【新文速递】2024年8月12日固体力学SCI期刊最新文章

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

International Journal of Solids and Structures

Machine learning applications in sheet metal constitutive Modelling: A review

Armando E. Marques, Tomás G. Parreira, André F.G. Pereira, Bernardete M. Ribeiro, Pedro A. Prates

doi:10.1016/j.ijsolstr.2024.113024

机器学习在钣金本构建模中的应用综述

The numerical simulation of sheet metal forming processes depends on the accuracy of the constitutive model used to represent the mechanical behaviour of the materials. The formulation of these constitutive models, as well as their calibration process, has been an ongoing subject of research. In recent years, there has been a special focus on the application of data-driven techniques, namely Machine Learning, to address some of the difficulties of constitutive modelling. This review explores different methodologies for the application of Machine Learning algorithms to sheet metal constitutive modelling. These methodologies include the use of machine learning algorithms in the identification of constitutive model parameters and the replacement of the constitutive model by a metamodel created by a machine learning algorithm. A discussion about the merits and limitations of the different methodologies is presented, as well as the identification of some possible gaps in the literature that represent opportunities for future research.

板料成形过程的数值模拟取决于用来表示材料力学行为的本构模型的准确性。这些本构模型的制定，以及它们的校准过程，一直是一个正在进行的研究课题。近年来，人们特别关注数据驱动技术的应用，即机器学习，以解决本构建模的一些困难。这篇综述探讨了机器学习算法应用于金属板本构建模的不同方法。这些方法包括使用机器学习算法来识别本构模型参数，以及用机器学习算法创建的元模型替换本构模型。讨论了不同方法的优点和局限性，并指出了文献中可能存在的一些空白，这些空白代表了未来研究的机会。

On an efficient global/local stochastic methodology for accurate stress analysis, failure prediction and damage tolerance of laminated composites

P. Minigher, A. Arteiro, A. Turon, J. Fatemi, S. Guinard, L. Barrière, P.P. Camanho

doi:10.1016/j.ijsolstr.2024.113026

基于有效全局/局部随机方法的层合复合材料精确应力分析、失效预测和损伤容限研究

The quantification of uncertainties in the mechanical response of composite structures can be a computationally demanding task. This is due both to the number of uncertain parameters in a real study case and the complexity of the model to be analyzed. In this paper, an efficient global/local approach to estimate the uncertainties of the quantities of interest in specific regions of interest with limited computational effort is proposed. This is achieved by refining only locally the model taking advantage of Refined Structural Theories. At the same time, since the variance of the uncertain parameters is usually relatively small, the stochastic analysis is dealt with a sensitivity study carried out both in the global and in the local model. In this way, it is possible to assess the influence of global and local uncertain parameters in the same submodeling analysis. The methodology presented is applied to several study cases of interest. The results focus on obtaining probabilistic distributions of the stress field that can be later used in failure criteria to evaluate the subsequent distribution of the failure index. Furthermore, a damage tolerance study case is investigated, showing good correlation with the reference Monte Carlo simulations.

复合材料结构力学响应的不确定性量化是一项计算要求很高的任务。这是由于实际研究案例中不确定参数的数量和待分析模型的复杂性。本文提出了一种有效的全局/局部方法，在有限的计算量下估计特定兴趣区域中兴趣数量的不确定性。这是通过利用精炼结构理论对模型进行局部精炼来实现的。同时，由于不确定参数的方差通常相对较小，因此对随机分析进行了全局和局部模型的敏感性研究。这样，就可以在同一子模型分析中评估全局和局部不确定参数的影响。所提出的方法被应用于几个感兴趣的研究案例。结果着重于获得应力场的概率分布，该概率分布可用于制定破坏准则，以评估破坏指数的后续分布。此外，还研究了一个损伤容限研究案例，结果与蒙特卡罗模拟结果具有良好的相关性。

