今日更新：Journal of the Mechanics and Physics of Solids 1 篇，Mechanics of Materials 3 篇，Thin-Walled Structures 1 篇Journal of the Mechanics and Physics of SolidsSouriau’s general covariant formulation of Relativistic Hyperelasticity revisitedKolev B., Desmorat R.doi:10.1016/j.jmps.2023.105463重新审视苏里奥相对论超弹性的一般协变公式We present and modernize Souriau’s 1958 geometric framework for Relativistic continuous media, and enlighten the necessary and the ad hoc modeling choices made since. We focus as much as possible on the Continuum Mechanics point of view and describe the general covariant formulation of Hyperelasticity in (Variational) General Relativity. At this level of generality, different relativistic strain and stress tensors are formulated and discussed. Then, the choice of an observer, through the introduction of a spacetime structure allows us to make deeper insights into the foundations of Continuum Mechanics. We extend Souriau’s calculations, initially performed in the flat Minkowski spacetime, to the Schwarzschild spacetime accounting for gravitation. Finally, we recover the Classical Galilean Hyperelasticity with gravity, as the Newton–Cartan infinite light speed limit of this formulation.我们提出并更新了苏里奥1958年关于相对论连续介质的几何框架，并启发了自那以后所做的必要的和特别的建模选择。我们尽可能集中于连续介质力学的观点，并描述(变分)广义相对论中超弹性的一般协变公式。在这个一般性的水平上，不同的相对论应变张量和应力张量被表述和讨论。然后，观察者的选择，通过时空结构的引入，使我们对连续介质力学的基础有了更深入的了解。我们将最初在平坦的闵可夫斯基时空中进行的Souriau的计算扩展到考虑万有引力的史瓦西时空。最后，我们用重力恢复了经典的伽利略超弹性，作为该公式的牛顿-卡坦无限光速极限。Mechanics of MaterialsA modified Gibson-Ashby model for functionally graded lattice structuresJalali Seyed Kamal, Beigrezaee Mohammad Javad, Misseroni Diego, Pugno Nicola Mariadoi:10.1016/j.mechmat.2023.104822 功能梯度晶格结构的改进Gibson-Ashby模型The current paper extends the classic Gibson-Ashby model of cellular solids for repetitive graded lattices. Three well-known porous unit cells, i.e., simple cubic (SC), body-centered cubic (BCC), and their combination (BCC＋), are considered and the corresponding graded lattices are geometrically defined by functional variation in the diameters of the ligaments based on a power law. The analytical expressions for the relative elastic modulus of the cells, which vary along the graded direction, are provided by structural analysis of the representative beam framework containing tapered beams using the Euler–Bernoulli theory. After that, continuous approximation functions for variation of the relative density and the relative elastic modulus are presented by curve fitting over the analytical expressions along the graded direction. Then, the graded lattices are considered to be fully homogenized and as a homogeneous media, the exact expressions for the effective relative density and the effective relative modulus are presented. The modified version of the Gibson-Ashby model is proposed to relate the effective relative modulus to the effective relative density by introducing a correction factor to the classic model. It is shown that the classic Gibson-Ashby model with the coefficients fitted on uniform lattices, is not accurate for relating the effective properties of the graded lattices. The proposed model, presented as an analytical expression with fitting parameters and a correction factor, serves as a useful guideline for designing optimized functionally graded lattice structures, accommodating a wide range of geometric variations.本文将经典的Gibson-Ashby模型扩展到重复梯度晶格。考虑了三种众所周知的多孔单元格，即简单立方(SC)、体心立方(BCC)和它们的组合(BCC+)，并根据幂律根据韧带直径的功能变化从几何上定义了相应的梯度晶格。利用欧拉-伯努利理论对具有代表性的含锥形梁的梁框架进行了结构分析，得到了单元相对弹性模量沿梯度方向变化的解析表达式。然后，对解析表达式沿梯度方向进行曲线拟合，得到了相对密度和相对弹性模量变化的连续逼近函数。然后，将梯度晶格视为完全均质介质，给出了有效相对密度和有效相对模量的精确表达式。通过在经典模型中引入修正因子，提出了修正版的Gibson-Ashby模型，将有效相对模量与有效相对密度联系起来。结果表明，将系数拟合在均匀格上的经典Gibson-Ashby模型对于描述梯度格的有效性质是不准确的。该模型是一种具有拟合参数和校正因子的解析表达式，可为设计适应大范围几何变化的优化功能梯度晶格结构提供有用的指导。