nanostructures (SBNs) and octet nanostructures (ONs). The study reveals a strong correlation between mechanical behaviors and the relative density of the nanostructures. The findings show that for both ONs and SBNs, the plateau stress increases with increasing the relative density, while an opposite trend is observed for densification strain. The maximum energy absorption capacity is achieved for ONs and SBNs at a relative density 0.6. Additionally, the energy absorption capacity of ONs is higher than that of SBNs across all relative densities, attributed to the higher plateau stress in ONs compared to SBNs. The distinction in mechanical characteristics is further explored by considering the dislocation evolution in ONs and SBNs. The study shows in SBNs that the dislocation increases rapidly, leading to a significant release of stored elastic energy and low plateau stress. Conversely, in ONs, the dislocation increases monotonically, allowing for a gradual release of stored elastic energy and maintenance of high plateau stress. Furthermore, the evolution of atomic configurations demonstrates that intrinsic and extrinsic stacking faults dominate planar defects in ONs, while several types of planar defects play a role in SBNs, including intrinsic stacking fault, extrinsic stacking fault, twin boundary, and hexagonal close-packed laths. The study also shows the effect of temperature on the energy absorption capacity.研究了具有随机双连续纳米结构(sbn)和八元纳米结构(ONs)的高熵合金(HEAs)的压缩力学行为和能量吸收性能。该研究揭示了纳米结构的力学行为与相对密度之间有很强的相关性。结果表明:无论是on还是sbn，高原应力都随相对密度的增加而增加，而致密化应变则相反。在相对密度为0.6时，纳米粒子和纳米粒子的能量吸收能力最大。此外，在所有相对密度下，网状结构的能量吸收能力都高于网状结构，这是由于网状结构的高原应力高于网状结构。通过考虑氮化硅和氮化硅的位错演化，进一步探讨了两者力学特性的区别。研究表明，在sbn中，位错迅速增加，导致储存的弹性能显著释放，平台应力较低。相反，在氮化镓中，位错单调增加，允许储存的弹性能逐渐释放并保持高平台应力。此外，原子构型的演化表明，内禀和外源性层错主导了氮化硼的平面缺陷，而在sbn中起作用的平面缺陷有几种类型，包括内禀层错、外源性层错、孪晶界和六边形密排板条。研究还表明了温度对能量吸收能力的影响。Prediction of long-term creep modulus of thermoplastics using brief tests and interpretable machine learningHéctor Lobato, Carlos Cernuda, Kepa Zulueta, Aitor Arriaga, Jon M. Matxain, Aizeti Burgoadoi:10.1016/j.ijsolstr.2024.113014 预测热塑性塑料的长期蠕变模量使用简短的测试和可解释的机器学习The prediction of creep behavior plays a critical role in the design of thermoplastic materials intended for prolonged use. The creep modulus, which describes the relationship between stress and strain that a material experiences over time, is a key property to determine the long-term thermo-mechanical performance of thermoplastics. Due to the time-consuming and resource-intensive nature of testing for this property, the present work investigates the potential of data-driven techniques as an alternative approach. To accomplish this, a dataset comprising more than 400 distinct thermoplastic grades was obtained from CAMPUS® online open database. Then, various interpretable machine learning models (linear regression, decision trees, random forests, XGBoost, and LightGBM) were evaluated to predict the long-term creep modulus with data from brief tests. To accurately assess the models’ ability to generalize to new data, rigorous model evaluation techniques such as cross-validation and group-splitting were employed, showing that various algorithms can predict the creep modulus with R2 scores above 0.99. Interestingly, linear regression not only matches but, in some cases, also surpasses the performance of more complex models, while being the most simple and interpretable. The present work demonstrates that machine learning can bypass the most lengthy creep tests; reducing costs, energy consumption, material waste, and product development time.