Mechanics of Materials

Mesoscale modeling of deformations and defects in thin crystalline sheets

Lucas Benoit–Maréchal, Ingo Nitschke, Axel Voigt, Marco Salvalaglio

doi:10.1016/j.mechmat.2024.105114

薄晶片变形和缺陷的中尺度模拟

We present a mesoscale description of deformations and defects in thin, flexible sheets with crystalline order, tackling the interplay between in-plane elasticity, out-of-plane deformation, as well as dislocation nucleation and motion. Our approach is based on the Phase-Field Crystal (PFC) model, which describes the microscopic atomic density in crystals at diffusive timescales, naturally encoding elasticity and plasticity effects. In its amplitude expansion (APFC), a coarse-grained description of the mechanical properties of crystals is achieved. We introduce surface PFC and surface APFC models in a convenient height-function formulation encoding deformation in the normal direction. This framework is proven consistent with classical aspects of strain-induced buckling, defect nucleation on deformed surfaces, and out-of-plane relaxation near dislocations. In particular, we benchmark and discuss the results of numerical simulations by looking at the continuum limit for buckling under uniaxial compression and at evidence from microscopic models for deformation at defects and defect arrangements, demonstrating the scale-bridging capabilities of the proposed framework. Results concerning the interplay between lattice distortion at dislocations and out-of-plane deformation are also illustrated by looking at the annihilation of dislocation dipoles and systems hosting many dislocations. With the novel formulation proposed here, and its assessment with established approaches, we envision applications to multiscale investigations of crystalline order on deformable surfaces.

我们提出了一个中尺度的变形和缺陷的描述，在薄，柔性片与晶体顺序，处理面内弹性，面外变形，以及位错成核和运动之间的相互作用。我们的方法基于相场晶体(PFC)模型，该模型描述了晶体在扩散时间尺度上的微观原子密度，自然地编码了弹性和塑性效应。在其振幅扩展(APFC)中，实现了晶体力学性能的粗粒度描述。我们以一种方便的高度函数形式引入表面PFC和表面APFC模型，编码在法向上的变形。这一框架被证明与经典的应变诱导屈曲、变形表面上的缺陷成核和位错附近的面外松弛相一致。特别地，我们通过观察单轴压缩下屈曲的连续极限以及缺陷和缺陷排列变形的微观模型的证据，对数值模拟的结果进行了基准测试和讨论，展示了所提出框架的尺度桥接能力。通过观察位错偶极子的湮灭和包含许多位错的系统，还说明了位错处晶格畸变与面外变形之间相互作用的结果。通过本文提出的新公式及其与既定方法的评估，我们设想应用于可变形表面上晶体秩序的多尺度研究。

International Journal of Plasticity

Strong and Ductile Low Carbon Low Alloy Steels with Multiphase Bimodal Microstructure

Chenhe Wang, Ran Chen, Chenyang Wang, Yumeng Zhang, Xiaodong Wang, Mingwei Chen

doi:10.1016/j.ijplas.2024.104097

具有多相双峰组织的高韧性低碳低合金钢

Restrained by the strength-ductility tradeoff, it is still challenging to develop advanced high-strength low carbon low alloy (LCLA) steels with superior strength-ductility combinations and cost-effectiveness to satisfy industry demands. In this study, an innovative 2-cyclic quenching and partitioning (Q&P) heat treatment was developed to produce a novel LCLA steel with the optimized microstructure, in which a bimodal grain size distribution across various constituent phases was achieved. Tensile test results show that the 2-cyclic Q&P LCLA steel exhibits excellent mechanical properties with a uniform elongation, close to 18%, nearly triple that of conventional Q&P LCLA steel while maintaining a tensile strength above 1 GPa. To reveal the underlying mechanisms of such exceptional strength-elongation synergy, the detailed deformation behaviors of the developed LCLA steel were characterized while the evolution of hetero-deformation-induced (HDI) stress and effective stress was investigated from the perspective of the dislocation model. It is indicated that, with increasing strain, the heterogeneous structures promote strong strain partitioning which leads to extensive geometrically necessary dislocations (GNDs) pile-ups at hetero-interface and persistently strong HDI strengthening effect, and produce the coordinated deformation among constituent phases to realize dislocation forest strengthening, collectively contributing to the enhanced work hardening capacity and hence overcoming the strength-ductility tradeoff. This study provides a new processing strategy for developing strong and ductile LCLA steels.

受强度-延性平衡的制约，开发出具有优异强度-延性组合和成本效益的先进高强度低碳低合金(LCLA)钢仍是一项挑战。在本研究中，开发了一种创新的2循环淬火和分配(Q&P)热处理方法，以生产具有优化组织的新型LCLA钢，其中实现了不同组成相的双峰晶粒尺寸分布。拉伸试验结果表明，2循环Q&P LCLA钢具有优异的力学性能，伸长率接近18%，是常规Q&P LCLA钢的近3倍，同时抗拉强度保持在1 GPa以上。为了揭示这种特殊的强度-延伸协同作用的潜在机制，研究了所开发的LCLA钢的详细变形行为，并从位错模型的角度研究了异质变形诱导(HDI)应力和有效应力的演变。结果表明，随着应变的增加，非均质结构促进了强应变分配，导致异质界面上广泛的几何必要位错(GNDs)堆积和持续强的HDI强化效应，并在各组成相之间产生协调变形，实现位错森林强化，共同提高了加工硬化能力，从而克服了强度-塑性平衡。本研究为开发高韧性LCLA钢提供了一种新的加工策略。

