今日更新:International Journal of Solids and Structures 1 篇,Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 3 篇
Critical Exposure Time for Panel Paintings due to Change in Environmental Conditions
Pietro Foti, America Califano, Chao Gao, Raffaele Sepe, Chiara Bertolin, Filippo Berto
doi:10.1016/j.mechmat.2024.105234
由于环境条件的变化,面板画的关键曝光时间
Balancing the preservation of historical collections with energy consumption related to climate control is vital in museums and historical buildings to reduce carbon footprints. This is especially important for the structural integrity of hygroscopic objects like panel paintings, which are susceptible to damage from environmental changes. To address these challenges, a Finite Element (FE) hygro-mechanical-uncoupled model has been developed to assess the safety of panel paintings under changing environmental conditions, specifically changes in relative humidity (RH%) at a constant temperature (T). The model, similar to a thermal problem, uses material parameters from literature expressed consistently with RH as the driving potential. It evaluates scenarios involving panel paintings with different wood supports (Pine and Poplar) subjected to abrupt environmental changes, with or without moisture exchange through the gesso layer. This simulation approach investigates the environmental effects and their temporal evolution on panel paintings. The main outcome is the evaluation of the critical exposure time for a panel painting to experience new damage, particularly in the gesso layer, due to internal cracks.
平衡历史收藏品的保存与与气候控制相关的能源消耗对于博物馆和历史建筑减少碳足迹至关重要。这对于吸湿性物体的结构完整性尤其重要,如面板画,容易受到环境变化的破坏。为了应对这些挑战,我们开发了一个有限元(FE)湿-机械-不耦合模型,以评估在不断变化的环境条件下面板绘画的安全性,特别是在恒定温度(T)下相对湿度(RH%)的变化。该模型类似于热问题,使用文献中与RH一致的材料参数作为驱动势。它评估了不同木材支撑的面板画(松木和杨木)受到突然环境变化的影响,有或没有通过石膏层进行水分交换。这种模拟方法研究了环境对面板绘画的影响及其时间演化。主要结果是评估面板绘画经历新损伤的临界暴露时间,特别是在石膏层,由于内部裂缝。
Breaking the strength-ductility trade-off in aluminum matrix composite through "dual-metal" heterogeneous structure and interface control
Yanzhi Peng, Caiju Li, Min Song, Zunyan Xu, Chenmaoyue Yang, Qiong Lu, Liang Liu, Xiaofeng Chen, Yichun Liu, Jianhong Yi
doi:10.1016/j.ijplas.2024.104216
通过“双金属”非均质结构和界面控制打破铝基复合材料的强度-延性平衡
Heterogeneous microstructure design has been a prevalent strategy for breaking the strength-ductility dilemma in structural materials. However, it is still difficult to achieve customizable heterogeneous microstructures. Here, we employ a simple powder metallurgy method to construct "dual-metal" heterogeneous structure in aluminum matrix composite (AMC) by introducing hard high-entropy alloy particles into the soft aluminum matrix. By using mutual diffusion and self-organization strategies, reinforcements with special core-shell structures were synthesized in situ, forming multi-level heterogeneous structures within the composites. The results show that the heterogeneity of the microstructure plays an effective role in regulating the strain gradient and maintaining significant strain hardening ability during plastic deformation. In addition, the nanograin layer of the core-shell reinforcement outer shell possesses good toughness and stress-bearing capacity, enabling it to accommodate deformation and inhibit crack propagation effectively. This study provides a feasible method for designing AMCs with heterogeneous structures and contributes a conceptual framework for designing strong and ductile metal matrix composites.