蠕变行为的预测在设计用于长期使用的热塑性材料时起着至关重要的作用。蠕变模量描述了材料随时间变化而产生的应力和应变之间的关系，是确定热塑性塑料长期热机械性能的关键属性。由于测试这一性能需要耗费大量时间和资源，因此本研究将数据驱动技术作为一种替代方法进行研究。为此，我们从 CAMPUS® 在线开放数据库中获取了由 400 多个不同热塑性塑料牌号组成的数据集。然后，对各种可解释的机器学习模型（线性回归、决策树、随机森林、XGBoost 和 LightGBM）进行了评估，以利用简短测试的数据预测长期蠕变模量。为了准确评估模型对新数据的泛化能力，我们采用了交叉验证和分组拆分等严格的模型评估技术，结果表明，各种算法都能预测蠕变模量，R2 分数都在 0.99 以上。有趣的是，线性回归不仅能与更复杂的模型相媲美，在某些情况下还能超越它们，同时它也是最简单、最易解释的模型。目前的工作表明，机器学习可以绕过最漫长的蠕变试验，降低成本、减少能耗、减少材料浪费、缩短产品开发时间。Journal of the Mechanics and Physics of SolidsExploiting interfacial instability during peeling a flexible plate from elastic filmsJinghao Shen, Zhengxing He, Huan Chen, Yuehua Yang, Hongyuan Jiangdoi:10.1016/j.jmps.2024.105821从弹性薄膜中剥离柔性板时利用界面不稳定性Adhesive interactions between soft materials are prevalent in both biological systems and various engineering applications, including soft robots, flexible electronics, and antifouling coatings. Many studies have demonstrated that cavitation and fingering instabilities emerge at the adhesive interface between rigid objects and soft films, owing to the geometric attributes of the contact region. However, in the context of peeling configurations, defining the geometric features is challenging, resulting in relatively scant exploration of interfacial instabilities. Hence, the modulation of instability patterns during the peeling process of a flexible plate from a thin elastic film, alongside the consequential effects on mechanical responses, remains poorly understood. To elucidate the mechanisms underlying interfacial instability during peeling process and its impacts on peel-off force, we use finite element methods to simulate the evolution of interface separation. Consistent with previous experimental observations, we find that the interfacial instability will occur when the bending stiffness of the flexible plate is bigger than a critical value. We show that the interfacial instability is mainly induced by the competition between the adhesion energy and the strain energy of the film, and the incompressibility of the thin film is critical for the appearance of the interfacial instability. Combining theory and finite element simulation, we propose the scaling laws for the critical peel-off force for stable and unstable peelings, respectively, and show that the critical peel-off force will decrease when the interfacial instability occurs. Finally, we demonstrate that weakening the tangential adhesion strength and loosening the constraints between the film and the rigid substrate effectively suppress fingering instability. Collectively, our findings elucidate the pivotal factors influencing interfacial instability, offering invaluable insights for the design of structures or systems involving soft materials.软材料之间的粘合相互作用在生物系统和各种工程应用中都很普遍，包括软机器人、柔性电子产品和防污涂料。许多研究表明，由于接触区域的几何属性，在刚性物体与软膜之间的粘附界面会出现空化和指入不稳定性。然而，在剥离结构的背景下，定义几何特征是具有挑战性的，导致对界面不稳定性的探索相对较少。因此，在柔性板从薄弹性膜剥离过程中不稳定模式的调制，以及对机械响应的相应影响，仍然知之甚少。为了阐明剥离过程中界面失稳的机理及其对剥离力的影响，采用有限元方法模拟了剥离过程的演化过程。与以往的实验观察结果一致，我们发现当柔性板的弯曲刚度大于某一临界值时，会发生界面失稳。研究表明，界面不稳定性主要是由薄膜的粘附能和应变能之间的竞争引起的，而薄膜的不可压缩性是界面不稳定性出现的关键。结合理论和有限元模拟，分别给出了稳定剥离和不稳定剥离临界剥离力的标度规律，并表明界面不稳定时临界剥离力减小。最后，我们证明了削弱切向粘附强度和放松薄膜与刚性衬底之间的约束可以有效地抑制指指不稳定性。