Thin-Walled Structures

An investigation of vibration responses for bolted composite flanged-cylindrical shells considering material and joint nonlinearity

Xiaofeng Liu, Wei Sun, Honghao Liu, Hongwei Ma, Dongxu Du, Hui Li

doi:10.1016/j.tws.2024.112335

考虑材料非线性和节点非线性的螺栓复合法兰-圆柱壳振动响应研究

In this paper, a thorough investigation into the vibration response of bolted composite flanged-cylindrical shell structures, considering the material nonlinearity of carbon fiber-reinforced polymer composites (CFRP) and the joint nonlinearity of bolt connections, is presented. Firstly, a general semi-analytical modeling method for bolted composite flanged-cylindrical shell is developed based on the first-order shear deformation theory (FSDT) and the energy method. In this method, material nonlinearity is introduced by accounting for the frequency-strain dependency of material parameters. A joint model with non-uniform distribution parameters and dynamic boundaries is proposed to simulate the interface pressure distribution and nonlinear mechanical behavior of bolted joints. Then, for the general numerical model that incorporates both types of nonlinearities, the ability to accurately predict the nonlinear vibration behavior of a bolted composite flanged-cylindrical shell is demonstrated through experimental testing. Finally, an in-depth discussion is conducted on the influence of fiber layup patterns and bolt numbers on the nonlinear vibration response of the bolted composite flanged-cylindrical shells. The conducted analysis indicates that the proposed method can offer utility to designers, empowering them with the insights necessary for the dynamic optimization of such structures.

考虑碳纤维增强聚合物复合材料(CFRP)的材料非线性和螺栓连接的连接非线性，对螺栓复合材料法兰-圆柱壳结构的振动响应进行了深入的研究。首先，基于一阶剪切变形理论(FSDT)和能量法，建立了螺栓复合材料法兰-圆柱壳的通用半解析建模方法;该方法考虑了材料参数的频率-应变关系，引入了材料的非线性。提出了一种具有非均匀分布参数和动态边界的连接模型，用于模拟螺栓连接的界面压力分布和非线性力学行为。然后，通过实验验证了结合两种非线性因素的通用数值模型能够准确预测螺栓复合材料法兰-圆柱壳的非线性振动行为。最后，深入讨论了纤维铺层方式和螺栓数对螺栓复合法兰-圆柱壳非线性振动响应的影响。所进行的分析表明，所提出的方法可以为设计人员提供实用工具，使他们能够对此类结构的动态优化提供必要的见解。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年8月16日复合材料SCI期刊最新文章

