【新文速递】2023年12月30日固体力学SCI期刊最新文章

18天前浏览200

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

International Journal of Solids and Structures

Phase-field modeling of anisotropic crack propagation based on higher-order nonlocal operator theory

Nhon Nguyen-Thanh, Timon Rabczuk

doi:10.1016/j.ijsolstr.2023.112632

基于高阶非局部算子理论的各向异性裂纹扩展相场建模

This paper presents a novel higher-order nonlocal operator theory for the phase-field modeling of brittle fracture in anisotropic materials. Incorporating higher order nonlocal operators can enhance the accuracy of the phase-field model by effectively capturing long-range interactions that hold significance in numerous materials. The reproducing kernel particle method is employed to derive a nonlocal differential operator to enhance computational stability and accuracy. Moreover, the proposed method eliminates the need for direct computation of derivatives of the modified kernel function, which avoids the calculation of moment matrix derivatives and improves computational efficiency. The phase-field modeling of polycrystalline materials, considering the anisotropic fracture resistance of each grain, is implemented using this numerical framework. The present method is able to capture different scenarios intergranular and transgranular crack propagation patterns in polycrystalline materials. The proposed method involves a detailed representation of the complex process of crack initiation and propagation in 2D and 3D models of polycrystalline materials.

提出了一种新的高阶非局部算子理论，用于各向异性材料脆性断裂相场建模。结合高阶非局部算符可以通过有效地捕获在许多材料中具有重要意义的远程相互作用来提高相场模型的准确性。采用再现核粒子法推导非局部微分算子，提高了计算的稳定性和精度。此外，该方法不需要直接计算修正核函数的导数，避免了矩矩阵导数的计算，提高了计算效率。采用该数值框架对多晶材料进行了相场建模，考虑了各晶粒的抗断裂性能各向异性。该方法能够捕获多晶材料中不同情况下的晶间和穿晶裂纹扩展模式。该方法在二维和三维多晶材料模型中详细描述了裂纹萌生和扩展的复杂过程。

Fracture resistance enhanced by both nonlocal interaction and damping of locally resonant structure

Xuan Zhang, Yi-Ze Wang

doi:10.1016/j.ijsolstr.2023.112635

非局部相互作用和局部共振结构的阻尼增强了抗断裂能力

In this study, the arrest behavior of locally resonant structure with nonlocal interaction and damping are analyzed. Based on the Wiener-Hopf method, the energy release ratio G0/G which denotes the arrest property is derived. The effects of nonlocal interaction and damping parameters on the oscillation and stability regions during the crack growth are discussed. The arrest characteristics of three locally resonant structures are compared. In order to support the theoretical calculation, both the finite element simulation and fracture experiment are performed. Results show that the locally resonant structure with nonlocal interaction and damping has smaller energy release ratio G0/G. It indicates that the coupling of both nonlocal interaction and damping can significantly enhance the propagation resistance of crack propagation.

本研究分析了具有非局部相互作用和阻尼的局部谐振结构的阻滞行为。基于 Wiener-Hopf 方法，推导出了表示停滞特性的能量释放比 G0/G。讨论了非局部相互作用和阻尼参数对裂纹生长过程中振荡区和稳定区的影响。比较了三种局部共振结构的抑制特性。为了支持理论计算，进行了有限元模拟和断裂实验。结果表明，具有非局部相互作用和阻尼的局部共振结构的能量释放比 G0/G 较小。这表明，非局部相互作用和阻尼的耦合可以显著增强裂纹的抗扩展能力。