总的来说，我们的发现阐明了影响界面不稳定性的关键因素，为涉及软材料的结构或系统的设计提供了宝贵的见解。Second-order Willis metamaterials: Gradient elasto-momentum coupling in flexoelectric compositesHai D. Huynh, S.S. Nanthakumar, Xiaoying Zhuangdoi:10.1016/j.jmps.2024.105820二阶Willis超材料:弹性电复合材料中的梯度弹性动量耦合Willis materials are composites whose the overall constitutive relations exhibit coupling between momentum and strain. Recently, Willis materials that are piezoelectric are studied that allow the macroscopic momentum to be additionally coupled to non-mechanical stimulus. Such metamaterials classified as first-order Willis materials generate cross-couplings due to their asymmetric microstructures in order to realize novel phenomena in wave propagation. In this work, we study Willis materials that are flexoelectric, offer electric field induced by strain gradient. We show that in the case of flexoelectric Willis materials, the momentum also gets coupled to the strain gradient term under an effective description. Hereby, an ensemble averaging-based dynamic homogenization theory is developed for flexoelectric composites to compute constitutive relations of the macroscopic fields. This second-order Willis metamaterial offers a novel coupling termed as gradient elasto-momentum coupling. The presence of non-uniform strain that can break inversion symmetry of a unit cell is thus significant to generate the imaginary portion of all cross-couplings in the absence of asymmetric microstructures.威利斯材料是一种整体本构关系表现为动量和应变耦合的复合材料。最近，研究人员研究了一种压电材料，这种材料允许宏观动量与非机械刺 激额外耦合。这类一阶威利斯材料由于其不对称的微观结构而产生交叉耦合，从而实现波传播中的新现象。在这项工作中，我们研究了柔性电Willis材料，提供由应变梯度引起的电场。我们表明，在柔性电Willis材料的情况下，动量也在有效描述下耦合到应变梯度项。在此基础上，建立了基于系综平均的柔性电复合材料动态均匀化理论，用于计算宏观场的本构关系。这种二阶威利斯超材料提供了一种称为梯度弹性动量耦合的新型耦合。因此，在没有不对称微结构的情况下，非均匀应变的存在可以打破单位细胞的反转对称性，这对于产生所有交叉耦合的虚部是重要的。International Journal of PlasticityCreep-fatigue damage level evaluation based on the relationship between microstructural evolution and mechanical property degradationLi Sun, Xian-Cheng Zhang, Kai-Shang Li, Ji Wang, Shun Tokita, Yutaka S. Sato, Shan-Tung Tu, Run-Zi Wangdoi:10.1016/j.ijplas.2024.104086基于微观组织演化与力学性能退化关系的蠕变疲劳损伤等级评定Creep-fatigue interaction is identified as a primary failure mode for components operating under high temperatures. As operational durations extend, this interaction not only alters the material's microstructures but also initiates a gradual degradation in mechanical properties, significantly impacting its deformation and damage behaviors. In this work, the dynamic microstructural evolution of GH4169 superalloy during creep-fatigue was elucidated via qualitative characterization, and damage level evaluation method was subsequently developed by bridging microstructure degradation to mechanical property degradation. Creep-fatigue tests were performed at 650°C with various tensile holding times and were interrupted at lifetime fractions of 10%, 50% and 80% for further analysis and tensile evaluations. Results revealed that the prolonged exposure to holding times induced the coarsening of γ ″ precipitates alongside an increase in low-angle grain boundaries, culminating a reduction in creep-fatigue strength. The development of voids and cracks exacerbated the degradation of elongation, leading to a hybrid fracture mode encompassing both intergranular and transgranular cracking paths. Synthesizing microstructural