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【新文速递】2024年6月9日复合材料SCI期刊最新文章

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今日更新:Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 2 篇

Composites Part A: Applied Science and Manufacturing

Intelligently optimized arch-honeycomb metamaterial with superior bandgap and impact mitigation capacity

Sihao Han, Nanfang Ma, Haokai Zheng, Qiang Han, Chunlei Li

doi:10.1016/j.compositesa.2024.108298

智能优化的拱形蜂窝超材料,具有优越的带隙和抗冲击能力

Engineering applications concurrently face challenges related to vibration, impact, load-bearing and energy absorption. Here, an arch-honeycomb metamaterial with split-ring resonators is proposed for wave attenuation and impact mitigation, with better energy absorption and lower initial peak stress. The split-ring resonators effectively induce bandgaps below 3kHz, and the mechanisms of bandgap generation and polarization are studied through mode shapes, frequency contours and equivalent mass densities. Subsequently, a machine learning-based optimization framework is introduced to tailor the bandgaps, leading to a 155.59% increase in bandgap width. Furthermore, superior vibration isolation and impact mitigation are confirmed through experiments. Obvious attenuation peaks are observed in the bandgaps of the acceleration transmission spectrum in frequency domain. In time domain, the impact test demonstrates peak weakening and delay. The metamaterials offer advantages in wave attenuation, impact mitigation, load-bearing and energy absorption, providing valuable insights for the advancement of multifunctional metamaterials and their practical engineering applications.

工程应用同时面临着与振动、冲击、承载和能量吸收相关的挑战。本文提出了一种具有劈裂环谐振腔的拱形蜂窝超材料,该材料具有较好的能量吸收和较低的初始峰值应力,可用于波衰减和冲击缓解。劈裂环谐振器可有效诱导3kHz以下的带隙,并通过模态振型、频率轮廓和等效质量密度研究了带隙产生和极化机理。随后,引入了基于机器学习的优化框架来定制带隙,导致带隙宽度增加了155.59%。通过实验验证了该结构具有良好的隔振和减振效果。在频域加速度传输谱带隙中观察到明显的衰减峰。在时域上,冲击试验表现出峰值减弱和延迟。超材料在波衰减、冲击缓解、承载和能量吸收方面具有优势,为多功能超材料的发展及其实际工程应用提供了宝贵的见解。


Composites Part B: Engineering

The key role of water on the transformation of the precursors to nano-crystalline C–S–H

Xuyan Shen, Pan Feng, Qi Zhang, Yuxi Cai, Chen Chen, Xueqin Han, Weiwei Zhu, Jinxiang Hong, Jian Chen

doi:10.1016/j.compositesb.2024.111601

水对前驱体向纳米晶C-S-H转变的关键作用

The mechanism of multi-step nucleation, which means that a precursor phase exists before the formation of the final crystal, has undergone significant development as an advanced strategy for the production of high-performance structural materials and the mitigation of carbon emissions. This study investigated the potential transformation of C–S–H precursors in water, 98 % RH, and high-temperature environments. The findings suggest that C–S–H precursors, produced by disrupting the two-step nucleation process, can transform in both aqueous and 98%RH conditions, while high temperature alone is insufficient to induce the transformation. The progress of the transformation under 98%RH was impeded by the limited mass transport resulting from the constrained formation of nano-crystalline C–S–H in adsorbed water on the external surface and the pores. This study emphasizes the crucial role of water in facilitating the transformation process, presenting potential opportunities for the nanoengineering of C–S–H-based composites and cementitious materials.

作为生产高性能结构材料和减少碳排放的先进策略,多步成核机制(即在最终晶体形成之前存在前驱相)已经取得了重大进展。本研究考察了C-S-H前体在水、98% RH和高温环境下的潜在转化。研究结果表明,通过破坏两步成核过程产生的C-S-H前体可以在水溶液和98%RH条件下转化,而仅高温不足以诱导转化。在98%RH条件下,由于外表面和孔隙中吸附的纳米晶C-S-H的形成受到限制,导致质量传递受限,从而阻碍了相变的进行。该研究强调了水在促进转化过程中的关键作用,为碳硫氢基复合材料和胶凝材料的纳米工程提供了潜在的机会。


Versatile Hybrid Transparent Triboelectric Nanogenerator-Solar Cell Device Enables Efficient Energy Harvesting and Personal Handwriting Recognition

