【新文速递】2024年6月29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 8 篇

International Journal of Solids and Structures

Experimental correlation between bending crack evolution and load-drop criterion in tight-radius three-point bending test with GPa-grade steels

Kyucheol Jeong, Yuhyeong Jeong, Jaewook Lee, Giseok Chung, Geun-ho Kim, Jonghun Yoon

doi:10.1016/j.ijsolstr.2024.112949

在 GPa 级钢的紧半径三点弯曲试验中，弯曲裂纹演变与载荷下降准则之间的实验相关性

Determining the bending-fracture limit, also referred to as local formability, is crucial for sheet metal forming. However, this is limited by existing methods such as the VDA-238-100 standard due to limitations in its failure criterion based on the punch load. This study addresses this limitation by proposing a quantitative crack-based failure criterion and investigating its relationship to the load-drop point. Along with surface and cross-sectional optical analyses, an integrated line-scanning system for the VDA-238 test is developed, and advanced high-strength steel (AHSS) grades are analysed with yield strengths ranging from 980 to 1500 MPa in both the rolling and transverse directions. The results showed that, while the load-drop point marks a rapid shift in the crack-propagation direction, the true onset of crack initiation occurs earlier, with different patterns for each AHSS and direction. For all the AHSS and directions tested, a crack depth exceeding 1 % of the sheet thickness occurs at 90 % of the switch-off stroke in the VDA-238 test, suggesting an empirical tendency toward microcrack growth for a more accurate evaluation of the local formability based on early cracks.

确定弯曲断裂极限（也称为局部可成形性）对于金属板材成型至关重要。然而，现有的方法（如 VDA-238-100 标准）在此方面存在局限性，原因在于其基于冲压载荷的失效标准存在局限性。本研究针对这一局限性，提出了基于裂纹的定量失效标准，并研究了其与载荷下降点的关系。在进行表面和横截面光学分析的同时，还开发了用于 VDA-238 试验的集成线扫描系统，并对轧制和横向屈服强度范围为 980 至 1500 兆帕的先进高强度钢 (AHSS) 进行了分析。结果表明，虽然载荷下降点标志着裂纹扩展方向的快速转变，但真正的裂纹起始点却出现得更早，而且每种 AHSS 和方向的起始点形态各异。对于所测试的所有 AHSS 和方向，在 VDA-238 试验中，当开关行程达到 90% 时，裂纹深度会超过板材厚度的 1%。

Journal of the Mechanics and Physics of Solids

Initiation and arrest of cracks from corners in multi-chip semiconductor devices

Guodong Nian, Yu-Sheng Lin, Jia-Ming Yang, Sammy Hassan, Jyun-Lin Wu, Sherwin Tang, Jun He, Joost J. Vlassak, Zhigang Suo

doi:10.1016/j.jmps.2024.105755

多芯片半导体器件边角裂纹的产生与消除

A contemporary semiconductor device often contains multiple chips. Corners of the chips concentrate stress, and are principal sites to initiate failure. Here we propose to characterize the corners using a double cantilever beam, in which two silicon beams sandwich a row of chips. As the two beams are pulled open, a crack initiates at the corner of a chip, and runs unstably on the interface between the chip and a beam. The crack may or may not arrest, depending on various experimental conditions. We calculate energy release rate as a function of crack length by using a combination of finite element method and an analytical solution of the singular field around a corner. At a fixed applied displacement, the energy release rate is low for a short crack, peaks for a crack of intermediate length, and drops for a long crack. This non-monotonic behavior explains how a crack initiates, grows unstably, and possibly arrests. If the crack does arrest, as the two beams open further, the crack grows stably. We relate the initiation and arrest of the crack to machine compliance, specimen geometry, and flaw size. The force at which the crack initiates can be used to characterize the manufacturing process, whereas the stable growth of the crack can be used to measure interfacial toughness. It is hoped that this work will aid the development of multi-chip semiconductor devices.