evolutions to qualitatively categorize diverse degradation levels imparted a robust physical basis for damage evaluation. A mapping model was established to correlate the average kernel average misorientation (micro-degradation indicator) with the tensile plastic strain energy density (macro-degradation indicator). The damage level evaluation method was endowed with quantitative metrics utilizing this model, and its generality was additionally validated in P92 steel. This work offers an insight into the quantitative damage evaluations of creep-fatigue-induced degradations in materials, thereby providing a theoretical basis for the development of operation management and inspection plans of components.蠕变-疲劳相互作用被认为是构件在高温下工作的主要失效模式。随着使用时间的延长，这种相互作用不仅会改变材料的微观结构，还会引发机械性能的逐渐退化，显著影响其变形和损伤行为。本研究通过定性表征阐明了GH4169高温合金蠕变疲劳过程中微观组织的动态演变，并建立了连接微观组织退化与力学性能退化的损伤等级评价方法。蠕变疲劳试验在650°C下进行，拉伸保持时间不同，并在寿命分数为10%、50%和80%时中断，以进一步分析和拉伸评估。结果表明，长时间保温导致γ″相粗化，同时低角晶界增加，最终导致蠕变疲劳强度降低。孔洞和裂纹的发展加剧了延伸率的退化，导致沿晶和穿晶断裂路径的混合断裂模式。综合微观结构演变对不同退化程度进行定性分类，为损伤评估提供了坚实的物理基础。建立了平均核平均取向偏差(微观退化指标)与拉伸塑性应变能密度(宏观退化指标)之间的映射模型。利用该模型赋予了损伤等级评价方法定量指标，并在P92钢中进一步验证了其通用性。本研究为材料蠕变疲劳退化的定量损伤评估提供了深入的见解，从而为部件的运行管理和检查计划的制定提供了理论依据。Thin-Walled StructuresAnalytical solutions for forced vibration and dispersion property of periodic multilayer elastically connected plate structuresBin Li, Shuantao Li, Xin Yao, Yongbin Madoi:10.1016/j.tws.2024.112321周期性多层弹性连接板结构强迫振动和频散特性的解析解An analytical approach is developed based on the wave propagation theory for the forced vibration and dispersion analysis of a system of periodic multilayer elastically connected plates. On the one hand, the proposed approach makes up for the traditional analytical methods that cannot consider the mass of the connection junction between two adjacent plates, on the other hand, it fills the gap in the analytical method for the vibration and dispersion analysis of periodic multilayer elastically connected plate structures. First, the coupled vibration equations of the multilayer plates considering the mass of the connection junction are established and decoupled; and a general vibration state is introduced and transferred into the dual system. Next, the general vibration state is described in terms of analytical waves. By considering the periodic condition and compatibility condition on the discontinuous boundaries of the unit cell, an eigenvalue equation for dispersion analysis is formed. Finally, by using the boundary conditions and wave scattering relationships, the forced responses of the periodic multilayer elastically connected plate system are analytically calculated. In the numerical examples, the forced vibration and dispersion properties of a double-plate system are investigated. The effectiveness of the proposed method is validated by comparing the present results with the finite element method (FEM) results. The accuracy of the FEM model is verified by experimental tests on a specimen prepared by additive manufacturing. The numerical results show that the mass of the connection junction cannot be ignored when performing the vibration analysis of a multilayer plate system. In addition, the periodic multilayer plate structure has rich dispersion characteristics and is a good candidate for band gap design.提出了一种基于波传播理论的周期性多层弹性连接板系统强迫振动和频散分析方法。该方法一方面弥补了传统分析方法无法考虑相邻两板连接接点质量的不足，另一方面填补了周期性多层弹性连接板结构振动与频散分析分析方法的空白。