Composites Part C Open Access最新文献_第4页

Structure–property relationships in 3D-printed onyx-based composites reinforced with continuous fibers: role of temperature and fiber orientation 连续纤维增强3d打印玛瑙基复合材料的结构-性能关系：温度和纤维取向的作用

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-09-15 DOI: 10.1016/j.jcomc.2025.100649

Vishista Kaushik, Suresh Kurra, Ramesh Adusumalli

This study investigates the flexural performance of 3D-printed continuous fiber-reinforced composites, focusing on the influence of fiber types, orientation, and temperature. Using a carbon, glass, kevlar fiber- and Onyx matrix- filaments, specimens were fabricated as 24 or 30-layer composites. Three-point bending tests were conducted under different temperatures. The results reveal a significant influence of fiber type and orientation. Carbon fiber composite showed the highest strength of 281 MPa at 0° orientation and 127 MPa at 90° orientation at RT. At -20 °C, Carbon, Glass and Kevlar composites revealed flexural strength of 422, 308 and 188 MPa respectively (0°). Similarly, with an increase in temperature, a decrement in flexural properties can be observed in all the fiber types. The modulus for kevlar decreased from 8.29 to 5.71 to 4.15 GPa with an increase in temperature from -20 to 27 to 85 °C. Additionally, microscopic analysis highlights the failure mechanisms, including fiber pull-out, delamination, and matrix softening. Grey relation analysis used two mutually conflicted parameters (strength, cost) and reported the best and worst composite amongst 18 combinations considered. The findings provide valuable insights for optimizing the design of 3D-printed composites at different fiber orientations and temperatures enhancing their applicability in structural applications.

本研究研究了3d打印连续纤维增强复合材料的弯曲性能，重点研究了纤维类型、取向和温度的影响。使用碳、玻璃、凯夫拉纤维和缟玛瑙基体长丝，将样品制成24层或30层复合材料。在不同温度下进行三点弯曲试验。结果表明，纤维类型和取向对其有显著影响。碳纤维复合材料在0°取向下的抗弯强度最高，为281 MPa，在90°取向下为127 MPa。在-20℃时，碳纤维、玻璃和凯夫拉复合材料的抗弯强度分别为422、308和188 MPa（0°）。同样，随着温度的升高，在所有类型的纤维中都可以观察到弯曲性能的下降。当温度从-20℃升高到27℃至85℃时，芳纶的模量从8.29 ~ 5.71 ~ 4.15 GPa下降。此外，微观分析强调了破坏机制，包括纤维拔出、分层和基体软化。灰色关联分析使用了两个相互冲突的参数（强度、成本），并在考虑的18种组合中报告了最佳和最差的组合。研究结果为在不同纤维取向和温度下优化3d打印复合材料的设计提供了有价值的见解，增强了其在结构应用中的适用性。

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引用次数: 0

Parametric finite element analysis of flexural behavior in FRP-reinforced beams frp加固梁受弯性能的参数化有限元分析

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-11-04 DOI: 10.1016/j.jcomc.2025.100677

M. Talha Junaid , Rouba Alzoubi , Aroob Alateyat , Samer Barakat

The increasing use of fiber-reinforced polymer (FRP) bars as internal reinforcement offers a corrosion-resistant and lightweight alternative to steel in concrete structures; however, their linear-elastic behavior often limits ductility and crack control. To address this challenge, the combination of FRP reinforcement with advanced and sustainable concrete types such as fiber-reinforced and alkali-activated concretes, has emerged as a promising yet underexplored solution. This study investigates the flexural behavior of beams made from four concrete types: Portland Cement Concrete (PCC), Alkali-Activated Concrete (AAC), Fiber-Reinforced Concrete (FRC), and Fiber-Reinforced Alkali-Activated Concrete (FRAAC), all reinforced with Glass FRP (GFRP) bars. A detailed nonlinear finite element model was developed using ABAQUS software, employing 3D solid (C3D8R) elements for concrete and truss (T3D2) elements for FRP bars with embedded-region constraints. The Concrete Damaged Plasticity (CDP) model simulated concrete behavior, while FRP reinforcement was modeled as linear-elastic up to rupture. The model was calibrated and validated against experimental results, achieving high accuracy in predicting load–deflection responses and failure modes. A comprehensive parametric study of 224 simulations examined the influence of FRP type, reinforcement ratio, and beam depth. Results showed that CFRP bars yielded the highest load increase (up to 90%), while increasing tensile reinforcement ratio (0.5–3.28%) enhanced capacity by 11–132% and reduced deflection by 54%. Increasing beam depth (250–400 mm) improved load capacity by up to 172%, with compression reinforcement contributing less than 11%. The findings highlight the significance of integrating FRP reinforcement with sustainable fiber- and geopolymer-based concretes, demonstrating the capability of finite element analysis in optimizing hybrid high-performance structural systems.