现代半导体器件通常包含多个芯片。芯片的边角集中了应力，是引发故障的主要部位。在这里，我们建议使用双悬臂梁来描述芯片边角的特性，在双悬臂梁中，两根硅梁夹着一排芯片。当两根梁被拉开时，芯片角落处会出现裂纹，并在芯片和梁之间的界面上不稳定地延伸。裂纹可能停止，也可能不停止，这取决于各种实验条件。我们结合有限元方法和拐角处奇异场的解析解，计算出能量释放率与裂纹长度的函数关系。在固定的外加位移下，短裂缝的能量释放率较低，中等长度裂缝的能量释放率达到峰值，而长裂缝的能量释放率则有所下降。这种非单调行为解释了裂缝是如何产生、不稳定增长并可能停止的。如果裂缝确实停止，随着两根梁进一步打开，裂缝会稳定增长。我们将裂纹的产生和停止与机器顺应性、试样几何形状和缺陷大小联系起来。裂纹产生时的作用力可用来描述制造过程，而裂纹的稳定生长可用来测量界面韧性。希望这项工作能有助于多芯片半导体器件的开发。

International Journal of Plasticity

Effect of dynamic strain ageing on flow stress and critical strain for jerky flow in Al-Mg alloys

Surajit Samanta, Jyoti Ranjan Sahoo, Sumeet Mishra

doi:10.1016/j.ijplas.2024.104053

动态应变时效对铝镁合金中的流动应力和涩流临界应变的影响

A comprehensive approach addressing the flow behavior and the critical strain for the initiation of serrations in Al-Mg alloys is developed in the present work. The basic premise of the approach is that the solute atmosphere influences the friction as well as the strain hardening component of the flow stress. The friction effect of the solute cloud is modeled by considering the interplay between the characteristic solute migration time and the dislocation waiting time according to the cross-core diffusion mechanism. The impact on strain hardening is modeled by considering the apparent strengthening of the forest dislocations because of formation of solute aggregates near the vicinity of dislocation junctions. The apparent forest strengthening effect scales as the square root of the ratio of solute concentration in vicinity of the dislocation junctions and the bulk solute concentration. The modified constitutive model is validated against experimental flow curves obtained for strain rates varying over several orders of magnitude. It was observed that the modified constitutive model outperforms the standard constitutive model (considers only the friction effect of solute atmosphere) in predicting the flow curves in the dynamic strain aging domain. Furthermore, the modified constitutive model also accurately predicts the critical strain for the initiation of the jerky flow in both the normal and inverse regimes of the critical strain versus strain rate curve. Additional validation of the modified constitutive model is provided by dislocation character and density measurements via X-ray diffractograms, dislocation structure investigation via transmission electron microscopy along with fracture surface analysis.

本研究针对铝镁合金的流动行为和锯齿产生的临界应变开发了一种综合方法。该方法的基本前提是，溶质云会影响摩擦力以及流动应力的应变硬化分量。溶质云的摩擦效应是根据跨芯扩散机制，通过考虑特征溶质迁移时间和位错等待时间之间的相互作用来建模的。由于在差排交界处附近形成了溶质聚集体，因此对应变硬化的影响是通过考虑森林差排的明显增强来模拟的。表观森林强化效应的大小为差排连接附近溶质浓度与体积溶质浓度之比的平方根。修改后的构成模型根据应变率变化超过几个数量级时获得的实验流动曲线进行了验证。结果表明，在预测动态应变老化域的流动曲线方面，修正的构成模型优于标准构成模型（只考虑溶质大气的摩擦效应）。此外，在临界应变与应变速率曲线的正态和反态中，修正后的构成模型还能准确预测启动涩流的临界应变。通过 X 射线衍射图测量位错特征和密度，通过透射电子显微镜研究位错结构，并进行断裂表面分析，进一步验证了修改后的构成模型。