今日更新：Composite Structures 2 篇，Composites Part A: Applied Science and Manufacturing 4 篇，Composites Part B: Engineering 1 篇，Composites Science and Technology 2 篇Composite StructuresComprehensive FRP-concrete bond behavior: Impact of test methods and the innovative UBoTFaisal Mukhtardoi:10.1016/j.compstruct.2024.118475综合frp -混凝土粘结性能:测试方法的影响和创新的UBoTThe lack of a standardized bond test method for fiber-reinforced polymer (FRP)-concrete interfaces leads to variations in forms of the popular single-lap shear, double-lap shear, beam, mixed-mode, and pull-off tests. Recognizing the limitations of each bond test technique and the importance of analyzing all results as complementary, a detailed evaluation of these variations is essential for accurate bond behavior assessment prior to design and field deployment, to avoid subjective decisions and predictions. This study pioneers the evaluation of FRP-concrete bond test methods, offering the industry a consistent dataset for informed decision-making. Single- and double-lap shear tests yield trilinear bond-slip responses; however, the single-lap test’s lack of symmetry reduces bond strength by 15% compared to the double-lap test. The beam test, unsuitable for bond-slip modeling, shows comparable average bond strength to the single- and double-lap tests. The mixed-mode test better simulates field applications, while the pull-off test provides the most consistent results. Given that each test method reflects only one field scenario, the Universal Bond Tester (UBoT) was developed. This device can convert to all FRP-concrete bond test types. It also addresses the modified double-lap shear test’s limitations (e.g., inapplicability to pultruded laminate and FRP rupture in wet layup systems) and present a modified ASTM D7958 beam and mixed-mode tests cost-effectively. The UBoT captures full bond behavior and variabilities, overcoming the limitations of existing methods which fail to capture all failure modes in bond-critical applications. It reduces specimen sizes, weight, and data acquisition needs by half for most tests. This study allows test laboratories to use any preferred testing method with the UBoT. Link to video demonstrations for all tested specimens are provided in the supplementary material.纤维增强聚合物(FRP)-混凝土界面缺乏标准化的粘结试验方法，导致流行的单搭接剪切、双搭接剪切、梁、混合模式和拉脱试验形式各异。认识到每种胶结测试技术的局限性以及分析所有结果作为补充的重要性，在设计和现场部署之前，对这些变化进行详细评估对于准确评估胶结行为至关重要，以避免主观决策和预测。这项研究开创了frp -混凝土粘结测试方法的评估，为行业提供了一个一致的数据集，以进行明智的决策。单搭接和双搭接剪切试验产生三线性粘结滑移响应;然而，与双搭接测试相比，单搭接测试缺乏对称性，使粘合强度降低了15%。不适合粘结滑移模型的梁试验显示出与单搭接和双搭接试验相当的平均粘结强度。混合模式测试更好地模拟了现场应用，而下拉测试提供了最一致的结果。鉴于每种测试方法只能反映一个现场场景，因此开发了通用粘结测试仪(UBoT)。该设备可转换为所有frp -混凝土粘结试验类型。它还解决了改进的双搭剪试验的局限性(例如，不适用于湿铺层系统中的拉挤层压和FRP断裂)，并提出了一种改进的ASTM D7958梁和混合模式试验，具有成本效益。UBoT捕获了完整的键行为和变化，克服了现有方法在键关键应用中无法捕获所有失效模式的局限性。它将大多数测试的样品尺寸、重量和数据采集需求减少了一半。这项研究允许测试实验室使用任何首选的测试方法与UBoT。在补充材料中提供了所有测试样本的视频演示链接。Nature-inspired 3D printing-based double-graded aerospace negative Poisson’s ratio metastructure: Design, Fabrication, Investigation, optimizationYuze Nian, Shui Wan, Mehmet Avcar, Xiao Wang, Ru Hong, Ru Yue, Mo Lidoi:10.1016/j.compstruct.2024.118482 基于自然灵感的3D打印双级航天负泊松比元结构:设计，制造，调查，优化The advanced metamaterials concept has been widely explored and utilized in many industries, ranging from automotive applications to medicine, and has great potential in the aerospace field. Novel nature-inspired 3D printed double-graded aluminum foam-filled negative Poisson’s ratio metamaterials (DGAT) were designed, fabricated, and investigated. Their mechanical properties were examined by the finite element method and experiments. The geometrical parameters and combination types show different effects on the mechanical properties of DGAT metastructures. Under axial