【新文速递】2023年10月8日固体力学SCI期刊最新文章

今日更新：International Journal of Solids and Structures 3 篇，Journal of the Mechanics and Physics of Solids 2 篇，International Journal of Plasticity 1 篇，Thin-Walled Structures 2 篇

International Journal of Solids and Structures

Adaptive control to prevent transfer between bistable configurations of a tensegrity

Hong Hao, Deng Hua

doi:10.1016/j.ijsolstr.2023.112503

自适应控制，防止张力整体双稳态配置之间的转移

The adaptive control capability of tensegrities is investigated in terms of preventing the transfer between bistable configurations due to load-induced structural instability. In contrast to conventional structures, the structural geometry and internal force of tensegrities can be changed synchronously by member length actuation, thus achieving the adjustment of the structural elastic and geometric stiffnesses. The concept of the domain of attraction (DOA) is introduced to intuitively demonstrate the ability of a tensegrity to remain stable at the current configuration, and a method is suggested to estimate the DOA for a given load. Based on the quasistatic assumption, the analytical relationship between the eigenvalues of the structural tangent stiffness matrix and the member length actuations is derived. Further combining it with the structural equilibrium relationship, the equation that can be employed to simultaneously correct both the eigenvalues of the tangent stiffness matrix and the structural geometry is established. An adaptive control strategy is thus proposed to prevent the buckling of a loaded bistable tensegrity by specifying a threshold for the eigenvalues of the tangent stiffness matrix. A 6-bar 24-cable bistable tensegrity is employed as an illustrative example to verify the validity of the proposed adaptive control strategy by preventing mutual transfers between its bistable configurations. The results show that the load resistance of the tensegrity can be significantly improved by adaptive control without loss of the structural stability, and both the elastic stiffness and the geometrical stiffness provide comparable contributions to the adjustment of the eigenvalues of its tangent stiffness matrix.

研究了张拉结构的自适应控制能力，以防止由于荷载引起的结构不稳定性导致的双稳态配置之间的转移。与传统结构相比，张力网的结构几何和内力可通过构件长度驱动同步改变，从而实现结构弹性和几何刚度的调整。本文引入了吸引力域（DOA）的概念，直观地展示了张拉实体在当前配置下保持稳定的能力，并提出了一种方法来估算给定载荷下的 DOA。基于准静态假设，得出了结构切向刚度矩阵特征值与构件长度作用力之间的分析关系。将其与结构平衡关系进一步结合，建立了可同时修正切向刚度矩阵特征值和结构几何的方程。因此提出了一种自适应控制策略，通过指定切向刚度矩阵特征值的阈值来防止加载双稳态张拉实体发生屈曲。以一个 6 杆 24 索双稳态张拉整体为例，通过防止其双稳态配置之间的相互转移，验证了所提出的自适应控制策略的有效性。结果表明，在不损失结构稳定性的情况下，通过自适应控制可以显著提高张拉整体的抗载荷能力，而且弹性刚度和几何刚度对调整其切线刚度矩阵特征值的贡献相当。

A computational framework for the lifetime prediction of vertical-axis wind turbines: CFD simulations and high-cycle fatigue modeling

Geng F., Suiker A.S.J., Rezaeiha A., Montazeri H., Blocken B.

doi:10.1016/j.ijsolstr.2023.112504

垂直轴风力涡轮机寿命预测计算框架：CFD 模拟和高循环疲劳建模

A novel computational framework is presented for the lifetime prediction of vertical-axis wind turbines (VAWTs). The framework uses high-fidelity computational fluid dynamics (CFD) simulations for the accurate determination of the aerodynamic loading characteristics on the wind turbine, and includes these loading characteristics in a detailed 3D finite element method (FEM) model to predict fatigue cracking in the structure with a fatigue interface damage model. The fatigue interface damage model allows to simulate high-cycle fatigue cracking processes in the wind turbine in an accurate and robust fashion at manageable computational cost. The FEM analyses show that the blade-strut connection is the most critical structural part for the fatigue life of the VAWT, particularly when it is carried out as an adhesive connection (instead of a welded connection). The sensitivity of the fatigue response of the VAWT to specific static and fatigue modeling parameters and to the presence of a structural flaw is analysed. Depending on the flaw size and flaw location, the fatigue life of the VAWT can decrease by 25%. Additionally, the decrease of the fatigue resistance of the VAWT appears to be mainly characterized by the monotonic reduction of the tensile strength of the adhesive blade-strut connection, rather than by the reduction of its mode I toughness, such that fatigue cracking develops in a brittle fashion under a relatively small crack opening. It is emphasized that the present computational framework is generic; it can also be applied for analyzing the fatigue performance of other rotating machinery subjected to fluid–structure interaction, such as horizontal-axis wind turbines, steam turbine generators and multistage pumps and compressors.

