【新文速递】2023年10月3日复合材料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 1 篇，Mechanics of Materials 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 1 篇International Journal of Solids and StructuresOn the generalized plane strain assumption for pressurized membranesThbaut M., Brisard S.doi:10.1016/j.ijsolstr.2023.112506关于加压膜的广义平面应变假设We revisit the problem of translation-invariant pressurized membranes that are squeezed without friction between several planes, all parallel to the axis of translation-invariance (such problem involves material and geometric nonlinearities, including contact). Quite remarkably, it was shown by De Simone and Luongo (2013) that such problems simplify considerably under the plane strain assumption. Indeed, the complex initial boundary-value problem reduces to a simple set of non-linear, algebraic equations. We argue that in many practical cases, the plane strain assumption does not hold. Instead, we introduce the generalized plane strain assumption, that is necessary to account for the longitudinal equilibrium of the membrane. We show how the equations of De Simone and Luongo (2013) are modified, while remaining extremely simple. We thus define an extended class of problems that become (nearly) tractable analytically.我们重新探讨了平移不变的受压膜问题，这些膜在多个平面之间受到挤压而没有摩擦，所有平面都平行于平移不变轴（此类问题涉及材料和几何非线性，包括接触）。值得注意的是，De Simone 和 Luongo（2013 年）的研究表明，在平面应变假设下，此类问题大大简化。事实上，复杂的初始边界值问题简化为一组简单的非线性代数方程。我们认为，在许多实际情况下，平面应变假设并不成立。相反，我们引入了广义平面应变假设，这对于解释膜的纵向平衡是必要的。我们展示了 De Simone 和 Luongo（2013 年）的方程是如何被修改的，同时仍然非常简单。因此，我们定义了一类扩展问题，这些问题变得（几乎）可以通过分析解决。Journal of the Mechanics and Physics of SolidsMechanics, modeling, and shape optimization of electrostatic zipper actuatorsAkerson Andrew, Liu Tianshudoi:10.1016/j.jmps.2023.105446静电拉链致动器的力学、建模和形状优化Generating actuation for haptic feedback is a major challenge for wearable devices and soft robotics. Current methods such as piezoelectric, pneumatic, or responsive material actuators are limited by the response time, power consumption, and their reliance on external mechanisms such as pumps or large voltage amplifiers. The emerging technology of electrostatic zipper actuators, where a dielectric-filled pouch is sandwiched between flexible conducting electrodes, is a promising alternative. However, the voltage required to actuate such systems remains in the relatively large kilovolt range. Additionally, there do not currently exist efficient modeling methods to explore more effective designs. Our work looks to address both of these issues. We start by discussing the mechanics of the zipping phenomenon which leads to actuation. Then, we formulate a novel mechanics model for these systems. By considering an elastic plate coupled with the electrostatic interactions, we develop an efficient and robust numerical method to simulate the actuation process. We then verify the model by demonstrating excellent agreement to analytical predictions for simplified cases. As the complex physics of such systems create challenges for intuitive design, we turn to optimal design methods. We formulate the shape optimization problem through the method of mappings to design actuators for maximum actuation pressure and work of actuation. Our method navigates the trade-offs between zipping susceptibility and volume displacement, and we explore optimal designs for various geometric and loading scenarios. Finally, we discuss further directions and open problems relevant to the industrial deployment of zipper actuators moving forward.