【新文速递】2023年12月9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 1 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 3 篇
International Journal of Solids and Structures
Influence of crystal orientations on the creep fracture of a nickel-based single crystal superalloy
Chengjiang Zhang, Ping Wang, Yajie Deng, Xiaoshuai Wang, Zhixun Wen, Yeda Lian, Pengfei He
doi:10.1016/j.ijsolstr.2023.112614
晶体取向对镍基单晶超级合金蠕变断裂的影响
Due to the anisotropy of the modulus of face-centered cubic cells, the nickel-based single crystal alloys exhibits substantial anisotropy at high temperatures. Their creep properties, especially the creep rupture lives, are related to the actuation of the slip system and the magnitude of the shear stress on the slip plane. The creep orientation sensitivity has been analyzed through creep experiments, as well as the microstructure and morphology of the fracture. On the macroscale, the necking sections of [001], [011] and [111] orientations are circular, elliptical and circular, respectively. Meanwhile, on the microscopic scale, the damage evolution caused by the expansion of the internal micropores in the single crystal alloy under the three orientations shows fourfold symmetry, double symmetry and triple symmetry, respectively. Based on the crystal plasticity theory, an anisotropic creep constitutive model and damage model are established to reflect the difference in creep deformation and damage evolution caused by orientation. The numerical simulations of the whole creep process of a second generation nickel-based single crystal superalloy show that the creep constitutive model and damage model can simulate the deformation and damage of the specimen under different orientations, and the creep life can be obtained.
由于面心立方晶胞模量的各向异性，镍基单晶合金在高温下表现出很大的各向异性。它们的蠕变特性，尤其是蠕变断裂寿命，与滑移系统的驱动和滑移面上的剪应力大小有关。通过蠕变实验分析了蠕变取向敏感性以及断口的微观结构和形态。在宏观尺度上，[001]、[011]和[111]取向的缩颈截面分别为圆形、椭圆形和圆形。同时，在微观尺度上，三种取向下单晶合金内部微孔扩张导致的损伤演化分别呈现四重对称、双重对称和三重对称。基于晶体塑性理论，建立了各向异性蠕变构成模型和损伤模型，以反映取向引起的蠕变变形和损伤演化的差异。对第二代镍基单晶超合金整个蠕变过程的数值模拟表明，蠕变构效模型和损伤模型能够模拟不同取向下试样的变形和损伤，并可得到蠕变寿命。
Journal of the Mechanics and Physics of Solids
Size effects in a power law creeping layer under compression or shear, and implications for deformation mechanisms of lithium films
Alessandro Leronni, Vikram S. Deshpande, Norman A. Fleck
doi:10.1016/j.jmps.2023.105505
压缩或剪切作用下幂律蠕变层的尺寸效应及其对锂膜变形机制的影响
The axisymmetric compression of a power law creeping metallic sandwich layer of micron-scale thickness is analysed. Account is taken of the elevation in flow strength due to the presence of a spatial gradient in plastic strain rate. Numerical and analytical solutions reveal that the average compressive traction is enhanced by a combination of strain rate gradients and plastic constraint. A similar size effect is predicted for simple shear of the creeping sandwich layer. The difference in responses for compression and shear is traced to the different profiles of shear strain rate through the thickness of the layer. The sensitivity of compressive and shear strengths to the choice of higher-order boundary condition is explored, and good agreement with recent experiments on compression and shear of a thin sandwich layer of lithium is achieved by assuming fully clamped higher-order boundary conditions and a material length scale on the order of 3 − 5 μm in the strain gradient-based creep theory.