本文介绍了一种新型计算框架，用于预测垂直轴风力涡轮机（VAWT）的使用寿命。该框架利用高保真计算流体动力学（CFD）模拟准确确定风力涡轮机的空气动力载荷特性，并将这些载荷特性纳入详细的三维有限元法（FEM）模型，通过疲劳界面损伤模型预测结构的疲劳开裂。疲劳界面损伤模型能够以精确、稳健的方式模拟风轮机的高循环疲劳开裂过程，且计算成本可控。有限元分析表明，叶片-支柱连接是影响风力涡轮机疲劳寿命的最关键结构部分，尤其是在采用粘合连接（而非焊接连接）的情况下。我们分析了 VAWT 的疲劳响应对特定静态和疲劳建模参数以及结构缺陷存在的敏感性。根据缺陷的大小和位置，VAWT 的疲劳寿命可缩短 25%。此外，VAWT 抗疲劳性能的降低似乎主要表现为粘合叶片-支柱连接抗拉强度的单调降低，而非其模式 I 韧性的降低，因此疲劳裂纹会在相对较小的裂纹开口下以脆性方式发展。需要强调的是，本计算框架是通用的；也可用于分析其他受流体-结构相互作用影响的旋转机械的疲劳性能，如水平轴风力涡轮机、蒸汽涡轮发电机以及多级泵和压缩机。

Thermoelastic free vibration analysis of functionally graded conical shell based on trigonometric higher-order shear deformation theory

Pal Subhendu, Rout Mrutyunjay, Karmakar Amit

doi:10.1016/j.ijsolstr.2023.112505

基于三角高阶剪切变形理论的功能分级锥壳热弹性自由振动分析

The fundamental frequency of a rotating cantilevered porous functionally graded (FG) twisted conical shell with varying thickness along the longitudinal direction is calculated using a trigonometric higher-order shear deformation theory under thermal loading. Finite element method is employed for this purpose. The shell is discretized using eight noded isoparametric shell elements with seven degrees of freedom per node. Using a simple power law across the transverse direction, the temperature-dependent material properties of the FG shell are determined. The nonlinear temperature distribution across the thickness direction is calculated using the one-dimensional Fourier heat conduction equation. The dynamic equation of motion is derived using Lagrange's equation. Finally, a parametric investigation of the effects of taper ratio, porosity, pretwist angle, temperature, and rotational speed on the fundamental frequency of the porous FG rotating conical shell is performed. It is also discussed how such characteristics affect mode shapes.

采用三角高阶剪切变形理论，计算了沿纵向厚度变化的旋转悬臂多孔功能分级（FG）扭曲锥形壳体在热负荷下的基频。为此采用了有限元法。壳体采用八个节点的等参数壳体元素离散化，每个节点有七个自由度。利用横向的简单幂律，确定了 FG 壳体随温度变化的材料特性。使用一维傅立叶热传导方程计算了厚度方向上的非线性温度分布。利用拉格朗日方程推导出动态运动方程。最后，对锥度比、孔隙率、预扭角、温度和转速对多孔 FG 旋转锥形壳基频的影响进行了参数化研究。此外，还讨论了这些特性如何影响模态振型。

Journal of the Mechanics and Physics of Solids

A continuous pleated birod for converting contractions into twisting through instability

Alessi Roberto, Brunetti Matteo, Paroni Roberto, Scardaoni Marco Picchi

doi:10.1016/j.jmps.2023.105451

通过不稳定性将收缩转化为扭转的连续褶皱生物棒

The mechanical behavior of a structure made by joining two flexible flanges with a deformable pleated web, simply called continuous birod, is investigated. When axially loaded, the continuous birod shows an unconventional buckling phenomenon that couples axial contractions and helical twist, with a softening-hardening postcritical force–displacement response. In this work we propose an analytical model capable to predict the critical load and displacement of a continuous birod under axial compression. Our model does not contain any heuristic term: all the parameters have a clear physical-geometrical interpretation and can be easily identified. The obtained closed-form expressions for the critical load and displacement are in good agreement with experimental evidences and finite element simulations. The model can be exploited for the design of compliance and multistable devices for advanced applications.

