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【新文速递】2024年7月25日复合材料SCI期刊最新文章

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今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 6 篇,Composites Part B: Engineering 3 篇

Composite Structures

Analytical homogenization for equivalent in-plane elastic moduli of prestressed lattices based on the micropolar elasticity model

Zhi Guo, Xiang Liu, Li Huang, S. Adhikari, Xifeng Liang

doi:10.1016/j.compstruct.2024.118391

基于微极弹性模型的预应力网格等效面内弹性模量解析均匀化

Highly compressible and stretchable lattice materials have gained significant attention due to their advanced structural characteristics. However, most existing research on homogenization relies on linear classical elasticity theory, omitting nonlinear deformation and/or the micropolar elasticity rotation. This paper addresses this gap by introducing a novel analytical homogenization method for the in-plane equivalent elastic moduli of prestressed two-dimensional lattices that incorporates both nonlinear elastic deformation and micropolar elastic effects. First, the stiffness matrices of a lattice cell wall under axial force is formulated. Based on the micropolar elasticity theory, the micropolar elastic constitutive relations for four lattice materials under prestresses were established, i.e., rectangular, diamond, equilateral triangular, and mixed diamond lattices. Then, the micropolar elastic constants for different prestressed lattices are formulated. The closed-form expressions for the equivalent elastic moduli of nonlinear micropolar elastic bodies were derived from these micropolar elastic constants by their physical significance. The analytical expressions for the lattice elastic moduli are validated by using independent nonlinear finite element simulation in ANSYS with relative errors less than 4%. The proposed analytical method and new closed-form expressions provide a framework with high computational efficiency and accuracy for the analysis and parametric design of lattice materials under external stress.

高可压缩和高可拉伸晶格材料因其先进的结构特性而受到广泛关注。然而,现有的均匀化研究大多依赖于线性经典弹性理论,忽略了非线性变形和/或微极弹性旋转。本文通过引入一种新的二维预应力网格面内等效弹性模量的解析均匀化方法来解决这一空白,该方法同时考虑了非线性弹性变形和微极弹性效应。首先,建立了轴向力作用下晶格胞壁的刚度矩阵。基于微极弹性理论,建立了矩形、菱形、等边三角形和混合菱形四种晶格材料在预应力作用下的微极弹性本构关系。然后,给出了不同预应力格的微极弹性常数。根据这些微极弹性常数的物理意义,导出了非线性微极弹性体等效弹性模量的封闭表达式。通过ANSYS独立非线性有限元仿真,验证了晶格弹性模量解析表达式的正确性,相对误差小于4%。所提出的解析方法和新的封闭表达式为晶格材料在外加应力作用下的分析和参数化设计提供了一个计算效率高、精度高的框架。


Composites Part A: Applied Science and Manufacturing

Modified lap shear test for intralaminar shear failure of fiber reinforced composites

Malik John, John Park, Kedar Kirane

doi:10.1016/j.compositesa.2024.108368

纤维增强复合材料层间剪切破坏的改进搭接剪切试验

This work presents a modification of the lap shear test for application to the intralaminar shear failure of fiber reinforced composites. The proposed method involves an S-shaped double-cracked specimen loaded under uniaxial in-plane compression. The resulting loading is akin to a lap shear test but inducing intralaminar shear failure (not interlaminar). Elastic stress analysis confirms a shear dominated stress state in specimen ligament, and numerical contour-integral confirms a mode II dominance in the near tip region. Experimental results for an epoxy/carbon twill woven composite are presented, demonstrating the ease of the test method. Nonlinear quasi-ductile behavior is observed, as expected, and necessitates the use of elastoplastic fracture mechanics to interpret the fracture toughness. The estimated initiation toughness values are successfully verified via cohesive crack simulations. The presented test represents a simple and repeatable method to characterize the intralaminar shear failure of fiber-reinforced composites.

提出了一种适用于纤维增强复合材料层间剪切破坏的搭接剪切试验的改进方法。所提出的方法涉及一个s形双裂纹试件,在单轴面内压缩下加载。由此产生的荷载类似于搭接剪切试验,但会引起层内剪切破坏(而不是层间)。弹性应力分析证实了试样韧带的剪切主导应力状态,数值轮廓积分证实了近尖端区域的II型主导应力状态。最后给出了环氧/碳斜纹织物复合材料的实验结果,证明了该测试方法的可行性。正如预期的那样,观察到非线性准延性行为,需要使用弹塑性断裂力学来解释断裂韧性。通过内聚裂纹模拟成功验证了估算的起裂韧性值。本试验为表征纤维增强复合材料层间剪切破坏提供了一种简单、可重复的方法。


Copper oxide decorated one-dimensional mineral nanorods: Construction of strengthened gas-phase and condensed-phase coupled intumescent flame retardant