Thin-Walled Structures

Wire and Arc Additive Manufacturing for Strengthening of Metallic Components

H. Dahaghin, M. Motavalli, H. Moshayedi, S.M. Zahrai, E. Ghafoori

doi:10.1016/j.tws.2024.112074

用于强化金属部件的线弧快速成型技术

Wire and arc additive manufacturing (WAAM), also known as wire arc directed energy deposition (WA-DED), offers valuable capabilities not only for manufacturing but also for strengthening and repairing aging components. This paper employs the finite element (FE) method to investigate the influence of deposition parameters on the strengthening efficiency of damaged steel plates strengthened by WAAM material. The study calibrates the inherent strain method (ISM) with thermo-mechanical analysis to accurately predict residual stresses (RS) in manufactured samples, demonstrating that the ISM enhances computational efficiency while effectively predicting RS. It thoroughly examines key parameters such as the deposition direction, maximum thickness, and the geometric configuration of the WAAM material, including shapes and in-plane dimensions. The results indicate that deposition perpendicular to the loading direction provides better performance compared to deposition along the loading direction as it induces less normal and through-thickness stresses. Furthermore, this research determines the optimal maximum thickness for the WAAM material, showing that an increase in thickness can lead to higher maximum tensile stresses at the interface between the newly WAAM material and the underlying base plate. The study also establishes the optimal in-plane dimensions for the WAAM material. The results suggest placing the maximum thickness of WAAM material near the damaged area and gradually decreasing it in two directions to ensure sufficient stiffness around the cracked area, while avoiding an abrupt change in stiffness. This approach generates appropriate compressive stresses around the crack tip and decreases maximum tensile stresses in the plate. The study further illustrates that employing a proper printing strategy without a subsequent machining process can effectively reduce the maximum tensile stress in the steel plate while minimizing material usage.

线弧增材制造（WAAM），又称线弧定向能沉积（WA-DED），不仅可用于制造，还可用于加固和修复老化部件。本文采用有限元（FE）方法研究了沉积参数对使用 WAAM 材料加固的受损钢板加固效率的影响。研究将固有应变法 (ISM) 与热机械分析法进行了校准，以准确预测制造样品中的残余应力 (RS)，证明固有应变法在有效预测 RS 的同时还提高了计算效率。它彻底检查了关键参数，如沉积方向、最大厚度以及 WAAM 材料的几何配置，包括形状和面内尺寸。结果表明，与沿加载方向沉积相比，垂直于加载方向沉积的性能更好，因为它引起的法向应力和贯通厚度应力更小。此外，这项研究还确定了 WAAM 材料的最佳最大厚度，结果表明，增加厚度会导致新 WAAM 材料与底层基板之间的界面产生更大的最大拉伸应力。研究还确定了 WAAM 材料的最佳平面尺寸。研究结果表明，将最大厚度的 WAAM 材料置于受损区域附近，并在两个方向上逐渐减小，以确保裂纹区域周围有足够的刚度，同时避免刚度的突然变化。这种方法可在裂纹尖端周围产生适当的压应力，并降低板中的最大拉应力。该研究进一步说明，采用适当的印刷策略而不进行后续加工工艺，可有效降低钢板的最大拉伸应力，同时最大限度地减少材料用量。

Aerogel honeycombs with orientation-induced microstructures for high-temperature lightweight composite sandwich structures

Zhen Fan, Xupeng Fan, Tingting Jia, Chengyang Wang, Qing Zhu, Dezhi Wang, Liwei Zhao, Si Cheng, Dongpeng Zhou, Qi Sun, Dianpeng Qi, Changwei Liu

doi:10.1016/j.tws.2024.112156

具有取向诱导微结构的气凝胶蜂窝，用于高温轻质复合材料夹层结构

Lightweight honeycomb structures are widely used in applications that require high strength-to-weight ratios and low densities, including aircraft, automobiles, and various engine components. However, due to the immaturity of microstructure conditioning techniques and the fact that highly porous structures usually fracture during stretching, it is challenging to obtain both high-strength and lightweight porous structures. Herein, a newly developed multilayer interconnected polyimide aerogel-based paper honeycomb is successfully prepared based on the ice crystal reverse template method and multi-level structure regulation via chemical and physical interactions. The synergistic effect of the hot extrusion-stress strategy and the heat imidization process provides the submicron layer of the paper honeycomb wall with more orderly molecular chain stacking, excellent orientation, and an enhanced folding degree between layers. The prepared polyimide aerogel paper honeycombs have low density (approx. 8-9 kg/m3), good shear strength of 1.07 MPa (W direction) and 0.86 MPa (L direction), excellent specific compressive strength (0.38MPa), and excellent thermal stability. These integrally molded polyimide paper honeycombs, as sandwich resin-based composite structures, provide a new versatile platform for aerospace and marine applications.