产生触觉反馈的致动器是可穿戴设备和软机器人技术面临的一大挑战。压电、气动或响应材料致动器等现有方法受限于响应时间、功耗以及对泵或大型电压放大器等外部机制的依赖。新兴的静电拉链致动器技术是一种很有前途的替代方法，这种致动器将充满电介质的小袋夹在柔性导电电极之间。然而，驱动此类系统所需的电压仍然在相对较大的千伏范围内。此外，目前还没有有效的建模方法来探索更有效的设计。我们的工作旨在解决这两个问题。我们首先讨论了导致驱动的拉链现象的力学原理。然后，我们为这些系统制定了一个新颖的力学模型。通过考虑弹性板与静电相互作用的耦合，我们开发了一种高效、稳健的数值方法来模拟致动过程。然后，我们验证了该模型，证明它与简化情况下的分析预测非常吻合。由于此类系统的物理结构复杂，给直观设计带来了挑战，因此我们转向优化设计方法。我们通过映射法来制定形状优化问题，从而设计出最大致动压力和致动功的致动器。我们的方法可以在拉链敏感性和体积位移之间进行权衡，并探索各种几何和负载情况下的最佳设计。最后，我们讨论了与拉链致动器的工业应用相关的进一步方向和未解决问题。Mechanics of MaterialsComposition, heat treatment, microstructure and loading condition based machine learning prediction of creep life of superalloysWu Ronghai, Zeng Lei, Fan Jiangkun, Peng Zichao, Zhao Yunsongdoi:10.1016/j.mechmat.2023.104819基于成分、热处理、微观结构和加载条件的超合金蠕变寿命机器学习预测Creep life is a key property of superalloys that are typically used in advanced engine turbine. The creep life of superalloys is mainly determined by factors including compositions, heat treatment processes, microstructures and loading conditions. Nevertheless, it still remains a big challenge to link these factors and creep life, due to massive variables and complex relations regarding the factors affecting creep life. In the present work, we solve this issue by a machine learning method. The dimension of the factors affecting creep life is reduced by principle component analysis, followed by clustering of the principle components. Then a proper regression method is chose for each cluster such that an optimal model is formed for each cluster. The results show that the predicted creep lives agree with experimental creep lives well. New combinations of composition, heat treatment, microstructure and loading condition with better creep lives are proposed for the development of superalloys. Additionally, the present machine learning method is compared with existing machine learning methods for creep of superalloys. The comparison shows that the accuracy and intelligence of the present machine learning method are both considerably improved. Hence, the present method is useful for effective development of superalloys.蠕变寿命是通常用于先进发动机涡轮的超级合金的一项关键性能。超合金的蠕变寿命主要由成分、热处理工艺、微观结构和加载条件等因素决定。然而，由于影响蠕变寿命的因素存在大量变量和复杂关系，如何将这些因素与蠕变寿命联系起来仍然是一个巨大的挑战。在本研究中，我们通过机器学习方法解决了这一问题。首先通过原理成分分析降低蠕变寿命影响因素的维度，然后对原理成分进行聚类。然后为每个聚类选择适当的回归方法，从而为每个聚类建立一个最佳模型。结果表明，预测的蠕变寿命与实验蠕变寿命非常吻合。为超合金的开发提出了具有更好蠕变寿命的成分、热处理、微观结构和加载条件的新组合。此外，本机器学习方法还与现有的超合金蠕变机器学习方法进行了比较。比较结果表明，本机器学习方法的准确性和智能性都有显著提高。因此，本方法有助于超合金的有效开发。International Journal of PlasticityNegative Stacking Fault Energy in FCC materials-Its ImplicationsYou D., Celebi O., Mohammed ASK., Sehitoglu H.doi:10.1016/j.ijplas.2023.103770催化裂化材料中的负堆积断层能及其影响Recent atomistic simulations on medium entropy alloys uncovered the possibility of negative intrinsic stacking fault energies (SFEs), which suggest infinite stacking fault widths (SFWs). However, experimental measurements of SFWs in the same alloys have shown that SFWs are finite, which contradicts the classical derivations based on force balance. To address this contradiction, we develop an advanced treatment employing atomistic lattice and continuum theories that produce finite SFW solutions corresponding to negative SFEs. The idea is based on energy minimization, where the finite SFW corresponds to the first local minimum in the energy landscape. By exploring combinations of intrinsic and unstable fault energies, we identify