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【新文速递】2024年3月21日复合材料SCI期刊最新文章

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今日更新:Composite Structures 5 篇,Composites Part A: Applied Science and Manufacturing 3 篇

Composite Structures

Thermoelastic diffusion in nonlocal orthotropic medium with porosity

Abhishek Mallick, Siddhartha Biswas

doi:10.1016/j.compstruct.2024.118043

有孔隙率的非局部正交介质中的热弹性扩散

The present article investigates the linear theory of nonlocal thermoelasticity in homogeneous orthotropic porous medium with diffusion in the context of dual-phase-lag model. The focal point of the present study involves an examination of Fick’s mass diffusion law and the generalized Fourier’s law within the context of the dual-phase-lag model of hyperbolic thermoelasticity. The incorporation of voids, mass diffusion with phase lagging in the diffusion flux is the basis for establishing the void diffusion-elasticity models. Furthermore, the new dual-phase-lag diffusion model introduces the consideration of nonlocal effects in mass transfer. The resolution of the problem involves the utilization of normal mode analysis, employed for solving, and encompasses the application of thermal shock at the surface boundary. Numerical calculations of stress components, displacement components, voids, temperature, and concentration of the diffusive material are performed for various distances and time intervals.

本文以双相位滞后模型为背景,研究了均质各向同性多孔介质中具有扩散的非局部热弹性线性理论。本研究的重点是在双相滞后双曲热弹性模型的背景下研究菲克质量扩散定律和广义傅里叶定律。在扩散通量中加入空隙、相滞后的质量扩散是建立空隙扩散弹性模型的基础。此外,新的双相滞后扩散模型还引入了对传质非局部效应的考虑。问题的解决涉及利用法向模态分析进行求解,包括在表面边界施加热冲击。在不同距离和时间间隔内,对扩散材料的应力分量、位移分量、空隙、温度和浓度进行了数值计算。


Influencing mechanism on sensitivity of carbonized fabric strain sensors and modification of bridge-connection model: Comparison of three silk woven structures

Shilin Liu, Wenting Zhang, Jingzong He, Yonggen Lu, Bin Sun, Qilin Wu, Malcolm Xing

doi:10.1016/j.compstruct.2024.118041

 

碳化织物应变传感器灵敏度的影响机理及对桥接模型的修正三种丝织结构的比较

Given the great potential of carbonized fabric strain sensors in wearable devices, carbonized silk fabrics (CSF) with three characteristic woven structures including georgette (CSF-g), crepe de chine (CSF-c) and crepe satin plain (CSF-p) were employed to investigate the dependence of gauge factor (GF) on two critical parameters: initial resistance (R0) and resistance change (ΔR). The results showed that increasing carbonization temperature can effectively reduce R0 and increase GF of CSF-g, but has little effect on CSF-c and CSF-p. It was further found that the GF of both CSF-c and CSF-p were dominated by ΔR related to the crack propagation path, i.e. high sensitivity CSF was typically accompanied by dense “islands” and fine gaps, while low sensitivity CSF was accompanied by wide cracks and sparse “islands”. Accordingly, a modified bridge connection model was proposed to elucidate the relationship between crack morphology and resistance variation. This model successfully achieved continuous exponential fitting of resistance with admirable fitting goodness. Finally, the prepared sensor exhibited an ultra-high GF (916.5) and was well applied in health monitoring and thermal treatment. These efforts put forward guidance to the design and fabrication of ultrasensitive CSF strain sensors.

鉴于碳化织物应变传感器在可穿戴设备中的巨大潜力,我们采用了三种特征编织结构的碳化丝织物(CSF),包括乔其纱(CSF-g)、绉绸(CSF-c)和绉缎平纹布(CSF-p),研究了计测因子(GF)对两个关键参数的依赖性:初始电阻(R0)和电阻变化(ΔR)。结果表明,提高碳化温度可有效降低 R0 并提高 CSF-g 的 GF,但对 CSF-c 和 CSF-p 影响不大。研究还发现,CSF-c 和 CSF-p 的 GF 受与裂纹扩展路径相关的 ΔR 的支配,即高灵敏度 CSF 通常伴随着密集的 "孤岛 "和细小的间隙,而低灵敏度 CSF 则伴随着宽大的裂纹和稀疏的 "孤岛"。因此,我们提出了一个改进的桥梁连接模型,以阐明裂纹形态与电阻变化之间的关系。该模型成功地实现了电阻的连续指数拟合,拟合效果令人满意。最后,制备的传感器显示出超高的 GF 值(916.5),并在健康监测和热处理中得到了很好的应用。这些工作为设计和制造超灵敏 CSF 应变传感器提供了指导。


