This study examines the propagation of circumferential shear horizontal (SH) waves through a cylindrical composite structure with three concentric layers. The configuration includes an innermost functionally graded orthotropic (FGO) layer, a self-reinforced (SR) middle layer for mechanical stability, and an outer piezoelectric (PE) layer designed to enhance sensitivity for sensor and actuator applications. The interfaces between the layers are imperfectly bonded, leading to mechanical and electro-mechanical coupling imperfections. Dispersion relations were developed under specific boundary conditions, revealing how interface imperfections, initial stresses, and changes in radii influence the wave phase velocity. This research also explores the complex interlayer surface response, a phenomenon often overlooked in prior studies, offering new insights into layer interactions and their effects on wave propagation. Results indicate a strong wavenumber dependency of phase velocity with significant variations due to functional gradation and higher angular modes. The FGO layer shows the highest stress levels, while the PE layer contributes minimally to stress but plays a crucial role in electromechanical conversion. Interface imperfections and initial stress in the PE layer subtly alter stress distribution, affecting the overall performance of the composite structure. These findings enhance the functionality of surface acoustic wave sensors, piezoelectric actuators, and other related devices.
Composites Part A: Applied Science and Manufacturing
Multi-source lay-up error analysis and lay-up pressure optimization for robotic automated fiber placement (AFP)
Xiaokang Xu, Liang Cheng, Zhijia Cai, Jiangxiong Li, Yinglin Ke
doi:10.1016/j.compositesa.2025.108825
机器人自动铺放光纤的多源铺放误差分析及铺放压力优化
Automated Fiber Placement (AFP) offers significant advantages in manufacturing large aircraft structures but is prone to defects impacting product quality and mechanical performance. Lay-up Pressure Error (LPE), influenced by various factors, notably lay-up pressure, affects AFP quality. Our study focuses on a heavy-duty robot with pre-positioned lay-up mechanisms for AFP. We analyze the impact of robot and end effector (AFP head) errors on LPE, developing analytical models for compaction rollers and prepreg to establish constitutive relationships. A Generalized Tool Point Error (GTE) incorporating mold path point offsets is formulated. Additionally, models for joint torsion and bending deformation, considering end forces and robot gravity, are established. Mapping joint errors to AFP robot end-effector errors (ARE) is achieved using extended Jacobian matrices. We comprehensively analyze error effects on LPE and establish an optimization index for robot pose to mitigate LPE. Experimental results validate the effectiveness of our optimization method in enhancing lay-up pressure uniformity, accuracy, and overall quality while reducing defects.
3D printing of ceramic matrix composites: strengthening and toughening strategies
Feng Zhang, Shixiang Zhou, Huaying You, Gang Zhang, Jiquan Yang, Yusheng Shi
doi:10.1016/j.compositesb.2025.112335
陶瓷基复合材料的3D打印：强化和增韧策略
Three dimensional (3D) printing, or additive manufacturing (AM) of ceramics has obtained broad attentions in recent years among industry and academia. However, ceramic materials inevitably suffer from their inherent brittleness and unexpected fracture. Thus, many researchers have developed various ceramic composites for diverse applications to overcome this drawback. In this review, versatile 3D printed ceramic composites are investigated, including carbonaceous materials reinforced ceramic matrix composites (CMrCMCs), metal reinforced ceramic matrix composites (MrCMCs), polymer reinforced ceramic matrix composites (PrCMCs), and ceramic reinforced ceramic matrix composites (CrCMCs), a particular focus is placed on scrutinizing how the added reinforcements strengthen and toughen the 3D printed ceramic composite structures. Based on the categories of four reinforcement phases and seven main 3D printing technologies, various ceramic strengthening and toughening mechanisms are discussed, and it was found that CrCMCs encompass the most sophisticated toughening strategies, such as phase transformation toughening, microcrack toughening, crack deflection and bridging, whiskers/fiber toughening, and in-situ toughening etc. Some specific 3D printing technologies such as coaxial extrusion, and material extrusion of ceramic ink and continuous fibers are introduced. Finally, summary and a perspective for future research work in 3D printing of strengthened and toughened ceramic composites are discussed.