Zahra Razaghi, Fahimeh Zamanpour, Mohaddeseh Vafaiee, Mehdi Letafati, Mostafa Gholami, Nima Taghavinia, Babak Hossein Khalaj, Raheleh Mohammadpour, Azam Iraji zad

doi:10.1016/j.compositesb.2024.111615

 

多功能混合透明摩擦电纳米发电机-太阳能电池装置实现高效的能量收集和个人手写识别

The continuous energy supply for wearable electronic devices, including health monitoring sensors and human-machine interface devices, poses a significant challenge to their development. Renewable energy sources, such as nanogenerators and solar cells, offer promising solutions to this challenge. In this study, we explore the potential of a versatile device based on a smart hybrid triboelectric nanogenerator (SH TENG) and photovoltaic (PV) cell for efficient energy harvesting and personal handwriting recognition. A transparent, self-cleaning, UV-protective, bidirectional, non-rigid, lightweight, ultra-durable, eco-friendly, and uniform composite of epoxy resin/ZnO/Ag nanowires-based sandwich-like TENG can produce a power density of 2.3 W.m-2. Integrating SH TENG with PV led to improved energy harvesting and increased the charging voltage of the capacitor by up to 5 times. Moreover, this material is a multifunctional sensor capable of detecting temperature, humidity, pressure, handwriting content, and the writer. These features make it an intriguing candidate for e-skin applications. By employing a generalized deep neural network (DNN) model, our device can accurately recognize handwritten letters, numbers, and personal identification with a high level of precision, achieving an accuracy of 97%. This device can function as an intelligent touch screen with dual-purpose energy production and detection, paving the way for developing highly efficient and sustainable wearable electronic devices.

包括健康监测传感器和人机界面设备在内的可穿戴电子设备的持续能源供应对其发展提出了重大挑战。可再生能源,如纳米发电机和太阳能电池,为这一挑战提供了有希望的解决方案。在这项研究中,我们探索了一种基于智能混合摩擦电纳米发电机(SH TENG)和光伏(PV)电池的多功能设备的潜力,用于高效的能量收集和个人手写识别。一种透明、自清洁、防紫外线、双向、非刚性、轻质、超耐用、环保、均匀的环氧树脂/ZnO/Ag纳米线复合三明治状TENG可产生2.3 w .m . 2的功率密度。将SH TENG与光伏相结合,提高了能量收集,并将电容器的充电电压提高了5倍。此外,该材料是一种多功能传感器,能够检测温度、湿度、压力、手写内容和书写器。这些特性使它成为电子皮肤应用程序的一个有趣的候选者。通过采用广义深度神经网络(DNN)模型,我们的设备可以准确识别手写字母、数字和个人身份,精度很高,准确率达到97%。该装置可作为智能触摸屏,具有能量产生和检测的双重功能,为开发高效、可持续的可穿戴电子设备铺平了道路。


来源:复合材料力学仿真Composites FEM
ACT振动复合材料电子ADSUGUM电机化机Electric材料太阳能试验
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首次发布时间:2024-11-20
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【新文速递】2024年5月6日复合材料SCI期刊最新文章

