【新文速递】2024年12月29日固体力学SCI期刊最新文章

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

International Journal of Solids and Structures

A LATIN-PGD reduced order approximation dedicated to the solution of an optimal control based identification strategy for non-linear constitutive parameters

Mainak Bhattacharyya, Pierre Feissel

doi:10.1016/j.ijsolstr.2024.113189

拉丁- pgd降阶近似用于求解基于最优控制的非线性本构参数辨识策略

The objective of the research is to obtain deterministic identification of non-linear material parameters from full field measurements of kinematic data acquired from digital image correlation (DIC). The inverse problem involves proposal of the optimal control approach, considered to be a variant of modified constitutive relation error (MCRE), where the complete knowledge of the boundary conditions and the measurement data are not required. The optimisation problem essentially translates into minimisation of a quadratic functional under non-linear constraints. The non-linear optimisation is solved through the iterative large time increment (LATIN) method. A proper generalised decomposition (PGD) based reduced order approximation is also incorporated in this procedure for the sake of numerical frugality of the iterative method. Finally, a few numerical examples are depicted that establish the efficacy of the methodology.

该研究的目的是通过对数字图像相关（DIC）获得的运动数据进行现场测量，获得非线性材料参数的确定性识别。反问题涉及最优控制方法的提出，该方法被认为是修正本构关系误差（MCRE）的一种变体，其中不需要完全了解边界条件和测量数据。优化问题本质上转化为非线性约束下二次泛函的最小化。采用迭代大时间增量法求解非线性优化问题。为了使迭代方法的数值简化，在此过程中引入了适当的基于降阶近似的广义分解（PGD）。最后，通过数值算例验证了该方法的有效性。

Journal of the Mechanics and Physics of Solids

Re-interpretation of the Weibull Strength Distribution of Polycrystalline Ceramics – Characteristic Strength and Fracture Toughness

Xiaozhi Hu, Yiu-Wing Mai

doi:10.1016/j.jmps.2024.106021

多晶陶瓷威布尔强度分布的再解释——特征强度和断裂韧性

A Weibull strength distribution pertinent to micro-grain structures can be measured for a polycrystalline ceramic after the influence of micro-cracks is sufficiently suppressed (or nearly all pre-existing processing defects are less than or much less than the average grain size). We outlined the conditions for measurements of this “intrinsic” micro-grain Weibull strength distribution, and showed the characteristic strength σch, supported by a reasonably high Weibull modulus M, could be used to estimate the fracture toughness KIC without testing specimens with man-made long cracks. Fine- and coarse-grained alumina ceramics, nano-grain dental ceramic (3Y-TZP), fine- and coarse-grained transparent spinel ceramics, and nano-sized specimens of single crystal silicon were analysed by the simple statistical fracture model proposed in this study. KIC predictions from the “intrinsic” micro-grain Weibull strength distributions compared well with direct measurements from the standard test methods using specimens with man-made long cracks.

对于多晶陶瓷，在充分抑制微裂纹的影响（或几乎所有预先存在的加工缺陷都小于或远小于平均晶粒尺寸）之后，可以测量出与微晶结构相关的威布尔强度分布。我们概述了测量这种“固有”微晶威布尔强度分布的条件，并表明由合理的高威布尔模量 M 支持的特征强度 σch 可用于在不测试具有人工长裂纹的试样情况下估算断裂韧性 KIC。通过本研究中提出的简单统计断裂模型，对细晶和粗晶氧化铝陶瓷、纳米晶牙科陶瓷（3Y-TZP）、细晶和粗晶透明尖晶石陶瓷以及纳米级单晶硅试样进行了分析。从“固有”微晶威布尔强度分布预测的 KIC 与使用具有人工长裂纹的试样通过标准测试方法直接测量的结果相比，吻合良好。

Thin-Walled Structures

Seismic Design of Midspan Beam Connection of Chevron-Configured Special Concentrically Braced Frames

Qiyang Tan, Charles W. Roeder, Chen Wang, Dawn E. Lehman, Jeffrey W. Berman, Andrew D. Sen

doi:10.1016/j.tws.2024.112881

字形异形同心支撑框架跨中梁连接抗震设计

This paper reveals and addresses the misconception in capacity-based seismic design of midspan beam connections in chevron braced and multi-story X-braced frames. Under the capacity-based seismic design approach, the structural safety and reliability of concentrically braced frames are assumed to be ensured by significant yielding and inelastic deformation of fuse elements such as brace buckling, tensile yielding, and post-buckling deformation. However, under strong earthquakes, the inelastic structural response may not be as expected. In this study, parametric studies are performed to identify critical issues in the beam and midspan connection design of both chevron braced and multi-story X-braced frames. It is revealed that traditional design methods for midspan gusset connections, which rely solely on stress calculation, are insufficient for capturing the true seismic behavior, necessitating updated approaches that incorporate inelastic deformations. It is recommended to use vertical stiffeners at midspan beam connection where the beam web is thinner than the gusset plate to reduce inelastic deformations and ensure the integrity of the structure during large seismic events.