Mechanical behavior of interpenetrating phase composite structures based on triply periodic minimal surface lattices

Kedi Wang, Han Wang, Jiaqi Zhang, Xueling Fan

doi:10.1016/j.compstruct.2024.118044

基于三重周期性最小表面晶格的互穿相复合结构的力学行为

The triple periodic minimal surface (TPMS) structures have received widespread attention due to their excellent mechanical properties, such as high specific strength and energy absorption. However, these structures are prone to suffering catastrophic damage due to stress concentration and shear deformation in actual loading environments, affecting their load-bearing performance. In this work, interpenetrating phase composite (IPC) structures were fabricated by filling thermoplastic polyurethane (TPU) as a soft material into the diamond minimal surface structure using the multi-material fused deposition modeling technique, and their mechanical behavior was investigated numerically and experimentally. The effects of topological types and volume fractions on the performance of IPC structures were investigated. It is shown that the IPC structure undergoes stretching-dominated deformation, and its strength and toughness are significantly improved compared to the TPMS structure. Due to the addition of a complementary phase structure made of TPU, stress concentration and shear failure are reduced. The global deformation of the IPC structure and stress distribution of the TPMS phase are more uniform, effectively protecting the entire structure from catastrophic failure.

三重周期性最小表面(TPMS)结构因其出色的机械性能(如高比强度和能量吸收)而受到广泛关注。然而,这些结构在实际加载环境中容易因应力集中和剪切变形而遭受灾难性破坏,影响其承载性能。本研究采用多材料熔融沉积建模技术,将热塑性聚氨酯(TPU)作为软材料填充到金刚石最小表面结构中,制备了互穿相复合材料(IPC)结构,并对其力学行为进行了数值和实验研究。研究了拓扑类型和体积分数对 IPC 结构性能的影响。结果表明,与 TPMS 结构相比,IPC 结构发生了以拉伸为主的变形,其强度和韧性得到了显著提高。由于添加了由热塑性聚氨酯制成的互补相结构,应力集中和剪切破坏现象有所减少。IPC 结构的整体变形和 TPMS 相的应力分布更加均匀,有效地保护了整个结构免受灾难性破坏。


Strength models of near-surface mounted (NSM) fibre-reinforced polymer (FRP) shear-strengthened RC beams based on machine learning approaches

Y. Ke, S.S. Zhang, M.J. Jedrzejko, G. Lin, W.G. Li, X.F. Nie

doi:10.1016/j.compstruct.2024.118045

基于机器学习方法的近表面安装 (NSM) 纤维增强聚合物 (FRP) 抗剪加固 RC 梁强度模型

The shear strengthening of reinforced concrete (RC) beams using near-surface mounted (NSM) fibre-reinforced polymer (FRP) bars/strips has gained substantial research attention worldwide. However, owing to the complex failure mechanisms and many influencing parameters, the shear capacities of NSM FRP shear-strengthened beams are difficult to predict. Accordingly, this study adopted machine learning approaches to predict the shear capacity of strengthened beams. An experimental database was constructed comprising 130 rectangular/T-shaped beams and their 15 parameters, collected from the existing literature. Subsequently, a genetic-algorithm-improved back propagation neural network (GA-BPNN) trained with a Bayesian regularisation (BR) algorithm was employed, which was capable of giving accurate predictions on shear capacities of strengthened beams and own good generalisation ability. Furthermore, the GA-BPNN was used for parametric studies to investigate the parameter effects on the contributions of concrete, steel stirrups, and NSM FRP to the shear capacity. Finally, with reference to the GA-BPNN parametric analyses and existing models, a design-oriented strength model for calculating the shear capacities of NSM FRP shear-strengthened beams was proposed and optimised using the genetic algorithm. A comparison with existing models proved the higher prediction accuracy of the proposed strength model.