今日更新:Composite Structures 7 篇,Composites Part B: Engineering 3 篇,Composites Science and Technology 1 篇Composite StructuresAdaptive deep homogenization theory for periodic heterogeneous materialsJiajun Wu, Qiang Chen, Jindong Jiang, George Chatzigeorgiou, Fodil Meraghnidoi:10.1016/j.compstruct.2024.118171周期性非均质材料的自适应深度均质理论We present an adaptive physics-informed deep homogenization neural network (DHN) approach to formulate a full-field micromechanics model for elastic and thermoelastic periodic arrays with different microstructures. The unit cell solution is approximated by fully connected multilayers via minimizing a loss function formulated in terms of the sum of residuals from the stress equilibrium and heat conduction partial differential equations (PDEs), together with interfacial traction-free or adiabatic boundary conditions. In comparison, periodicity boundary conditions are directly satisfied by introducing a network layer with sinusoidal functions. Fully trainable weights are applied on all collocation points, which are simultaneously trained alongside the network weights. Hence, the network automatically assigns higher weights to the collocation points in the vicinity of the interface (particularly challenging regions of the unit cell solution) in the loss function. This compels the neural networks to enhance their performance at these specific points. The accuracy of adaptive DHN is verified against the finite element and the elasticity solution respectively for elliptical and circular cylindrical pores/fibers. The advantage of the adaptive DHN over the original DHN technique is justified by considering locally irregular porous architecture where pore–pore interaction makes training the network particularly slow and hard to optimize.我们提出了一种自适应物理信息的深度均匀化神经网络(DHN)方法来建立具有不同微观结构的弹性和热弹性周期阵列的全场微观力学模型。通过最小化由应力平衡和热传导偏微分方程(PDEs)的残差总和以及界面无牵引力或绝热边界条件所表示的损失函数,完全连接的多层近似表示单元胞解。相比之下,引入带正弦函数的网络层可以直接满足周期性边界条件。在所有的并置点上应用完全可训练的权值,并与网络权值同时训练。因此,网络自动为损失函数中界面附近的配点(特别是具有挑战性的单元胞解区域)分配更高的权重。这迫使神经网络在这些特定点上增强其性能。分别针对椭圆孔/纤维和圆筒形孔/纤维的有限元和弹性解验证了自适应DHN的准确性。考虑到局部不规则的孔隙结构,使得训练网络特别缓慢且难以优化,自适应DHN技术优于原始DHN技术。Modeling of thin-walled edge cutting angle in end milling of honeycomb coresChao Li, Chunzheng Duan, Chao Wang, Xiaodong Tian, Longyun Yang, Xiaochen Li, Shaoshuai Yuandoi:10.1016/j.compstruct.2024.118173蜂窝芯端铣薄壁刃口切削角建模Thin-walled edge cutting angle (TWECA) refers to a unique trait of honeycomb core materials in the course of cutting, which is also a main influencing factor for the surface quality of machining. To validly overcome machining defects, making accurate TWECA prediction during the cutting process is necessary. In this study, a TWECA model for various kinds of thin-walled edges was proposed. Firstly, the thin-walled edges composing honeycomb cores were classified and unified based on the structural features of the cores, which lays the foundation for the modeling of honeycomb core architecture as well as the TWECA prediction. Then, the geometric relationships between tool and various types of thin-walled edges during contact were analyzed, and the differences in TWECAs of thin-walled edges in different tool feed directions were explored. Finally, the TWECA model accuracy was validated by using the tool mark characteristics on the machined surface as the research target. As demonstrated by findings of this research, our model achieves accurate TWECA forecasting during cutting process, thus providing a theoretical foundation for the requirements of low-damage and high-quality machining.薄壁边缘切削角(TWECA)是蜂窝芯材料在切削过程中所具有的一种独特特性,也是影响加工表面质量的主要因素。为了有效地克服加工缺陷,在切削过程中进行准确的TWECA预测是必要的。本文提出了一种适用于各种薄壁边缘的TWECA模型。首先,根据蜂窝芯的结构特征,对蜂窝芯构成的薄壁边缘进行分类统一,为蜂窝芯结构建模和TWECA预测奠定基础;然后,分析了刀具与不同类型薄壁边缘在接触过程中的几何关系,探讨了不同刀具进给方向薄壁边缘TWECAs的差异。