compressive loading, the DGAT structure has a lower peak force and higher specific energy absorption. Then, parametric analysis shows that several design parameters (e.g. m, T, θ, tmin, tmax) have a very strong effects on the mechanical performance. Finally, multi-objective optimization is performed to maximize specific energy absorption while reducing maximum impact force. Optimization results show that the novel graded metamaterials have stronger energy absorption capacity than the ordinary counterparts. Especially, the specific energy absorption can be increased to 80% with 15% peak loading force rising. Due to their unique structural design and excellent mechanical properties, the DGAT metastructures have great potential applications in the fields of transportation protection, military protection engineering, manned spacecraft cushioning and energy-absorbing boxes.先进的超材料概念已被广泛探索和应用于许多行业，从汽车应用到医学，并在航空航天领域具有巨大的潜力。设计、制造和研究了一种新颖的受自然启发的3D打印双层泡沫铝填充负泊松比超材料(DGAT)。采用有限元法和实验对其力学性能进行了检验。几何参数和组合类型对DGAT元组织的力学性能有不同的影响。在轴向压缩载荷作用下，DGAT结构具有较低的峰值力和较高的比能吸收。然后，参数化分析表明，若干设计参数(如m, T, θ, tmin, tmax)对机械性能有很强的影响。最后进行多目标优化，使比能吸收最大化，同时减小最大冲击力。优化结果表明，新型梯度超材料比普通材料具有更强的能量吸收能力。其中，峰值载荷力上升15%，比能吸收提高到80%。由于其独特的结构设计和优异的力学性能，DGAT元结构在交通防护、军事防护工程、载人飞船缓冲和吸能箱等领域具有巨大的应用潜力。Composites Part A: Applied Science and ManufacturingHyperelastic and multifunctional SiC/SiO2 composite aerogels with excellent mechanical, thermal insulation and electromagnetic wave absorbing propertiesMingyuan Yan, Yuelei Pan, Pan He, Lunlun Gong, Yangyang Fu, Xudong Chengdoi:10.1016/j.compositesa.2024.108408 超弹性多功能SiC/SiO2复合气凝胶具有优异的机械、隔热和电磁波吸收性能SiC (silicon carbide) aerogels have attracted extensive attention due to their excellent thermal stability and large porosity. But at present, the serious challenge of SiC aerogel application is still poor mechanical properties. To address the above challenge, here we report SiC/SiO2 composite aerogels (SSCAs) with a mutually supported dual-network structure. SiO2 nanoporous networks are introduced into SiC networks to achieve the multifunctional properties, including mechanics, thermal insulation and electromagnetic wave absorption properties. Benefiting from the dual-network structure, the maximum compressive stress of the SSCAs is increased to 2551 kPa. In addition, SSCAs can withstand a large elastic strain of up to 60 %. Furthermore, the SSCAs exhibit an ultra-low thermal conductivity of 0.023 W·m−1 K−1 at room temperature. More importantly, SiC/SiO2 heterointerface structure optimizes impedance matching, resulting in an effective absorption bandwidth of 6.5 GHz. This work provides new ideas and insights for the preparation of multifunctional ceramic aerogels.碳化硅气凝胶以其优异的热稳定性和大孔隙率而受到广泛关注。但目前，SiC气凝胶应用面临的严峻挑战仍然是力学性能差。为了解决上述挑战，本文报道了具有相互支持双网络结构的SiC/SiO2复合气凝胶(ssca)。将二氧化硅纳米孔网络引入到碳化硅网络中，实现了包括力学、隔热和电磁波吸收性能在内的多功能性能。得益于双网络结构，ssca的最大压应力提高到2551 kPa。此外，ssca可以承受高达60% %的大弹性应变。此外，ssca在室温下表现出0.023 W·m−1 K−1的超低导热系数。更重要的是，SiC/SiO2异质界面结构优化了阻抗匹配，使有效吸收带宽达到6.5 GHz。本研究为多功能陶瓷气凝胶的制备提供了新的思路和见解。Investigation of MXene@APP/FDS/AgNPs@EG system for preparing multifunctional thermoplastic polyurethane composites with flame retardancy and electromagnetic shielding performanceMinghao Li, Chunhui Chen, Wenqing Hai, Ziyang Jiang, Qian Meng, Enquan Hao, Hongjie Li, Huiqi Shao, Guangwei Shao, Jinhua Jiang, Nanliang Chen, Siyi Bidoi:10.1016/j.compositesa.2024.108409MXene@APP/FDS/AgNPs@EG体系制备阻燃、电磁屏蔽多功能热塑性聚氨酯复合材料的研究In order to comply with the requirement of flame retardancy and electromagnetic interference (EMI) shielding for encapsulant applied to electronic devices, multifunctional thermoplastic polyurethane (TPU) composites are prepared with the construction of an intumescent flame retardant (IFR) system comprising