使用近表面贴装(NSM)纤维增强聚合物(FRP)条/带对钢筋混凝土(RC)梁进行剪切加固的研究在全球范围内获得了极大的关注。然而,由于复杂的破坏机制和众多的影响参数,NSM FRP 剪力加固梁的抗剪能力很难预测。因此,本研究采用机器学习方法来预测加固梁的抗剪承载力。从现有文献中收集了 130 个矩形/T 形梁及其 15 个参数,构建了一个实验数据库。随后,采用贝叶斯正则化(BR)算法训练的遗传算法改进反向传播神经网络(GA-BPNN),能够准确预测加固梁的抗剪承载力,并具有良好的泛化能力。此外,GA-BPNN 还用于参数研究,以调查参数对混凝土、钢箍筋和 NSM FRP 对剪切能力贡献的影响。最后,参考 GA-BPNN 参数分析和现有模型,提出了一个以设计为导向的强度模型,用于计算 NSM FRP 剪力加固梁的抗剪承载力,并使用遗传算法进行了优化。与现有模型的比较证明,所提出的强度模型具有更高的预测精度。


Quasi-periodic sonic black hole with low-frequency acoustic and elastic bandgaps

Hui Sheng, Meng-Xin He, Heow Pueh Lee, Qian Ding

doi:10.1016/j.compstruct.2024.118046

具有低频声带隙和弹性带隙的准周期声波黑洞

Metamaterials with the capability to control wave propagation in fluid or solid mediums have attracted plenty of fundamental scientific and engineering research in recent decades. This paper proposes a novel metamaterial, named Quasi-periodic sonic black hole (Q-SBH), to achieve both acoustic bandgap and elastic bandgap. The Q-SHB consists of two functional units: outer soft shells and inner stiff rings. The stiff rings with decaying inner radii are connected by soft shells, and the distances between rings take linear variation. The Q-SBH reserves the slow-sound effect of sonic black hole and the non-uniformly distributed rings serve as mistuning vibration absorbers. On the basis of these characteristics, broadband low-frequency acoustic and elastic bandgaps are generated simultaneously. We demonstrate the attenuation performance of the Q-SBH by theoretical, numerical and experimental methods. Parametric analysis and multi-objective optimization of the structure are carried out. The results demonstrate the great potential of the proposed Q-SBH in a broad range of physical fields requiring both air-borne noise reduction and structural vibration suppression.

近几十年来,能够控制波在流体或固体介质中传播的超材料吸引了大量基础科学和工程研究。本文提出了一种新型超材料,名为准周期声波黑洞(Quasi-periodic sonic black hole,Q-SBH),可同时实现声带隙和弹性带隙。Q-SHB 由两个功能单元组成:外部软壳和内部硬环。内半径逐渐减小的硬环由软壳连接,硬环之间的距离呈线性变化。Q-SBH 保留了声波黑洞的慢声效应,而非均匀分布的环则起到了失谐吸振的作用。在这些特性的基础上,同时产生了宽带低频声带隙和弹性带隙。我们通过理论、数值和实验方法证明了 Q-SBH 的衰减性能。我们还对该结构进行了参数分析和多目标优化。结果表明,所提出的 Q-SBH 在需要降低气载噪声和抑制结构振动的广泛物理领域具有巨大潜力。


Composites Part A: Applied Science and Manufacturing

X-ray microtomography observation of interfacial debonding in CFRP under combined loading

Yi Zhou, Ying Wang, Zheng-Ming Huang, Jian-Xiu Wang, Yan Li

doi:10.1016/j.compositesa.2024.108160

联合加载下 CFRP 的界面脱粘 X 射线显微层析观察

One of the remaining challenges for advancing the theoretical mechanics of composite materials is to describe the relationship between interfacial debonding and the mechanical properties of composites. The fiber/matrix interfacial debonding of model composites caused by combined loading has been observed by in-situ X-ray radiography and post-mortem X-ray computed tomography (CT) in this paper. Off-axis tension (fiber axis lying at 30°, 45°, 60° or 90° with respect to the loading direction) tests have been performed on carbon fiber reinforced polymer (CFRP) cruciform specimens using an in-situ loading rig. The morphological characteristics of the cracks at the interface and in the matrix are recorded. Based on our observations, the difference between interfacial debonding caused by normal tension and tangential shear stresses and their cooperative actions in composites under combined loading have been studied. This research can give insights into interfacial debonding in composites and help to build an accurate micro-mechanical model.