本文揭示并解决了基于能力的斜撑和多层斜撑框架跨中梁连接抗震设计中的误解。在基于能力的抗震设计方法下，同心支撑框架结构的安全性和可靠性是由支撑屈曲、拉伸屈服和屈曲后变形等融合单元的显著屈服和非弹性变形来保证的。然而，在强震作用下，结构的非弹性反应可能不像预期的那样。在本研究中，进行了参数化研究，以确定v形支撑和多层x形支撑框架的梁和跨中连接设计中的关键问题。研究表明，仅依靠应力计算的跨中扣板连接的传统设计方法不足以捕捉真实的地震行为，需要采用包含非弹性变形的更新方法。建议在梁腹板比扣板薄的跨中梁连接处采用竖向加劲筋，以减少非弹性变形，保证结构在大地震时的完整性。

Research on post-fire cold-formed steel back-to-back built-up columns with local buckling

Kai Luo, Haifeng Li, Jingjie Yang, Sibao Fang, Fengzuo Yan, Jinglei Yu, Xue Han, Yuye Xu, Xizhan Ning

doi:10.1016/j.tws.2024.112883

火灾后冷弯型钢背靠背组合柱局部屈曲研究

Cold-formed steel back-to-back built-up columns (CFS-BBC) are extensively used in lightweight steel structures because of their high load-bearing capacity and torsional stiffness. When the CFS structure suffers from a fire, some columns may still be elastic due to low-level internal force, so reusing them after the fire is very economical. However, research on evaluating the residual load-bearing capacity of CFS-BBC after fire exposure is still lacking. This study conducted experimental and finite element analyses on the post-fire local buckling behavior of CFS-BBC. Experimental research included shear tests of self-tapping screw fasteners after fire exposure and axial compression tests of post-fire CFS-BBC. Subsequently, a finite element model was developed and calibrated, and parametric analyses were carried out to extensively investigate the local buckling behavior of the CFS-BBC. Test results indicated that the ultimate load-bearing capacity of local buckling CFS-BBC was initially increased and then decreased with the heating-treatment temperatures. After exposure to 600°C, the load-bearing capacity was enhanced by within 10%. However, there was a 20% decrease in load-bearing capacity after exposure to 800°C. Based on the test and parametric analysis results, a predictive formula for the reduction factor of the post-fire local buckling load-bearing capacity of CFS-BBC was proposed. Furthermore, the coefficients in the Direct Strength Method (DSM) were modified to have a better prediction when the slenderness factor was relatively small.

冷弯型钢背对背组合柱（CFS-BBC）由于具有较高的承载力和抗扭刚度，在轻钢结构中得到了广泛的应用。当CFS结构发生火灾时，由于内力较低，一些柱仍然具有弹性，因此在火灾后重新使用它们是非常经济的。然而，关于CFS-BBC火灾后残余承载能力的评估研究仍然缺乏。本文对CFS-BBC火灾后的局部屈曲行为进行了试验和有限元分析。实验研究包括火灾后自攻螺钉紧固件剪切试验和火灾后CFS-BBC轴压试验。随后，建立并校准了有限元模型，并进行了参数化分析，广泛研究了CFS-BBC的局部屈曲行为。试验结果表明，随着热处理温度的升高，局部屈曲的CFS-BBC极限承载能力先升高后降低。暴露于600°C后，承载能力提高了10%以内。然而，暴露于800°C后，承载能力下降了20%。根据试验结果和参数分析结果，提出了CFS-BBC火灾后局部屈曲承载能力折减系数的预测公式。此外，对直接强度法（DSM）中的系数进行了修正，使其在长细系数较小时具有较好的预测效果。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年12月31日固体力学SCI期刊最新文章