对厚度为微米级的幂律蠕变金属夹层的轴对称压缩进行了分析。考虑到了塑性应变率的空间梯度导致的流动强度升高。数值和分析结果表明，平均压缩牵引力在应变率梯度和塑性约束的共同作用下得到增强。蠕变夹心层的简单剪切也会产生类似的尺寸效应。压缩和剪切响应的差异可追溯到通过层厚度的剪切应变率的不同剖面。研究还探讨了压缩和剪切强度对高阶边界条件选择的敏感性，并通过在基于应变梯度的蠕变理论中假设完全夹紧的高阶边界条件和 3 - 5 μm 量级的材料长度尺度，与最近的锂薄夹心层压缩和剪切实验取得了良好的一致性。
International Journal of Plasticity
Nanoprecipitate and stacking fault-induced high strength and ductility in a multiscale heterostructured high-entropy alloy
Liyuan Liu, Yang Zhang, Zhongwu Zhang, Junpeng Li, Weiguo Jiang, Lixin Sun
doi:10.1016/j.ijplas.2023.103853
多尺度异质结构高熵合金中的纳米沉淀和堆叠断层诱导的高强度和延展性
Two-phase high-entropy alloys (HEAs) have high strength due to the contribution of interface-dependent strengthening, but the deformation incompatibility between the two phases causes instability. The initiation of cracks occurs at the two-phase interfaces, which ultimately leads to low ductility. To overcome this problem, the strategy proposed in this work is to introduce nanoprecipitates as a buffer zone and simultaneously promote stress release caused by the formation of stacking faults (SFs) at the two-phase interfaces, reducing the stress localization at the two-phase interface, thus improving the ductility. The Al16Cr20Fe10Co30Ni24 HEA was chosen as the model material to evaluate this approach. After rolling at 800°C, the HEA had a two-phase lamellar structure consisting of a face-centered cubic (FCC) phase and an ordered body-centered cubic BCC (B2) phase. Recrystallization occurred within the FCC phase, and precipitates were present in both the FCC and B2 lamellae. The B2 nanoprecipitates in the FCC phase play the most important role, contributing to the improvement of yield strength and buffering the direct contact between gliding dislocations and the two-phase interface. In addition, the B2 nanoprecipitates also promote the widespread formation of SFs at the two-phase interfaces, leading to stress release. More importantly, nanoprecipitates are nucleation sites for SFs. The formation of an SF network improves the strain-hardening ability. The HEA shows a yield strength of 1,120 MPa and an ultimate tensile strength of 1,540 MPa while still exhibiting an elongation to fracture of ∼25%.
两相高熵合金（HEAs）由于界面强化作用而具有高强度，但两相之间的变形不相容性会导致不稳定性。裂纹在两相界面处产生，最终导致低延展性。为了克服这一问题，本研究提出的策略是引入纳米沉淀物作为缓冲区，同时促进两相界面上形成堆叠断层（SFs）引起的应力释放，减少两相界面上的应力局部化，从而提高延展性。我们选择 Al16Cr20Fe10Co30Ni24 HEA 作为模型材料来评估这种方法。在 800°C 下轧制后，HEA 具有两相薄片结构，包括面心立方（FCC）相和有序体心立方 BCC（B2）相。再结晶发生在 FCC 相中，FCC 和 B2 层状结构中都存在沉淀。FCC 相中的 B2 纳米析出物发挥了最重要的作用，有助于提高屈服强度，缓冲滑动位错与两相界面之间的直接接触。此外，B2 纳米沉淀物还能促进两相界面上 SFs 的广泛形成，从而导致应力释放。更重要的是，纳米沉淀物是 SF 的成核点。SF 网络的形成提高了应变硬化能力。HEA 的屈服强度为 1,120 兆帕，极限拉伸强度为 1,540 兆帕，而断裂伸长率仍为 25%。
Thin-Walled Structures
Kirigami-based inverse design for 3D surfaces formed by mechanically guided method
Fuhua Ye, Jiaying Chang, Zhichao Fan
doi:10.1016/j.tws.2023.111462
基于折纸的反向设计，以机械引导法形成三维表面
The mechanically guided assembly method utilizes the compressive buckling behavior of thin-film structures to transform two-dimensional (2D) precursors into three-dimensional (3D) structures. Previous research has shown that by inverse designing thickness and width distributions in 2D precursors, various 3D surfaces with target geometries can be accurately assembled. However, the variation in thickness poses significant challenges for the fabrication of the 2D precursor, especially on a small scale. In this paper, we propose a Kirigami-based inverse design framework that utilizes pre-specified incision patterns as critical parameters to control the bending stiffness distribution of 2D precursors. This enables the fabrication of target 3D structures with constant thickness, which greatly simplifies the production of 2D precursors. By studying the deformation characteristics of beam models during pure bending, we have established an analytical relationship between incision patterns and bending stiffness distribution. To validate the effectiveness of our inverse design theory, we conducted a series of simulations and experiments on 3D structures, yielding favorable comparison results. Moreover, guided by this inverse design theory, we have developed a microneedle structure through conceptual design, demonstrating the capability of Kirigami patterns in the inverse design of complex three-dimensional structures, and highlighting the potential application of our method in the biomedical field.