越来越多地使用纤维增强聚合物（FRP）钢筋作为内部钢筋，为混凝土结构中的钢材提供了一种耐腐蚀和轻质的替代品；然而，它们的线弹性特性往往限制了延性和裂纹控制。为了应对这一挑战，将FRP加固与先进且可持续的混凝土类型（如纤维增强混凝土和碱活化混凝土）相结合，已经成为一种有希望但尚未得到充分探索的解决方案。本研究调查了由四种混凝土类型制成的梁的弯曲行为：波特兰水泥混凝土（PCC），碱活化混凝土（AAC），纤维增强混凝土（FRC）和纤维增强碱活化混凝土（FRAAC），均用玻璃钢（GFRP）钢筋加固。采用ABAQUS软件建立了详细的非线性有限元模型，混凝土采用三维实体（C3D8R）单元，FRP筋采用桁架（T3D2）单元，具有嵌入式区域约束。混凝土损伤塑性（CDP）模型模拟混凝土的行为，而FRP筋模型为线弹性直至破裂。根据实验结果对模型进行了标定和验证，在预测载荷-挠度响应和破坏模式方面具有较高的准确性。224个模拟的综合参数研究检验了FRP类型、配筋率和梁深度的影响。结果表明：CFRP筋的荷载增幅最大，可达90%；提高抗拉配筋率（0.5 ~ 3.28%），承载力提高11% ~ 132%，挠度降低54%；增加梁深（250 - 400mm）可使承载能力提高172%，而抗压加固的贡献不到11%。研究结果强调了将FRP加固与可持续纤维和地聚合物基混凝土相结合的重要性，证明了有限元分析在优化混合高性能结构体系中的能力。

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引用次数: 0

Effects of resin types on the durability of single yarn polymer composites exposed to hygrothermal environment 树脂类型对单纱聚合物复合材料在湿热环境下耐久性的影响

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-10-30 DOI: 10.1016/j.jcomc.2025.100676

Abdullah Iftikhar , Allan Manalo , Zaneta Senselova , Wahid Ferdous , Mazhar Peerzada , Hannah Seligmann , Kate Nguyen , Brahim Benmokrane

This study evaluated the durability of glass fibre composites prepared using bio-epoxy, vinyl ester and epoxy resin when exposed to a simulated hygrothermal environment. Initially, glass fibre yarns, resins and single yarn composites were exposed to 60oC at 98% relative humidity for up to 3000 h. This was followed by the thermal (DSC), chemical (FTIR), tensile and interfacial shear strength characterization, and the morphological observations under the scanning electron microscope. Results revealed that the resin types significantly influenced the durability of glass fibre yarn composites. Bio-epoxy and vinyl ester resin exhibited thermal stability after exposure to a hygrothermal environment for 3000 h, with an increment of 19oC in the glass transition temperature of epoxy because of the additional cross-linking of the polymeric chain. FTIR spectra reveal that bio-epoxy was chemically stable, while epoxy and vinyl ester resin have undergone chemical degradation because of hydrolysis. The tensile strength of fibre yarn was decreased by 37% because of blistering at the fibre surface, while a reduction of 22%, 10%, and 20% was observed for epoxy, bio-epoxy, and vinyl ester, respectively. Furthermore, the interfacial shear strength was reduced by 15%, 6%, and 25% for epoxy, bio-epoxy, and vinyl ester composites, respectively. Despite the Tg increase, hydrolytic chain scission and damage at the interface reduced the mechanical strength of epoxy. Analytical Hierarchy Process revealed that bio-epoxy resin performed best under hygrothermal conditions when mechanical properties were a priority, whereas vinyl ester resin performed best if physical or thermal properties were most important.