轻质蜂窝结构广泛应用于要求高强度重量比和低密度的领域，包括飞机、汽车和各种发动机部件。然而，由于微结构调节技术尚不成熟，而且高多孔结构在拉伸过程中通常会发生断裂，因此要获得高强度和轻质多孔结构具有挑战性。本文基于冰晶反向模板法，通过化学和物理相互作用进行多层次结构调控，成功制备了一种新开发的多层互联聚酰亚胺气凝胶纸蜂窝。在热挤压-应力策略和热亚胺化工艺的协同作用下，纸蜂窝壁的亚微米层具有更有序的分子链堆叠、优异的取向性和更强的层间折叠度。制备的聚酰亚胺气凝胶纸蜂窝密度低（约 8-9 kg/m3），剪切强度高（1.07 MPa（W 向）和 0.86 MPa（L 向）），抗压强度高（0.38MPa），热稳定性好。这些一体成型的聚酰亚胺纸蜂窝作为基于夹层树脂的复合材料结构，为航空航天和海洋应用提供了一个新的多功能平台。

Mode localization behavior and its generating mechanism of non-uniform rotating cylindrical shells

Jiucun Wei, Zhiguang Song

doi:10.1016/j.tws.2024.112165

非均匀旋转圆柱壳的模态定位行为及其产生机理

Rotating cylindrical shells are widely used in many engineering fields, and due to processing or other errors, non-uniform will happen from time to time, which will affect the vibration behaviors of the shell significantly. Therefore, in this paper, vibration analyses of non-uniform rotating cylindrical shells are carried out. The assumed mode method and Hamilton's principle are used to formulate the equation of motion. It is found that since the angular velocity tensor is an antisymmetric matrix, the damping matrix caused by the Coriolis force is also antisymmetric which in advance leads to traveling wave solutions. A method of expanding the assumed mode shape function to solve the traveling wave problem is proposed. Mode localization behaviors are found in the non-uniform cylindrical shells, and it is verified by the experiment. The generating mechanism for the mode localization is revealed. Moreover, mode veering is observed. The relationship between the model localization and mode veering is analyzed. In the fault diagnosis, inspired by the mode localization, a root mean square (RMS) curve method is introduced. The present study can provide a new idea for fault diagnosis of rotating cylindrical shells such as helicopter drive shafts.

旋转圆柱形壳体广泛应用于许多工程领域，由于加工或其他误差，不均匀现象时有发生，这将对壳体的振动行为产生重大影响。因此，本文对非均匀旋转圆柱壳进行了振动分析。采用假定模态法和汉密尔顿原理来计算运动方程。研究发现，由于角速度张量是一个非对称矩阵，科里奥利力引起的阻尼矩阵也是非对称的，这提前导致了行波解。本文提出了一种扩展假定模态振型函数以求解行波问题的方法。在非均匀圆柱形壳体中发现了模式局部化行为，并通过实验进行了验证。揭示了模式局部化的产生机制。此外，还观察到了模式矢量。分析了模式定位和模式偏移之间的关系。在故障诊断中，受模式定位的启发，引入了均方根（RMS）曲线法。本研究为直升机传动轴等旋转圆柱形壳体的故障诊断提供了新思路。