Thermoplastic polyurethane (TPU), a commonly used cable wrapping material for new energy vehicles and charging stations but faces the limitation of high fire hazard. However, conventional synthesis strategies of flame retardants (FRs) often fail to achieve the enhancement of the combination of fundamental properties of TPU, including flame retardancy, melt dropping resistance, stretchability, and toughness, which are necessary for practical applications. Herein, a novel strategy for the synthesis of a cobalt/copper coordinated organic-inorganic hybrid fibrous phosphorus-nitrogen FR (CoCu/P-N) inspired by supramolecular aggregates is proposed and used as an additive for TPU. TPU composites containing CoCu/P-N (TPU-CoCu/P-N) exhibited remarkable improvements in fire safety, melt dripping resistance, mechanical properties, and deicing performance. Cone calorimeter tests (CCT) revealed that TPU-6CoCu/P-N achieved substantial reductions in peak heat release rate (pHRR), total smoke production (TSP), and total carbon monoxide production (TCOP) values by 65.2%, 74.2%, and 59.3%, respectively, compared to pure TPU. Notably, only 2 wt% CoCu/P-N enabled TPU composite to achieve UL-94 V-0 rating. Additionally, ice on the surface of TPU-6CoCu/P-N melted and slid off significantly faster. Furthermore, TPU-6CoCu/P-N demonstrated a high tensile strength of 36.48 MPa and an elongation at break of 878.94%. Through comprehensive characterization and analysis, the underlying mechanisms responsible for the enhanced multifunctional performance of TPU-CoCu/P-N were elucidated. This work provides valuable insights and strategies for the design of advanced FRs, contributing to the development of safer high-performance TPU composites.
Amorphous calcium carbonate formation from carbonated recycled cement powder: a novel carbonation-activated cementitious material
Jiayu Huang, Yuxuan Chen, Qingliang Yu
doi:10.1016/j.compositesb.2025.112336
碳化再生水泥粉形成无定形碳酸钙：一种新型碳化活化胶凝材料
Research on recycled cement powder (RCP) has shown great potential for carbon sequestration, however understanding of calcium carbonate polymorphs evolution in carbonated recycled cement powder (C-RCP) remains limited, especially concerning the formation of amorphous calcium carbonate (ACC) and its impact on the development of concrete strength. In this study, ACC is produced from C-RCP using poly-aspartic acid (pAsp) to control the crystallization of CaCO3, aiming to create a highly reactive cementitious material. The research systematically investigates the effects of various processing parameters, specifically pAsp concentration, ethanol concentration, temperature, and carbonation duration on ACC formation, carbonation products microstructure, and chemical environment. Additionally, the compressive strength of C-RCP as supplementary cementitious materials (SCMs) is also evaluated. The results indicate that higher concentrations of pAsp (10-15%) and ethanol (50-70%) enhance the stabilization of ACC formation. The decrease in carbonation degree correlates with the increase in the formation of metastable CC (mCC), including ACC and vaterite within C-RCP. Furthermore, elevated temperature and extended carbonation duration promote the formation of vaterite due to an increased carbonation degree. The incorporation of novel C-RCP, characterized by a maximum relative content of mCC, significantly enhances the strength of cement paste, attributed to the transformation and crystallization of ACC. This method utilizes pAsp to control the crystallization of calcium carbonate in C-RCP, effectively activating the reactivity of the calcium carbonate phase. This approach significantly enhances the potential of C-RCP as a novel cement-based material by optimizing its hydration reactivity, making it particularly well-suited for application in carbonated cement composites.