如何描述复合材料界面脱落与复合材料力学性能之间的关系,是推进复合材料理论力学研究的挑战之一。本文通过原位 X 射线射线照相术和死后 X 射线计算机断层扫描(CT)观察了复合材料模型在联合加载作用下产生的纤维/基体界面脱粘现象。使用原位加载装置对碳纤维增强聚合物(CFRP)十字形试样进行了离轴拉伸(纤维轴与加载方向成 30°、45°、60° 或 90°)试验。记录了界面和基体中裂纹的形态特征。根据我们的观察结果,研究了复合材料在联合加载条件下,由法向拉应力和切向剪应力引起的界面脱粘之间的差异及其协同作用。这项研究有助于深入了解复合材料中的界面脱粘现象,并有助于建立精确的微观力学模型。


Phase change composites with ultra-high through-plane thermal conductivity achieved by vertically-aligned graphite film and double-shelled microcapsules

Lei Kang, Hongyu Niu, Liucheng Ren, Ruicong Lv, Shulin Bai

doi:10.1016/j.compositesa.2024.108162

 

通过垂直排列的石墨薄膜和双壳微胶囊实现具有超高通面热导率的相变复合材料

The heat dissipation in electronic devices has become bottleneck problem. One of the best solutions is to develop high performance materials which can not only dissipate the heat away, but also absorb heat energy. This kind of double function materials can be obtained by simultaneously using high thermal conductivity (TC) materials and phase change materials. The formation of continuous network of thermally conductive fillers is demonstrated as one of the most effective methods for fabricating highly thermally conductive composites. Here, graphite films (GF) are stacked and vertically cut to endow the composites with high through-plane TC. The obtained composites exhibit a through-plane TC of 51.55 W m−1 K−1 and a low thermal resistance of 0.398 °C cm2 W−1. Besides, double-shelled PDA@SiO2@paraffin (Pa) microcapsules are embedded into the composite to give its good heat-absorption capacity. Via a CPU thermal stress test, the composites demonstrate satisfactory temperature controlling performance.

电子设备的散热已成为瓶颈问题。最好的解决方案之一就是开发既能散热又能吸收热能的高性能材料。通过同时使用高导热(TC)材料和相变材料,可以获得这种双功能材料。导热填料连续网络的形成被证明是制造高导热复合材料的最有效方法之一。在这里,将石墨薄膜(GF)堆叠并垂直切割,使复合材料具有较高的通面导热系数。所获得的复合材料具有 51.55 W m-1 K-1 的通面热导率和 0.398 °C cm2 W-1 的低热阻。此外,复合材料中还嵌入了双壳 PDA@SiO2@paraffin (Pa) 微胶囊,使其具有良好的吸热能力。通过中央处理器热应力测试,复合材料显示出令人满意的温度控制性能。


Porous nanofibers and micro-pyramid structures array for high-performance flexible pressure sensors

Tao Wang, Xue Shang, Hu Wang, Jilai Wang, Chengpeng Zhang

doi:10.1016/j.compositesa.2024.108163

 

用于高性能柔性压力传感器的多孔纳米纤维和微金字塔结构阵列

Flexible pressure sensors have attracted extensive research interest as smart wearable devices’ core components. However, developing flexible pressure sensors with high sensitivity and wide pressure detection range remains a great challenge. Utilizing electrospinning and mould transfer technology, this paper presents a novel ‘sandwich’ flexible pressure sensor composed of a sensitive layer of poly (lactic acid) (PLA) porous nanofiber network film and electrodes made of polydimethylsiloxane (PDMS) micro-pyramid structure array film. Through ultrasonic treatment, carbon black particles penetrate into the PLA porous nanofiber film, which effectively enhances the conductivity of the PLA film. Due to the complex conductive pathways formed by the ultra-high specific surface area of the PLA porous nanofibers and the three-dimensional amplification structure of the PDMS micro-pyramid arrays, the sensor has a high sensitivity of 54.06 kPa−1, a wide detection range of 0–56 kPa, an ultra-low detection limit of 2.5 Pa and excellent durability (10000 cycles). Impressively, the sensor is able to accurately monitor various physiological activities of the human body in real time, which is believed to be a strong impetus for the development of the next generation of wearable products.