Journal of the Mechanics and Physics of Solids

Rate Induced Thermomechanical Interactions in NiTi Tensile Tests on Strips

Solon Tsimpoukis, Stelios Kyriakides

doi:10.1016/j.jmps.2023.105530

带材镍钛拉伸试验中速率诱导的热-机械相互作用

The paper uses tensile experiments on NiTi strips at different displacement rates to establish and simulate the thermomechanical interactions caused by the latent heat of the reversible transformation between the austenitic and martensitic phases. The evolution of deformation in the specimen is synchronously monitored with digital image correlation, and the temperature field through infrared imaging, essential for structural modelling. Transformation leads to localized deformation that propagates through the specimen, while the latent heat released/absorbed at the propagating fronts locally heats/cools the specimen. The sensitivity of the transformation stress to temperature results in a complex interaction between the heat transfer conditions and the nucleation and evolution of transformation in the specimen. At low rates of loading, the alternate phase propagates nearly isothermally with a small number of fronts producing relatively flat stress plateaus. Higher rates lead to significant heating/cooling that results in progressive nucleation of multiple fronts and apparent "hardening" responses. The experiments are simulated in a three-dimensional static displacement transient temperature finite element analysis, using a new fully coupled thermomechanical constitutive model. Transformation strain and entropy are its internal variables whose evolution is governed by the motion in the stress-temperature space of a single transformation surface governing both transformations. The prevailing localization is captured by the introduction of softening over the unstable branches of the recorded isothermal material response. The results demonstrate how the important role of the thermal interaction between the specimen and the environment can be addressed. This, together with appropriate calibration of the constitutive and structural model, enable the analysis to reproduce the effect of rate on the recorded response, the evolution of localization patterns, and the associated thermal fields. The results can guide the development of constitutive and structural models of phase transforming materials with strong thermomechanical interactions.

本文采用不同位移速率下NiTi带材的拉伸实验，建立并模拟了奥氏体与马氏体可逆相变潜热引起的热力相互作用。通过数字图像相关同步监测试样的变形演变，并通过红外成像同步监测温度场，这对结构建模至关重要。相变导致局部变形在试样中传播，而在传播前沿释放/吸收的潜热局部加热/冷却试样。相变应力对温度的敏感性导致传热条件与试样的形核和相变演化之间存在复杂的相互作用。在低加载速率下，交替相几乎等温传播，少数锋面产生相对平坦的应力高原。较高的速率导致显著的加热/冷却，导致多个锋面逐渐成核和明显的“硬化”反应。采用一种新的全耦合热-力本构模型，对实验进行了三维静位移瞬态温度有限元模拟。相变应变和熵是其内部变量，其演化由控制两种相变的单一相变表面在应力-温度空间中的运动决定。通过在记录的等温材料响应的不稳定分支上引入软化，捕获了普遍的局部化。结果表明，如何在试样和环境之间的热相互作用的重要作用可以解决。这与本构和结构模型的适当校准一起，使分析能够重现速率对记录响应的影响，定位模式的演变以及相关的热场。研究结果对具有强热力相互作用的相变材料的本构模型和结构模型的建立具有指导意义。

International Journal of Plasticity

Revealing the effects of martensitic transformation and dislocation slip in austenite on the micromechanical behaviors of a 9Ni steel using crystal plasticity finite element method

W.X. Zhang, Y.B. Cong, J. Wang, C. Li, J. Wan, Y.Z. Chen

doi:10.1016/j.ijplas.2023.103869

利用晶体塑性有限元法揭示了马氏体相变和奥氏体位错滑移对9Ni钢微观力学行为的影响

Austenite is an extremely important phase that significantly influence the mechanical properties of (austenite + martensite) duplex steels. Two different deformation mechanisms, i.e., dislocation slip and martensitic transformation, can be activated in the austenite upon plastic deformation. However, these two deformation mechanisms make different contributions to the work hardening and flow stress of the austenite which are hardly separated by experimental methods, making it difficult to clarify the effect of austenite on the micromechanical behavior of (austenite + martensite) duplex steels. In this work, the influence of martensitic transformation and dislocation slip in austenite on the micromechanical behaviors is investigated in a model 9Ni steel consisting of austenite and tempered martensite (TM) using the crystal plasticity finite element method (CPFEM). The austenite and fresh martensite (FM) formed within the austenite grain upon deformation process are regarded as a whole named as FM/A island in the CPFEM. To accurately model the rate of martensitic transformation, the martensitic transformation kinetics law used in the CPFEM is developed by relating the number of possible nucleation sites for fresh martensite to the mechanical driving force originating from the resolved shear stress on each transformation system. The material parameters for the TM were determined by micropillar compression tests. Besides, the method for separating and determining the material parameters accounting for dislocation slip in austenite and martensitic transformation by a combination of neutron diffraction and measurements of stress-strain curves and austenite volume fractions is developed and exemplified. The CPFEM simulation results show that the local concentration of equivalent plastic strain and stress triaxiality in the FM/A island can be enhanced by the dislocation slip in austenite but suppressed by the martensitic transformation. In addition, the martensitic transformation has a remarkable effect on strengthening the local concentration of maximum principal stress in the FM/A island.