Zeyang Gao, Yu Zhu, Xiaoyong Liu, Bihe Yuan, Ranzhao Shen, Kailin Li, Yao Yin, Zhipeng Zhang

doi:10.1016/j.compositesa.2024.108373

氧化铜修饰一维矿物纳米棒:强化气相-冷凝相耦合膨胀阻燃剂的构建

Polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) features superior mechanical properties but suffers from high flammability, presenting a grand challenge in enhancing its flame retardancy with halogen-free additives. Herein, we developed an efficient flame-retardant system (BH/CuATP) by incorporating phosphazene additive (HP), copper oxide modified attapulgite (CuATP) and bisphenol A bis (diphenyl phosphate) (BDP). This system achieves a UL-94V-0 rating without melt-dripping and leads to reductions in the peak heat release rate (43.1 %), total heat release (29.8 %) and total smoke production (5.7 %). The strength effect of CuATP in both gas-phase and condensed-phase significantly contributes to its enhanced fire safety. Additionally, the mechanical properties of PC/ABS/B1H1/CuATP1 are improved due to the rod-like CuATP, showing enhanced comprehensive properties superior to other reported systems. This work presents valuable insights into the effectiveness of mineral-strength intumescent flame retardancy for PC/ABS, offering practical guidance for the development of high-performance PC/ABS composites.

聚碳酸酯/丙烯腈-丁二烯-苯乙烯(PC/ABS)具有优异的机械性能,但具有较高的可燃性,使用无卤添加剂增强其阻燃性是一个巨大的挑战。本文采用磷腈添加剂(HP)、氧化铜改性凹凸棒土(CuATP)和双酚A双(二苯基磷酸)(BDP)为原料,研制了一种高效阻燃体系(BH/CuATP)。该系统达到UL-94V-0等级,无熔滴,并导致峰值放热率(43.1% %),总放热率(29.8% %)和总烟雾产量(5.7% %)的降低。CuATP在气相和冷凝相中的强度效应显著提高了其防火安全性。此外,由于棒状CuATP的存在,PC/ABS/B1H1/CuATP1的力学性能得到了改善,其综合性能优于其他已报道的体系。本工作对PC/ABS矿物强度膨胀阻燃的有效性提出了有价值的见解,为高性能PC/ABS复合材料的开发提供了实践指导。


Developing an efficient analytical model for predicting the electrical conductivity of polymeric nanocomposites containing hybrid carbon nanotube/carbon black nanofillers

Maedeh Saberi, Alireza Moradi, Reza Ansari, Mohammad Kazem Hassanzadeh-Aghdam, Jamaloddin Jamali

doi:10.1016/j.compositesa.2024.108374

建立了一种预测含碳纳米管/炭黑纳米填料的聚合物纳米复合材料电导率的有效分析模型

Inter-cluster bridging of carbon nanotubes (CNTs) and carbon black (CB) nanoparticles conjoins inactive branches of carbonaceous nanofillers within the matrix and reduces the electron tunneling distance. This mechanism moderately overcomes quantum tunneling and provides percolative polymer networks exhibiting favorable electrical responses. This study focuses on devising an analytical procedure to scrutinize the electrical conductivity and percolation threshold of CNT/CB/polymer nanocomposites. To involve the physics of electrical processes, the modeling approach considers cylindrical CNTs and spherical CB nanoparticles surrounded by a continuum interphase, which serves as an electron hopping duct. This model is extended in a bottom-up micromechanics generalization to a level where it is capable of predicting the effects of a wide range of microstructural properties. The comparison of predictions with those obtained via experimental examinations, while affirming the infrastructure for investigating the electrical behavior of binary systems, convincingly captures the electrical conductivity/percolation threshold of ternary nanocomposites containing CNT/CB nanofillers.

碳纳米管(CNTs)和炭黑(CB)纳米颗粒簇间桥接连接了基体内碳基纳米填料的非活性分支,减少了电子隧穿距离。这种机制适度地克服了量子隧道效应,并提供了具有良好电响应的渗透聚合物网络。本研究的重点是设计一种分析程序来仔细检查碳纳米管/碳炭黑/聚合物纳米复合材料的电导率和渗透阈值。为了涉及电过程的物理学,建模方法考虑了圆柱形碳纳米管和球形碳纳米管,它们被一个连续的界面所包围,作为一个电子跳跃管道。该模型在自下而上的微观力学推广中扩展到能够预测各种微观结构特性的影响的水平。将预测结果与实验结果进行比较,确定了研究二元体系电学行为的基础设施,并令人信服地捕获了含有碳纳米管/碳纳米管纳米填料的三元纳米复合材料的电导率/渗透阈值。


Regulating the bimodal structure and strength-ductility synergy of Zn-decorated Ti particles reinforced AZ91 composite through high-volume fraction Mg17Al12 precipitations