柔性压力传感器作为智能可穿戴设备的核心部件,已经引起了广泛的研究兴趣。然而,开发具有高灵敏度和宽压力检测范围的柔性压力传感器仍然是一项巨大的挑战。本文利用电纺丝和模塑转移技术,提出了一种新型 "三明治 "柔性压力传感器,由聚乳酸(PLA)多孔纳米纤维网络薄膜敏感层和聚二甲基硅氧烷(PDMS)微金字塔结构阵列薄膜电极组成。通过超声波处理,炭黑颗粒渗入聚乳酸多孔纳米纤维薄膜,从而有效增强了聚乳酸薄膜的导电性。由于聚乳酸多孔纳米纤维的超高比表面积和 PDMS 微金字塔阵列的三维放大结构形成了复杂的导电通路,该传感器具有 54.06 kPa-1 的高灵敏度、0-56 kPa 的宽检测范围、2.5 Pa 的超低检测限和出色的耐用性(10000 次循环)。令人印象深刻的是,该传感器能够实时准确地监测人体的各种生理活动,相信这将有力地推动下一代可穿戴产品的开发。



来源:复合材料力学仿真Composites FEM
ACTMechanicalFluxDeform振动复合材料多孔介质电子UGECAD裂纹理论材料控制试验
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首次发布时间:2024-11-13
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【新文速递】2024年3月5日固体力学SCI期刊最新文章