奥氏体是影响(奥氏体 + 马氏体)双相钢力学性能的重要相。塑性变形时，奥氏体可激活两种不同的变形机制，即位错滑移和马氏体相变。然而，这两种变形机制对奥氏体的加工硬化和流动应力的贡献各不相同，且难以通过实验方法加以区分，因此很难阐明奥氏体对(奥氏体 + 马氏体)双相钢微观力学行为的影响。本文采用晶体塑性有限元法(CPFEM)研究了奥氏体和回火马氏体(TM)组成的9Ni钢中马氏体相变和位错滑移对微观力学行为的影响。在CPFEM中，将形变过程中在奥氏体晶粒内形成的奥氏体和新马氏体(FM)视为一个整体，称为FM/ a岛。为了准确地模拟马氏体转变的速率，CPFEM中使用的马氏体转变动力学定律是通过将新马氏体可能成核的位置的数量与每个转变系统上由分解的剪切应力产生的机械驱动力相关联而建立的。通过微柱压缩试验确定了TM的材料参数。此外，还提出了利用中子衍射、应力-应变曲线和奥氏体体积分数测量相结合的方法来分离和确定奥氏体和马氏体相变中位错滑移的材料参数。CPFEM模拟结果表明，奥氏体位错滑移增强了FM/A岛的局部等效塑性应变集中和应力三轴性，但马氏体相变抑制了等效塑性应变的集中。此外，马氏体相变对强化FM/ a岛局部最大主应力集中有显著作用。

Thin-Walled Structures

Experimental and numerical study on the lightweight design of load-bearing energy absorption structure for subway train

Jialin Li, Guangjun Gao, Yao Yu, Tianyu Zhuo, Jian Li

doi:10.1016/j.tws.2023.111542

地铁列车承载吸能结构轻量化设计的试验与数值研究

The load-bearing underframe is widely utilized on the crashworthiness design of subway trains. However, studies on load-bearing underframes mainly focused on conceptual design and structural optimization, and didn't consider the combination of bearing loads during the normal operation and absorbing impact kinetic energy under collisions. In addition, the traditional load-bearing underframe for subway trains is mainly made of stainless steel, which has a relatively large weight and cannot meet the requirement of lightweight design. To address these limitations, this paper presents a novel lightweight aluminum alloy load-bearing underframe with the alternative thin-walled energy absorption component, which can both satisfy the function of bearing loads and energy absorption. Firstly, the impact tests and numerical simulations are conducted to compare the crashworthiness of the energy absorption component, i.e., the thin-walled square tube made of S304 (abbreviated as S3N4) and aluminum alloy 5083P-O (abbreviated as A3N4). The result shows that S3N4 has higher energy absorption and mean crushing force, and A3N4 is 56.94 % lower than S3N4 in initial peak crushing force and 53.79 % higher in special energy absorption. Then, the aluminum alloy thin-walled tube is adopted on the novel load-bearing underframe and the parameter study on the wall thickness and number of diaphragms for the energy absorption component is conducted. The result reveals that the 5083P-O thin-walled tube with 5 mm wall thickness and 4 diaphragms can provide the stable and ordered deformation mode and high energy absorption. Finally, a real vehicle impact test is conducted to verify the crashworthiness of the optimized load-bearing underframe, which shows that the deformation modes and mechanical responses are consistent with the numerical simulation. The proposed aluminum alloy load-bearing underframe energy absorption structure can be adopted on subway trains.