Numerical modeling of the mechanical response of asphalt concrete in tension and compressionTan Zhifei, Leng Zhen, Jelagin Denis, Cao Peng, Jiang Jiwang, Kumar Ashish Prabin, Zou Fuliaodoi:10.1016/j.mechmat.2023.104823沥青混凝土拉压力学响应的数值模拟Asphalt concrete (AC) shows significant tension-compression (TC) asymmetry, i.e., different properties in tension and compression (T&C). This asymmetry may profoundly affect AC's performance and deterioration in the field, but limited studies have been performed to quantify this behavior. This study aims to quantitively characterize the global and local mechanical responses of AC in T&C through numerical modeling. To this end, three AC mixtures: the gap-graded SMA10, dense-graded AC20, and open-graded mixtures PA13, were evaluated experimentally and numerically. Digital image processing was used to generate image-based AC models with contact regions (CR), and dynamic simulations were conducted using the steady-state dynamics (SSD) approach. The results indicate that the measured and predicted master curves for AC in T&C qualitatively agree and demonstrate significant asymmetry, with higher moduli but lower phase angles in compression compared to tension. Among the mixtures, PA13 exhibited the most pronounced asymmetry, followed by SMA10 and AC20. Statistical analyses of local stress and strain found that the stress and strain in different phases show significant variations, with more pronounced disparities observed at lower frequencies. Notably, at 10−6 Hz for PA13 in compression, the stress within the aggregate phase exceeded that of the matrix phase by over 250 times, while the strain within the matrix phase surpassed the aggregate phase by more than 600 times. To enhance pavement durability, it is recommended to consider AC's TC asymmetry in pavement design.沥青混凝土(AC)表现出显著的拉压不对称性，即在拉压(T&C)性能上存在差异。这种不对称可能会深刻地影响AC的性能和在现场的恶化，但有限的研究已经进行了量化这种行为。本研究旨在通过数值模拟定量表征交流系统在T&C中的整体和局部力学响应。为此，对间隙级配的SMA10、密级配的AC20和开级配的PA13三种AC混合物进行了实验和数值评价。采用数字图像处理技术建立了基于图像的接触区域(CR)交流模型，并采用稳态动力学(SSD)方法进行了动态仿真。结果表明，实测和预测的T&C中交流的主曲线在定性上一致，并表现出明显的不对称性，压缩时的模量比张力时高，相位角比张力时低。其中PA13表现出最明显的不对称性，其次是SMA10和AC20。对局部应力应变的统计分析发现，不同阶段的应力应变有明显的变化，在较低的频率处观察到更明显的差异。值得注意的是，在10−6 Hz的压缩条件下，聚集体相内的应力超过基体相的250多倍，而基体相内的应变超过了聚集体相的600多倍。为了提高路面的耐久性，建议在路面设计中考虑AC的TC不对称。Fully-coupled piezoelectric field in the semiconductor heterostructure with an ellipsoidal anisotropic inhomogeneityHe Junxiong, Ye Weidoi:10.1016/j.mechmat.2023.104837具有椭球各向异性非均匀性的半导体异质结构中的全耦合压电场The elastic and piezoelectric fields induced by misfit strain in semiconductor heterostructures are crucial for the design of semiconductor devices. This work formulates analytically the fully-coupled piezoelectric field in the heterostructure with a general anisotropic inhomogeneity. The application of the ellipsoidal inhomogeneity is numerically solved by implementations of the generalized Green's function and its derivatives as well as their surface integrals. Elaborations will be made on the similarities and differences for the usage of the inclusion and inhomogeneity in the fully-coupled analysis, along with some discussions about the shape and size effects in the end.半导体异质结构中由失配应变引起的弹性场和压电场对半导体器件的设计至关重要。本文对具有一般各向异性非均匀性的异质结构中的全耦合压电场进行了解析推导。通过实现广义格林函数及其导数及其表面积分，在数值上解决了椭球体非均匀性的应用。最后将详细阐述全耦合分析中包含和非均匀性使用的异同点，并讨论形状和尺寸效应。Thin-Walled StructuresInvestigation on a novel in-line incremental die forming process for sheet metalsLee Jinwoo, Bong Hyuk Jong, Kim Chanyang, Kim Daeyong, Lee Myoung-Gyudoi:10.1016/j.tws.2023.111281 一种新型板料在线增量成形工艺的研究In this study, an alternative to the conventional cold-roll-forming process was developed. The new in-line incremental die forming process is a continuous manufacturing process that can provide rapid prototyping of automotive components. This new process combines the pressing and drawing operations. The feasibility of using ultra-high-strength steel (UHSS) sheets to manufacture real automotive components usually produced with the conventional cold-roll forming process was evaluated. Finite-element simulations incorporating the mechanical properties of plasticity and ductile fracture were conducted to validate the new process. The results demonstrated that the proposed forming process efficiently produced automotive components with consistent shapes and lengths, and the simulation outputs were in good agreement with the experimental data in terms of dimensional accuracy and quality. Additionally, sensitivity analyses of process parameters such as friction and die design provide valuable insights for optimizing the newly proposed formation process of UHSS sheets.在本研究中，开发了一种替代传统冷轧成形工艺的方法。新型的在线增量模压成形工艺是一种连续制造工艺，可以提供汽车零部件的快速成型。这种新工艺结合了压制和拉伸操作。对利用超高强度钢(UHSS)薄板制造传统冷轧成形工艺生产的汽车零部件的可行性进行了评价。结合塑性和韧性断裂力学性能进行了有限元模拟，验证了新工艺的有效性。结果表明，所提出的成形工艺能有效地生产出形状和长度一致的汽车零部件，仿真结果在尺寸精度和质量上与实验数据吻合较好。此外，摩擦和模具设计等工艺参数的敏感性分析为优化新提出的超高压钢板成形工艺提供了有价值的见解。来源：复合材料力学仿真Composites FEM