本研究评估了生物环氧树脂、乙烯基酯和环氧树脂制备的玻璃纤维复合材料在模拟湿热环境下的耐久性。首先，将玻璃纤维纱线、树脂和单纱复合材料暴露在60℃、98%相对湿度下长达3000小时。随后进行热（DSC）、化学（FTIR）、拉伸和界面剪切强度表征，并在扫描电镜下进行形态学观察。结果表明，树脂类型对玻璃纤维纱复合材料的耐久性有显著影响。生物环氧树脂和乙烯基酯树脂在湿热环境中暴露3000 h后表现出热稳定性，由于聚合物链的额外交联，环氧树脂的玻璃化转变温度增加了19℃。红外光谱分析表明，生物环氧树脂具有化学稳定性，而环氧树脂和乙烯基酯树脂由于水解而发生了化学降解。由于纤维表面起泡，纤维纱线的抗拉强度降低37%，而环氧树脂、生物环氧树脂和乙烯基酯的抗拉强度分别降低22%、10%和20%。此外，环氧树脂、生物环氧树脂和乙烯基酯复合材料的界面剪切强度分别降低了15%、6%和25%。尽管Tg升高，但水解链断裂和界面损伤降低了环氧树脂的机械强度。层次分析法表明，生物环氧树脂在湿热条件下表现最佳，当机械性能优先考虑时，乙烯基酯树脂在物理或热性能最重要时表现最佳。

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引用次数: 0

Viscoelastic high-damping vibration attenuation of sandwich FG-GPLRC face sheets by incorporating full nonlinear effects 考虑全非线性效应的FG-GPLRC夹层面板粘弹性高阻尼减振

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-09-17 DOI: 10.1016/j.jcomc.2025.100650

Hamidreza Rostami , Sattar Jedari Salami

This article deals with the study of geometrically and materially nonlinear free-damped vibration analysis of Sandwich beams incorporating flexible cores governed by various frequency-dependent viscoelastic models, surrounded with top and bottom face sheets reinforced through a functionally graded distribution of graphene platelets (GPLs) in large deformation. In fact, two types of nonlinearities are considered in the formulation: one arising from the nonlinear strain-displacement relationship, and the other due to the viscoelastic material behavior in the sandwich beam. To analyze the impact of including nonlinear terms in both geometric and material behavior—which has not been reported in the literature—the results are computed by adopting the geometrically nonlinear von Kármán assumptions for the core and the face sheets on one hand, and by employing a viscoelastic core material with complex frequency-dependent Young's/shear modulus that induces material nonlinearity on the other. Based on the Extended Higher-Order Sandwich Panel Theory (EHSAPT), a set of coupled nonlinear governing equations is derived using the Lagrangian technique. As a progressive step, this is the first time that a displacement control technique has been enhanced to simultaneously account for both geometric and material nonlinearities in order to obtain the vibrational characteristics of a system, making it valid for large vibration amplitudes and high damping. To validate the approach, the results obtained from EHSAPT are compared with available data in the literature. Additionally, the problem is also examined by applying Euler–Bernoulli and Timoshenko beam theories to the face sheets and core, respectively. The complex nonlinear eigenvalue problem is solved, and the natural frequencies and loss factors of the viscoelastically damped sandwich beam are calculated. Parametric studies are discussed in detail to investigate the effects of weight fraction, graphene platelet distribution pattern, core-to-face sheet thickness ratio, boundary conditions, viscoelastic core temperature, and vibration amplitude. The results provide valuable and practical insights, showing that considering appropriate ranges of geometry and material in large-amplitude nonlinear vibrations of frequency-dependent viscoelastic core sandwich beams leads to improved design and industrial optimization.