internal conductive network. In this work, ammonium polyphosphate wrapped with MXene (MXene@APP) is attained by microencapsulation, and expandible graphite decorated with Ag nanoparticles (AgNPs@EG) is prepared by the reducibility of silk sericin. The IFR system with conductivity is established by the introduction of MXene@APP, AgNPs@EG and furfural-derived Schiff base (FDS). The as-prepared TPU/MXene@APP/FDS/AgNPs@EG composites are able to attain significant elevation in flame retardancy, exhibiting V-0 rating and a LOI value of 33.1 %. Furthermore, TPU composites are integrated with warp-knitted metal mesh (WMM) to fabricate TPU@WMM coated fabric, displaying strengthened electromagnetic interference (EMI) shielding effectiveness (SE) of 37.53 dB within X band. This work provides a potential method for application in encapsulant with flame retardancy and electromagnetic protection.为满足电子封装材料对阻燃性能和电磁干扰屏蔽性能的要求，构建了由内部导电网络构成的膨胀型阻燃体系，制备了多功能热塑性聚氨酯(TPU)复合材料。本研究采用微胶囊化的方法制备了MXene包裹的聚磷酸铵(MXene@APP)，并利用丝胶蛋白的还原性制备了Ag纳米颗粒修饰的可膨胀石墨(AgNPs@EG)。通过引入MXene@APP、AgNPs@EG和糠醛衍生希夫碱(FDS)，建立了具有导电性的IFR体系。制备的TPU/MXene@APP/FDS/AgNPs@EG复合材料的阻燃性能显著提高，阻燃系数为V-0, LOI值为33.1% %。此外，将TPU复合材料与经编金属网(WMM)相结合制备TPU@WMM涂层织物，在 X 波段内显示出37.53 dB的增强电磁干扰(EMI)屏蔽效果。本研究为阻燃和电磁防护封装材料的应用提供了一种潜在的方法。MoSe2 nanosheets implanting on 3D hollow carbon sphere for high-efficiency electromagnetic wave absorptionXiaonan Yang, Zhuguang Nie, Yang Feng, Xiaoli Guo, Zhiyue Zhao, Mingyu Jiang, Guiyu Chu, Shuhua Qi, Panbo Liudoi:10.1016/j.compositesa.2024.108411 三维中空碳球上MoSe2纳米片的高效电磁波吸收Carbon-based electromagnetic wave absorption (EMA) materials are extensively studied due to their unique advantages. Nevertheless, impedance matching issues was still constraining their further research. Consequently, we successfully synthesized MoSe2 nanosheets implanting on 3D hollow carbon sphere (HCS@MoSe2) composites with core–shell structure. The complex core–shell structure high-entropy composites provided multiple dissipation mechanisms for efficient dissipation of incident electromagnetic wave energy. The implanting MoSe2 nanosheets optimized the dielectric constant of the composites, thus ensuring optimal impedance matching. The HCS@MoSe2-1 composites exhibit excellent EMA properties and a significant minimum reflection loss (RLmin) of −56.19 dB. And HCS@MoSe2-1 had an ultra-wide effective absorption bandwidth (EAB) of 7.43 GHz. The significant EMA capability attributed to the synergistic effects of conductive loss, polarization loss, and optimized impedance matching. This work paved a new path for synthesizing transition metal selenide-modified carbon-based composite materials, offering great potential as high-performance materials for EMA applications.碳基电磁波吸收材料因其独特的优点而受到广泛的研究。然而，阻抗匹配问题仍然制约着他们的进一步研究。因此，我们成功地合成了MoSe2纳米片植入三维空心碳球(HCS@MoSe2)复合材料。复杂核壳结构的高熵复合材料为入射电磁波能量的有效耗散提供了多种耗散机制。MoSe2纳米片的植入优化了复合材料的介电常数，从而保证了最佳的阻抗匹配。HCS@MoSe2-1复合材料具有优异的EMA性能，最小反射损耗(RLmin)为−56.19 dB。HCS@MoSe2-1具有7.43 GHz的超宽有效吸收带宽(EAB)。显著的EMA能力归因于导电损耗、极化损耗和优化的阻抗匹配的协同效应。该研究为过渡金属硒化碳基复合材料的合成开辟了新的道路，为EMA应用提供了巨大的高性能材料潜力。Constructing bidirectional heat flow pathways by curved alumina for enhanced thermal conductivity of epoxy compositesJiani Tan, Zhen Xu, Fei Ding, Zongxian Yang, Fangli Yuan, Yuge Ouyangdoi:10.1016/j.compositesa.2024.108412 用弯曲氧化铝构筑双向热流通道以增强环氧复合材料的导热性The polymer-based composites filled with high thermal conductive fillers have received much attention in the filed of electronic package. However, traditional Al2O3 filled polymer-based composites always hardly simultaneously achieve high thermal conductivity in both horizontal and vertical directions with a low loading. Herein, curved Al2O3 particles have been fabricated via spray assembly and high-temperature sintering