最后,以加工表面刀具刻痕特征为研究目标,验证了TWECA模型的精度。研究结果表明,该模型在切削过程中实现了准确的TWECA预测,为实现低损伤、高质量加工的要求提供了理论依据。Detection of edge delamination in composite laminates using edge wavesJinhang Wu, Chang Jiang, Ching-Tai Ng, Han Fangdoi:10.1016/j.compstruct.2024.118177利用边缘波检测复合材料层合板的边缘分层Detecting near-edge damage in composite structural elements using guided wave-based techniques can be challenging, primarily due to the complexity of wave analysis arising from material anisotropy. Furthermore, scattered waves containing damage information can be contaminated by waves reflected from the edges, which makes detecting near-edge damage difficult to implement. In the literature, studies showed that in elastic materials, the edge of a structure can serve as a waveguide, enabling the existence of typical edge modes with concentrated energy at the edge. However, studies regarding edge waves in composite structures have received limited attention. This paper aims to explore the potential of detecting edge delamination damage in composite laminates using edge waves. The modal properties of edge waves in [(0/90)2]s composite laminates are investigated using the Semi-Analytical Finite Element (SAFE) method. Additionally, dispersion curves for quasi-isotropic composite laminates are calculated. Following this, numerical and experimental studies were conducted to investigate the sensitivity of edge waves in detecting edge delamination in the [(0/90)2]s composite laminates. The outcomes of this study offer physical insights into the modal properties of edge waves and confirm their effectiveness in detecting damage near the edges.利用导波技术检测复合材料结构元件的近边缘损伤具有挑战性,主要是由于材料各向异性引起的波分析的复杂性。此外,包含损伤信息的散射波可能被边缘反射波污染,这使得近边缘损伤检测难以实现。文献研究表明,在弹性材料中,结构的边缘可以作为波导,使得边缘存在能量集中的典型边缘模式。然而,关于复合材料结构中边缘波的研究却受到了有限的关注。本文旨在探讨利用边缘波检测复合材料层合板边缘脱层损伤的潜力。采用半解析有限元法研究了[(0/90)2]s复合材料层合板边缘波的模态特性。此外,计算了准各向同性复合材料层合板的色散曲线。在此基础上,对边缘波在[(0/90)2]s复合材料层合板边缘分层检测中的灵敏度进行了数值和实验研究。本研究的结果提供了对边缘波模态特性的物理见解,并证实了它们在检测边缘附近损伤方面的有效性。Repeated loading damage analysis of thin-walled composite shell for lighter structural designHonghao Liu, Lei Zu, Qian Zhang, Ping Ren, Guiming Zhang, Jianhui Fu, Helin Pan, Qiaoguo Wu, Huabi Wang, Debao Li, Lichuan Zhoudoi:10.1016/j.compstruct.2024.118178面向轻量化结构设计的薄壁复合材料壳体重复载荷损伤分析The composite shell is one of the crucial components of solid rocket motors. Its design goal is to reduce the shell mass as much as possible while ensuring technical and cost requirements. This paper proposes a damage analysis method for the thin-walled composite shell secondary loading process based on a refined finite element model to verify the damage caused by the thin-walled composite shell secondary loading process and the performance decline of the shell and to assist in the lightweight design of the thin-walled composite shell. The shell’s damage failure state and crack propagation path are analyzed by establishing the acceptable finite element model and introducing the damage failure criterion and the stiffness degradation model. Based on the model, the damage state of the shell during the secondary loading process is described, and it is determined that the re-loading has little effect on the blasting performance of the shell. For composite shells used in small quantities, the effects of damage due to initial loading can be of no concern during design. This method can provide a theoretical basis for thin-walled composite shell safety factor selection and damage state assessment to achieve the thin-walled composite shell lightweight design goal.复合壳体是固体火箭发动机的关键部件之一。其设计目标是在保证技术和成本要求的同时,尽可能减少壳体质量。本文提出了一种基于精细化有限元模型的薄壁复合材料壳体二次加载过程损伤分析方法,以验证薄壁复合材料壳体二次加载过程造成的损伤和壳体性能下降情况,为薄壁复合材料壳体的轻量化设计提供辅助。通过建立可接受有限元模型,引入损伤破坏准则和刚度退化模型,分析了壳体的损伤破坏状态和裂纹扩展路径。