今日更新:International Journal of Solids and Structures 2 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 2 篇International Journal of Solids and StructuresFatigue life prediction and energy conversion efficiency evaluation of a photovoltaic-thermoelectric device subjected to time-varying thermal and wind hybrid loadsC. Liu, Y.J. Cui, K.F. Wang, B.L. Wangdoi:10.1016/j.ijsolstr.2024.112741受时变热和风力混合负载影响的光伏热电装置的疲劳寿命预测和能量转换效率评估The photovoltaic-thermoelectric (PV-TE) device is one of the most promising pollution-free devices along with the booming demand for green electricity. The multilayered PV-TE device has poor interfacial mechanical performance and is subjected to complex cyclic loads. Thus, the interfacial stresses and crack propagation are investigated to deepen understanding of the interfacial fatigue failure mechanism of PV-TE device subjected to the time-varying thermal and wind hybrid loads. The continuity of thermo-electrical–mechanical coupled stress at the interface is fulfilled by employing the modified laminated plate theory. Equations of motion are derived by means of Hamilton’s principle and Galerkin method. It is found that the thermally induced interlaminar shear stress is much larger than the wind-induced stress. The fatigue life varies linearly with wind speed and cold side temperature of the substrate layer. The fatigue life can be prolonged by reducing thickness of the TE leg and decreasing the efficiency temperature coefficient of the PV cell. A balance between the improvements of fatigue life and energy conversion efficiency of the device can be achieved by designing a reasonable thickness of PV cell. The fatigue life and energy conversion efficiency of the device without considering heat losses from PV cell are underestimated, especially at high wind speeds. The simple but useful expressions of fatigue life and energy conversion efficiency with respect to the wind speed and environment temperature are given to guide the engineering applications.随着人们对绿色电力需求的不断增长,光伏热电(PV-TE)装置成为最有前途的无污染装置之一。多层 PV-TE 设备的界面机械性能较差,而且要承受复杂的循环负载。因此,本文研究了界面应力和裂纹扩展,以加深对 PV-TE 器件在时变热和风力混合载荷作用下的界面疲劳失效机理的理解。界面上热-电-机耦合应力的连续性是通过采用修正的层压板理论来实现的。通过汉密尔顿原理和 Galerkin 方法推导出运动方程。研究发现,热引起的层间剪切应力远大于风引起的应力。疲劳寿命随风速和基材层冷侧温度呈线性变化。通过减小 TE 脚的厚度和降低光伏电池的效率温度系数,可以延长疲劳寿命。通过设计合理厚度的光伏电池,可以在提高设备疲劳寿命和能量转换效率之间取得平衡。如果不考虑光伏电池的热损失,设备的疲劳寿命和能量转换效率就会被低估,尤其是在高风速下。本文给出了疲劳寿命和能量转换效率随风速和环境温度变化的简单而有用的表达式,以指导工程应用。Effect of hydrogen on the rate-dependent deformation of superelastic NiTi shape memory alloy springs: Experimental observation and thermo-diffusional-mechanically coupled modelHan M. Jiang, Zhenghong Fu, Kaijuan Chen, Qianhua Kan, Chao Yu, Guozheng Kangdoi:10.1016/j.ijsolstr.2024.112743氢对超弹性镍钛形状记忆合金弹簧随速率变形的影响:实验观察和热扩散力学耦合模型In practical applications, NiTi shape memory alloy (SMA) devices are often serviced in hydrogen-rich environments, leading to a significant change in their service performance. In this paper, the influence of hydrogen on the rate-dependent deformation of superelastic NiTi SMA helical springs is investigated. In the experimental aspect, electrochemical hydrogen charging is performed for the NiTi SMA springs with two different spring indexes (8.5 and 11.7). Then, multi-step tension-unloading tests with the range of loading rate from 0.1 mm/s to 10 mm/s are performed for the springs with and without hydrogen charging. Experimental results show that hydrogen charging can significantly affect the rate-dependent deformation and temperature evolution of the springs. In the theoretical aspect, a thermo-diffusional-mechanically coupled constitutive model is constructed in the framework of irreversible thermodynamics. In the proposed model, the strains associated with the elasticity, martensite transformation (MT), thermal expansion, hydrogen expansion and plasticity are taken into account. The contributions of lattice and trapped hydrogens to the total hydrogen concentration are considered. The thermodynamic driving forces of MT and plastic