在地铁列车的耐撞性设计中，承重型车架得到了广泛的应用。然而，对承重型车架的研究主要集中在概念设计和结构优化上，没有考虑车架正常运行时承受载荷与碰撞时吸收冲击动能的结合。此外，传统的地铁列车承重底架以不锈钢为主，自重较大，不能满足轻量化设计的要求。针对这些局限性，本文提出了一种新型的轻质铝合金承载底架，并采用替代薄壁吸能组件，既能满足承载载荷又能满足吸能功能。首先，对S304薄壁方管(简称S3N4)和5083P-O铝合金(简称A3N4)两种吸能构件的耐撞性进行了冲击试验和数值模拟比较。结果表明，S3N4具有更高的能量吸收和平均破碎力，A3N4初始峰值破碎力比S3N4低56.94%，特殊能量吸收比S3N4高53.79%。然后，在新型承力底架上采用铝合金薄壁管，对吸能构件的壁厚和隔板数进行了参数研究。结果表明:5083P-O薄壁管的壁厚为5mm，隔板为4个，可以提供稳定有序的变形模式和较高的能量吸收。最后，进行了实车碰撞试验，验证了优化后的承载底架的耐撞性，结果表明，其变形模式和力学响应与数值模拟结果一致。本文提出的铝合金承力底架吸能结构可用于地铁列车。

An all-composite sandwich structure with PMI foam-filled for adjustable vibration suppression and improved mechanical properties

Jiaming Sun, Leilei Yan, Keyu Zhu, Pengfei Jiang, Yanlong Xu, Xitao Zheng

doi:10.1016/j.tws.2023.111544

采用PMI泡沫填充的全复合夹层结构，可调抑制振动，提高力学性能

A novel all-composite double-layer sandwich structure with tubular cores (DSST) is designed and fabricated to achieve the both of vibration suppression and enhancement of mechanical properties. The suppression effect of the proposed sandwich structure on the structural vibration is verified numerically and experimentally, and the mechanism of bandgap generation as well the structural wave propagation modes are revealed and analyzed. The anisotropy of the carbon fiber reinforced polymer (CFRP) is utilized to enables the intermediate resonant layer to exist a wide frequency adjustment range of vibration suppression without altering its geometrical parameters. Then, the improvement of structural vibration characteristics (i.e., natural frequencies and mode shapes) by filling the polymethacrylimide (PMI) foam in the DSST is discussed. And PMI foam-filling also leads to improved mechanical properties, out-of-plane compression tests are conducted to reveal the mechanism of mechanical enhancement, and it is found that the interaction effect of the foam filled in DSST in the axial direction enhances the compressive strength and the specific energy absorption (SEA) compared to the one without foam by 35.7% and 26.2%, respectively. In addition, the core configuration and the composite material preparation enable the proposed structure to outperform competing ones in terms of load-bearing capacity and bandgap characteristics.

设计并制造了一种新型的双层管状芯夹芯全复合材料结构(DSST)，以达到抑制振动和提高力学性能的目的。通过数值和实验验证了夹层结构对结构振动的抑制作用，揭示和分析了带隙产生的机理以及结构波的传播模式。利用碳纤维增强聚合物(CFRP)的各向异性，使中间谐振层在不改变其几何参数的情况下存在较宽的频率调节范围来抑制振动。然后讨论了在DSST中填充聚甲基丙烯酰亚胺(PMI)泡沫对结构振动特性(即固有频率和振型)的改善。PMI泡沫填充也能改善材料的力学性能，通过面外压缩试验揭示了力学增强的机理，结果发现，在轴向填充泡沫后，材料的抗压强度和比能吸收(SEA)比未填充泡沫时分别提高了35.7%和26.2%。此外，核心配置和复合材料制备使所提出的结构在承载能力和带隙特性方面优于竞争结构。