本文研究了由两个柔性凸缘与可变形褶皱腹板连接而成的结构（简称为连续双杆）的力学行为。当受到轴向载荷时，连续双向拉杆显示出一种非常规的屈曲现象，即轴向收缩和螺旋扭曲耦合，以及临界力-位移响应后的软化-硬化。在这项工作中，我们提出了一种分析模型，能够预测轴向压缩下连续生物棒的临界载荷和位移。我们的模型不包含任何启发式术语：所有参数都有明确的物理几何解释，并且易于识别。所获得的临界载荷和位移闭式表达式与实验证据和有限元模拟结果十分吻合。该模型可用于设计先进应用中的顺应性和多稳态装置。

Stabilization against gravity and self-tuning of an elastic variable-length rod through an oscillating sliding sleeve

Koutsogiannakis P., Misseroni D., Bigoni D., Dal Corso F.

doi:10.1016/j.jmps.2023.105452

通过摆动滑动套筒实现弹性变长杆的抗重力稳定和自调整

An elastic rod, straight in its undeformed state, has a mass attached at one end and a variable length, due to a constraint at the other end by a frictionless sliding sleeve. The constraint is arranged with the sliding direction parallel to a gravity field, in a way that the rod can freely slip inside of the sleeve, when the latter is not moving. In this case, the free fall of the mass continues until the rod is completely injected into the constraint. However, when the sliding sleeve is subject to a harmonic transverse vibration, it is shown that the fall of the mass and the rod injection are hindered by the presence of a configurational force developing at the sliding sleeve and acting oppositely to gravity. During the dynamic motion, such a configurational force is varying in time because it is associated with the variable bending moment at the sleeve entrance. It is (experimentally, analytically, and numerically) demonstrated that, in addition to the states of complete injection or ejection of the elastic rod (for which the mass falls down or is thrown out), a stable sustained oscillation around a finite height can be realized. This ‘suspended motion’ is the signature of a new attractor, that arises by the constraint oscillation. This behaviour shares similarities with parametric oscillators, as for instance the Kapitza inverted pendulum. However, differently from the classical parametric oscillators, the ‘suspended’ configuration of the rod violates equilibrium and the stabilization occurs through a transverse mechanical input, instead of a longitudinal one. By varying the sliding sleeve oscillation amplitude and frequency within specific sets of values, the system spontaneously adjusts the sustained motion through a self-tuning of the rod’s external length. This self-tuning property opens the way to the design of vibration-based devices with extended frequency range.

一根在未变形状态下笔直的弹性杆，一端连接着一个质量，另一端受到一个无摩擦滑动套筒的约束，长度可变。该约束的滑动方向平行于重力场，当套筒不动时，杆可以在套筒内自由滑动。在这种情况下，质量的自由落体一直持续到杆完全插入约束装置中为止。然而，当滑动套筒受到谐波横向振动时，由于在滑动套筒处产生了与重力相反的构型力，质量块的下落和杆的注入都受到了阻碍。在动态运动过程中，这种配置力随时间而变化，因为它与滑动套筒入口处的可变弯矩有关。实验、分析和数值）证明，除了弹性杆完全注入或射出（质量落下或抛出）的状态外，还可以实现围绕有限高度的稳定持续振荡。这种 "悬浮运动 "是由约束振荡产生的新吸引子的特征。这种行为与参量振荡器（如卡皮查倒立摆）有相似之处。然而，与经典参数振荡器不同的是，杆的 "悬浮 "配置违反了平衡，稳定是通过横向机械输入而不是纵向机械输入实现的。通过在特定值范围内改变滑动套筒的振幅和频率，系统可通过杆外部长度的自调节自发地调整持续运动。这种自调节特性为设计频率范围更广的振动装置开辟了道路。

International Journal of Plasticity

Dual influences of deformation-induced W precipitates on dynamic recrystallization and fracture mechanism of the hot-extruded Mg-Y-Zn alloys: an experimental and phase field study