deformation are derived by the newly established Helmholtz free energy. The evolution of temperature is derived from the energy conservation equation and Fourier’s law. The evolution of hydrogen concentration is obtained by combining the mass conservation equation and Fick’s law. To accurately describe the deformation behavior of helical spring, a new semi-analytical model is established by addressing the thermo-diffusional-mechanical coupling effect and both the torsion and bending deformation modes. By comparing the predictions with the experimental results, the proposed model's capability to reproduce the rate-dependent deformation of NiTi SMA springs with and without hydrogen charging is validated. Moreover, the deformation behavior of the spring at a variety of loading rates during in-situ hydrogen charging is predicted.在实际应用中,镍钛形状记忆合金(SMA)器件经常在富氢环境中进行维修,导致其使用性能发生显著变化。本文研究了氢对超弹性镍钛 SMA 螺旋弹簧随速率变化的变形的影响。在实验方面,对两种不同弹簧指数(8.5 和 11.7)的镍钛 SMA 弹簧进行了电化学充氢。然后,对充氢和未充氢的弹簧进行了多步拉伸-卸载试验,加载速率范围为 0.1 mm/s 至 10 mm/s。实验结果表明,充氢会显著影响弹簧随速率变化的变形和温度变化。在理论方面,在不可逆热力学框架下构建了一个热扩散-机械耦合构成模型。在提议的模型中,与弹性、马氏体转变(MT)、热膨胀、氢膨胀和塑性相关的应变都被考虑在内。还考虑了晶格氢和捕获氢对总氢浓度的贡献。马氏体转变和塑性变形的热力学驱动力由新建立的亥姆霍兹自由能推导得出。温度的演变由能量守恒方程和傅里叶定律得出。氢浓度的演变则由质量守恒方程和菲克定律共同得出。为了准确描述螺旋弹簧的变形行为,通过解决热扩散-机械耦合效应以及扭转和弯曲变形模式,建立了一个新的半解析模型。通过将预测结果与实验结果进行比较,验证了所提出的模型能够再现镍钛 SMA 弹簧在充氢和不充氢时随速率变化的变形。此外,还预测了弹簧在原位充氢过程中各种加载速率下的变形行为。International Journal of PlasticityPlastic deformation and strengthening mechanism in CoNiV medium-entropy alloy fiberLin Deng, Ruixuan Li, Jinru Luo, Shilei Li, Xuefeng Xie, Shangshu Wu, Weiran Zhang, Peter K. Liaw, Elena A. Korznikova, Yong Zhangdoi:10.1016/j.ijplas.2024.103929 CoNiV 中熵合金纤维的塑性变形和强化机理High/medium-entropy alloys (H/MEAs) are regarded as a potentially viable alternative to conventional metallic fibers for the production of ductile, high-strength fibers, to resolve the inherent trade-off between strength and ductility. The present study involved the cold drawing technique to produce a CoNiV MEA fiber measuring 300 μm in diameter with a length of more than 3 m. The mechanical properties of the FCC matrix can be improved through the inclusion of an appropriate amount of the κ phase via the optimized thermal treatment process. In addition to a yield strength of 1681 MPa and a well-coordinated elongation of 13.4%, the ideal CoNiV fiber demonstrated a substantial ultimate tensile strength of 1932 MPa. Further calculations revealed that the κ phase, which possesses a substantial Von Mises stress of approximately 2715 MPa and an area fraction of 18.2 ±1.1%, was observed to be a primary contributor to the strength. Deformation twins were generated in the FCC matrix as a result of the ultra-high flow stress, which provided adequate ductility. This study offers significant contributions to the understanding of the deformation mechanisms and strengthening effect of the κ phase, thereby facilitating the development of high-performance metallic fibers.高/中熵合金(H/MEA)被认为是生产延展性高强度纤维的传统金属纤维的潜在可行替代品,可解决强度和延展性之间的固有权衡问题。本研究采用冷拔技术生产出直径为 300 微米、长度超过 3 米的 CoNiV MEA 纤维。除了 1681 兆帕的屈服强度和 13.4% 的协调伸长率外,理想的 CoNiV 纤维还具有 1932 兆帕的巨大极限拉伸强度。进一步的计算表明,κ相具有约 2715 兆帕的巨大 Von Mises 应力和 18.2 ±1.1% 的面积分数,是提高强度的主要因素。超高流动应力在催化裂化基体中产生了变形孪晶,从而提供了足够的延展性。这项研究为了解 κ 相的变形机制和强化效果做出了重要贡献,从而促进了高性能金属纤维的开发。Thin-Walled StructuresExperimental and numerical investigations of circular concrete filled steel double-skin and double-tube columns exposed to fireHongjie Zhu, Shicai Chen, Mizan Ahmed, Qing Quan Liangdoi:10.1016/j.tws.2024.111766暴露于火灾中的圆形混凝土填充钢双层和双管柱的实验和数值研究Circular concrete-filled steel double-tube (CFSDT) columns have shown excellent ductility and load-carrying capacity. However, research on the fire resistance of CFSDT columns is still limited. This paper presents the fire tests, finite element (FE) modeling, behavior, and design of circular CFSDT columns and concrete-filled steel double-skin (CFSDS) columns exposed to fire. The fire resistance tests of one CFSDS and six CFSDT columns are described. Analysis is given on