and subsequently are infiltrated by epoxy (EP) to obtain Al2O3/EP composites. The formation mechanism of the curved Al2O3 is analyzed in this work. The curved Al2O3 architectures are orderly stacked in EP matrix, which achieve significantly enhanced in-plane (1.21  W/m·K) and through-plane (1.46  W/m·K) thermal conductivity with a low filler loading (19.9 vol%). Importantly, the wall structure of curved Al2O3 particle consists of continuous network structure and interconnected channels, which reduce the thermal expansion coefficient of the composites. Consequently, the design of curved Al2O3 offers a new strategy for next-generation thermal management materials.高导热填料填充聚合物基复合材料在电子封装领域受到广泛关注。然而，传统的Al2O3填充聚合物基复合材料很难同时在水平方向和垂直方向上获得高导热性，并且具有低载荷。本文通过喷雾组装和高温烧结制备了弯曲的Al2O3颗粒，然后用环氧树脂(EP)渗透得到Al2O3/EP复合材料。分析了弯曲Al2O3的形成机理。弯曲Al2O3结构在EP基体中有序堆叠，在低填充量(19.9 vol%)的情况下，显著提高了平面内(1.21  W/m·K)和平面内(1.46  W/m·K)导热系数。重要的是，弯曲Al2O3颗粒的壁结构由连续的网络结构和相互连接的通道组成，这降低了复合材料的热膨胀系数。因此，弯曲Al2O3的设计为下一代热管理材料提供了一种新的策略。Composites Part B: EngineeringEffect of microstructural roughness on the performance and fracture mechanism of multi-type single lap jointsKai Pang, Xing-er Wang, Jianqiao Ye, Craig Carnegie, Xiaonan Houdoi:10.1016/j.compositesb.2024.111763显微组织粗糙度对多类型单搭接接头性能及断裂机理的影响Surface roughness of adherends is a crucial factor in determining the performance and failure mechanism of adhesive joints. However, the research dedicated to the examination of fracture mechanism for adhesive joints influenced by surface roughness at microscale is limited. This work conducts systematic experimental and numerical investigations into the effect of microstructural roughness on the performance and fracture mechanism of multi-type adhesive single lap joints (SLJ). The adherend materials are aluminium alloy (Al) and polyphthalamide (PPA), ground into three roughness grades for the fabrication of SLJs using an epoxy adhesive. The mechanical properties of the adhesive, adherends and SLJs derived from experimental studies are utilized to calibrate the microparameters in Discrete Element Method (DEM) models for a numerical analysis. The newly developed DEM models demonstrate efficacy in predicting the performance and capturing the failure modes of multi-type SLJs realistically with distinct microroughness profiles. Finally, the influencing mechanisms of microstructural roughness on the performance of multi-type SLJs are investigated, including the microscale interfacial bonds and mechanical interlockings. The effects of microstructural roughness on the microscale failure mechanisms of multi-type SLJs are also explored and discussed, including the crack initiation, coalescence, and propagation within the adhesive and interface.粘结剂的表面粗糙度是决定粘结接头性能和失效机理的关键因素。然而，在微观尺度上对表面粗糙度对粘接接头断裂机理的研究还很有限。本文系统地研究了显微组织粗糙度对多型胶合单搭接接头(SLJ)性能和断裂机理的影响。粘附材料是铝合金(Al)和聚苯二胺(PPA)，研磨成三个粗糙度等级，用于使用环氧粘合剂制造slj。利用实验研究得到的胶粘剂、黏合剂和slj的力学性能，标定离散元法(DEM)模型中的微参数，进行数值分析。新开发的DEM模型可以有效地预测具有不同微孔分布的多类型slj的性能和捕获其失效模式。最后，研究了微观结构粗糙度对多类型slj性能的影响机制，包括微观界面键和机械互锁。探讨了微观结构粗糙度对多类型slj微尺度破坏机制的影响，包括胶粘剂和界面内的裂纹萌生、裂纹合并和裂纹扩展。Composites Science and TechnologyA parametric modeling method for 2.5D warp-reinforced woven composites considering the extruded distortion of yarnsXiangling Zhang, Junhua Guo, Huabing Wen, Haitao Cui, Hongjian Zhang, Weidong Wen, Chun Guo, Yifan Zhang, Wantao Guodoi:10.1016/j.compscitech.2024.110807 考虑纱线挤压变形的2.5维经编增强机织复合材料参数化建模方法2.5D warp-reinforced woven composites (2.5DWRWC) are widely used in various industries, but it is currently difficult to model parametrically considering the molding effects due to their complex structure. Accordingly, two special parameters (ψ and φ) are introduced to regulate the degree of yarn extrusion, where ψ is used to