首先，建立了考虑连接结点质量的多层板耦合振动方程并解耦;并将一般振动状态引入到双系统中。其次，用解析波来描述一般振动状态。通过考虑单元胞不连续边界上的周期条件和相容条件，建立了色散分析的特征值方程。最后，利用边界条件和波散射关系，对周期性多层弹性连接板系统的强迫响应进行了解析计算。通过数值算例，研究了双板系统的强迫振动和频散特性。通过与有限元计算结果的比较，验证了所提方法的有效性。通过增材制造试样的试验验证了有限元模型的准确性。数值计算结果表明，在对多层板结构进行振动分析时，连接处的质量是不能忽略的。此外，周期性多层板结构具有丰富的色散特性，是带隙设计的良好候选者。Study on in situ laser shock modulation of molten pool and defects in wire-feed laser additive manufacturing of steel to aluminum alloyYi He, Heng Lu, Xiaohan Zhang, Shuoheng Xu, Hui Li, Yaowu Hudoi:10.1016/j.tws.2024.112326 钢-铝合金激光增材加工熔池的原位激光冲击调制及缺陷研究A method was proposed to address the porosity defects and intermetallic compound production during laser additive manufacturing in dissimilar metals by employing in situ laser shock modulation of molten pool in a hybrid additive manufacturing process. Using wire-feed laser additive manufacturing directed energy deposition technology, single-layer and multi-layer thin-walled samples were prepared. The modulation of molten pool and porosity defects in single-layer molten tracks was analyzed under different pulsed laser shock energies. The mechanism of in situ laser shock modulation of molten pool was investigated through experiment and numerical simulations. The findings indicate that the shock force is the main factor causing oscillating convection in the molten pool, thereby accelerating Marangoni convection, bubble overflow, and pore closure. A pulsed laser shock energy of 2 J resulted in the optimal interface between the aluminum alloy and stainless steel. This interface exhibited a desirable molten track feature size, achieved a maximum densification of 99.73% and an ultimate tensile strength of 140.25 MPa. Furthermore, in situ laser shock modulation of molten pool has the potential to reduce porosity defects and enhance microhardness, the number of porosity defects decreased by approximately 53.51% and the total volume of porosity defects decreased by approximately 50.09%, and microhardness approximately enhanced by 7.86% at 2 J. Consequently, this method is anticipated to be implemented in the joining of critical thin-walled components to reduce defects and enhance tensile performance.针对异种金属激光增材制造过程中存在的气孔缺陷和金属间化合物产生问题，提出了一种采用原位激光冲击调制混合增材制造工艺的方法。采用线馈激光增材制造定向能沉积技术制备单层和多层薄壁样品。分析了不同脉冲激光冲击能量对熔池和单层熔道气孔缺陷的调制作用。通过实验和数值模拟研究了熔池激光原位冲击调制的机理。研究结果表明，激波力是引起熔池内振荡对流的主要因素，从而加速了Marangoni对流、气泡溢出和孔隙闭合。当脉冲激光冲击能量为2j时，铝合金与不锈钢的界面最优。该界面具有理想的熔融轨迹特征尺寸，最大密度达到99.73%，抗拉强度达到140.25 MPa。此外，原位激光冲击调制熔池具有减少气孔缺陷和提高显微硬度的潜力，在2 j时气孔缺陷数量减少约53.51%，气孔缺陷总量减少约50.09%，显微硬度提高约7.86%，因此，该方法有望应用于关键薄壁部件的连接，以减少缺陷和提高拉伸性能。Thermo-mechanical-chemo-seepage coupling analysis on cure simulation of composite laminates with damagesD.H. Li, Z.J. Zhu, J.M. Yang, A.S. Wandoi:10.1016/j.tws.2024.112327含损伤复合材料层合板固化模拟的热-力学-化学-渗流耦合分析The numerical thermo-chemical–mechanical-seepage (TCMS) analysis is carried out for the autoclave curing process of thermosetting composite laminates with interface damages. A TCMS extended layerwise (TCMS-XLW) method is developed for solving this dynamic multi-physical problem. In this paper, the TCMS variational principle in weak forms is presented. The multi-physical Euler equations and boundary conditions are derived from the this principle; the multiple delaminations are simulated by the strong discontinuous function along the thickness direction. The governing formulations of dynamic