Yuhui Zhang, Shengli Han, Pengfei Gao, Pengju Chen, Jun Xia, Jianbo Li, Jia She, Xianhua Chen, Kaihong Zheng, Fusheng Pan

doi:10.1016/j.compositesa.2024.108376

通过高体积分数Mg17Al12析出调节zn修饰Ti颗粒增强AZ91复合材料的双峰结构和强度-塑性协同作用

In this work, Mg-9Al-1Zn (AZ91) alloy reinforced with zinc-decorated titanium (Zn@Ti) particles was fabricated using the powder metallurgy method. Zn nanoparticles effectively dissolved into magnesium (Mg) matrix, which led to a reduction in the solid solubility of aluminum (Al) and precipitations of submicron sized Mg17Al12. As a result, the Zn@Ti/AZ91 composite displays a bimodal grain structure, achieving a remarkable balance between strength and ductility, with a yield strength of 248 ± 3.5 MPa, an ultimate tensile strength of 378 ± 5.3 MPa, and an elongation of 15.0 ± 2.8 %. The improved strength of Zn@Ti/AZ91 composite primarily stems from the synergistic effect of a significant volume fraction of submicron sized Mg17Al12 and Al8Mn5 precipitations strengthening, Zn solid solution strengthening, and grain boundary strengthening. Regarding ductility mechanisms, the presence of Mg17Al12 and Al8Mn5 precipitations effectively impede crack propagation and enhance ductility. This innovative approach represents a promising strategy for developing high strength and ductility of Mg composites.

本文采用粉末冶金方法制备了锌修饰钛(Zn@Ti)颗粒增强Mg-9Al-1Zn (AZ91)合金。锌纳米粒子有效地溶解在镁基体中,导致铝的固溶性降低,亚微米级Mg17Al12析出。因此,Zn@Ti / AZ91复合显示双峰晶粒结构,实现非凡的强度和延性之间的平衡,屈服强度248 ±3.5  MPa,极限抗拉强度378 ±5.3  MPa,和15.0的伸长 ±2.8  %。Zn@Ti/AZ91复合材料强度的提高主要源于大量体积分数的亚微米级Mg17Al12和Al8Mn5析出强化、Zn固溶体强化和晶界强化的协同作用。在延性机制方面,Mg17Al12和Al8Mn5析出物的存在有效地阻碍了裂纹扩展,增强了延性。这种创新的方法代表了开发高强度和高塑性镁复合材料的一种有前途的策略。


Experimental investigation on microstructure, mechanical and optical properties of RB-SiC ablated by nanosecond pulsed laser in nitrogen atmosphere

Hong An, Yongfeng Qian, Zhiyu Zhang, Hu Huang, Jiwang Yan

doi:10.1016/j.compositesa.2024.108377

氮气氛下纳秒脉冲激光烧蚀RB-SiC的显微组织、力学和光学性能的实验研究

Reaction-bonded silicon carbide (RB-SiC) has gained significant attention owing to its exceptional physical and chemical properties. Improving the photovoltaic efficiency and mechanical properties of RB-SiC is conducive to further enhancing its applicability. Laser gas nitriding is an effective strategy to simultaneously reduce the surface reflectivity and enhance the surface hardness of materials. Accordingly, the evolution of microstructure, mechanical and optical properties of RB-SiC composite ablated by nanosecond pulsed laser in nitrogen atmosphere was comprehensively investigated. After laser gas nitriding, the surface hardness of RB-SiC composite was increased by 10.6–44.6 %. The chemical composition analysis indicated that Si-based nitride was formed on the laser-ablated surface, which was mainly responsible for the hardness enhancement. Additionally, the reflectivity of the laser-ablated surface was reduced by up to 95.2 % compared to the original RB-SiC composite. This study provides a straightforward and effective method to simultaneously improve the mechanical and optical properties of RB-SiC composites.

反应键合碳化硅(RB-SiC)由于其优异的物理和化学性能而受到广泛关注。提高RB-SiC的光伏效率和力学性能有利于进一步增强其适用性。激 光气体氮化是降低材料表面反射率、提高材料表面硬度的有效方法。在此基础上,对纳秒脉冲激光在氮气气氛下烧蚀RB-SiC复合材料的显微组织、力学性能和光学性能的演变进行了全面研究。激光 气体氮化后,RB-SiC复合材料的表面硬度提高了10.6 ~ 44.6% %。化学成分分析表明,激光烧蚀表面形成了硅基氮化物,这是硬度增强的主要原因。此外,激光烧蚀表面的反射率比原始RB-SiC复合材料降低了95.2% %。本研究为同时提高RB-SiC复合材料的力学性能和光学性能提供了一种简单有效的方法。


Data-driven thermal modeling of in-situ Automated Fiber Placement

Allyson Fontes, Farjad Shadmehri

doi:10.1016/j.compositesa.2024.108379

原位自动铺放纤维的数据驱动热建模

This study proposes a data-driven model for thermal history prediction during in-situ Automated Fiber Placement of thermoplastic composites. Temperature data was experimentally collected with fast-response thermocouples placed within carbon fiber AS4/PEEK composite substrates. The temperature for various combinations of hot gas torch temperatures, heat source velocity, and locations through the thickness and width were collected. A feedforward neural network (FNN) was developed to predict the entire 3-dimensional thermal history. The FNN had five input features and one output: the temperature at a given position and a combination of the process parameters. The FNN predictions for data unseen during training are validated for cases of interpolation and extrapolation. As expected, suitable performance was obtained for cases of interpolation, but predictions suffered in extrapolation. The computational efficiency of FNNs makes them an appropriate candidate for on-line thermal history prediction or process optimization, given that they are used within their training range