来源：复合材料力学仿真Composites FEM

【新文速递】2024年1月1日复合材料SCI期刊最新文章

今日更新：Composite Structures 3 篇，Composites Part A: Applied Science and Manufacturing 2 篇，Composites Part B: Engineering 1 篇，Composites Science and Technology 1 篇Composite StructuresInfluence of compaction and curing in the Automated Fiber Placement Process on the mechanical performance of composite laminatesSylvester Vogl, Ralf Knott, Silvano Sommacal, Paul Compston, Klaus Drechslerdoi:10.1016/j.compstruct.2023.117826自动纤维铺放工艺中的压实和固化对复合材料层压板机械性能的影响This paper investigates the effect of compaction and curing states on the mechanical properties and void content of AFP-manufactured laminates. For the mechanical characterization, tensile tests, 4-point-bending tests and interlaminar shear strength (ILSS) tests were applied. The internal structure was evaluated via micro CT. For the surface structure evaluation, an optical profilometer was used. The void content was determined via segmentation of the micro CT images. The paper is subdivided into the description of the applied materials and methods, the results and their discussion and a conclusion. The study showcases the potential of AFP-manufactured aerospace composites to attain high-quality results even without the need for an autoclave, making them well-suited for unmanned applications.本文研究了压实和固化状态对 AFP 制造的层压板的机械性能和空隙率的影响。在机械性能表征方面，采用了拉伸试验、4 点弯曲试验和层间剪切强度（ILSS）试验。内部结构通过微型 CT 进行评估。表面结构评估则使用了光学轮廓仪。通过对微型 CT 图像进行分割，确定了空隙含量。本文分为应用材料和方法描述、结果及其讨论和结论。该研究展示了 AFP 制造的航空航天复合材料的潜力，即使无需高压灭菌也能获得高质量的结果，使其非常适合无人驾驶应用。Enhanced prediction of transverse mechanical behavior of unidirectional fiber-reinforced composites using new spatial descriptors based on deep neural networksSun Won Kim, Jae Hyuk Lim, Seong Su Kimdoi:10.1016/j.compstruct.2023.117870利用基于深度神经网络的新空间描述符增强单向纤维增强复合材料横向力学行为的预测能力In this study, we developed a data-driven approach using a deep neural network (DNN) to predict the nonlinear stress-strain behavior of fiber-reinforced composites under transverse tensile loading. We explored the impact of different input features characterizing the composite microstructure on the prediction accuracy of the DNN model. Specifically, we introduced a spatial descriptor representing fiber arrangement and proposed new spatial descriptors based on fiber area to improve input feature quality. Incorporating widely-used spatial descriptors such as the second-order intensity function and radial distribution function improved the prediction performance compared to previous methods. Combining spatial descriptors for both fiber distribution and alignment further enhanced prediction accuracy. To address the limitations of conventional spatial descriptors, we developed new spatial descriptors using a continuous function. Our findings demonstrate the importance of selecting appropriate input features for improved DNN model performance, even with the same dataset. Moreover, the proposed fiber area-based spatial descriptors offer insights into the micromechanical behavior of composite materials.在这项研究中，我们利用深度神经网络（DNN）开发了一种数据驱动方法，用于预测横向拉伸载荷下纤维增强复合材料的非线性应力应变行为。我们探索了表征复合材料微观结构的不同输入特征对 DNN 模型预测精度的影响。具体来说，我们引入了代表纤维排列的空间描述符，并提出了基于纤维面积的新空间描述符，以提高输入特征的质量。与之前的方法相比，结合二阶强度函数和径向分布函数等广泛使用的空间描述符提高了预测性能。结合纤维分布和排列的空间描述符进一步提高了预测精度。为了解决传统空间描述符的局限性，我们使用连续函数开发了新的空间描述符。我们的研究结果表明，即使使用相同的数据集，选择适当的输入特征对于提高 DNN 模型性能也非常重要。