基于该模型,描述了二次装填过程中炮壳的损伤状态,确定了二次装填对炮壳爆破性能影响不大。对于少量使用的复合材料壳体,在设计过程中可以不考虑初始载荷的损伤影响。该方法可为薄壁复合材料壳体的安全系数选择和损伤状态评估提供理论依据,实现薄壁复合材料壳体轻量化设计目标。Shear behavior of circular concrete short columns reinforced with GFRP longitudinal bars and CFRP grid stirrupsJinJing Liao, Bo Di, Yu Zheng, Zhi-Wen Xuan, Jun-Jie Zengdoi:10.1016/j.compstruct.2024.118181GFRP纵筋和CFRP格栅箍加固圆形混凝土短柱的抗剪性能Although fiber-reinforced polymer (FRP) reinforcements have become popular, the post-pultrusion bending leads to significant deficiency in bent portions. This study adopts flexible carbon FRP (CFRP) grids as stirrups, and investigates the shear behavior of circular short columns reinforced with GFRP bars and CFRP grid stirrups. Six specimens with different shear reinforcement ratios, axial load ratios and types of stirrups (CFRP grids and steel hoops) were tested to shear failures. The failure models, crack and strain developments, and shear load-horizontal displacement responses are presented for discussion. All specimens experienced shear-compression failures, and the critical diagonal crack widths increased approximately linearly with shear loads. The typical shear load-horizontal displacement curve consists of three branches: a linear elastic branch, a cracking branch with progressive slope deteriorations, and an almost flat failure branch. Increasing CFRP grid stirrup ratio could not only enhance strength and ductility performances, but also alleviate the slope degradations, while increasing axial load ratio could enhance the initial cracking load, restrain crack propagations, and reduce the lateral displacements. In terms of strength performance, steel hoops can be replaced by CFRP grid stirrups even with smaller stirrup ratio. Additionally, analytical investigations suggested that the effective stresses and strains of CFRP grids at failure may be lower than code limits.尽管纤维增强聚合物(FRP)增强材料已成为流行,但拉挤后弯曲导致弯曲部分显着不足。本研究采用柔性碳纤维布(CFRP)格栅作为箍筋,研究了碳纤维布筋和碳纤维布格栅箍筋加筋圆形短柱的抗剪性能。对6个具有不同抗剪配筋率、轴向载荷比和不同箍筋类型(CFRP格栅和钢箍)的试件进行了抗剪破坏试验。提出了破坏模型、裂缝和应变发展以及剪切荷载-水平位移响应的讨论。所有试件均经历剪切压缩破坏,且临界斜缝宽度随剪切荷载近似线性增加。典型的剪切荷载-水平位移曲线包括三个分支:线弹性分支、边坡逐步退化的开裂分支和几乎平坦的破坏分支。增加碳纤维布格筋比不仅可以提高强度和延性,还可以缓解边坡的退化,而增加轴向荷载比可以提高初始开裂荷载,抑制裂缝扩展,减小侧向位移。在强度性能方面,即使箍比较小,碳纤维布格栅箍也可以代替钢箍。此外,分析研究表明,CFRP网格在破坏时的有效应力和应变可能低于规范限值。Dynamic stability analysis of laminated cylindrical shells considering fluid–structure interactionJihang Feng, Yongfu Wu, Jianghong Xue, Jixin Lindoi:10.1016/j.compstruct.2024.118183考虑流固耦合的层合圆柱壳动力稳定性分析This paper investigates the dynamic stability of laminated cylindrical shell submerged in a fluid. Assuming that the fluid is incompressible satisfying the Laplace equation, the coupling relationship between the external pressure from fluid acting on the cylindrical shell and the velocity potential function of the fluid is deduced by using Bernoulli law. Based on Kárman-Donnell’s thin shell theory, the governing equations for dynamic buckling of the composite laminated cylinder are established by introducing the constitutive relationship for laminated composite structures. Likely functions of the displacement and the stress function for cylindrical shell are proposed to construct Mathieu-Hill equation for dynamic stability of laminated cylindrical shell with fluid–structure interaction and the first three order dynamic instability regions are derived. A good agreement between the solutions from the proposed analysis and from the available literatures justified the accuracy and validity of the proposed analysis. With the established analysis, the influence of various parameters on the dynamic stability of cylinders are analyzed, from which a dynamic stability enhancement scheme suitable for composite laminated cylinders is summarized. It is found that the fluid–structure interaction will greatly reduce the excitation frequency of laminated cylindrical shells but has no effect on their vibration modes.