the effects of the material strength, the thickness of the inner steel tube, and the load ratio on the fire resistance of the specimens. Finite element models are developed that simulate the fire behavior of filled composite columns with double tubes and are verified by fire test results. The verified FE models are employed to undertake parametric studies on the structural responses of CFSDS and CFSDT columns under fire exposure. A design model is proposed for calculating the fire resistances of CFSDT columns. The results show that the load ratio and the column slenderness ratio have the most significant effect on the fire resistance of CFSDT columns; the cross-sectional parameters remarkably affect the fire resistance; and the material strength has a moderate impact on the fire resistance of CFSDT columns. Compared with CFSDS specimens, the existence of the core concrete significantly increases the fire resistance of CFSDT columns. The proposed design model for fire resistance can yield a safe prediction.圆形混凝土填充钢双管(CFSDT)柱具有出色的延展性和承载能力。然而,对 CFSDT 柱耐火性的研究仍然有限。本文介绍了圆形 CFSDT 柱和混凝土填充钢双层管(CFSDS)柱在火灾中的耐火试验、有限元(FE)建模、行为和设计。论文介绍了一个 CFSDS 和六个 CFSDT 柱的耐火试验。分析了材料强度、内钢管厚度和荷载比对试样耐火性的影响。开发的有限元模型模拟了双管填充复合材料柱的防火行为,并通过防火测试结果进行了验证。利用经过验证的有限元模型,对 CFSDS 和 CFSDT 柱在火灾暴露下的结构响应进行了参数研究。提出了计算 CFSDT 柱耐火性的设计模型。结果表明,荷载比和柱细长比对 CFSDT 柱的耐火性能影响最大;截面参数对耐火性能影响显著;材料强度对 CFSDT 柱的耐火性能影响适中。与 CFSDS 试件相比,核心混凝土的存在显著提高了 CFSDT 柱的耐火性。所提出的耐火性设计模型可以进行安全预测。Nonlinear Vibrations of Porous-Hyperelastic Cylindrical Shell under Harmonic Force using Harmonic Balance and Pseudo-Arc Length Continuation MethodsJ. Zhang, W. Zhang, Y.F. Zhangdoi:10.1016/j.tws.2024.111767使用谐波平衡法和伪弧长连续法计算多孔-超弹性圆柱壳在谐波力作用下的非线性振动The resonant responses are investigated for the porous-hyperelastic Mooney-Rivlin cylindrical shell subjected to a radial harmonic excitation. Considering the higher-order shear deformation theory (HSDT), fourth-order strain-displacement relations are derived, which include the radial geometric imperfections varying along the thickness direction. Using the porous-hyperelastic Mooney-Rivlin constitution relation and Lagrange equation, the differential governing equations of motion are obtained for the porous-hyperelastic cylindrical shells. The resonant conditions are presented and the accuracy of the mathematical models is verified. The harmonic balance and pseudo-arc length continuation methods are used to obtain the amplitude-frequency and forced-amplitude curves. The stability of the solutions is analyzed by Floquet theory. The effects of the external excitation amplitudes, structure parameters and porosity infill parameters on the linear frequencies, amplitude-frequency responses and force-amplitude responses are discussed for the imperfect porous-hyperelastic cylindrical shells. The results show that the linear frequencies of the porous-hyperelastic cylindrical shells increase obviously as the uniform and sigmoid function porosity parameters reach the certain values. The increase of the structure parameters enhances the response amplitudes of the first-order mode and minified response amplitudes of the second-order mode. The decreasing porosity ratios weaken the softening nonlinear behaviors of the porous-hyperelastic cylindrical shells. With the changes of the external excitation amplitudes and structure parameters, the motion of the porous-hyperelastic cylindrical shell indicates that the synchronous vibrations occur with the period and chaotic vibrations alternately.研究了多孔-热弹性穆尼-里夫林圆柱形壳体在径向谐波激励下的共振响应。考虑到高阶剪切变形理论(HSDT),得出了四阶应变-位移关系,其中包括沿厚度方向变化的径向几何缺陷。利用多孔-热弹性穆尼-里夫林构成关系和拉格朗日方程,得到了多孔-热弹性圆柱壳的微分控制运动方程。提出了共振条件,并验证了数学模型的准确性。利用谐波平衡和伪弧长延续方法获得了振幅-频率和强迫-振幅曲线。利用 Floquet 理论分析了解的稳定性。讨论了外部激励振幅、结构参数和孔隙率填充参数对不完全多孔热弹性圆柱壳的线性频率、振幅-频率响应和力-振幅响应的影响。结果表明,当均匀孔隙率参数和 sigmoid 函数孔隙率参数达到一定值时,多孔-超弹性圆柱壳的线性频率明显增加。结构参数的增加增强了一阶模态的响应振幅,减小了二阶模态的响应振幅。孔隙率的减小削弱了多孔-超弹性圆柱壳的软化非线性行为。随着外部激励振幅和结构参数的变化,多孔-超弹性圆柱壳的运动显示出周期振动和混沌振动交替出现的同步振动。来源:复合材料力学仿真Composites FEM

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