今日更新：International Journal of Plasticity 1 篇，Thin-Walled Structures 1 篇International Journal of PlasticityStrategic enhancement of CoCrFeMnNi high-entropy alloy mechanical properties through a high-strength nano-scale nitride layer without geometrical or tolerance constraintsGang Hee Gu, Shin Hyun Kim, Sung-Gyu Heo, Yongju Kim, Soo-Hyun Kim, Hyeonseok Kwon, Donghwa Lee, Goo-Hwan Jeong, Yoon-Uk Heo, Dong Jun Lee, Hyoung Seop Kimdoi:10.1016/j.ijplas.2024.104235 通过无几何或公差约束的高强度纳米氮化层战略性地增强CoCrFeMnNi高熵合金的力学性能Plasma nitriding is a class of surface treatment method that improves wear, corrosion, and fatigue properties along with the benefits of excellent geometry freedom and minimal dimensional distortion. Yet, previous plasma nitriding studies related to tensile properties have mostly compromised strength or ductility mainly due to grain growth or the brittle nature of bulky micrometer-scale nitride layer. We propose a strategy to simultaneously improve mutually exclusive strength and elongation through a high-strength nano-scale nitride layer fabricated via plasma nitriding, overcoming the typical trade-off relationship; for example, ultimate tensile strength and uniform elongation were improved by ∼74.6 MPa and ∼7.9%, respectively. Using extraordinarily controlled processing parameters (e.g., low-pressure, short-time, warm-temperature), we successfully produced CoCrFeMnNi HEA with a nano-scale nitride layer of ∼291.9 nm near the surface without any change in grain size. The enhanced mechanical properties of the plasma nitrided CoCrFeMnNi HEA are attributed to the combined effects of pre-existing dislocation density, high-strength nano-scale nitride layer, and compressive residual stress. This work introduces an innovative approach to nano-scale hard regions, providing a novel framework for post-processing strategies ranging from fundamental research to various industrial applications.等离子体氮化是一种表面处理方法，可以改善磨损、腐蚀和疲劳性能，同时具有优异的几何自由度和最小的尺寸畸变。然而，先前的等离子体氮化研究与拉伸性能有关，主要是由于晶粒生长或体积庞大的微米级氮化层的脆性而损害了强度或延展性。我们提出了一种策略，通过等离子体氮化制备高强度纳米级氮化层，同时提高互斥的强度和伸长率，克服了典型的权衡关系；例如，极限抗拉强度和均匀伸长率分别提高了~ 74.6 MPa和~ 7.9%。利用非常可控的工艺参数（例如，低压、短时间、暖温度），我们成功地生产出了CoCrFeMnNi HEA，其表面附近的纳米级氮化物层为~ 291.9 nm，晶粒尺寸没有任何变化。等离子体氮化CoCrFeMnNi HEA材料力学性能的增强是位错密度、高强度纳米级氮化物层和残余压应力共同作用的结果。这项工作介绍了一种纳米级硬区域的创新方法，为从基础研究到各种工业应用的后处理策略提供了一个新的框架。Thin-Walled StructuresAutomatic assessment of CFRP-steel interfacial performance under adhesive curing using PZT-based EMI-integrated deep learning techniqueJun Deng, Xingpei Wu, Xiaoda Li, Yang Qin, Kaijin Zhongdoi:10.1016/j.tws.2024.112894基于pzt emi集成深度学习技术的cfrp -钢粘结固化界面性能自动评估Although externally bonding FRP with adhesive has been widely adopted for structural strengthening, the rapid and accurate prediction of early-age interfacial performance in CFRP-strengthened steel structures remained challenging. This study investigated the interfacial performance of CFRP-strengthened notched steel beams over curing periods ranging from 3 to 168 hours, utilizing two types of adhesives with conventional curing (CC) and rapid curing (RC) rates. Furthermore, an electromechanical impedance (EMI)-integrated deep learning (DL) approach, based on a convolutional neural network-long short-term memory-sparrow search algorithm (CNN-LSTM-SSA) model, was developed to automatically predict bond-slip characteristic parameters at various curing stages using raw EMI responses. The results revealed that the interfacial performance varied significantly and generally improved with increasing curing time. The maximum shear stress was peaked at 72 hours and 48 hours for the CC and RC series specimens, respectively, with the maximum improvement reaching 238.32% during the curing period. Moreover, the proposed model accurately predicted early-stage interfacial performance, achieving R2 values of 0.98, 0.94, and 0.97 for initial stiffness, fracture energy, and maximum shear stress, respectively. Additionally, the proposed network outperformed traditional machine learning and deep learning methods in terms of prediction accuracy, strong noise resistance (5dB), and robustness. These findings highlight the significant potential of the proposed method for the rapid and accurate estimation of early-age interfacial performance in FRP-strengthened structures.尽管外粘接FRP与粘合剂已广泛用于结构加固，但快速准确地预测FRP增强钢结构的早期界面性能仍然是一个挑战。本研究采用常规固化（CC）和快速固化（RC）两种胶粘剂，研究了cfrp增强缺口钢梁在3至168小时的固化期间的界面性能。此外，基于卷积神经网络-长短期记忆-麻雀搜索算法（CNN-LSTM-SSA）模型，开发了机电阻抗（EMI）集成深度学习（DL）方法，利用原始EMI响应自动预测不同固化阶段的粘结滑移特征参数。结果表明，随着固化时间的延长，界面性能变化明显，总体上有所改善。CC系列和RC系列试件的最大剪切应力分别在72 h和48 h达到峰值，在养护期间最大增幅达到238.32%。此外，该模型能准确预测界面早期性能，初始刚度、断裂能和最大剪应力的R2分别为0.98、0.94和0.97。此外，该网络在预测精度、强抗噪性（5dB）和鲁棒性方面优于传统的机器学习和深度学习方法。这些发现突出了该方法在快速准确估计frp增强结构早期界面性能方面的巨大潜力。来源：复合材料力学仿真Composites FEM