本研究提出了一种数据驱动模型,用于热塑性复合材料原位自动铺放纤维过程中的热历史预测。温度数据通过放置在碳纤维AS4/PEEK复合材料衬底内的快速响应热电偶进行实验采集。收集了不同温度组合下的温度、热源速度以及不同厚度和宽度下的位置。提出了一种前馈神经网络(FNN)来预测整个三维热历史。FNN有五个输入特征和一个输出特征:给定位置的温度和过程参数的组合。FNN对训练期间未见数据的预测在插值和外推的情况下得到验证。正如预期的那样,在插值的情况下获得了合适的性能,但外推的预测受到影响。fnn的计算效率使其成为在线热历史预测或过程优化的合适候选者,因为它们在其训练范围内使用


Composites Part B: Engineering

Applications of Artificial Intelligence/Machine Learning to High-Performance Composites

Yifeng Wang, Kan Wang, Chuck Zhang

doi:10.1016/j.compositesb.2024.111740

人工智能/机器学习在高性能复合材料中的应用

With the booming prosperity of artificial intelligence (AI) technology, it triggers a paradigm shift in engineering fields including material science. The integration of AI and machine learning (ML) techniques in material science brings significant advancements in understanding and characterizing underlying physics. Due to the overall outstanding properties compared to conventional metallic materials, high-performance fiber reinforced polymer (FRP) composites have attracted great interest. This article aims to provide a comprehensive review of the state-of-the-art works of applying AI/ML methods in high-performance FRP composites, focusing on four critical stages throughout the product life cycle, i.e., design, manufacturing, testing, and monitoring. This present study covers the tasks of material development and selection, process modeling and optimization, material property prediction, and damage diagnosis and prognosis in the four stages, which are conducted with the aid of advanced AI/ML algorithms. An outlook for the incorporation of modern advanced AI/ML models into FRP composite research is provided by the identification of current challenges and potential future research directions.

随着人工智能(AI)技术的蓬勃发展,引发了包括材料科学在内的工程领域的范式转变。人工智能和机器学习(ML)技术在材料科学中的整合,在理解和表征基础物理方面取得了重大进展。由于与传统金属材料相比,高性能纤维增强聚合物(FRP)复合材料的整体性能突出,引起了人们的极大兴趣。本文旨在全面回顾在高性能FRP复合材料中应用AI/ML方法的最新工作,重点关注整个产品生命周期的四个关键阶段,即设计、制造、测试和监控。本研究采用先进的AI/ML算法,完成了材料开发与选择、工艺建模与优化、材料性能预测、损伤诊断与预测四个阶段的工作。通过确定当前的挑战和潜在的未来研究方向,展望了将现代先进的AI/ML模型纳入FRP复合材料研究的前景。


Based on the preparation of dual-absorber agents using Ni and Ni/rGO for the fabrication of a dual honeycomb nested structure for wideband microwave absorption

Shaokang Liu, Fangxin Zhang, Bin Chao, Wenxin Fu, Kaixin Deng, Yan Li, Haihua Wu

doi:10.1016/j.compositesb.2024.111735

本文在制备双吸收剂的基础上,利用Ni和Ni/rGO制备了用于宽带微波吸收的双蜂窝嵌套结构

Designing absorbers with structural support to achieve ultra-wideband and wide-angle absorption properties is crucial for addressing the growing concern of electromagnetic pollution. In this study, a strategy is proposed to further broaden the bandwidth of structural absorbers by applying different materials to different structures and then nesting these different structures. Six composite materials were prepared using Ni and rGO as absorbers, and a dual honeycomb nested structure was fabricated using 3D printing technology. The minimum reflection loss (RL) of the two types of composite materials was −19.3 dB and −15.8 dB, respectively, with effective absorption bandwidths (EAB) of 4.6 GHz and 4.4 GHz, demonstrating mechanical compatibility and electromagnetic substitutability. The dual honeycomb nested structure utilized a multiscale design approach, achieving broadband absorption up to 14.27 GHz and compressive strength of 5.92 MPa. Furthermore, stable frequency response of transverse electric (TE) waves was observed within an incident angle range of 0°–40°, while absorption frequencies exceeded 12 GHz as transverse magnetic (TM) waves incident angle varied from 0° to 60°, highlighting wide-angle absorption characteristics. The dual composite preparation strategy of materials and structures for absorber fabrication provides a new perspective for further expanding the bandwidth of absorbers.

设计具有结构支撑的吸波器以实现超宽带广角吸收特性是解决日益受到关注的电磁污染问题的关键。本研究提出了一种策略,通过将不同的材料应用于不同的结构,然后将这些不同的结构嵌套,进一步拓宽结构吸收器的带宽。以Ni和还原氧化石墨烯为吸波剂制备了6种复合材料,并利用3D打印技术制备了双蜂窝嵌套结构。两种复合材料的最小反射损耗(RL)分别为- 19.3 dB和- 15.8 dB,有效吸收带宽(EAB)分别为4.6 GHz和4.4 GHz,具有良好的机械相容性和电磁可替代性。双蜂窝嵌套结构采用多尺度设计方法,实现了高达14.27 GHz的宽带吸收和5.92 MPa的抗压强度。此外,在0°~ 40°入射角范围内,横电波的频率响应稳定,而横磁波在0°~ 60°入射角范围内,吸收频率超过12 GHz,显示出广角吸收特征。材料和结构的双重复合制备策略为进一步扩大吸波器的带宽提供了新的前景。