EXPERIMENTAL BEHAVIOUR OF DIAGONALLY STIFFENED STEEL I-GIRDERS

J.P. Martins, F. Ljubinković, H.S. Cardoso

doi:10.1016/j.tws.2024.112172

斜向加劲工字钢梁的实验行为

This paper reports on the experimental investigation carried out at the University of Coimbra, in which the behaviour of diagonally stiffened steel I-girders dominantly subject to shear is assessed. The experimental program consists of four specimens: one reference I-girder without a diagonal stiffener, and three specimens with different stiffener geometrical and materials characteristics, placed along the diagonal of the girder web to increase their stability and load-carrying capacity in shear. Moreover, two different stiffener joining techniques are explored, namely welding and bonding-bolting. The principal objective of this research is twofold: i) to qualitatively assess and compare the effects of these different diagonal stiffening strategies in terms of the shear capacity of I-girders, and ii) to critically assess currently available methodologies from the literature for the calculation of the shear resistance of diagonally stiffened I-girders. Regardless of the stiffener properties and joining technique, in all tested specimens the inclusion of a stiffener along the compression diagonal significantly increases the shear resistance when compared to the girder without diagonal stiffeners. However, the tests performed with bonded-bolted cold-formed stiffeners seem to show less ductile behaviour than those with a welded stiffener. Finally, a comparison of the experimental results with the available calculation methods was made and the conclusion is that they do not adequately predict the shear bearing capacity of the tested girders with the diagonal stiffeners, giving a large scatter of results.

本文报告了科英布拉大学进行的实验研究，其中评估了主要受剪的斜向加劲钢工字梁的行为。实验项目包括四个试样：一个不带对角加劲件的参考工字钢，以及三个具有不同加劲件几何和材料特性的试样，这些加劲件沿梁腹板的对角线放置，以提高其稳定性和剪切承载能力。此外，还探讨了两种不同的加劲件连接技术，即焊接和螺栓连接。本研究的主要目标有两个：i) 定性评估和比较这些不同的对角加劲策略对工字梁抗剪能力的影响；ii) 批判性评估目前文献中可用的计算对角加劲工字梁抗剪能力的方法。无论加劲件的性能和连接技术如何，在所有测试的试样中，与没有斜向加劲件的大梁相比，沿压缩对角线加入加劲件可显著提高抗剪能力。不过，与使用焊接加劲件的试验相比，使用粘接-螺栓连接冷弯加劲件的试验似乎表现出更差的延展性。最后，将实验结果与现有的计算方法进行了比较，得出的结论是，这些计算方法并不能充分预测使用斜向加劲梁的测试大梁的抗剪承载力，结果非常分散。

Effects of Web Distortion on the Lateral Torsional Buckling of Singly-symmetric I-beams

Chen Liang, Zhihua Xiong, Todd A. Helwig, Matthew C. Reichenbach, Zhenhua Pan

doi:10.1016/j.tws.2024.112174

腹板变形对单对称工字钢侧向扭转屈曲的影响

This paper presents an investigation on the negative effects of shear on the lateral torsional buckling (LTB) of singly-symmetric I-shaped beams due to web distortion associated with shear. Results from a parametric FEA study including eigenvalue buckling analyses and large-displacement analyses were utilized considering both stiffened and unstiffened webs to consider the impact of shear on the LTB resistance. Moment gradients caused by constant shear and a shear gradient were considered. The FEA solutions demonstrate that shear can significantly reduce the lateral-torsional buckling resistance. The FEA results were used to develop design equations that account for the reduction in the LTB capacity from shear. The solutions were compared with conventional methods proposed by Winter to account for the effects of web distortion on girders with slender webs. Results from the study show that i) the average flange area should be used to account for the effects of shear of singly-symmetric beams; ii) post-buckling strength has limited impact on the shear effects with regards to the LTB resistance; and, iii) compared to Winter's approach, the proposed method can capture the variation of the moment reduction factor with the shear force in the unbraced length, and is able to predict moment resistances with reasonable accuracy compared to refined FEA solutions using both eigenvalue analysis and large-displacement analysis. Design examples are provided to demonstrate the calculation procedure.