此外，所提出的基于纤维面积的空间描述符为复合材料的微观机械行为提供了见解。Mechanical vibration absorber for flexural wave attenuation in multi-materials metastructureLong Liu, Ji Wan Kim, Gil Ho Yoon, Bing Yidoi:10.1016/j.compstruct.2023.117859用于衰减多材料结构中挠曲波的机械减震器Vibration isolation is a promise to suppress mechanical vibration from a host structure, similarly, a mechanical vibration absorber, a simple but effective device to attenuate flexural wave propagation, which has been implemented in civil and mechanical engineering. This paper presents a type of composite sandwich phononic crystal to attenuate the flexural wave propagation in a beam structure, which can effectively suppress mechanical vibration in a broad band gap by repetitively arranging phononic crystal. First, the elastic wave dispersion characteristic in a composite sandwich beam structure is derived, and a triangular shape phononic crystal for flexural wave attenuation by taking advantage of destructive interference is presented. Then two dimensional phononic crystals are designed by assembling four different unit-cells of metabeam. Finally, numerical experiments are conducted to verify the effectiveness of the proposed mechanical metamaterial absorbers to attenuate flexural wave propagation, the numerical results indicate that the proposed metamaterial is of good performance in mechanical vibration suppression, which can effectively mitigate structure vibration in low-frequency domain than the structure without phononic crystal and single layer metamaterial beam structure. It is the first attempt to design a mechanical metamaterial absorber with the mechanism of destructive interference with composite sandwich phononic crystal.隔振是一种抑制来自主机结构的机械振动的承诺，同样，机械吸振器也是一种简单而有效的衰减挠性波传播的装置，在土木工程和机械工程中已经得到了应用。本文提出了一种用于衰减梁结构中挠曲波传播的复合夹层声子晶体，通过重复排列声子晶体，可有效抑制宽带隙中的机械振动。首先，推导了复合夹层梁结构中的弹性波色散特性，并提出了一种利用破坏性干涉来衰减挠曲波的三角形声子晶体。然后，通过组装四个不同的元梁单元，设计了二维声子晶体。最后，通过数值实验验证了所提出的机械超材料吸波材料对挠性波传播的衰减效果，数值实验结果表明，所提出的超材料在机械振动抑制方面具有良好的性能，与不含声子晶体的结构和单层超材料梁结构相比，能有效缓解结构在低频域的振动。这是首次尝试利用复合夹层声子晶体的破坏性干涉机制设计机械超材料吸波材料。Composites Part A: Applied Science and ManufacturingSpatial variability characterization and modelling of 2.5D woven SiO2f/SiO2 compositesHongyue Wang, Bing Wang, Maoqing Fu, Guodong Fang, Songhe Mengdoi:10.1016/j.compositesa.2023.107997 2.5D SiO2f/SiO2 编织复合材料的空间变化特征和建模2.5D woven SiO2f/SiO2 composites possess geometric variabilities across scales, such as the spatial fluctuations of fibers and yarns or the random distributions of defects and pores formed in the manufacturing process, which induces a complex stress and strain distribution in material testing. In this study, a multivariate cross-correlated non-Gaussian random field based on Vine Copula is proposed to characterize the spatial variability of mechanical properties. A database of material mechanical properties is acquired by stochastic representative volume element (SRVE) simulation results which contains realistic meso-geometry characteristics and spatially random voids. Based on this database, the cross- and auto-correlations of the mechanical properties are quantified by Vine Copula and non-Gaussian random field model. In a comparison of different numerical models and experimental results, the proposed method is verified, which shows great advantages in characterizing the spatial variability and big potential abilities in damage or reliability analysis.2.5D SiO2f/SiO2 编织复合材料具有跨尺度的几何变异性，如纤维和纱线的空间波动或制造过程中形成的缺陷和孔隙的随机分布，从而在材料测试中引起复杂的应力和应变分布。