A Porous Electrically and Thermally Conductive Composite Film for Heat Dissipation and Electromagnetic Interference Shielding
Lei Zhang, Xiaoxiao Ding, Debin Lin, Yongbao Feng, Huili Fu, Guang Xiao, Peng Xu, Qiulong Li
doi:10.1016/j.compositesb.2025.112339
一种用于散热和电磁干扰屏蔽的多孔导电导热复合膜
MXene, as an emerging graphene-like 2D material, has exhibited excellent electromagnetic interference (EMI) shielding performance because of its outstanding electrical conductivity, multiple interfaces, low density, and easy structure-constructing feature. However, the easy to stack for the 2D structure will seriously weaken the attenuation of electromagnetic waves, and heighten the secondary reflection because of high conductivity. Herein, we prepared the 3D porous MXene@fractal Ag micro-dendrites (Ag FDs) composite films by using vacuum filtration method that is induced by K ions, and then used the freeze-drying way to construct the 3D porous structure. The introduction of Ag FDs into the system can significantly improve the electrical conductivity and thermal conductivity. Additionally, the design of porous structure dramatically enhanced the multiple dissipation of electromagnetic waves, thereby augmenting the EMI shielding performance. The obtained porous composite film (thickness: 55 μm) with only 20 wt% Ag FDs delivers an outstanding EMI shielding effectiveness (SE) of 69 dB with an excellent specific EMI SE (1.25 × 104 dB cm2 g-1), and a distinguished thermal conductivity of 26.6 W m-1 K-1. This porous MXene@Ag FDs composite film demonstrates exceptional EMI shielding and thermal transport properties, offering new strategies for integrating EMI shielding with thermal management.
MXene作为一种新兴的类石墨烯二维材料，由于其优异的导电性、多界面、低密度、易构造等特点，具有优异的电磁干扰屏蔽性能。然而，二维结构的易叠加性将严重削弱电磁波的衰减，并因其高导电性而使二次反射增强。本文采用K离子诱导的真空过滤法制备三维多孔MXene@fractal银微枝晶（Ag FDs）复合薄膜，然后采用冷冻干燥的方法构建三维多孔结构。在系统中引入Ag fd可以显著提高系统的导电性和导热性。此外，多孔结构的设计大大提高了电磁波的多重耗散，从而提高了电磁干扰屏蔽性能。所获得的多孔复合膜（厚度：55 μm）仅含20 wt% Ag fd，具有69 dB的出色EMI屏蔽效能（SE），具有出色的比EMI SE (1.25 × 104 dB cm2 g-1)，以及26.6 W m-1 K-1的杰出导热系数。这种多孔MXene@Ag FDs复合膜具有出色的电磁干扰屏蔽和热传输性能，为集成电磁干扰屏蔽和热管理提供了新的策略。
Desulfurization-modified red mud for supersulfated cement production: Insights into hydration kinetics, microstructure, and mechanical properties
Zhongtao Luo, Mengxiao Ge, Lei Liu, Xiaohai Liu, Wensheng Zhang, Jiayuan Ye, Mingkang Gao, Yifan Yang, Maoliang Zhang, Xinhong Liu
doi:10.1016/j.compositesb.2025.112340
用于超硫酸盐水泥生产的脱硫改性赤泥：水化动力学、微观结构和机械性能的见解
Investigating the production of supersulfated cement (SSC) using desulfurization-modified red mud is essential for enhancing the high-value utilization of calcium-based solid waste and advancing the development of low-carbon cementitious materials. In this study, red mud (RM) underwent desulfurization modification via a simulated flue gas desulfurization process, yielding red mud desulfurization residue (RMD). This RMD was subsequently employed as a resource component for the production of SSC samples. The effect of RMD addition on compressive strength was examined. The hydration kinetics and microstructural characteristics of the SSC based on RMD (SSCR) system were analyzed using various techniques, including ICC, XRD, TGA, FT-IR, MAS NMR, MIP and SEM-EDS. The results indicated that gypsum generated from the desulfurization reaction constituted the primary component of the resulting RMD. The gypsum particles exhibited a regular columnar morphology, while the unreacted residual particles displayed a coarser and more porous microstructure. Compared to a single alkali-activated system utilizing Ca(OH)2, the appropriate incorporation of RMD significantly accelerated the hydration process of the SSCR system. The increase in products such as AFt and C-(A)-S-H gels, along with an increased proportion of gel pores (<10 nm), collectively contributed to the enhancement of mechanical properties. However, the presence of larger residual particles within the RMD might lead to the formation of larger voids and microcracks in the hardened paste, potentially limiting strength development, particularly when RMD was incorporated in excessive amounts.
