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【新文速递】2024年10月16日固体力学SCI期刊最新文章

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今日更新:Journal of the Mechanics and Physics of Solids 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 3 篇

Journal of the Mechanics and Physics of Solids

Twinning in porous elastomers

P.J. Caulfield, P. Ponte Castañeda

doi:10.1016/j.jmps.2024.105896

多孔弹性体中的孪生

It has been known for some time that constitutive models for the large-deformation response of porous elastomers can develop ‘macroscopic’ instabilities as a consequence of loss of strong ellipticity. Indeed, constitutive models obtained by homogenization methods for porous elastomers with periodic and random microstructures can lose strong ellipticity under appropriate loading conditions. For periodic microstructures, it has been shown theoretically, and verified experimentally and numerically, that ‘microscopic’ instabilities consisting in solutions that are periodic on ensembles of unit cells tend to occur before the long-wavelength ‘macroscopic’ instabilities that are captured by the loss of strong ellipticity of the homogenized response. But what about the response of porous elastomers with random microstructures? In this case, microscopic instabilities can be excluded, and the question then arises as to what happens after the onset of a macroscopic instability. Building on earlier work for reinforced elastomers, it is shown here that porous elastomers can undergo twinning after the onset of a macroscopic instability. For this purpose, use is made of a generalized Maxwell-type construction arising from the theory of relaxation and applied to linear comparison variational homogenization estimates for a certain class of two-dimensional porous elastomers consisting of aligned cylindrical pores in a rubber matrix subjected to plane strain loadings. It is shown that such porous elastomers recover Legendre-Hadamard stability by twinning after the onset of a macroscopic instability. Interestingly, the porous elastomers behave like elastic fluids in the twinned region, losing their ability to support shear stresses.

一段时间以来,人们已经知道多孔弹性体大变形响应的本构模型会由于失去强椭圆性而产生“宏观”不稳定性。事实上,均匀化方法得到的具有周期性和随机微观结构的多孔弹性体的本构模型在适当的加载条件下会失去强椭圆性。对于周期性微结构,理论已经证明,实验和数值验证了,在单位细胞的周期性集 合的溶液中组成的“微观”不稳定性往往发生在长波长的“宏观”不稳定性之前,这种不稳定性是由均匀化响应的强椭圆性损失捕获的。但是具有随机微观结构的多孔弹性体的响应如何呢?在这种情况下,微观的不稳定性可以被排除在外,然后问题就出现了,在宏观的不稳定性开始之后会发生什么。基于早期对增强弹性体的研究,本文表明多孔弹性体在宏观不稳定发生后可以发生孪生。为此,使用了由松弛理论产生的广义麦克斯韦型构造,并将其应用于某一类二维多孔弹性体的线性比较变分均匀化估计,这些弹性体由橡胶基体中排列的圆柱形孔隙组成,承受平面应变载荷。结果表明,这种多孔弹性体在宏观失稳发生后通过孪晶恢复了勒让德-阿达玛稳定性。有趣的是,多孔弹性体在孪晶区域表现得像弹性流体,失去了支持剪切应力的能力。


International Journal of Plasticity

Modified crystal plasticity constitutive model considering tensorial properties of microstructural evolution and creep life prediction model for Ni-based single crystal superalloy with film cooling hole