非均质微结构设计已成为解决结构材料强度-延性困境的常用策略。然而,实现可定制的异质微结构仍然很困难。本文采用简单的粉末冶金方法,在软铝基体中引入硬质高熵合金颗粒,构建了铝基复合材料(AMC)的“双金属”非均相结构。利用相互扩散和自组织策略,原位合成具有特殊核壳结构的增强材料,在复合材料内部形成多层非均质结构。结果表明,在塑性变形过程中,微观组织的非均匀性对调节应变梯度和保持显著的应变硬化能力起着有效的作用。此外,核壳增强外壳的纳米颗粒层具有良好的韧性和承载能力,能够有效地容纳变形和抑制裂纹扩展。本研究为非均质结构的复合材料设计提供了一种可行的方法,并为强韧性金属基复合材料的设计提供了概念框架。
Seismic performance evaluation of a tall tower structure with integrated heat-absorbing and air-cooling capabilities: A shaking table test study
Suyang Qiao, Hao Wu, Ying Zhou, Hongxing Li, Dong Jiang, Xiaohan Wu
doi:10.1016/j.tws.2024.112863
具有吸热和风冷功能的高塔结构抗震性能评价:振动台试验研究
Solar Power Tower (SPT) system plays a pivotal role among various solar power generation methodologies. However, the heat-absorbing towers, which is a critical component within the SPT system, have garnered insufficient attention from engineering researchers. Traditional SPT systems use heat-absorbing towers primarily for supporting the heat absorber, requiring additional structures for other functions, like indirect cooling. Consequently, the budget limit associated with the SPT systems have constrained their widespread adoption. In order to address the cost-related limitations of SPT systems, a pioneering design for a heat-absorbing and air-cooling tower was proposed through finite element analysis comparison. In the proposed structural design, the horizontal components are almost omitted due to ventilation requirements. The vertical components employ shear walls oriented towards a common center, facilitating a spatial configuration. This approach not only ensures vertical support but also guarantees uniform structural stiffness in all directions. This innovative design successfully combines the functions of indirect air-cooling and vertical resistance. In this paper, the seismic performance of the proposed structure was investigated through shaking table test. A constructed 1:25 scaled model for the proposed structure was employed for the shake table test excited by two natural and one artificial earthquake ground motion records. Results demonstrate that the structural deformation exhibited by the proposed design satisfies the requirements of the Chinese standards and functional demands under earthquakes with an intensity of 8 degree. Notably, the observed damage primarily occurred at structural joints, manifesting predominantly as cracks due to bending in individual components. After major earthquakes, the structure sustained severe damage under intensity of 8 degree, but remained structurally integrity without experiencing a catastrophic collapse. Furthermore, it is imperative to emphasize that, by combing the analysis of acceleration and displacement responses along with test observations, the proposed structure display no indication of whipping or torsion effect, even in the presence of substantial mass situated atop the structure. This finding underscores the structural integrity and seismic resilience of the heat-absorbing and air-cooling tower design.
太阳能发电塔(SPT)系统在各种太阳能发电方式中起着举足轻重的作用。然而,作为SPT系统中关键部件的吸热塔却没有引起工程研究人员足够的重视。传统的SPT系统主要使用吸热塔来支撑吸热器,需要额外的结构来实现其他功能,如间接冷却。因此,与防范酷刑小组委员会系统有关的预算限制限制了它们的广泛采用。为了解决SPT系统的成本限制,通过有限元分析比较,提出了一种吸热和空气冷却塔的开创性设计。在提出的结构设计中,由于通风要求,水平构件几乎被省略。垂直组件采用朝向共同中心的剪力墙,促进空间配置。这种方法不仅保证了垂直支撑,而且保证了各个方向的均匀结构刚度。这种创新的设计成功地结合了间接风冷和垂直阻力的功能。本文通过振动台试验对该结构的抗震性能进行了研究。在两个自然地震记录和一个人工地震记录的激励下,建立了一个1:25比例模型进行了振动台试验。结果表明,设计方案的结构变形满足中国标准要求和8度地震作用下的功能要求。值得注意的是,观察到的损伤主要发生在结构接缝处,主要表现为单个部件弯曲引起的裂缝。大地震后,该结构在8度烈度下遭受了严重破坏,但没有发生灾难性的倒塌,保持了结构的完整性。此外,必须强调的是,通过结合对加速度和位移响应的分析以及测试观察,即使在结构顶部存在大量质量的情况下,所提出的结构也没有显示出鞭打或扭转效应的迹象。这一发现强调了吸热和空气冷却塔设计的结构完整性和抗震能力。
Compressive behaviour and design of rectangular concrete columns strengthened with high strength thin-walled octagonal steel tube and sandwiched ECC layer
Jiong-Yi Zhu, Jiayang Hu, Haixin Liu, Qin Yang, Yangqing Liu, Jun-Jie Zeng
doi:10.1016/j.tws.2024.112852
高强度薄壁八角形钢管夹ECC层加固矩形混凝土柱的抗压性能及设计
Traditional strengthening techniques like concrete jacketing and steel jacketing may no longer suffice to meet the demands of high-performance, efficiency, and low carbon footprint. This paper presents an experimental investigation on a novel strengthening method for reinforced concrete (RC) columns, using external thin-walled octagonal high strength steel tube and sandwiched ECC layers. The impact of steel grade, sandwiched layer material, sandwiched layer thickness, tube aspect ratio, and ECC-concrete interface roughness on the failure mode, load-bearing capacity, and strain responses of the strengthened concrete columns were explored. Uniaxial compression tests results illustrated the effectiveness of the proposed strengthening technique in utilizing the compressive strength of the steel tube and the advantages of confinement. This method resulted in a notable enhancement in load-bearing capacity, ranging from 304% to 814%, with a modest increase in section size of 51% to 140%. Furthermore, a significant improvement of up to 24% in strength was observed when comparing the strengthened column to its nominal strength. Design recommendations was provided based on the design approaches from GB 50936-2014, EN 1994-1-1:2004 and ANSI/AISC 360-22 for CFSTs. The results showed that the design approaches for circular CFSTs in EN 1994-1-1:2004 combined with the confinement coefficient for octagonal section could reasonable capture the compressive capacity of the strengthened columns.