本研究提出了一种基于 Vine Copula 的多元交叉相关非高斯随机场，用于描述力学性能的空间变异性。材料力学性能数据库由随机代表体积元素（SRVE）模拟结果获得，其中包含真实的中间几何特征和空间随机空隙。在该数据库的基础上，采用 Vine Copula 和非高斯随机场模型对力学性能的交叉和自相关性进行了量化。通过比较不同的数值模型和实验结果，验证了所提出的方法在表征空间变异性方面的巨大优势，以及在损伤或可靠性分析方面的巨大潜力。Functionalizing chitosan-based film with highly sensitive fire response and commendable flame retardancy for intelligent fire-alarm systemRongkai Wu, Yu Wang, Yunyirui Liu, Bihe Yuandoi:10.1016/j.compositesa.2023.107999 将壳聚糖基薄膜功能化，使其具有高度灵敏的火灾反应和值得称赞的阻燃性能，用于智能火灾报警系统Recently, the extensive use of combustible materials has amplified building fire damage, making it essential to incorporate fire-detection devices and flame-retardant materials in building. Herein, the chitosan/gelatin (CG) film and KH2PO4-modified CG (KCG) films were fabricated via an eco-friendly water evaporation method. Impressively, KCG films demonstrate swift response times: 0.5 s at 100 ℃ and 1.8 s under flame, facilitating prompt alarms during fire incidents. Compared to CG, KCG achieve a 70.4% and 46.2% reduction in peak heat release rate and total heat release respectively. They also offer flexibility, transparency, repeated fire-warning efficacy and superior char formation. With these properties, KCG hold promise for innovative building fire safety solutions like smart fire-alarm wallpaper. Besides, a tailored wireless-based fire-alarm system for KCG further decreases building fire damage. This work mitigates damages arising from building fires work, marking significant leap forward in the use of bio-based materials for fire prevention in architecture.近年来，可燃材料的广泛使用加剧了建筑物的火灾损失，因此在建筑物中加入火灾探测装置和阻燃材料至关重要。本文采用环保的水蒸发法制作了壳聚糖/明胶（CG）薄膜和 KH2PO4 改性 CG（KCG）薄膜。令人印象深刻的是，KCG 薄膜的响应时间很快：在 100 ℃ 下为 0.5 秒，在火焰下为 1.8 秒，有助于在火灾事故中迅速报警。与 CG 相比，KCG 的峰值放热率和总放热率分别降低了 70.4% 和 46.2%。此外，KCG 还具有柔韧性、透明性、多次火灾预警效果和优异的炭化性能。凭借这些特性，KCG有望成为智能火警墙纸等创新型建筑消防安全解决方案的首选。此外，为 KCG 量身定制的基于无线的火灾报警系统还能进一步降低建筑火灾损失。这项工作减轻了建筑火灾造成的损失，标志着生物基材料在建筑防火领域的应用取得了重大飞跃。Composites Part B: EngineeringThe synergistic effect of greenhouse gas CO2 and silica fume on the properties of 3D printed mortarHao Lucen, Li Long, Zhang Shipeng, Zhang Huanghua, Xiao Jianzhuang, Poon Chi Sundoi:10.1016/j.compositesb.2023.111188温室气体二氧化碳和硅灰对 3D 打印砂浆性能的协同效应To fulfil the requirements of pumpability and buildability, the rheological properties of mortar/concrete for 3D printing should follow much stricter requirements than traditional-cast mortar/concrete. This study proposed to use a secondary CO2 mixing technique coupled with the addition of silica fume (SF) to achieve in-situ rheology control of 3D printed mortar. The influences of CO2 mixing on the properties of the cast mortar and the 3D printed mortar prepared with SF were systematically studied. The pH, conductivity and ion concentration were tested to revel the essential chemical reactions and phase evolutions during CO2 mixing. It was found that the CO2 mixing effectively enhanced the early-age penetration resistance and yield stress of mortar incorporated with SF, and thus significantly improved the buildability of 3D printed mortar, while the maximum printing layer increased higher than 33 layers. Meanwhile, the mechanical properties of the SF-incorporated mortar were