本文研究了层合圆柱壳在流体中的动力稳定性。假设流体是不可压缩的,满足拉普拉斯方程,利用伯努利定律推导了作用于圆柱壳的流体的外压力与流体的速度势函数之间的耦合关系。以Kárman-Donnell薄壳理论为基础,引入复合材料层合结构的本构关系,建立了复合材料层合圆柱体动态屈曲的控制方程。提出了柱壳的位移函数和应力函数的似然函数,建立了流固耦合作用下层合柱壳动力稳定的Mathieu-Hill方程,并推导出了层合柱壳的前三阶动力不稳定区域。所提分析的解与现有文献的解之间的良好一致性证明了所提分析的准确性和有效性。在此基础上,分析了各参数对复合材料复合气瓶动力稳定性的影响,总结出适合复合材料复合气瓶的动力稳定性增强方案。研究发现,流固耦合作用会大大降低层合圆柱壳的激振频率,但对层合圆柱壳的振动模态没有影响。Effect of BFRP ties on the axial performance of RC columns reinforced with BFRP and GFRP rebarsFarid Abed, Nour Ghazal Aswad, Khaled Obeidatdoi:10.1016/j.compstruct.2024.118184BFRP筋对BFRP筋和GFRP筋配筋RC柱轴向性能的影响The adoption of fiber-reinforced polymer (FRP) bars in lieu of traditional steel reinforcement for concrete structures has gained prominence. Nevertheless, prevailing international standards have not incorporated provisions to assess the significant contribution of FRP materials to the axial capacity and deformability of compression members. This study investigates the impact of Basalt (BFRP) ties on the axial performance of full-scale concrete columns reinforced with BFRP and Glass (GFRP) rebars, alongside traditional steel longitudinal rebars. Ten columns were subjected to concentric loading, with parameters including the type of longitudinal rebars (BFRP, GFRP, and steel), spacing of BFRP ties (180 mm, 120 mm, and 60 mm), and diameter of steel rebars (16 mm and 20 mm). Varied steel rebar diameters aimed to discern the influence of axial stiffness on column behavior. Results indicate an 18 % to 26 % higher axial load capacity in steel-reinforced concrete (RC) columns compared to FRP-RC columns. Both types of FRP rebars contributed approximately 12 % to the axial capacity. Reducing BFRP tie spacing from 180 mm to 60 mm significantly increased deformability by up to 250 % in FRP-RC columns and ductility by up to 14 % in steel-RC columns. The study highlights conservative predictions in existing design equations (ACI 440.11–22 and CSA S806-12) for the axial load capacity of BFRP and GFRP RC columns, underestimating by 14 % to 20 %, as they neglect the contribution of FRP rebars. Utilizing a concrete crushing strain of 3,000 µε and 3,500 µε as the ultimate FRP compressive strain produced predictions closest to the experimental axial load capacity采用纤维增强聚合物(FRP)钢筋代替传统的钢筋用于混凝土结构已得到重视。然而,现行的国际标准并没有纳入规定来评估FRP材料对受压构件的轴向能力和变形能力的重大贡献。本研究探讨了玄武岩(BFRP)绑扎对BFRP和玻璃(GFRP)钢筋加筋的全尺寸混凝土柱轴向性能的影响,以及传统的纵向钢筋。对10根柱进行同心加载,参数包括纵向钢筋类型(BFRP、GFRP和钢材)、BFRP筋间距(180 mm、120 mm和60 mm)和钢筋直径(16 mm和20 mm)。不同的钢筋直径旨在辨别轴向刚度对柱性能的影响。结果表明,钢-钢筋混凝土(RC)柱的轴向承载力比FRP-RC柱高18 %至26 %。两种FRP筋对轴向承载力的贡献约为12% %。将BFRP筋间距从180 mm减少到60 mm,可显著提高FRP-RC柱的变形能力高达250 %,钢- rc柱的延性高达14 %。该研究强调了现有设计方程(ACI 440.11-22和CSA S806-12)对BFRP和GFRP RC柱轴向承载能力的保守预测,低估了14% %至20% %,因为它们忽略了FRP筋的贡献。利用混凝土破碎应变为3000µε和3500µε作为FRP极限压缩应变,得出的预测结果最接近实验轴向载荷能力Composites Part B: EngineeringMicro-CT image-based computation of effective thermal and mechanical properties of fibrous porous materialsDonglai Liu, Hailong Chen, Luis A. Chacon, Vijay Mohan Ramu, Savio J. Poovathingaldoi:10.1016/j.compositesb.2024.111502基于微ct图像的纤维状多孔材料有效热力学性能计算Fibrous porous materials are extensively employed as heat shielding material for space vehicles and capsules. To predict the performance of these materials using computational modeling at the vehicle/capsule scale, the effective material properties are needed. In this work, the effective thermal conductivity and elastic constants of a carbon fibrous porous material called FiberForm (precursor of PICA) were calculated using a direct image-based approach. In this image-based approach, the microstructures obtained using X-ray computed tomography technique are represented