Multi-Objective Optimization Through Desirability Function Analysis on the Crashworthiness Performance of Thermoplastic/Thermoset Hybrid Structures

Mahmoud M. Awd Allah, Marwa A. Abd El-baky

doi:10.1016/j.compositesb.2024.111742

基于期望函数分析的热塑性/热固性混合结构耐撞性能多目标优化

This paper aims to optimize the crashworthiness capability of glass-reinforced epoxy composites (GFRE) over wrapped polyvinyl chloride (PVC) circular tubes with cutouts. The intended tubes were prepared by a wet wrapping method; then subjected to quasi-static axial compression. To compute crashworthiness indications, three design parameters, each at three levels, were used. The design parameters are the hole diameter (d), the hole’s number (n), and the hole position (L). A few runs were accompanied by the L9 orthogonal array based on the Taguchi technique. With the lowest initial peak crash force () and the largest absorbed energy (U), the optimal parameters were found. Furthermore, the main effect, signal-to-noise ratio (S/N), as well as the analysis of variance (ANOVA), have been studied using the commercial software program MINITAB 18. Furthermore, to optimize the process parameters in terms of the crashworthiness indicators, desirability function analysis (DFA) was applied. Lastly, tests for confirmation were performed to verify the predicted values in light of the experimental results and compare them with the intact tubes. Regarding the single optimization, the optimum  tube is smaller than the intact PVC tube and intact hybrid tube, at 24.01 and 72.85%, respectively. Nonetheless, the optimal U was 21.43% lower than the intact hybrid tube and 152.75% greater than the intact PVC tube. While, for  and U, the multi-objective optimization specimen achieves 5.13 and 70.02% greater than the intact PVC tube. But it was 62.44% and 47.14% less than what the intact hybrid tube had accomplished.

本文旨在优化玻璃增强环氧复合材料(gfr)覆盖有切口的聚氯乙烯(PVC)圆管的耐撞性能。所述管采用湿包膜法制备;然后进行准静态轴向压缩。为了计算耐撞性指标,使用了三个设计参数,每个参数在三个级别上。设计参数为孔直径(d)、孔数(n)和孔位置(L)。少量井眼采用基于田口技术的L9正交阵列。以最小的初始峰值碰撞力()和最大的吸收能量(U)为最优参数。此外,利用商业软件MINITAB 18对主效应、信噪比(S/N)以及方差分析(ANOVA)进行了研究。在此基础上,应用理想函数分析(DFA)方法,从耐撞性指标出发对工艺参数进行优化。最后,根据实验结果对预测值进行了验证,并与完整管进行了对比。对于单次优化,最优管材比完整PVC管材和完整杂化管材小,分别为24.01和72.85%。最优U值比杂交管材整体低21.43%,比聚氯乙烯管材整体高152.75%。而对于和U,多目标优化试样比完整PVC管分别大5.13和70.02%。但与完整杂交管相比,分别降低了62.44%和47.14%。