responses, including displacement, cure-induced temperature, degree of cure and pore pressure, are obtained by using the finite element method. A fully coupled time integration method is developed to calculate the aforementioned dynamic multi-physical responses simultaneously. The corresponding computing program is complied with C++. In the numerical examples, the proposed TCMS-XLW method is applied to the carbon-firber/epoxy resin laminate under a typical curing cycle, considering the delamination. The dynamic responses of the TCMS-XLW model are in good agreement with those of a 3D elastic model developed by the commercial finite element software.对具有界面损伤的热固性复合材料层合板的热压釜固化过程进行了数值热化学-力学-渗流分析。针对这一动态多物理问题，提出了一种TCMS扩展分层(TCMS- xlw)方法。本文给出了弱形式下的TCMS变分原理。根据这一原理导出了多物理欧拉方程和边界条件;利用沿厚度方向的强不连续函数模拟了多层分层。利用有限元方法得到了包括位移、固化温度、固化度和孔隙压力在内的动力响应的控制表达式。提出了一种完全耦合的时间积分方法来同时计算上述动态多物理响应。相应的计算程序用c++编写。在数值算例中，将提出的TCMS-XLW方法应用于典型固化周期下考虑分层的碳纤维/环氧树脂层合板。TCMS-XLW模型的动态响应与商用有限元软件开发的三维弹性模型的动态响应吻合较好。Electrically controllable and reversible coupling degree in a phononic crystal with double piezoelectric defectsSoo-Ho Jodoi:10.1016/j.tws.2024.112328双压电缺陷声子晶体的可控可逆耦合度Research in the field of phononic crystals (PnCs) has traditionally focused on single defects for energy localization and frequency-selective filtering. Recent attention has turned to exploring double defects to expand frequency options. Advancements in this area have introduced differently patterned double defects, which can be either coupled or decoupled. Yet, the conventional mechanical approach locks in double defect characteristics early in the design process. To overcome this limitation, this study proposes a novel electrical control method to adjust the coupling degree between double defects for the first time. By attaching bimorph piezoelectric elements with respective inductive circuits to defects, this work offers a flexible means of manipulating their interaction, allowing them to interactively behave as double defects or independently function as single defects, depending on the user's purpose, even after mechanical design finalization. Through analytical and numerical models, the proposed approach is comprehensively validated, demonstrating its effectiveness in two scenarios of double defects with identical and different structural configurations. Two main contributions of this work are as follows. First, this is the first attempt to achieve electrically controllable and reversible coupling degrees of double defects. Second, the developed analytical model enables the rapid prediction of tunable defect-band frequencies, thereby reducing computational time. We believe this research opens new avenues for dynamically controlling defective PnC behaviors, promising advancements in applications like structural health monitoring, prognostics health and management, and medical imaging.传统上，声子晶体的研究主要集中在单缺陷的能量定位和频率选择滤波上。最近的注意力转向探索双缺陷以扩大频率选择。该领域的进步引入了不同模式的双缺陷，它们可以耦合或解耦。然而，传统的机械方法在设计过程的早期就锁定了双重缺陷特征。为了克服这一局限性，本研究首次提出了一种新的电气控制方法来调节双缺陷之间的耦合度。通过将具有各自感应电路的双晶片压电元件连接到缺陷上，这项工作提供了一种灵活的方法来操纵它们的相互作用，允许它们作为双缺陷交互地表现或独立地作为单缺陷运行，这取决于用户的目的，甚至在机械设计完成之后。通过分析模型和数值模型对该方法进行了全面验证，验证了该方法在结构构型相同和不同双缺陷两种情况下的有效性。这项工作的两个主要贡献如下。首先，这是首次尝试实现电气可控和可逆耦合程度的双缺陷。其次，所开发的分析模型能够快速预测可调缺陷频带的频率，从而减少计算时间。我们相信这项研究为动态控制有缺陷的PnC行为开辟了新的途径，有望在结构健康监测、健康预测和管理以及医学成像等应用中取得进展。