本文研究了包含柔性芯的夹层梁的几何和材料非线性自由阻尼振动分析，这些柔性芯由各种频率相关的粘弹性模型控制，周围是通过大变形的石墨烯片（GPLs）的功能梯度分布加强的顶部和底部面板。实际上，公式中考虑了两种非线性：一种是由非线性应变-位移关系引起的，另一种是由夹层梁中的粘弹性材料行为引起的。为了分析在几何和材料行为中包括非线性项的影响-这在文献中尚未报道-结果是通过采用几何非线性的von Kármán假设来计算一方面的核心和面片，并通过采用具有复杂频率相关的杨氏/剪切模量的粘弹性核心材料来计算材料非线性。基于扩展高阶夹层板理论，利用拉格朗日技术导出了一组耦合非线性控制方程。作为一个进步的步骤，这是位移控制技术第一次得到加强，同时考虑几何非线性和材料非线性，以获得系统的振动特性，使其适用于大振动幅值和高阻尼。为了验证该方法，将EHSAPT获得的结果与文献中的现有数据进行了比较。此外，该问题还通过应用欧拉-伯努利和Timoshenko梁理论分别对面板和核心进行了检验。求解了复合非线性特征值问题，计算了粘弹性阻尼夹层梁的固有频率和损耗因子。详细讨论了参数研究，以研究重量分数、石墨烯血小板分布模式、芯与面片厚度比、边界条件、粘弹性芯温度和振动幅度的影响。结果提供了有价值和实用的见解，表明在频率相关粘弹性芯芯夹层梁的大幅非线性振动中考虑适当的几何形状和材料范围可以改进设计和工业优化。

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引用次数: 0

Axial compressive performance of sustainable BFRP-confined rectangular columns using recycled brick aggregates 使用再生砖骨料的可持续bfrp约束矩形柱的轴压性能

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-09-28 DOI: 10.1016/j.jcomc.2025.100653

Chisanuphong Suthumma , Ali Ejaz , Muhammad Jawed Iqbal , Ekkachai Yooprasertchai , Qudeer Hussain , Gritsada Sua-iam , Burachat Chatveera , Preeda Chaimahawan , Panumas Saingam

This study examines the mechanical behavior of basalt FRP confined rectangular concrete columns using crushed brick aggregates, addressing a research gap. While previous work focused on circular and square columns, this is the first to explore rectangular ones. The use of waste brick aggregates promotes sustainability. The study aims to assess the mechanical properties, expecting improvements in strength and ductility, and could lead to broader applications of basalt FRP. A total of 32 rectangular specimens were tested to evaluate the influence of aggregate type, concrete grade, and number of BFRP layers (0, 2, 4, and 6) on axial compressive performance. Results showed that BFRP confinement significantly enhanced strength and ductility, with maximum gains of 81% in strength and 230% in strain observed in low-strength natural aggregate concrete. Although recycled brick aggregate concrete (RBAC) exhibited lower stiffness, BFRP still provided up to 23% strength improvement. The effectiveness of confinement reduced with increasing unconfined strength. Post-peak analysis revealed that additional BFRP layers delayed stiffness degradation, promoting more ductile failure. Experimental elastic modulus closely matched ACI predictions in natural aggregate (NA) specimens but was overestimated in RBAC due to its higher porosity. The findings demonstrate the viability of BFRP confinement for enhancing the structural performance of sustainable concrete, while emphasizing the need for aggregate-specific design considerations. Design-oriented modelling was adopted to predict the complete stress-strain response of BFRP-confined concrete incorporating both natural and recycled brick coarse aggregates. A two-branch idealization of the compressive response was performed. Several key points were identified and predicted by using nonlinear regression analysis. The proposed approach closely predicted the response of BFRP-confined concrete.