来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveOpticalSystem断裂复合材料碰撞非线性化学光学冶金电子裂纹BIM理论材料
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【新文速递】2024年7月28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,Mechanics of Materials 1 篇,Thin-Walled Structures 3 篇International Journal of Solids and StructuresDesign and crashworthiness evaluation of corrugated honeycomb with multi-directional energy absorption capacityJiaming Wang, Zhigang Li, Haifeng Yang, Zengtao Hao, Danyang Guo, Xulong Xi, Xiaocheng Li, Huiqing Landoi:10.1016/j.ijsolstr.2024.113001具有多向吸能能力的波纹蜂窝设计及耐撞性评价In this study, three novel multi-directional energy-absorbing honeycombs were designed to meet the requirements in the crash of uncertain directions, which are named as bow-shaped honeycomb (BSHC), staggered honeycomb (SGHC) and corrugated honeycomb (CGHC). These innovative designs can significantly narrow the huge gap of the energy absorption capacity between the in-plane and out-of-plane directions of traditional honeycombs. Compression tests were conducted in three orthogonal directions. The BSHC is found to have the smallest densification strain but the highest plateau stress in each direction. The SGHC can only balance the energy absorption between out-of-plane and in-plane-x directions. The CGHC demonstrates a better densification strain and the highest multi-directional energy absorption coefficient. The detailed and equivalent finite element models of CGHC were further established and validated, and both exhibited high accuracy. Finally, a honeycomb anti-climber, with only about half length of the traditional guided honeycomb anti-climber, was designed and equipped with metro vehicles. Simulations were conducted under eccentric collision scenario. The results demonstrated that the CGHC anti-climber was capable of orderly deformation in the axial direction (out-of-plane direction) while effectively resisting the vertical (in-plane-y direction) force during collision. The energy absorption capacity of CGHC anti-climber was significantly enhanced as compared to the HEHC anti-climber under eccentric collision scenario.本研究针对不确定方向碰撞的要求,设计了三种新型多向吸能蜂窝,分别命名为弓形蜂窝(BSHC)、交错蜂窝(SGHC)和波纹蜂窝(CGHC)。这些创新设计可以显著缩小传统蜂窝在面内方向和面外方向之间巨大的能量吸收能力差距。在三个正交方向上进行压缩试验。BSHC各方向致密化应变最小,高原应力最大。SGHC只能平衡面外和面内x方向的能量吸收。CGHC具有较好的致密化应变和最高的多向能量吸收系数。进一步建立并验证了CGHC的详细有限元模型和等效有限元模型,均具有较高的精度。最后,设计了一种蜂窝式防攀爬器,其长度仅为传统导向式蜂窝防攀爬器的一半左右。在偏心碰撞场景下进行了仿真。结果表明,CGHC防攀爬器在碰撞过程中,既能在轴向(面外方向)进行有序变形,又能有效抵抗垂直方向(面内y方向)的作用力。偏心碰撞情况下,CGHC防攀爬器的吸能能力比HEHC防攀爬器显著增强。Journal of the Mechanics and Physics of SolidsA multiscale mechanics model for disordered biopolymer gels containing junction zones with variable lengthHashem Moosavian, Tian Tangdoi:10.1016/j.jmps.2024.105792含变长结区的无序生物聚合物凝胶的多尺度力学模型Disordered biopolymer gels, such as those synthesized from polysaccharide and gelatin, play an important role in biomedical applications, particularly in tissue engineering. During the gelation process of these gels, polymer chains associate in the presence of gelling agents, forming physical cross-links known as the junction zones. In contrast to rubber-like networks, the resulting network comprises two main regions: the ordered region due to the junction zones and the amorphous region due to the unassociated chains. Under thermal fluctuations and/or external loading, the number and locations of junction zones can change leading to “zipping” (lengthening, i.e., expansion of the junction zones) and “unzipping” (shortening, i.e., shrinkage of the junction zones). This gives rise to intriguing features in biopolymer gels such as healing and damage-like energy dissipation. Despite the recognition of zipping and unzipping in such gels, the development of mathematical models that incorporate the microscopic mechanisms into the material’s macroscopic mechanical properties is still in its early stages. In this paper, we provide a systematic framework for such multiscale modeling. Several critical steps are taken to equip the eight-chain network model with a previously developed micromechanics model for a coil-rod structure, where the coil represents an unassociated chain and the rod represents a junction zone. Most importantly, for a network of coil-rod structures under zero stress, the rigidity induced by the rod leads to an end-to-end distance ( r 0 ) for the coil-rod which is different from a classical result for a Gaussian coil: n b where b is the Kuhn length and n is the number of Kuhn segments in the coil. By relaxing the incompressible assumption in the original eight-chain model, r 0 is determined for the gel network, which depends on the length of the junction zone. Consequently, as the junction zone extends/shrinks following zipping/unzipping under an external load, an irreversible deformation can occur after unloading, consistent with