机械引导装配法利用薄膜结构的压缩屈曲行为将二维（2D）前体转化为三维（3D）结构。以往的研究表明，通过对二维前驱体的厚度和宽度分布进行反向设计，可以精确装配出具有目标几何形状的各种三维表面。然而，厚度的变化给二维前驱体的制造，尤其是小规模制造带来了巨大挑战。在本文中，我们提出了一种基于桐花纹的逆向设计框架，利用预先指定的切口模式作为关键参数来控制二维前驱体的弯曲刚度分布。这样就能制造出厚度恒定的目标三维结构，从而大大简化了二维前驱体的生产。通过研究梁模型在纯弯曲过程中的变形特征，我们建立了切口模式与弯曲刚度分布之间的分析关系。为了验证逆向设计理论的有效性，我们在三维结构上进行了一系列模拟和实验，取得了良好的对比结果。此外，在这一逆向设计理论的指导下，我们通过概念设计开发了一种微针结构，证明了桐神图案在复杂三维结构逆向设计中的能力，并突出了我们的方法在生物医学领域的潜在应用。
Frequency-constrained topology optimization in incompressible multi-material systems under design-dependent loads
Thanh T. Banh, Soomi Shin, Joowon Kang, Dongkyu Lee
doi:10.1016/j.tws.2023.111467
设计相关载荷下不可压缩多材料系统中的频率约束拓扑优化
In the realm of engineering design, structures grappling with fluidic pressure loads within precise frequency constraints necessitate innovative approaches. This study introduces a method to address the intricacies of design-dependent load-based structures, focusing on three key aspects: (i) managing structures constrained by frequency under fluidic pressure loads dependent on the design, (ii) integrating the use of multiple materials, and (iii) dealing with nearly incompressible materials. The proposed approach, detailed in this paper, employs polytopal composite finite elements (PCEs) to overcome the inherent volumetric locking phenomenon in incompressible materials. By incorporating Darcy’s law and a drainage term alongside the representative-solid phase, this approach ensures consistent treatment of fluidic pressure loads, dynamically adjusting their direction and location during the multi-material design process. The porosity of each element, intricately linked to its density variable through a Heaviside function, facilitates a smooth transition between solid and void phases. The application of Darcy’s law establishes a specific pressure field, solved using PCEs, enabling the computation of consistent nodal loads. This method simplifies the assessment of load sensitivities through the adjoint-variable technique. The method’s effectiveness and reliability are validated through numerical examples, demonstrating its capability to optimize compliance within specific volume constraints for frequency-limited structures subjected to design-dependent pressure loading and considering a diverse range of materials from compressible to nearly incompressible.