Shuai Chuan, Liu Wei, Li Huanqing, Wang Kaile, Zhang Yuntao, Xie Taoze, Chen Liwen, Hou Hua, Zhao Yuhong

doi:10.1016/j.ijplas.2023.103772

变形诱导的 W 沉淀对热挤压 Mg-Y-Zn 合金动态再结晶和断裂机制的双重影响：实验和相场研究

Understanding the relationship between nano-sized precipitates and dynamic recrystallization (DRX) during thermo-mechanical processing is vital for developing high-performance Mg-based alloys. This work uses experiment and phase field model to investigate the dynamic precipitation of W particles and DRX grains in the hot-extruded Mg98.5Y1Zn0.5 alloys at 360, 380 and 400°C and clarifies the fracture mechanisms in detail. The results reveal that under all temperatures, the hot-extruded Mg98.5Y1Zn0.5 alloys are composed of block 18R long-period stacking order (LPSO) phase, lamellar 14H-LPSO phase, W particles and a typical bimodal structure containing fine DRX grains and coarse non-DRX grains. Noted that the W particles not only promote the DRX nucleation by hindering dislocation motion to increase elastic energy, but also inhibit the growth of DRX grains by pinning grain boundaries during deformation. In addition, the strength decreases while the plasticity increases with increasing temperature for the hot-extruded Mg98.5Y1Zn0.5 alloys, but an excellent strength-plasticity balance is achieved at 400°C. More importantly, analyzing the crack extension in non-DRX, DRX and non-DRX/DRX coexistence regions shows that a ductile-brittle fracture mechanism dominates in the non-DRX regions due to the difficulty of basal slip and low fracture toughness. But a hole-joining fracture mechanism dominates in the DRX regions. The fracture mechanism in the non-DRX/DRX coexistence region is mainly determined by the DRX volume fraction. These results can provide insights and valuable references for developing high-performance Mg-based alloys.

了解热机械加工过程中纳米尺寸析出物与动态再结晶（DRX）之间的关系对于开发高性能镁基合金至关重要。本研究利用实验和相场模型研究了 360、380 和 400°C 下热挤压 Mg98.5Y1Zn0.5 合金中 W 粒子和 DRX 晶粒的动态析出，并详细阐明了断裂机制。结果表明，在所有温度下，热挤压 Mg98.5Y1Zn0.5 合金都由块状 18R 长周期堆积阶（LPSO）相、片状 14H-LPSO 相、W 粒子以及包含细小 DRX 晶粒和粗大非 DRX 晶粒的典型双峰结构组成。注意到 W 粒子不仅通过阻碍位错运动来增加弹性能量，从而促进 DRX 成核，而且在变形过程中通过钉住晶界来抑制 DRX 晶粒的生长。此外，热挤压 Mg98.5Y1Zn0.5 合金的强度随着温度的升高而降低，而塑性则随着温度的升高而升高，但在 400°C 时达到了极佳的强度-塑性平衡。更重要的是，对非 DRX、DRX 和非 DRX/DRX 共存区域的裂纹扩展进行分析后发现，由于基底滑移困难和断裂韧性低，韧性-脆性断裂机制在非 DRX 区域占主导地位。但在 DRX 区域，孔洞连接断裂机制占主导地位。非 DRX/DRX 共存区域的断裂机制主要由 DRX 体积分数决定。这些结果可为开发高性能镁基合金提供启示和有价值的参考。

Thin-Walled Structures

Block shear failure of austenitic stainless steel bolted connections

Song Yuchen, Lin Xue-Mei, Yam Michael C.H., Ke Ke

doi:10.1016/j.tws.2023.111251

奥氏体不锈钢螺栓连接的块状剪切失效

Austenitic stainless steel possesses very high ductility and ultimate-to-yield strength ratio, which could possibly affect the block shear failure mechanism and the corresponding ultimate capacity of bolted connections made of this material. In response to this concern, a comprehensive experimental and numerical study on the block shear behaviour of austenitic stainless steel bolted connections (ASSBCs) is conducted and reported in this paper. Based on the results of 15 experimental tests, it is found that the governing block shear mechanism of ASSBCs (for 14 out of the 15 tests) at the ultimate load corresponds to cracking of the shear sections prior to fracture of the tensile sections. This differs significantly from the conventionally accepted block shear mechanism of mild steel bolted connections, which is net section fracture of the tension area and yielding of the shear area. This observation was further confirmed by a numerical study based on validated finite element models, where three block shear mechanisms were identified for ASSBCs. A thorough parametric study was then carried out to clarify the effects of key design parameters on the block shear behaviour of ASSBCs. Finally, the experimental and numerical results are used to evaluate the applicability of existing design equations to predicting the block shear capacity of ASSBCs. An improved block shear equation is subsequently proposed based on the available data.