Modelling of pallet rack connections by means of a geometrically nonlinear analysis based on the Generalized Beam theoryJ. Bonada, I. López, O. Bové, M. Casafontdoi:10.1016/j.tws.2024.112329基于广义梁理论的托盘架连接几何非线性分析建模This paper presents a formulation to reproduce the main connections of pallet rack structures by means of a Generalized Beam Theory analysis. Different approaches to modelling the upright-to-brace and upright-to-beam connections are presented and compared. Additional constraint equations which couple beam-node displacements, cross-sectional nodal displacements or modal and cross-sectional nodal springs are added into the FE model to include these joints in the numerical analysis. Moreover, the upright-to-floor connection is modelled through an advanced rotational spring, which considers the influence of the upright axial load to determine its characteristics. Finally, the GBT numerical results are successfully compared with experimental tests.本文利用广义梁理论的分析方法，提出了一种再现托盘架结构主要连接的公式。提出并比较了不同的方法来建模直立-支撑和直立-梁连接。在有限元模型中加入梁节点位移、截面节点位移或模态与截面节点弹簧耦合的附加约束方程，将这些节点纳入数值分析。此外，通过一个先进的旋转弹簧来模拟垂直与楼板的连接，考虑了垂直轴向载荷的影响来确定其特性。最后，将GBT数值计算结果与实验结果进行了比较。Remaining useful life prediction of pipelines considering the crack coupling effect using genetic algorithm-back propagation neural networkMingjiang Xie, Ziqi Wei, Jianli Zhao, Yifei Wang, Xihui Liang, Xianjun Peidoi:10.1016/j.tws.2024.112330 基于遗传算法-反向传播神经网络的管道剩余使用寿命预测The propagation of fatigue cracks can be influenced by the crack coupling effect. Previous studies qualitatively focused on observing simulation data to determine the influence patterns of crack parameters on stress intensity factors (SIFs). In this study, investigating the crack coupling effect innovatively, the simulation data is integrated into a neural network and SIFs are predicted over time, enabling the remaining useful life of pipelines with coupling effect can be predicted systematically. Specifically, by establishing a finite element model with coupling cracks, the comprehensive effects of crack depth, as well as relative position and growth angle based on cylindrical coordinates, on the crack coupling effect were investigated. After obtaining the simulation data, a genetic algorithm-back propagation (GA-BP) neural network is constructed to predict the SIFs. Finally, by integrating the SIF prediction model with Paris' law, a method for predicting cracks growth and pipeline remaining useful life (RUL) considering the coupling effect of coupling cracks in complex relative positions was proposed. To ensure the accuracy of the predictions, the differences between the predictive results of this study and API 579 in predicting the SIF of coupling cracks were compared. The proposed method quantitatively predicts the cracks coupling effect and improves the system of the RUL prediction under the comprehensive influence of multiple cracks, thus to predict pipeline health more realistically and lay the foundation for maintenance.裂纹耦合效应会影响疲劳裂纹的扩展。以往的研究定性地集中于观察模拟数据，以确定裂纹参数对应力强度因子(SIFs)的影响规律。本研究创新性地研究了裂纹耦合效应，将模拟数据集成到神经网络中，并对随时间变化的SIFs进行预测，从而能够系统地预测具有耦合效应的管道的剩余使用寿命。具体而言，通过建立耦合裂纹的有限元模型，研究了裂纹深度以及基于柱坐标的相对位置和扩展角对裂纹耦合效应的综合影响。在获得仿真数据后，构建遗传算法-反向传播(GA-BP)神经网络对SIFs进行预测。最后，将SIF预测模型与Paris定律相结合，提出了一种考虑耦合裂纹在复杂相对位置耦合效应的裂纹扩展和管道剩余使用寿命(RUL)预测方法。为了保证预测的准确性，比较了本研究的预测结果与API 579在预测耦合裂纹SIF方面的差异。该方法定量预测了裂缝耦合效应，完善了多裂缝综合影响下的RUL预测系统，从而更真实地预测管道健康状况，为管道维修奠定基础。来源：复合材料力学仿真Composites FEM