Ping Wang, Zhixun Wen, Meng Li, Guangxian Lu, Hao Cheng, Pengfei He, Zhufeng Yue

doi:10.1016/j.ijplas.2024.104150

考虑微观组织演化张拉性能的改进晶体塑性本构模型及含膜冷却孔镍基单晶高温合金蠕变寿命预测模型

Accurate assessment of the creep life of film cooling hole structures is critical for long-life design and safe operation of aero engines and gas turbines. Firstly, through the high temperature creep experiment of nickel-based single crystal superalloy with film cooling hole, the microstructure evolution process under multiaxial stress state around film hole is characterized. Then, considering the directional effect of rafting structure and the influence of multiaxial stress, a fourth-order tensor is used to describe the evolution of γ phase width, and the microstructure evolution model accounting for multi-axial stress states is established. The microstructure evolution is coupled into the crystal plasticity constitutive model by Orowan stress. Meanwhile, based on continuous damage mechanics, a new multiaxial damage evolution law is established by introducing a multiaxial ductility factor into the constitutive model. The improved crystal plasticity constitutive model can effectively predict the microstructural evolution under multiaxial stress conditions. Furthermore, the combination of the modified crystal plasticity constitutive model and the critical distance method considering stress gradients is used for life prediction of film cooling hole structures. The prediction results show the effectiveness and necessity of considering the microstructure evolution in the life prediction.

准确评估气膜冷却孔结构的蠕变寿命对航空发动机和燃气轮机的长寿命设计和安全运行至关重要。首先,通过带膜状冷却孔的镍基单晶高温合金的高温蠕变实验,表征了膜状冷却孔周围多轴应力状态下的组织演变过程。然后,考虑漂流结构的定向效应和多轴应力的影响,采用四阶张量描述γ相宽度的演化,建立了考虑多轴应力状态的微观结构演化模型。显微组织演化通过Orowan应力耦合到晶体塑性本构模型中。同时,基于连续损伤力学,在本构模型中引入多轴延性因子,建立了新的多轴损伤演化规律。改进的晶体塑性本构模型可以有效预测多轴应力条件下的微观组织演变。将改进的晶体塑性本构模型与考虑应力梯度的临界距离法相结合,用于膜状冷却孔结构的寿命预测。预测结果表明,在寿命预测中考虑组织演变的有效性和必要性。


Thin-Walled Structures

The bending of 3D-printed Bio-inspired sandwich panels with wavy cylinder cores

Xindi Yu, Qicheng Zhang, Rodrigo J da Silva, Tulio Halak Panzera, Mark Schenk, Fabrizio Scarpa

doi:10.1016/j.tws.2024.112538

弯曲的3d打印仿生夹心板与波浪圆柱芯

Beetle Elytron Plates (BEPs) represent a new class of biomimetic sandwich cores with excellent mechanical properties inspired by the microstructure of the beetle elytra. The cores have a hexagonal centre-symmetric configuration with through-thickness cylinders in the unit cell. In this work, we describe the behaviour of sandwich panels with novel BEP core configurations possessing wavy cylinders under four-point bending tests. Full-scale simulations are also carried out to validate the experimental data. The results show that all the sandwich panels produced with face skins adhesively bonded have material failure earlier than the adhesive bond failure. BEPs with wavy cylinders have larger peak loads compared to those with straight cylinders, and all BEPs show higher peak loads than those of sandwich panels with classical hexagonal honeycombs. Additionally, all the BEPs exhibit an enhanced ductility compared to honeycomb sandwich panels.

甲虫鞘翅片(BEPs)是一种新型仿生三明治芯,具有优异的机械性能,灵感来自甲虫鞘翅的微观结构。芯具有六角形的中心对称结构,在单元胞中具有贯穿厚度的圆柱体。在这项工作中,我们描述了具有波浪圆柱体的新型BEP芯结构的夹层板在四点弯曲试验中的行为。为了验证实验数据,还进行了全尺寸仿真。结果表明:面皮粘接生产的夹层板材料破坏均早于胶合破坏;波浪柱面夹层板的峰值载荷比直柱面夹层板的峰值载荷要大,且所有夹层板的峰值载荷都高于经典六边形蜂窝夹层板。此外,与蜂窝夹层板相比,所有bep都具有增强的延展性。


An improved modal tracking algorithm for dispersion analysis of arbitrary prestressed plates