传统的加固技术如混凝土护套和钢护套可能已经不能满足高性能、高能效和低碳足迹的要求。本文研究了一种新型的钢筋混凝土柱加固方法,即采用外薄壁八角形高强度钢管夹芯ECC加固柱。探讨了钢种、夹层材料、夹层厚度、管径比、ecc -混凝土界面粗糙度对钢筋混凝土柱破坏模式、承载力和应变响应的影响。单轴压缩试验结果表明了所提出的加固技术在利用钢管抗压强度方面的有效性和约束的优越性。这种方法显著提高了承载能力,从304%到814%不等,截面尺寸适度增加了51%到140%。此外,当将加固柱与其标称强度进行比较时,可观察到强度显著提高24%。根据GB 50936-2014、EN 1994-1-1:2004和ANSI/AISC 360-22的cfst设计方法提供了设计建议。结果表明,EN 1994-1-1:2004中圆形钢管混凝土柱的设计方法结合八角形截面约束系数能够合理地反映加固柱的抗压能力。
Development, 3D printing, and Mechanics of Novel Auxetic Unit Cell Monostructures
Celia Rufo-Martín, Diego Infante-García, José Díaz-Álvarez, María Henar Miguélez, Behrad Koohbor, George Youssef
doi:10.1016/j.tws.2024.112859
新型补体单细胞结构的发展、3D打印和力学
Complex structures with unique mechanics are pivotal to advancing additive manufacturing, enabling applications where traditional methods are impractical. This study presents a novel 3D auxetic S-shaped monostructure designed for scalability, tunability, and printability using vat photopolymerization. Unit cell geometries were fabricated and experimentally evaluated under quasi-static loading conditions, with full-field analyses providing insights into their structural performance. Benchmarking against common auxetic structures (re-entrant and star topologies) highlighted the superior capabilities of the proposed design. The S-shaped monostructures exhibited geometric insensitivity in their force-displacement responses, with a stiffness of ∼180 N/m, withstanding large displacements of 11 mm without fracture or self-contact and supporting forces up to 1.8 N (i.e., 95 times their weight) before fully recovering upon unloading. Computational and experimental results demonstrated robust spatial auxeticity, persisting up to 85% of axial global displacement due to geometry-driven rigid body motion, independent of base material properties. The S-shaped structures achieved superior auxetic performance ( ν m a x ≈ −0.43) compared to re-entrant ( ν m a x ≈ −0.30) and star ( ν m a x ≈ −0.05) counterparts, with a monotonic and reversible auxetic response throughout loading. Strain contour analyses from digital image correlation validated the reduced stress concentrations and rigid body-dominated mechanism. The exceptional auxeticity and mechanical resilience of the S-shaped monostructures suggest promising applications in advanced designs, including 3D stackable configurations for impact mitigation applications.
具有独特力学的复杂结构是推进增材制造的关键,使传统方法无法实现的应用成为可能。本研究提出了一种新颖的3D增塑型s形单结构,采用还原光聚合技术,具有可扩展性、可调性和可打印性。在准静态载荷条件下,制作并实验评估了单元胞的几何形状,并进行了现场分析,以深入了解其结构性能。对常见的辅助结构(可重入和星型拓扑)进行基准测试,突出了所建议设计的优越性能。s形单体结构在力-位移响应中表现出几何不敏感性,刚度为~ 180 N/m,在卸载后完全恢复之前,可以承受11 mm的大位移而不会断裂或自接触和高达1.8 N(即其重量的95倍)的支撑力。计算和实验结果表明,由于几何驱动的刚体运动,与基材性能无关的轴向全球位移持续高达85%,具有强大的空间互性。与重入式结构(ν ma x≈−0.30)和星形结构(ν ma x≈−0.05)相比,s形结构具有更好的辅助性能(ν ma x≈−0.43),在整个加载过程中具有单调和可逆的辅助响应。基于数字图像相关的应变轮廓分析验证了应力集中减小和刚体主导机理。s形单体结构具有优异的可塑性和机械弹性,在先进设计中具有广阔的应用前景,包括用于减缓冲击的3D可堆叠配置。