本文研究了剪力对单对称工字形梁横向扭转屈曲（LTB）的负面影响，这种影响是由与剪力相关的腹板变形引起的。利用参数有限元分析研究的结果，包括特征值屈曲分析和大位移分析，考虑了加劲和非加劲腹板，以考虑剪切对 LTB 抗力的影响。研究还考虑了由恒定剪力和剪力梯度引起的力矩梯度。有限元分析结果表明，剪切会显著降低侧向扭转屈曲阻力。有限元分析结果被用于制定设计方程，以考虑剪切力对 LTB 承载能力的影响。这些解决方案与温特提出的传统方法进行了比较，以考虑腹板变形对细长腹板梁的影响。研究结果表明：i）应使用翼缘平均面积来考虑单对称梁的剪切影响；ii）屈曲后强度对 LTB 抗力的剪切影响有限；iii）与温特的方法相比，所提出的方法可以捕捉到弯矩折减系数随无支撑长度上剪力的变化，并且与使用特征值分析和大位移分析的精细有限元分析方法相比，能够以合理的精度预测弯矩抗力。设计实例演示了计算过程。

Mechanical properties of double-sided stainless-clad bimetallic steel at elevated temperatures

Hai-Ting Li, Chen-Yu Xu, Xiaojing Cai, Bo Yan

doi:10.1016/j.tws.2024.112175

双面不锈钢包层双金属钢在高温下的机械特性

This paper presents a comprehensive test program on the elevated-temperature mechanical properties of double-sided stainless-clad bimetallic steel (DSSCBS), which is a new type of high-efficiency material that has potential to be used for cold-formed thin-walled structural members. A total of 49 coupon specimens were extracted from two DSSCBS sheets as well as their corresponding substrate and cladding materials. Fire tests were carried out on tensile coupons by applying steady-state test method at 13 different temperatures up to 900°C. Full range of stress-strain curves were obtained and key mechanical properties including elastic modulus, yield strength, strength at 2% strain, ultimate strength, ultimate strain, and fracture strain were reported in this paper. The measured reduction factors of the DSSCBS specimens were compared with their corresponding values of the substrate and cladding materials, with the influence of clad ratios evaluated. In addition, the applicability of prediction curves for single-sided stainless-clad bimetallic steel, along with current design regulations as stipulated in American and European standards for carbon steel and stainless steel, was assessed. New design methods were proposed for reduction factor estimation of key mechanical properties and a constitutive model was formulated for stress-strain relationships of the bimetallic steel materials at various temperatures. Furthermore, the impact of peak temperature history on mechanical properties of DSSCBS at elevated temperatures was explored.

双面不锈钢包覆双金属钢（DSSCBS）是一种新型高效材料，有望用于冷弯薄壁结构构件，本文介绍了双面不锈钢包覆双金属钢高温力学性能的综合测试项目。从两块 DSSCBS 板材及其相应的基材和覆层材料中共提取了 49 块试样。在 13 种不同温度（最高达 900°C）下，采用稳态试验方法对拉伸试样进行了耐火试验。本文获得了全范围的应力-应变曲线，并报告了包括弹性模量、屈服强度、2%应变时的强度、极限强度、极限应变和断裂应变在内的关键机械性能。将测得的 DSSCBS 试样降低系数与基体和覆层材料的相应值进行了比较，并评估了覆层比率的影响。此外，还评估了单面不锈钢包覆双金属钢的预测曲线，以及美国和欧洲碳钢和不锈钢标准中规定的现行设计规范的适用性。针对关键机械性能的折减系数估算提出了新的设计方法，并为双金属钢材料在不同温度下的应力-应变关系制定了构成模型。此外，还探讨了峰值温度历史对高温下 DSSCBS 机械性能的影响。

Dual Characteristics of Static Stiffness and Adjustable Bandgap of Innovative Re-Entrant Hybrid Chiral Metamaterials

Jiawang Yong, Wanting Li, Yiyao Dong, Yanyan Chen, Nenglian Feng, Weiping Sun, Zhishuai Wan, Ming Liu, Daining Fang

doi:10.1016/j.tws.2024.112168

创新型再入式混合手性超材料的静态刚度和可调带隙双重特性

In this paper, an improved re-entrant metamaterial based on 3D printing was proposed, which exhibits enhanced stiffness and vibration suppression ability compared to the original metamaterial. The proposed metamaterial allows for intentional adjustment of the bandgap by incorporating metal pins of varying sizes or weight into the ring structures. Furthermore, the addition of particle damping inside the rings enhances the design flexibility of the bandgap, enabling customization of the middle and low frequency ranges. Experimental and simulation comparisons are conducted to evaluate the static properties and vibration suppression ability of the metamaterial. The results demonstrate a 172.4% increase in load-bearing capacity and a significant improvement in vibration suppression of the proposed metamaterial relative to the original configuration. The vibration suppression of the proposed metamaterial can be further enhanced by introducing particle damping into the metal tube, and the vibration suppression frequency can be intentionally adjusted by changing the dosage of particle damping. This research presents a novel approach for the design and optimization of metamaterials.