characterize the extrusion degree of the binder yarn on the weft yarn in the thickness direction, and φ is used to characterize the twisting degree of the warp yarn. On this basis, a parametric modeling method for 2.5DWRWC is constructed by uniting the essential weaving parameters, and the modeling code is written in TexGen software using Python language. Subsequently, the established model is verified experimentally, and the results show that the average comparison error of the geometric parameters is only 5.07%, the maximum prediction error of the mechanical properties is only 4.78%, validating the reasonableness of the proposed modeling method. Finally, the effects of the two special parameters on the mechanical properties are emphasized, and the results show that the mechanical properties in weft direction are enhanced with the increase of ψ, and the mechanical properties in warp direction are weakened with the increase of φ. This work can provide guidance for the molding process and mechanical design of 2.5DWRWC, which has significant theoretical value and engineering significance.2.5维经编增强机织复合材料(2.5DWRWC)广泛应用于各个行业，但由于其结构复杂，目前难以进行考虑成型效果的参数化建模。为此，引入两个特殊参数ψ和φ来调节纱线的挤压程度，其中ψ用于表征粘结纱在纬纱粗细方向上对纬纱的挤压程度，φ用于表征经纱的加捻程度。在此基础上，通过统一基本织造参数，构建了2.5DWRWC的参数化建模方法，并使用Python语言在TexGen软件中编写了建模代码。随后，对所建立的模型进行了实验验证，结果表明，几何参数的平均比较误差仅为5.07%，力学性能的最大预测误差仅为4.78%，验证了所提出建模方法的合理性。结果表明:经向的力学性能随ψ的增大而增强，经向的力学性能随φ的增大而减弱;该工作可为2.5DWRWC的成型工艺和机械设计提供指导，具有重要的理论价值和工程意义。Multi-Walled Carbon Nanotube-Enhanced Polyurethane Composite Materials and the Application in High-Performance 3D Printed Flexible Strain SensorsXinchun Luo, Hailong Cheng, Kaiqi Chen, Lin Gu, Sheng Liu, Xin Wudoi:10.1016/j.compscitech.2024.110818 多壁碳纳米管增强聚氨酯复合材料及其在高性能3D打印柔性应变传感器中的应用Flexile strain sensors hold vast potential for applications in monitoring human motion, enabling human-machine interaction, and facilitating information transfer, etc. However, the available materials and manufacturing techniques for fabricating flexible strain sensors with high sensitivity and extended sensing range still face significant challenges. By utilizing solution casting and twin-screw extrusion techniques, this study prepared high-performance thermoplastic polyurethane/multi-walled carbon nanotube (TPU/MWCNT) nanocomposite 3D printable filaments, and employed material extrusion 3D printing technology to facilely fabricate flexible strain sensors. The 1-pyrene carboxylic acid (PCA)-modified TPU/MWCNT(3wt%) nanocomposite exhibited outstanding mechanical properties, with a tensile strength of 24.3±0.5 MPa and a fracture elongation of 625.8±12.3%. The 3D printed TPU/MWCNT(3wt%)/PCA flexible strain sensors demonstrated amazing sensitivity (GFmax=10279.95) within a wide strain range (0-300% strain). The addition of PCA brings the benefits of improved dispersion of MWCNTs in the TPU composite, as well as enhanced thermal stability, and upgraded mechanical and electrical properties under different tensile strains. Meanwhile, the 3D printed samples displayed remarkable durability and reproducibility. Finally, the flexible strain sensors fabricated from this nanocomposite material could accurately perceive human motion, providing great prospects for wearable device applications.柔性应变传感器在监测人体运动、实现人机交互、促进信息传递等方面具有巨大的应用潜力。然而，制造具有高灵敏度和大范围传感的柔性应变传感器的材料和制造技术仍然面临着重大挑战。本研究采用溶液铸造和双螺杆挤压技术，制备了高性能热塑性聚氨酯/多壁碳纳米管(TPU/MWCNT)纳米复合材料3D打印长丝，并利用材料挤压3D打印技术方便地制造柔性应变传感器。1-芘羧酸(PCA)改性TPU/MWCNT(3wt%)纳米复合材料具有优异的力学性能，抗拉强度为24.3±0.5 MPa，断裂伸长率为625.8±12.3%。3D打印的TPU/MWCNT(3wt%)/PCA柔性应变传感器在宽应变范围(0-300%应变)内表现出惊人的灵敏度(GFmax=10279.95)。PCA的加入改善了MWCNTs在TPU复合材料中的分散性，增强了材料的热稳定性，提高了材料在不同拉伸应变下的力学和电学性能。同时，3D打印的样品显示出显著的耐用性和可重复性。最后，利用该纳米复合材料制备的柔性应变传感器能够准确感知人体运动，为可穿戴设备的应用提供了广阔的前景。来源：复合材料力学仿真Composites FEM