本研究考察了使用碎砖骨料的玄武岩FRP约束矩形混凝土柱的力学行为，解决了研究空白。虽然以前的工作主要集中在圆形和方形的柱子上，但这是第一次探索矩形的柱子。废砖骨料的使用促进了可持续性。该研究旨在评估玄武岩FRP的力学性能，期望在强度和延性方面有所改善，并可能导致玄武岩FRP的更广泛应用。为了评估骨料类型、混凝土等级和BFRP层数（0、2、4和6层）对轴压性能的影响，共对32个矩形试件进行了试验。结果表明，BFRP约束显著提高了混凝土的强度和延性，在低强度天然骨料混凝土中，强度和应变分别提高了81%和230%。虽然再生砖骨料混凝土（RBAC）表现出较低的刚度，但BFRP仍提供高达23%的强度提高。约束的有效性随着无侧限强度的增加而降低。峰后分析显示，额外的BFRP层延迟了刚度退化，促进了更多的延性破坏。实验弹性模量与天然骨料（NA）试样的ACI预测非常接近，但由于RBAC的孔隙率较高，因此高估了其弹性模量。研究结果证明了BFRP约束在增强可持续混凝土结构性能方面的可行性，同时强调了骨料特定设计考虑的必要性。采用面向设计的模型来预测含有天然和再生砖粗骨料的bfrp约束混凝土的完整应力-应变响应。压缩响应的两分支理想化被执行。利用非线性回归分析识别和预测了几个关键点。该方法能较好地预测bfrp约束混凝土的响应。

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引用次数: 0

Interfacial damage evolution in hygrothermally aged CF/PPA composites used in type V hydrogen tanks: A multi-scale approach V型储氢罐中湿热老化的CF/PPA复合材料界面损伤演化：多尺度方法

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-11-04 DOI: 10.1016/j.jcomc.2025.100679

Clara Penavayre , Joseph Fitoussi , Emmanuel Richaud , Philippe Papin , Jeremie Bouneb , Gilles Hochstetter , Mohammadali Shirinbayan

This paper presents a multi-scale experimental investigation into the damage mechanisms in carbon fiber-reinforced polyphthalamide (CF/PPA) composites subjected to hygrothermal aging. The study specifically targets their suitability for structural components in advanced hydrogen storage systems, such as Type V pressure vessels. Polyphthalamides (PPAs), as semi-aromatic polyamides, offer superior thermal stability, chemical resistance, and mechanical performance compared to conventional aliphatic polyamides, making them promising candidates for structural components exposed to harsh environments. In order to simulate more severe environmental exposure, accelerated hygrothermal aging tests were conducted at 50 °C in immersion. A range of microscopic to macroscopic characterization techniques were used to assess changes in mechanical performance and microstructural integrity. The analysis revealed that the CF/PPA composites retained good matrix ductility even after aging, indicating the resilience of the semi-aromatic polyamide matrix under hygrothermal stress. Multi-scale damage analysis has been performed on both unaged and aged samples at 50 °C for various aging times. The dominant damage mechanism identified was decohesion at the fiber/matrix interface, rather than bulk matrix degradation. This interfacial debonding has a significant impact on mechanical performance and is attributed to moisture-induced weakening of interfacial interactions. These findings emphasize the potential of CF/PPA composites for use in high-performance hydrogen storage applications, while highlighting the critical need for interface-tailored designs to enhance environmental durability.

采用多尺度实验研究了碳纤维增强聚苯二胺（CF/PPA）复合材料在湿热老化下的损伤机理。该研究特别针对它们在先进储氢系统（如V型压力容器）中的结构部件的适用性。与传统的脂肪族聚酰胺相比，聚酞胺（PPAs）作为半芳香族聚酰胺，具有优越的热稳定性、耐化学性和机械性能，使其成为暴露在恶劣环境下的结构部件的有希望的候选者。为了模拟更恶劣的环境暴露，在50°C浸泡下进行了加速湿热老化试验。一系列微观到宏观的表征技术被用来评估机械性能和微观结构完整性的变化。分析表明，CF/PPA复合材料在老化后仍保持良好的基体延展性，说明半芳香族聚酰胺基体在湿热应力下的弹性。在50°C下，对不同时效时间的未时效和时效样品进行了多尺度损伤分析。主要的损伤机制是纤维/基体界面的脱黏，而不是基体的降解。这种界面脱粘对机械性能有显著影响，并归因于水分引起的界面相互作用减弱。这些发现强调了CF/PPA复合材料在高性能储氢应用中的潜力，同时强调了对界面定制设计的迫切需求，以提高环境耐久性。