experimentally observed “permanent set”. The extension/shrinkage of the junction zone is captured by statistical mechanics analysis in the grand canonical ensemble, which allows the exchange of segments between the coil and the rod, driven by the binding energy of polymer chain association. The model also includes explicit consideration of swelling and the influence of solvent molecules as a result of their mixing with the polymer chains in the gel network. With physically reasonable parameters, the proposed model is shown to provide good matching with experimental data on the uniaxial testing of alginate gels, revealing progressive unzipping during loading and partial re-zipping during unloading leading to the appearance of a permanent set. This formulation not only paves the way for more advanced studies of disordered biopolymer gels but also lays the groundwork for modeling hybrid gels that contain coil-rod structures as a component.无序生物聚合物凝胶,如由多糖和明胶合成的,在生物医学应用中发挥着重要作用,特别是在组织工程中。在这些凝胶的凝胶化过程中,聚合物链在胶凝剂的存在下结合,形成被称为结区的物理交联。与类似橡胶的网络相反,所得到的网络包括两个主要区域:由于结区而形成的有序区域和由于非相关链而形成的无定形区域。在热波动和/或外部载荷的作用下,结带的数量和位置可能发生变化,导致"压缩"(延长,即结带的扩大)和"解压缩"(缩短,即结带的收缩)。这在生物聚合物凝胶中产生了有趣的特性,如愈合和损伤样能量耗散。尽管人们已经认识到这种凝胶中的拉链和解拉链,但将微观机制纳入材料宏观力学特性的数学模型的发展仍处于早期阶段。在本文中,我们为这种多尺度建模提供了一个系统框架。为了将八链网络模型与先前开发的线圈-杆结构的微观力学模型相结合,研究人员采取了几个关键步骤,其中线圈代表非相关链,杆代表连接区。最重要的是,对于零应力下的线圈-棒结构网络,由棒引起的刚度导致线圈-棒的端到端距离(r 0),这与高斯线圈的经典结果不同:n b,其中b是库恩长度,n是线圈中的库恩段数。通过放宽原始八链模型中的不可压缩假设,确定了凝胶网络的r0,它取决于结区的长度。因此,在外部载荷作用下,随着拉合/解合,结区扩展/收缩,卸载后会发生不可逆变形,与实验观察到的“永久集”一致。在大正则系综中,统计力学分析捕获了结区的扩展/收缩,这允许线圈和棒之间的片段交换,由聚合物链结合的结合能驱动。该模型还包括明确考虑溶胀和溶剂分子的影响,因为它们与凝胶网络中的聚合物链混合。在物理参数合理的情况下,该模型与海藻酸盐凝胶单轴试验数据吻合良好,加载过程中逐渐解压缩,卸载过程中部分重新压缩压缩,形成永久集。该配方不仅为无序生物聚合物凝胶的更高级研究铺平了道路,而且为包含线圈杆结构的混合凝胶建模奠定了基础。Mechanics of MaterialsA 3D finite strain constitutive model for shape memory polymers combined viscoelasticity and storage strainJiajun Chen, Chen Du, Qinghu Wang, Xiongqi Pengdoi:10.1016/j.mechmat.2024.105103粘弹性与存储应变相结合的形状记忆聚合物三维有限应变本构模型A 3D finite strain constitutive model combined viscoelasticity and storage strain for shape memory polymers (SMPs) is proposed. SMPs are phenomenally regarded as a homogeneous material of the viscoelastic glassy phase and hyperelastic rubbery phase in this model. Based on energy decomposition, the constitutive equation is derived using Clausius inequality and unified Helmholtz free energy. Then, an analytical expression for storage strain is presented, significantly simplifying the prediction of shape memory recovery process. The model is implemented in MATLAB and the commercial finite element software package ABAQUS using the UMAT subroutine. Our additional DMA tests and experimental data from the literature for various SMPs with different shape structures are used to verify the proposed model. All simulation results demonstrate the effectiveness of the proposed model in predicting the shape memory effect and complex thermomechanical behaviors of various SMPs.提出了一种结合粘弹性和存储应变的形状记忆聚合物三维有限应变本构模型。在该模型中,SMPs被看作粘弹性玻璃相和超弹性橡胶相的均匀材料。在能量分解的基础上,利用克劳修斯不等式和统一亥姆霍兹自由能导出了本构方程。然后,提出了存储应变的解析表达式,大大简化了形状记忆恢复过程的预测。利用UMAT子程序在MATLAB和商用有限元软件包ABAQUS中实现了该模型。我们对不同形状结构的各种smp进行了额外的DMA测试和文献中的实验数据,以验证所提出的模型。所有的仿真结果都证明了该模型在预测各种smp的形状记忆效应和复杂的热力学行为方面的有效性。Thin-Walled StructuresProcess planning for laser peen forming of complex geometry: An analytical-based inverse studyJiancheng Jiang, Zhi Li, Yi Zhang, Siyuan Chen, Yongxiang Hudoi:10.1016/j.tws.2024.112274 复杂几何形状激光喷丸成形工艺规划:基于解析的逆向研究Laser peen forming (LPF) is a promising process for the flexible manufacturing of complex thin-walled structures. However, process planning for LPF remains challenging due to the deformed geometry relying on the cumulative effect of thousands of laser shocks without dies. The optimization-based planning method is adaptable but easily gets trapped in local optima, leading to insufficient robustness and efficiency. To overcome these limitations, this study introduces an analytical-based inverse study to complement the optimization-based method. Firstly, an inherent and straightforward analytical model between eigen-moment and surface curvature is proposed, enabling a direct inverse determination of the eigen-moment field from the desired geometry shape. Subsequently, a clustering method is employed to achieve aggregation control over the analytically determined eigen-moment field, avoiding extensive optimization iterations. Moreover, a physical-based surface decomposition method is devised to formulate double-side LPF strategies for surfaces with negative or zero Gaussian curvature. To validate the proposed analytical-based process planning method, an elliptic paraboloid-like surface and a hyperbolic paraboloid surface are selected as the objectives. Experimental results show high conformity between the deformed and objective surfaces, validating the proposed method. The analytical-based planning method facilitates the efficient and robust determination of forming strategies, complementing the optimization-based method and providing a comprehensive solution for LPF process planning under small deformations.