研究利用脱硫改性赤泥生产过硫酸盐水泥（SSC），对于提高钙基固体废物的高价值利用和推进低碳胶凝材料的发展具有重要意义。本研究通过模拟烟气脱硫过程对赤泥（RM）进行脱硫改性，得到赤泥脱硫渣（RMD）。该RMD随后被用作生产SSC样品的资源组件。考察了添加RMD对抗压强度的影响。采用ICC、XRD、TGA、FT-IR、MAS NMR、MIP和SEM-EDS等技术对基于RMD （SSCR）体系的SSC水化动力学和微观结构特征进行了分析。结果表明，脱硫反应生成的石膏是生成的RMD的主要成分。石膏颗粒表现为规则的柱状结构，而未反应的残余颗粒则表现为较粗的多孔结构。与利用Ca(OH)2的单一碱活化体系相比，适当加入RMD可显著加快SSCR体系的水化过程。AFt和C-(A)- s - h凝胶等产物的增加，以及凝胶孔（<10 nm）比例的增加，共同促进了机械性能的增强。然而，RMD中较大残留颗粒的存在可能导致硬化膏体中形成较大的空隙和微裂纹，潜在地限制了强度的发展，特别是当RMD加入量过大时。
Self-reinforced thermoplastic polyurethane composite with excellent mechanical properties, heat resistance and sustainable recycling
The traditional reinforcement and toughening approaches of thermoplastic polyurethane (TPU) fail to adequately address the mechanical properties, compatibility and recyclability of TPU composites. In this study, the self-reinforced TPU composite was successfully prepared by introducing self-reinforced fiber structure. The reinforced fibers and matrix phase had the same chemical composition, and the reinforced fibers could be uniformly distributed in the TPU matrix. The fibril network structure formed by reinforced fibers enhanced the rheological properties of self-reinforced TPU composites. The hydrogen bond interactions between reinforced fibers and TPU matrix improved the micro-phase separation structure. The fibril network and excellent interfacial interactions significantly enhanced the strength and toughness of TPU matrix. When the reinforced fiber content was 7 wt.%, the tensile strength, elongation at break and tensile toughness of TPU7 were increased by 58.2%, 107.1% and 210.3%, respectively. The introduction of reinforced fibers increased the heat resistance of TPU composites by 20-30 °C. After ten-times closed-loop recycling process, the elongation at break of TPU7 only decreased by 11.0%. This work provides a solution strategy for preparing TPU composites with ultra-high mechanical properties, thermal stability and sustainable recycling-reprocessing.
The remarkable lightweight characteristics of magnesium (Mg) offer significant advantages in 5G communication, 3C products, and new energy vehicles. Yet, the unsatisfactory thermal conductivity of Mg alloys presents formidable challenges in accommodating the advancement of high power density, highly integrated, and miniaturized electronic components in the era of intelligence. Here, inspired by the neurons in the human brain, cell body-like graphite flakes (GF) and axon-like carbon fibers (CF) are constructed into a neuron-inspired structure through pre-mixed & laid powder stir casting (PPSC). Drawing inspiration from the myelin sheath of neurons, a biomimetic interfacial structure is constructed in situ to ensure efficient heat conduction. The neuron-inspired Mg-based materials at a GF:CF volume ratio of 1:3 display an ultrahigh and isotropic thermal conductivity of 200.5 W/(m·K) (393% of the common cast Mg alloys, AZ91D) and an exceptional low density of 1.80 g/cm3. This epitomizes the zenith of comprehensive properties among all thermal management materials reported to date. The ingeniously devised neuron-inspired structure, myelin sheath biomimetic interface, and tunable GF-CF volume ratio co-contribute to the superior thermal conductivity. This work offers an advanced biomimetic strategy towards the development of next-generation lightweight thermal management materials.
The interfacial mode II fracture toughness G_IIC is an important parameter that significantly affects the damage evolution of the composite materials under shear load. Traditional interlaminar fracture toughness test methods are no longer suitable for the measurement of interfacial fracture toughness within the 3D woven composites (3DWCs) because these methods cause yarn breakage, which could overestimate the fracture toughness by more than ten times. To this end, this paper proposes a new method to obtain the in situ interfacial G_IIC of the 3DWCs. The stable propagation of the mode II crack along the interface was achieved by the unique specimen design. A highly restored finite element (FE) model of the specimen was established, and the virtual crack closure technique (VCCT) was adopted to calculate the interfacial G_IIC. The rationality of the experiments and the validation of the simulation have been carefully demonstrated. The values of G_IIC obtained from three different off-axis angles are consistent, which proves the effectiveness of the proposed method.