奥氏体不锈钢具有极高的延展性和极限-屈服强度比，这可能会影响由这种材料制成的螺栓连接的块剪切破坏机制和相应的极限承载能力。针对这一问题，本文对奥氏体不锈钢螺栓连接（ASSBC）的块剪切行为进行了全面的实验和数值研究，并在文中进行了报告。根据 15 项实验测试的结果，我们发现奥氏体不锈钢螺栓连接（ASSBC）在极限载荷下（15 项测试中的 14 项）的主要块剪切机制是在拉伸部分断裂之前剪切部分出现裂纹。这与传统上公认的低碳钢螺栓连接的剪切机制有很大不同，后者是拉伸区域的净断面断裂和剪切区域的屈服。基于验证过的有限元模型进行的数值研究进一步证实了这一观察结果，并确定了 ASSBC 的三种块状剪切机制。然后进行了全面的参数研究，以明确关键设计参数对 ASSBC 的块体剪切行为的影响。最后，利用实验和数值结果评估了现有设计方程在预测 ASSBC 的块体剪切能力方面的适用性。随后，根据现有数据提出了一个改进的块体剪切方程。

Experimental study on post-fire mechanical properties and fracture behavior of Q690 steel

Cai Wenyu, Li Guo-Qiang

doi:10.1016/j.tws.2023.111253

Q690 钢着火后力学性能和断裂行为的实验研究

Fire is one of the most dangerous disasters for high-strength steel structures. After a fire event, the deterioration of mechanical properties of high-strength steel together with the complex stress state generated by external loading may lead to an unexpected failure or collapse of high-strength steel structures. Therefore, it is very critical to evaluate the post-fire behavior of high-strength steel considering stress state effects. This study conducted a series of tests on the Q690 steel specimens after being exposed to high temperatures ranging from 200 to 1000 °C with different cooling methods including air-cooling and water-cooling methods. The tested specimens including smooth round specimens, notched round specimens, and grooved plate specimens were designed to consider the failure mode in axisymmetric stress state and plane strain state. To validate the accuracy of the test results, the mechanical properties such as yield strength, ultimate strength, elastic modulus, and ultimate strain were first compared with other test results reported in the literature. The post-fire ultimate strength under different stress states was obtained directly from the test results. Then, the post-fire equivalent plastic strain at fracture of different specimens was obtained from test data together with the finite element analysis results and analyzed under different stress triaxialities and Lode angle parameters. According to this study, an increase in stress triaxiality can result in an increase in ultimate strength but a decrease in the equivalent plastic strain at fracture for Q690 steel after fire. When the exposed temperature was not higher than 800 °C, the post-fire strength of the plane strain specimen (Grooved Plane Specimen) was higher than that of the axisymmetric tension specimen (Notched Round Specimen) under a similar stress triaxiality; however, for their post-fire equivalent plastic strain at fracture, the results were opposite.

对于高强度钢结构来说，火灾是最危险的灾害之一。火灾发生后，高强度钢材机械性能的退化以及外部荷载产生的复杂应力状态可能会导致高强度钢结构意外失效或倒塌。因此，考虑应力状态效应来评估高强度钢的火灾后行为非常关键。本研究采用不同的冷却方法（包括空气冷却和水冷却），对暴露在 200 至 1000 ℃ 高温下的 Q690 钢试样进行了一系列测试。试验试样包括光滑圆形试样、带缺口圆形试样和凹槽板试样，设计时考虑了轴对称应力状态和平面应变状态下的破坏模式。为了验证试验结果的准确性，首先将屈服强度、极限强度、弹性模量和极限应变等力学性能与文献报道的其他试验结果进行了比较。试验结果直接得出了不同应力状态下的火灾后极限强度。然后，根据试验数据和有限元分析结果得出了不同试样断裂时的火后等效塑性应变，并对不同应力三轴度和洛德角参数进行了分析。研究结果表明，应力三轴度的增加会导致 Q690 钢火灾后极限强度的增加，但断裂等效塑性应变会减小。当暴露温度不高于 800 ℃ 时，在应力三轴度相似的情况下，平面应变试样（凹槽平面试样）的火烧后强度高于轴对称拉伸试样（缺口圆形试样）；但是，对于它们的火烧后断裂等效塑性应变，结果却相反。