本文提出了一种基于三维打印技术的改进型重入超材料，与原始超材料相比，它具有更强的刚度和振动抑制能力。通过在环状结构中加入不同尺寸或重量的金属针，所提出的超材料可以有意调整带隙。此外，在环内加入颗粒阻尼还能增强带隙设计的灵活性，从而实现中频和低频范围的定制。实验和模拟比较评估了超材料的静态特性和振动抑制能力。结果表明，与原始配置相比，拟议超材料的承载能力提高了 172.4%，振动抑制能力也有显著改善。通过在金属管中引入颗粒阻尼，可以进一步增强所提出的超材料的振动抑制能力，并且可以通过改变颗粒阻尼的剂量来有意调节振动抑制频率。这项研究为超材料的设计和优化提供了一种新方法。

Neural networks for critical load factors of unstiffened plates according to the reduced stresses method of EN 1993-1-5

R. Timmers, I. Lukas, R. Lang

doi:10.1016/j.tws.2024.112170

根据 EN 1993-1-5 减少应力法计算非加固板临界载荷系数的神经网络

The critical load factor resulting from the complete stress field is the main input parameter for the verification against plate buckling according to the reduced stresses method (RSM) from Eurocode EN 1993-1-5. Currently, the code provides just a simple and often conservative interaction formula with a limited application range. Realistic values can only be obtained by numerical methods, like the FEM, which is tedious for many load cases. To enhance the ease of use of the RSM, simple-to-use but accurate methods are needed, which can be automated and implemented into EN 1993-1-5. The current research deals with this problem by applying artificial neural networks (ANN) to predict the critical load factors of unstiffened plates under longitudinal, shear, and patch loading stresses, including their interaction behaviour. ANNs were used because approximated solutions with polynomials (as actual in the standard) are not suitable due to the complexity of the problem. The developed ANNs are highly accurate (as shown by an independent verification), can be implemented into the Eurocode, and can easily be used, even without in-depth programming skills. Moreover, a simple Python code is provided to demonstrate the ease of use. Still, the code can also be implemented into other software packages (like Excel), as only basic matrix operations are needed. The interaction surfaces are visualized, gaining a deeper understanding of plates under multiaxial loading situations. Finally, recommendations are given for generating ANNs for plate buckling problems.

根据欧洲规范 EN 1993-1-5 中的减小应力法 (RSM)，完整应力场产生的临界载荷系数是验证板材抗弯的主要输入参数。目前，该规范仅提供了一个简单且通常较为保守的相互作用公式，应用范围有限。只有通过有限元等数值方法才能获得真实值，而这种方法对于许多荷载情况都很繁琐。为了提高 RSM 的易用性，需要简单易用但精确的方法，这些方法可以在 EN 1993-1-5 中自动实施。目前的研究通过应用人工神经网络（ANN）来预测非刚性板在纵向、剪切和贴片加载应力下的临界载荷系数，包括其相互作用行为，从而解决了这一问题。由于问题的复杂性，使用多项式（如标准中的实际情况）近似求解并不合适，因此使用了人工神经网络。所开发的 ANNs 具有很高的准确性（如独立验证所示），可在 Eurocode 中实施，即使没有深入的编程技巧也能轻松使用。此外，还提供了一个简单的 Python 代码来演示其易用性。不过，该代码也可以在其他软件包（如 Excel）中实施，因为只需要进行基本的矩阵运算。交互曲面可视化可加深对多轴载荷情况下板的理解。最后，还给出了针对板材屈曲问题生成 ANN 的建议。