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引用次数: 0

Spectral method to determine the Tsai-Wu probability of failure of a composite laminate subjected to random vibrations 用谱法确定复合材料层合板在随机振动作用下的蔡武失效概率

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-11-21 DOI: 10.1016/j.jcomc.2025.100683

Javier Sanz-Corretge , Thanh-Dam Pham , Luan Trinh , Paul G. Leahy

This work presents a spectral-based methodology for the probabilistic failure analysis of composite laminates subjected to zero-mean, stationary Gaussian random vibrations. The proposed approach efficiently computes both the probability density (PDF) and cumulative distribution functions (CDF) of nonlinear failure indices, using the Tsai–Wu criterion as a case study. By integrating the frequency response functions (FRFs) of the stress tensor components with the excitation’s power spectral density (PSD), the method constructs the complete covariance matrix of the stress field. This enables the definition of a joint multivariate Gaussian distribution of stresses, from which Monte Carlo sampling is performed to evaluate any nonlinear failure function.

The methodology is general and can be applied to any nonlinear stress function, such as von Mises stress, provided the structure remains linear and the excitation Gaussian. Validation is performed through finite element (FE) simulations of a composite plate with a central hole. The RMS von Mises stresses predicted by the proposed method closely match those obtained with the Segalman spectral approach implemented in ANSYS, confirming its correctness. Further comparison with time-domain transient simulations demonstrates excellent agreement in failure probabilities while achieving a computational speedup exceeding two orders of magnitude.

这项工作提出了一种基于频谱的方法，用于复合材料层压板遭受零均值，平稳高斯随机振动的概率失效分析。该方法以Tsai-Wu准则为例，有效地计算非线性失效指标的概率密度和累积分布函数。该方法通过将应力张量分量的频响函数（frf）与激励的功率谱密度（PSD）进行积分，构建应力场的完整协方差矩阵。这使得应力的联合多元高斯分布的定义，从蒙特卡罗采样执行评估任何非线性破坏函数。该方法是通用的，可以应用于任何非线性应力函数，如von Mises应力，只要结构保持线性和激励是高斯的。通过对带中心孔的复合材料板的有限元模拟进行了验证。该方法预测的RMS von Mises应力与ANSYS中实现的Segalman谱法计算结果吻合较好，验证了该方法的正确性。进一步与时域瞬态模拟的比较表明，在实现超过两个数量级的计算速度的同时，失效概率具有很好的一致性。

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引用次数: 0

Seismic rehabilitation of flexure-damaged RC shear walls using a hybrid UHPC–FRP composites with EBROG-installed strips and FRP anchors 使用混合UHPC-FRP复合材料与ebrog安装条和FRP锚对受弯损伤的RC剪力墙进行地震修复

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-10-16 DOI: 10.1016/j.jcomc.2025.100665

Mehdi Khorasani, Davood Mostofinejad, Ali MohammadSalehi

This study investigates a hybrid repair strategy for flexural-damaged reinforced concrete (RC) shear walls, combining ultra-high-performance concrete (UHPC) and fiber-reinforced polymer (FRP) strips installed using the externally bonded reinforcement on grooves (EBROG) technique with FRP anchors. Three full-scale walls were tested under cyclic lateral loading: a reference wall (FCW), a UHPC-repaired wall (R-UHPC), and a hybrid UHPC–FRP wall (R-UHPC-FRP). Both repair approaches effectively restored strength, with the hybrid wall exceeding the control’s capacity by 13 % (279 vs. 249 kN). However, ductility decreased by 35–45 % compared to the control (3.8–4.9 vs. 2.25–3.2). Energy dissipation was partially recovered with UHPC but reached up to 90–95 % of the control’s capacity at 2 % drift in the hybrid system. Stiffness retention was also improved, with the hybrid wall maintaining values comparable to the control beyond 1 % drift. Despite lower hysteretic damping than the control, the hybrid wall showed improved damping at higher deformations. Overall, the UHPC–FRP hybrid repair, enhanced by the EBROG method, proves effective in restoring strength and stiffness while substantially recovering energy dissipation, offering a promising solution for seismic rehabilitation of RC shear walls.