as binary voxel data. Nonlocal interactions are introduced between neighboring voxels. Integro-differential equations, with respect to spatial and temporal dimensions respectively, are developed to govern material thermal and mechanical behaviors. Using this approach, energy-based computational procedures were developed to calculate the effective material properties of fibrous and porous materials irrespective of the periodicity of underlying microstructures. The size of representative volume element was determined by convergence of effective properties with respect to microstructure size.纤维多孔材料作为航天飞行器和太空舱的热屏蔽材料得到了广泛的应用。为了在车辆/胶囊尺度上使用计算模型预测这些材料的性能,需要有效的材料特性。在这项工作中,使用基于直接图像的方法计算了碳纤维多孔材料FiberForm (PICA前体)的有效导热系数和弹性常数。在这种基于图像的方法中,使用x射线计算机断层扫描技术获得的微观结构被表示为二值体素数据。相邻体素之间引入了非局部相互作用。积分微分方程,分别相对于空间和时间维度,开发来控制材料的热和力学行为。利用这种方法,开发了基于能量的计算程序来计算纤维和多孔材料的有效材料性能,而不考虑底层微观结构的周期性。代表性体积元的尺寸由有效性能对微观结构尺寸的收敛决定。Insight into annealing-induced hardening and softening behaviors in a laser powder-bed fusion printed in-situ composite eutectic high-entropy alloyYinuo Guo, Haijun Su, Hongliang Gao, Zhonglin Shen, Peixin Yang, Yuan Liu, Di Zhao, Zhuo Zhang, Min Guodoi:10.1016/j.compositesb.2024.111523 激光粉末床熔印原位复合共晶高熵合金退火诱导硬化和软化行为的研究Laser powder-bed fusion (LPBF) printed AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) typically exhibits an in-situ composite structure with an out-of-equilibrium character. Its distinctive hierarchical microstructure implies the potential challenges and opportunities in engineering advanced materials with high performances. Here, an informative overview of the microstructure evolution across various scales and its effect on tensile properties in LPBFed AlCoCrFeNi2.1 subjected to annealing treatments over a wide temperature range is discussed. Microstructural observations indicate that spinodal decomposition within the B2 lamellae becomes evident after annealing at 500 °C, marked by a pronounced compositional fluctuation of Cr. Annealing the sample at 600 °C leads to the precipitation of BCC nanoparticles through structural disordering of Cr-rich regions within the modulated nanostructure. Tensile tests and strengthening models reveal that the annealing-induced hardening responses are largely associated with precipitation strengthening resulting from the ordering strengthening of L12 nanoprecipitates and the coherency and modulus strengthening of BCC nanoprecipitates, as well as the spinodal hardening from modulated nanostructure. Notably, BCC precipitation strengthening plays a crucial role in enhancing the strength of the annealed alloys. A strong precipitation strengthening effect is realized due to the coarsening of the BCC and L12 nanoprecipitates at 600 °C, and the strengthening effect from BCC precipitates gradually weakens as their dissolution at 650 °C, resulting in abnormal hardening behavior. Upon annealing at higher temperatures (700 ∼ 1000 °C), phase decomposition, precipitation dissolution, even recrystallization occur sequentially, resulting in varying degrees of softening behaviors.激光粉末床熔合(LPBF)打印的AlCoCrFeNi2.1共晶高熵合金(EHEA)具有典型的非平衡原位复合结构。其独特的层次化微观结构意味着高性能工程先进材料的潜在挑战和机遇。本文讨论了LPBFed AlCoCrFeNi2.1在大温度范围内退火后的微观结构演变及其对拉伸性能的影响。微观结构观察表明,在500℃退火后,B2片层内出现明显的spinodal分解,Cr的成分出现明显的波动。在600℃退火后,BCC纳米颗粒通过在调制的纳米结构中富Cr区域的结构紊乱而析出。拉伸试验和强化模型表明,退火诱导的硬化响应主要与L12纳米相的有序强化、BCC纳米相的相干性和模量强化引起的析出强化以及调制纳米结构引起的spinodal硬化有关。值得注意的是,BCC析出强化在提高退火合金的强度方面起着至关重要的作用。600℃时,BCC和L12纳米相的析出强化作用较强,而650℃时,BCC析出的强化作用随着溶解逐渐减弱,导致异常硬化行为。在较高温度(700 ~ 1000℃)退火后,依次发生相分解、析出溶解、甚至再结晶,导致不同程度的软化行为。