improved by this process. It was revealed that during the CO2 mixing process, the injected CO2 rapidly reacted with calcium ions to form CaCO3, which further reacted with C3A to form monocarboaluminate (Mc). The fast precipitation of calcium ions during CO2 mixing accelerated the hydration of C3A and C3S, contributing to the rapid development of strength at early ages and the improved performance of hardened mortar. The addition of SF in mortar greatly amplified the beneficial effect of CO2 mixing, which due to SF as nucleation sites promoted the formation of CaCO3 and Mc during CO2 mixing.为了满足可泵性和可施工性的要求，3D 打印砂浆/混凝土的流变特性应遵循比传统浇注砂浆/混凝土更严格的要求。本研究建议采用二次二氧化碳混合技术，并添加硅灰（SF），以实现对 3D 打印砂浆的原位流变控制。该研究系统地研究了二氧化碳混合对浇注砂浆和用 SF 制备的 3D 打印砂浆性能的影响。测试了 pH 值、电导率和离子浓度，以揭示二氧化碳混合过程中的基本化学反应和相变。研究发现，CO2 混合能有效提高掺入 SF 的砂浆的早龄期抗渗透性和屈服应力，从而显著改善 3D 打印砂浆的可施工性，最大打印层数比 33 层更高。同时，该工艺还改善了掺入 SF 的砂浆的力学性能。研究发现，在二氧化碳混合过程中，注入的二氧化碳迅速与钙离子反应生成 CaCO3，再与 C3A 反应生成单碳铝酸盐（Mc）。CO2 混合过程中钙离子的快速析出加速了 C3A 和 C3S 的水化，有助于早期龄期强度的快速发展和硬化砂浆性能的改善。在砂浆中加入 SF 大大提高了 CO2 混合的有益效果，因为 SF 是成核场所，在 CO2 混合过程中促进了 CaCO3 和 Mc 的形成。Composites Science and TechnologyA self-powered piezoelectric Poly(vinyl alcohol)/Polyvinylidene fluoride fiber membrane with alternating multilayer porous structure for energy harvesting and wearable sensorsYaru Yu, Xiaowen Zhao, Huaiguo Ge, Lin Yedoi:10.1016/j.compscitech.2023.110429 具有交替多层多孔结构的自供电压电聚（乙烯醇）/聚偏氟乙烯纤维膜，用于能量采集和可穿戴传感器Development of flexible wearable electronic devices requires high-performance piezoelectric sensors, being advantageous in high sensitivity, ease to microintegration without external power supply. In this work, poly(vinyl alcohol) (PVA)/polyvinylidene fluoride (PVDF) fiber membranes with stable alternating multilayer structure were constructed through electrospinning and subsequent gas-phase crosslinking. The PVA/PVDF fiber was fully stretched with smooth surface and uniform diameter at appropriate PVDF concentration, exhibiting high porosity (88 %). The α-phase was transformed into the electroactive β-phase of PVDF in the electrospinning process, while the crystallinity and β-phase percentage (Fβ) were improved by mixing spinning of PVA and PVDF, with Fβ reaching above 90 %. The PVA/PVDF fiber membrane showed high mechanical strength/toughness and liquid absorbency (719.03 %). The significant electrical signal output (10.07 V and 166.42 nA) was generated, accompanying with high stress sensitivity, short response time and high stability, exhibiting excellent piezoelectricity and making the fiber membrane not only monitor large deformation movements of limbs as self-powered wearable sensor, but also sense weak signals of pulse, breathing etc. for monitoring human health, as well as environmental humidity. Meanwhile, the harvested energy could drive electronic device, showing prosperous potentials in fields of artificial intelligence.柔性可穿戴电子设备的开发需要高性能的压电传感器，这些传感器具有灵敏度高、易于微集成且无需外部电源等优点。在这项工作中，通过电纺丝和随后的气相交联，构建了具有稳定交替多层结构的聚乙烯醇（PVA）/聚偏氟乙烯（PVDF）纤维膜。在适当的 PVDF 浓度下，PVA/PVDF 纤维完全拉伸，表面光滑，直径均匀，孔隙率高（88%）。在电纺丝过程中，PVDF 的 α 相转变为具有电活性的 β 相，而通过 PVA 和 PVDF 的混合纺丝，结晶度和 β 相百分比（Fβ）得到了改善，Fβ 达到了 90% 以上。PVA/PVDF 纤维膜具有较高的机械强度/韧性和吸液率（719.03%）。产生的电信号输出（10.07 V 和 166.42 nA）具有应力灵敏度高、响应时间短和稳定性高等特点，表现出优异的压电性，使纤维膜不仅能监测肢体的大变形运动，成为自供电的可穿戴传感器，还能感知脉搏、呼吸等微弱信号，用于监测人体健康和环境湿度。同时，采集到的能量可以驱动电子设备，在人工智能领域大有可为。来源：复合材料力学仿真Composites FEM