在工程设计领域，要在精确的频率限制下解决流体压力负载问题，就必须采用创新方法。本研究介绍了一种方法来解决基于设计的复杂结构，重点关注三个关键方面：(i) 在流体压力载荷取决于设计的情况下管理受频率约束的结构；(ii) 综合使用多种材料；(iii) 处理几乎不可压缩的材料。本文详述的拟议方法采用了聚托帕尔复合有限元（PCE），以克服不可压缩材料固有的体积锁定现象。通过将达西定律和排水项与代表固体相结合，该方法可确保对流体压力负荷的一致处理，并在多材料设计过程中动态调整其方向和位置。通过海维塞德函数，每个元素的孔隙率都与其密度变量密切相关，从而促进了固相和空相之间的平稳过渡。达西定律的应用建立了一个特定的压力场，通过使用 PCEs 进行求解，可以计算出一致的节点荷载。这种方法通过邻接变量技术简化了对荷载敏感性的评估。该方法的有效性和可靠性通过数值示例得到了验证，证明了其在特定体积约束条件下优化频率受限结构的顺应性的能力，这些结构承受的压力荷载取决于设计，并考虑了从可压缩到几乎不可压缩的各种材料。
Multi-patch isogeometric Kirchhoff–Love shell analysis for post-buckling of functionally graded graphene platelets reinforced composite shells
Xiaoxiao Du, Ran Zhang, Wei Wang, Gang Zhao, Yazui Liu
doi:10.1016/j.tws.2023.111470
针对功能分级石墨烯平板增强复合材料壳体后屈曲的多斑块等几何基尔霍夫-洛夫壳分析
This paper develops a multi-patch isogeometric Kirchhoff–Love shell method for post-buckling of functionally graded graphene platelets reinforced composite (FG-GPLRC) cylindrical, spherical, and conoidal shell structures, which are built with single or multiple NURBS patches. A penalty strategy is employed to weakly couple nonconforming interfaces between adjacent patches. The coupling work induced by enforcing displacement continuity and rotational continuity is added to the equilibrium equation, and the corresponding stiffness matrix is derived in detail. A simplified arc-length method is utilized to capture the complex equilibrium paths including snap-through and snap-back behaviors. Five distribution patterns of the shells including uniform (UD), V-type, A-type, O-type, and X-type are considered. The cylindrical and spherical shells are subjected to concentrated loadings at central points while for conoidal shells the concentrated loadings are enforced at the center points of an edge. The post-buckling of isotropic and laminated shell structures is first studied to validate the developed formulations by comparing the obtained results with those given in existing literature. Then a series of numerical examples considering nonlinear FG-GPLRC shell problems are conducted to explore the effect of various parameters like geometric dimensions, GPL distribution patterns, and shell thickness on the mechanical performance. Finally, the post-buckling of a cylindrical shell subjected to an offset concentrated load, with extremely complicated equilibrium paths, is modeled and analyzed by using the developed multi-patch isogeometric method. The numerical results reveal that the X-type GPL distribution pattern demonstrates better performance in load–deflection responses and provides the largest buckling critical load among the five patterns. Additionally, the increase in height ratio could deteriorate the stability performance of FG-GPLRC conoidal shells.
本文针对功能分级石墨烯平板增强复合材料（FG-GPLRC）圆柱形、球形和圆锥形壳体结构的后屈曲问题，开发了一种多补丁等几何基尔霍夫-洛夫壳体方法，该方法由单个或多个 NURBS 补丁构成。采用惩罚策略对相邻贴片之间的不符合界面进行弱耦合。通过强制位移连续性和旋转连续性引起的耦合功被添加到平衡方程中，并详细推导出相应的刚度矩阵。利用简化弧长法捕捉复杂的平衡路径，包括快穿和快退行为。考虑了五种壳体分布模式，包括均匀（UD）、V 型、A 型、O 型和 X 型。圆柱形和球形壳体在中心点承受集中载荷，而圆锥形壳体则在边缘中心点承受集中载荷。首先研究了各向同性和层状壳体结构的后屈曲，通过比较所获得的结果和现有文献中给出的结果来验证所开发的公式。然后，通过一系列考虑非线性 FG-GPLRC 壳体问题的数值示例，探讨了几何尺寸、GPL 分布模式和壳体厚度等各种参数对力学性能的影响。最后，使用所开发的多补丁等几何方法对承受偏移集中载荷的圆柱形壳体的后屈曲进行了建模和分析，该壳体的平衡路径极其复杂。数值结果表明，X 型 GPL 分布模式在载荷-挠度响应方面表现更佳，在五种模式中提供了最大的屈曲临界载荷。此外，随着高度比的增加，FG-GPLRC 圆锥壳的稳定性能也会下降。