ROS-scavenging bioactive scaffold orchestrates bone regeneration for osteoporotic bone defect repairXiao Liang, Xindi Yang, Jing Liu, Lingfeng Tu, Wenxiang Wei, Hanjian Wang, Minhao Wu, Lin Cai, Yong Zheng, Yun Chendoi:10.1016/j.compositesb.2024.111528活性氧清除生物活性支架组织骨再生用于骨质疏松性骨缺损修复The repair of osteoporotic bone defects, particularly those with irregular shapes, remains a significant challenge due to insufficient bone regeneration and an abnormal level of reactive oxygen species (ROS), which impairs the balance of bone remodeling. Materials that intrinsically regulate ROS to rebalance the activation of osteoblasts and osteoclasts represent a highly desirable alternative to current grafting strategies for the management of osteoporotic defects. Inspired by the tea polyphenols and natural extracellular matrix of bone tissue, a novel biomimetic composite scaffold, the epichlorohydrin-crosslinked hydroxyethyl cellulose/soy protein isolate/polydopamine-coated hydroxyapatite composite sponge (EHSS/PHA) scaffold was designed to orchestrate bone-forming bone marrow mesenchymal stem cells (BMSCs) and bone-resorbing osteoclasts for the rejuvenation of osteoporotic bone defect repair. Benefiting from the distinctive capabilities of the EHSS/PHA, including scavenging active oxygen and osteoinduction, we found that the EHSS/PHA could inhibit the formation of osteoclasts and promote osteogenesis of BMSCs by up-regulating the ratio of Opg/Rankl and activating the β-catenin signaling pathway in an oxidative stress environment. With its antioxidant ability, osteogenic, and self-deploying capability, EHSS/PHA effectively promoted the repair of tibial defects in osteoporotic rats by removing excess reactive oxygen species at the defect site. Taken together, this work presents the EHSS/PHA with multifunctional properties that provide new insight into osteoporotic bone defects.由于骨再生不足和活性氧(ROS)水平异常,破坏了骨重塑的平衡,骨质疏松性骨缺损的修复,特别是那些不规则形状的骨缺损的修复仍然是一个重大挑战。从本质上调节活性氧以重新平衡成骨细胞和破骨细胞的激活的材料是目前治疗骨质疏松症缺陷的移植策略的一个非常理想的选择。受茶多酚和骨组织的天然细胞外基质的启发,设计了一种新型仿生复合支架,环氧氯丙烷交联羟乙基纤维素/大豆分离蛋白/聚多巴胺包被羟基磷灰石复合海绵(EHSS/PHA)支架,用于协调骨形成骨髓间充质干细胞(BMSCs)和骨吸收破骨细胞,以恢复骨质疏松性骨缺损修复。由于EHSS/PHA具有清除活性氧和诱导成骨的独特能力,我们发现EHSS/PHA在氧化应激环境下可以通过上调Opg/Rankl的比例和激活β-catenin信号通路,抑制破骨细胞的形成,促进骨髓间充质干细胞成骨。EHSS/PHA具有抗氧化能力、成骨能力和自展能力,通过清除缺损部位多余的活性氧,有效促进骨质疏松大鼠胫骨缺损的修复。综上所述,这项工作提出EHSS/PHA具有多功能特性,为骨质疏松性骨缺陷提供了新的见解。Composites Science and TechnologyEXPLICIT MODELLING OF MESO-SCALE DAMAGE IN LAMINATED COMPOSITES – COMPARISON BETWEEN FINITE FRACTURE MECHANICS AND COHESIVE ZONE MODELJean Vereecke, Christophe Bois, Jean-Christophe Wahl, Tanguy Briand, Ludovic Ballère, Florian Lavelledoi:10.1016/j.compscitech.2024.110640 层合复合材料细观损伤的显式建模——有限断裂力学与黏结区模型的比较The ability of carbon fibre reinforced polymers to respect functional requirements such as permeability is strongly related to their damage state. In order to identify the fracture properties on which transverse cracking kinetics depend, we combine experimental and virtual tests by explicitly modelling all transverse cracks. Two modelling methods are compared, the cohesive zone model (CZM) and finite fracture mechanics (FFM). Both models are based on a double criterion of energy and strength. Each potential crack is assigned a couple of material properties (fracture energy and strength) derived from a probability distribution. This study focuses on how modelling choice implies assumptions on energy dissipation and the cracking behaviour represented. The relevance of both modelling methods is also discussed. A methodology is provided for identifying fracture properties and predicting damage accumulation in an isolated ply.碳纤维增强聚合物满足功能要求的能力,如渗透性,与它们的损伤状态密切相关。为了确定横向裂纹动力学所依赖的断裂特性,我们通过明确模拟所有横向裂纹,将实验和虚拟测试结合起来。比较了两种建模方法,即黏聚区模型(CZM)和有限断裂力学(FFM)。这两种模型都基于能量和强度的双重标准。每个潜在的裂纹都被赋予了由概率分布得出的几个材料特性(断裂能和强度)。本研究的重点是如何建模选择暗示对能量耗散和开裂行为的假设。本文还讨论了两种建模方法的相关性。提供了一种识别裂缝性质和预测隔离层中损伤累积的方法。来源:复合材料力学仿真Composites FEM

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