本研究研究了受弯损伤的钢筋混凝土（RC）剪力墙的混合修复策略，将超高性能混凝土（UHPC）和纤维增强聚合物（FRP）条结合起来，使用外部粘结加固沟槽（EBROG）技术安装FRP锚。在循环横向荷载下测试了三面墙：参考墙（FCW）， uhpc -修复墙（R-UHPC）和UHPC-FRP混合墙（R-UHPC- frp）。两种修复方法都有效地恢复了强度，混合管壁的强度比对照管壁高出13%（279比249千牛）。然而，与对照组相比，延展性下降了35 - 45% （3.8-4.9 vs. 2.25-3.2）。在混合系统中，当漂移2%时，UHPC可以部分恢复能量耗散，但能量耗散达到控制能力的90 - 95%。刚度保持也得到了改善，混合壁保持值与超过1%漂移的对照组相当。尽管混合壁的滞回阻尼比对照组低，但在高变形下，混合壁的阻尼有所改善。总体而言，经EBROG方法增强的UHPC-FRP复合修复在恢复强度和刚度的同时有效地恢复了能量耗散，为RC剪力墙的抗震修复提供了一个有前途的解决方案。

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引用次数: 0

Revalorisation of recycled PLA through Halloysite nanotube integration for mechanical and thermal property improvement 利用高岭石纳米管整合再生PLA以改善其机械和热性能

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-10-24 DOI: 10.1016/j.jcomc.2025.100670

Anbuchezhiyan Gnanasambandam , Vigneshwaran Shanmugam , Elif Kaynak , Oisik Das

This study investigates the effect of Halloysite nanotube (HNT) reinforcement on the mechanical, thermal, and structural properties of recycled polylactic acid (rPLA) composites. Composites were prepared with 1-5 wt.% HNTs and characterised using tensile, flexural, compressive testing, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Tensile strength increased from 42.98 MPa for neat rPLA to a maximum of 49.39 MPa at 2 wt.% HNT, while tensile modulus improved steadily from 2423.13 MPa to 2971.26 MPa at 5 wt.%. Flexural strength peaked at 78.54 MPa (22 % improvement compared to neat rPLA) at 3 wt.%, and the highest flexural modulus of 2292.30 MPa was achieved at 4 wt.% HNT. Under compressive loading, strength and modulus increased from 100.94 MPa and 2361.52 MPa for neat rPLA to 108.69 MPa and 2479.87 MPa, respectively, at 5 wt.% HNT, showing improved resistance to deformation. Thermal degradation temperatures rose from 452.12 °C for rPLA to 465.58 °C at 5 wt.% HNT, with char residue at 600 °C increasing from 4.23 % to 9.96 %, confirming the thermal barrier effect of Halloysite. XRD analysis showed enhanced crystallinity, increasing from 57.49 % (neat rPLA) to 59.22 % at 5 wt.% HNT, indicating effective nucleation and structural ordering induced by the nanotubes. Overall, the incorporation of 2-4 wt.% Halloysite offered the most balanced improvement in strength, stiffness, and thermal stability. These results demonstrate that rPLA-Halloysite composites can be suitable for sustainable, high-performance applications in packaging, automotive interiors, and structural bioplastics.