激光喷丸成形(LPF)是一种很有前途的复杂薄壁结构柔性制造方法。然而,由于几何变形依赖于数千次无模具激光冲击的累积效应,LPF的工艺规划仍然具有挑战性。基于优化的规划方法适应性强,但容易陷入局部最优,鲁棒性和效率不足。为了克服这些局限性,本研究引入了一种基于分析的逆研究来补充基于优化的方法。首先,提出了本征矩与曲面曲率之间固有且直观的解析模型,实现了从所需几何形状直接反演本征矩场。随后,采用聚类方法实现对解析确定的特征矩场的聚集控制,避免了大量的优化迭代。此外,设计了一种基于物理的曲面分解方法,对高斯曲率为负或为零的曲面制定了双面LPF策略。为了验证所提出的基于解析的工艺规划方法,选择了一个椭圆抛物面和一个双曲抛物面作为目标曲面。实验结果表明,变形曲面与目标曲面高度吻合,验证了该方法的有效性。基于分析的规划方法有助于高效、稳健地确定成形策略,与基于优化的方法相辅相成,为小变形下的LPF工艺规划提供了全面的解决方案。Post-fire bond-slip performance of concrete-filled stainless steel tube columnsKang He, Yu Chen, Jiajun Tang, Xin Lidoi:10.1016/j.tws.2024.112275不锈钢管混凝土柱火灾后粘结滑移性能研究Concrete-filled stainless steel tube (CFSST) structures exhibit superior strength, durability, and fire resistance. These attributes, coupled with their aesthetic appeal and corrosion resistance, make them highly suitable for a broad range of civil engineering applications, ensuring long-term performance and safety across diverse environments. This study investigates the post-fire bond-slip performance of CFSST structures to facilitate the strengthening and retrofitting of fire-damaged CFSST structures. The paper reviews the bond-slip performance and fire resistance of CFSST. A series of fire tests and push-out tests were conducted on 99 circular CFSST stub columns, considering variables such as fire duration, wall thickness of the stainless steel tube, and concrete strength. The analysis covers the slip mechanism, load-slip relationship, sliding load, ultimate displacement, and ultimate bond strength of specimens post-fire. The bonding force between interfaces transitions from cementation to mechanical interlock and ultimately to friction, with some overlap among these mechanisms. A positive correlation exists between sliding load and wall thickness when fire duration is short. For shorter fire durations, fire exposure reduces the ultimate displacement while increasing bond-slip stiffness. Finally, a formula is proposed to predict the ultimate bond strength of CFSST stub columns following exposure to ISO 834 standard fire conditions.混凝土填充不锈钢管(CFSST)结构表现出优异的强度,耐久性和耐火性。这些特性,再加上它们的美观性和耐腐蚀性,使它们非常适合广泛的土木工程应用,确保在各种环境下的长期性能和安全性。本研究旨在研究火灾后CFSST结构的粘结滑移性能,为火灾后CFSST结构的加固和改造提供依据。本文综述了CFSST的粘结滑移性能和耐火性能。考虑火灾持续时间、不锈钢管壁厚、混凝土强度等因素,对99根圆形CFSST短柱进行了一系列的防火试验和推出试验。分析了火灾后试件的滑移机理、荷载-滑移关系、滑动荷载、极限位移和极限粘结强度。界面之间的结合力从胶结转变为机械联锁,最终转变为摩擦,这些机制之间存在一些重叠。当火灾持续时间较短时,墙体厚度与滑动荷载之间存在正相关关系。对于较短的火灾持续时间,火灾暴露减少了极限位移,同时增加了粘结滑移刚度。最后,提出了CFSST短柱暴露于ISO 834标准火灾条件下的极限粘结强度预测公式。Tests, simulations and web crippling design of S690 and S960 high strength steel unlipped channel sections under end-one-flange loadingXiaoyi Lan, Xian-Wei Xu, Ou Zhaodoi:10.1016/j.tws.2024.112276S690和S960高强度钢无唇槽钢端部单翼载荷试验、模拟及腹板破坏设计This paper presents experimental and numerical investigations into the web crippling behaviour and structural design of high strength steel unlipped channel sections under end-one-flange loading. An experimental programme including six grade S690 and four grade S960 steel test specimens was firstly carried out, and the corresponding test set-up, procedures and results were reported. The web crippling test results were subsequently used in a finite element programme to validate developed finite element models, which were then adopted to perform parametric studies to cover wider parameter ranges of the bearing length, web slenderness and inside bend radius. Considering that relevant codified design provisions are absent, the design rules of normal strength steel unlipped channel sections, as prescribed in EN 1993-1-3, EN 1993-1-5 and AISI S100, were assessed for their suitability to high strength steel unlipped channel sections. It is found that the ultimate web crippling strength of high strength steel unlipped channel sections increases with increasing bearing length but decreasing web slenderness and inside bend radius. The codified design methods provide inaccurate and scattered resistance predictions for high strength steel unlipped channel sections under end-one-flange loading. Thus, an improved AISI S100 design method and a novel slenderness-based design method were proposed, which can outperform the codified design methods.本文对高强度无唇槽钢在端部单翼荷载作用下的腹板破坏行为及结构设计进行了试验和数值研究。首先进行了包括6个S690级和4个S960级钢试件的试验方案,并报告了相应的试验装置、步骤和结果。腹板损伤试验结果随后用于有限元程序,以验证开发的有限元模型,然后采用该模型进行参数研究,以涵盖更广泛的轴承长度、腹板长细度和内弯曲半径参数范围。考虑到相关设计规范的缺失,对EN 1993-1-3、EN 1993-1-5和AISI S100中规定的标准强度钢非开口槽体截面设计规则对高强度钢非开口槽体截面的适用性进行了评估。研究发现,高强钢无唇沟道断面的腹板极限破坏强度随承载长度的增加而增大,而腹板长细比和内弯半径的减小而减小。规范的设计方法对高强度钢无唇槽钢在端部单翼荷载作用下的阻力预测不准确且分散。在此基础上,提出了一种改进的AISI S100设计方法和一种新的基于细长度的设计方法。来源:复合材料力学仿真Composites FEM

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