regimes in which solutions for finite SFWs exist for thousands of hypothetical materials. Elastic moduli and lattice constants also impact the results, with lower moduli and smaller lattice constants expanding the negative stacking fault energy domain corresponding to finite SFWs. Additionally, the study has revealed a distribution of SFEs due to possible chemical heterogeneities within the alloy, resulting in variations in SFWs within the same material. The work underscores the capabilities of the theory for SFW and CRSS (Critical Resolved Shear Stress) determination for medium to high entropy alloys in agreement with experiments.最近对中等熵合金进行的原子模拟发现了负本征堆积断层能（SFE）的可能性，这表明堆积断层宽度（SFW）是无限的。然而，相同合金中 SFW 的实验测量结果表明，SFW 是有限的，这与基于力平衡的经典推导相矛盾。为了解决这一矛盾，我们开发了一种先进的处理方法，采用原子晶格和连续体理论，产生与负 SFE 相对应的有限 SFW 解决方案。这一想法基于能量最小化，其中有限 SFW 相当于能量景观中的第一个局部最小值。通过探索本征能量和不稳定断层能量的组合，我们确定了数千种假定材料存在有限 SFW 解的情况。弹性模量和晶格常数也会影响研究结果，较低的弹性模量和较小的晶格常数会扩大与有限 SFW 相对应的负堆积断层能量域。此外，研究还揭示了由于合金内部可能存在的化学异质性而造成的 SFE 分布，从而导致同一种材料中 SFW 的变化。这项研究强调了该理论在确定中高熵合金的 SFW 和 CRSS（临界分辨剪切应力）方面的能力，与实验结果一致。Thin-Walled StructuresThermal vibration analysis of cracked nanobeams submerged in elastic foundations by nonlocal continuum mechanicsTaima Moustafa S., El-Sayed Tamer A., Friswell Michael I.doi:10.1016/j.tws.2023.111249利用非局部连续介质力学对浸没在弹性地基中的开裂纳米梁进行热振动分析Understanding the mechanical behavior of nanoscale structures is crucial in the development of advanced nanotechnologies. In this study, a novel approach to investigate the thermal lateral vibration of cracked nanobeams immersed in an elastic matrix is investigated. For this purpose, Reddy’s third-order shear deformation theory (TSDT) is considered. In contrast to Timoshenko beam theory (First-order Shear Deformation Theory, FSDT), TSDT does not depend on a shear correction coefficient. The nano-scale effect is modeled using Eringen’s nonlocal continuum mechanics theory. The nonlocal form of the governing equation is obtained through the application of Hamilton’s principle. The weak form of the finite element global mass and stiffness matrices are obtained using Lagrange linear and Hermitian cubic interpolation. To model the crack in bending vibration, two rotational springs are used for TSDT, unlike the use of a single rotational spring in traditional Bernoulli–Euler (Classical Beam Theory, CBT) and FSDT. The stiffness of the springs is adjusted based on the severity of the crack. The influences of the nonlocal parameter, beam slenderness, position of crack, crack severity, Pasternak and Winkler foundation parameters, thermal effects and boundary conditions on the natural frequencies are investigated. The model’s outcomes are compared with findings from prior publications, demonstrating a strong level of agreement. This study contributes to the growing research on nanostructures by presenting a novel approach to understanding the dynamics of cracked nanobeams using Reddy beam analysis-based solutions.了解纳米级结构的机械行为对于开发先进的纳米技术至关重要。本研究采用一种新方法来研究浸入弹性基质中的开裂纳米梁的热横向振动。为此，考虑了 Reddy 的三阶剪切变形理论（TSDT）。与季莫申科梁理论（一阶剪切变形理论，FSDT）不同，TSDT 不依赖于剪切修正系数。纳米尺度效应使用 Eringen 的非局部连续介质力学理论建模。通过应用汉密尔顿原理，可获得非局部形式的控制方程。有限元全局质量和刚度矩阵的弱形式是通过拉格朗日线性插值和赫尔米特三次插值获得的。与传统的伯努利-欧拉（经典梁理论，CBT）和 FSDT 使用单个旋转弹簧不同，TSDT 使用两个旋转弹簧来模拟弯曲振动中的裂缝。弹簧的刚度根据裂缝的严重程度进行调整。研究了非局部参数、梁的细长度、裂缝位置、裂缝严重程度、帕斯捷尔纳克和温克勒地基参数、热效应和边界条件对固有频率的影响。该模型的结果与之前发表的研究结果进行了比较，结果表明两者具有很高的一致性。这项研究提出了一种新方法，利用基于雷迪梁分析的解决方案来理解开裂纳米梁的动力学，从而为不断增长的纳米结构研究做出了贡献。来源：复合材料力学仿真Composites FEM