研究了高岭土纳米管（HNT）增强剂对再生聚乳酸（rPLA）复合材料力学性能、热性能和结构性能的影响。用1-5 wt.%的HNTs制备复合材料，并通过拉伸、弯曲、压缩测试、热重分析（TGA）和x射线衍射（XRD）对其进行表征。拉伸强度从纯rPLA的42.98 MPa增加到2 wt.% HNT时的最大值49.39 MPa，拉伸模量从2423.13 MPa稳步提高到5 wt.% HNT时的2971.26 MPa。在3 wt.% HNT时，抗弯强度达到78.54 MPa（比纯rPLA提高22%），在4 wt.% HNT时，抗弯模量达到2292.30 MPa。在压缩载荷作用下，纯rPLA的强度和模量分别从100.94 MPa和2361.52 MPa增加到108.69 MPa和2479.87 MPa，在5 wt.% HNT条件下，rPLA的抗变形能力有所提高。在5 wt.% HNT条件下，rPLA的热降解温度从452.12℃上升到465.58℃，600℃时炭渣从4.23%上升到9.96%，证实了高岭土的热障作用。XRD分析表明，在5 wt.% HNT条件下，纳米管的结晶度从57.49%（纯rPLA）提高到59.22%（纯rPLA），表明纳米管诱导了有效的成核和结构有序。总的来说，加入2-4 wt.%的高岭土在强度、刚度和热稳定性方面提供了最平衡的改善。这些结果表明，rpla -高岭土复合材料可以适用于包装、汽车内饰和结构生物塑料的可持续、高性能应用。

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引用次数: 0

Effective properties of viscoelastic piezoelectric materials using homogenisation on representative volume finite elements 粘弹性压电材料在代表性体积有限元上的有效性能研究

IF 7 Q2 MATERIALS SCIENCE, COMPOSITES

Composites Part C Open Access

Pub Date : 2025-10-01 Epub Date: 2025-10-31 DOI: 10.1016/j.jcomc.2025.100663

Felipe Ruivo Fuga , Yunior Muñoz Naranjo , Reinaldo Rodríguez-Ramos , José Antonio Otero , Volnei Tita , Ricardo De Medeiros

This paper introduces a comprehensive methodology for determining the effective piezo-electromechanical properties considering viscoelastic effects in the composite material. The methodology uses finite element (FE) analysis and homogenisation. By formulating the FE solution as a dynamic equilibrium problem, the proposed approach effectively couples linear elastic piezoelectric fibres within a linear viscoelastic matrix. This couples both complex constitutive behaviours into a single representative cell for time-dependent quasi-static load cases. A virtual stress relaxation test is conducted on a Representative Volume Element (RVE) with periodic boundary conditions. The methodology disregards inertial effects to represent quasi-static loading conditions. It assumes a polymeric matrix phase with only mechanical degrees of freedom. The computed effective time-dependent constitutive coefficients are compared with analytical solutions derived from effective field and asymptotic homogenisation methods for a circular piezoelectric fibre in a viscoelastic polymeric matrix. Despite the simplifying assumption for the polymer matrix, the usage of a time-independent Halpin–Tsai model for effective electric permittivity, coupled with the proposed FE approach, accurately predicts time-dependent behaviour of elastic, piezoelectric and dielectric effective coefficients for different fibre volume ratios. Thus, the proposed approach provides a robust and versatile framework for characterising effective piezoviscoelastic properties. This makes a contribution to the field of micromechanical piezoelectric simulation, paving the way for future research into dynamic effects, more complex material constitutive models, and intricate geometric features.

本文介绍了一种考虑粘弹性效应的复合材料有效压电机电性能测定方法。该方法使用有限元（FE）分析和均质化。通过将有限元解表述为一个动态平衡问题，该方法有效地将线性弹性压电纤维耦合在一个线性粘弹性矩阵中。这将两个复杂的本构行为耦合到一个具有代表性的单元中，用于时间相关的准静态负载情况。对具有周期边界条件的代表性体积单元进行了虚拟应力松弛试验。该方法不考虑惯性效应来表示准静态加载条件。它假设一个只有机械自由度的聚合物基质相。本文将计算得到的有效时变本构系数与用有效场法和渐近均质法得到的粘弹性聚合物基体中圆形压电纤维的解析解进行比较。尽管简化了聚合物基体的假设，但使用与时间无关的Halpin-Tsai有效介电常数模型，加上所提出的有限元方法，可以准确预测不同纤维体积比下弹性、压电和介电有效系数的时间相关行为。因此，所提出的方法为表征有效的压粘弹性特性提供了一个鲁棒和通用的框架。这为压电微机械仿真领域做出了贡献，为未来研究动态效应、更复杂的材料本构模型和复杂的几何特征铺平了道路。

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引用次数: 0