Xu Zhang, Lei Chen, Gang Liu, Zehui Zhang, Jiacheng Wang

doi:10.1016/j.tws.2024.112582

一种用于任意预应力板频散分析的改进模态跟踪算法

Determining the dispersion characteristics of prestressed plates is essential for guided wave-based structural health monitoring, which can provide theoretical guidance for optimizing excitation mode and frequency. However, the multi-mode nature of guided waves brings huge challenges for modal tracking. Conventional methods require sufficiently small frequency steps and may encounter tracking errors during mode crossing and overlap. To address these issues, this paper established a multi-step superposition model to obtain the dispersion relation of arbitrary prestressed plates and proposed a novel modal tracking method based on structural similarity (SSIM) image registration for identifying all guided wave modes. Drawing inspiration from the image quality assessment technique, a novel index was introduced to evaluate the consistency between modal eigenvectors quantitatively. Furthermore, an improved algorithm using eigenvector operations was developed to further enhance the efficiency and applicability of the modal tracking process. Subsequently, application examples were conducted to thoroughly evaluate the performance of the proposed methods through comparison with conventional modal tracking methods. The results indicated that the proposed methods have accurate and reliable tracking performance even with larger wavenumber steps, which is unattainable with conventional methods. Notably, the computational efficiency of the improved algorithm is nearly 13 times faster than the SSIM-based image registration method. Finally, an investigation into the dispersion characteristics of aluminum plates under tensile, bending, and shear stress demonstrated the versatility of the improved modal tracking algorithm. This study provides valuable insights into the dispersion behavior of guided waves in prestressed plates.

确定预应力板的频散特性是基于导波的结构健康监测的基础,可以为优化激励方式和频率提供理论指导。然而,导波的多模态特性给模态跟踪带来了巨大的挑战。传统的方法需要足够小的频率步长,并且可能在模式交叉和重叠时遇到跟踪误差。针对这些问题,本文建立了多步叠加模型来获取任意预应力板的频散关系,并提出了一种基于结构相似度(SSIM)图像配准的新型模态跟踪方法来识别所有导波模态。受图像质量评价技术的启发,引入了一种新的模态特征向量一致性定量评价指标。在此基础上,提出了一种基于特征向量运算的改进算法,进一步提高了模态跟踪的效率和适用性。最后,通过与传统模态跟踪方法的对比,对所提方法的性能进行了全面评价。结果表明,该方法在较大的波数步长下仍具有传统方法无法达到的准确可靠的跟踪性能。值得注意的是,改进算法的计算效率比基于ssim的图像配准方法快了近13倍。最后,对铝板在拉伸、弯曲和剪切应力作用下的色散特性进行了研究,证明了改进模态跟踪算法的通用性。本研究对预应力板中导波的频散特性提供了有价值的见解。


Analytical and numerical predictions of elastoplastic buckling behaviors of the subsea lined pipelines with ovality defects under hydrostatic pressure

Qian Zhang, Denglian Yang, Meiling Shen, Zhaochao Li

doi:10.1016/j.tws.2024.112584

静水压力下含椭圆形缺陷海底衬管弹塑性屈曲行为的分析与数值预测

The subsea pipelines may deteriorate and/or be cracked after a long period of service. A cost-effective trenchless rehabilitation technology is to install a thin-walled steel liner inside the pipelines. However, elliptical defects may occur in the liner due to issues such as insufficient inflation, deformation of the host pipelines, and joint misalignment in practical engineering. Thus, this study aims to develop a systematic analytical model and numerical model for the elastic and inelastic buckling behaviors of the thin-walled oval steel liner, respectively. An admissible radial displacement function is introduced to describe the single-lobe deformation of the liner. The governing equations are established to trace the equilibrium paths by applying the theory of thin-walled shells and the principle of minimum potential energy. A two-dimensional finite element model is developed for the elastic and inelastic buckling performance of the liner. The analytical solutions of elastic buckling are in good agreement with other closed-form solutions, numerical results, and respective test results available in the literature. Finally, parametric evaluations are carried out in terms of ovality, non-uniform liner-pipeline gap, internal pressure, and liner yield strength.

海底管道在长期使用后可能会恶化和/或破裂。一种具有成本效益的非开挖修复技术是在管道内安装薄壁钢衬垫。但在实际工程中,由于膨胀不足、主管道变形、接头不对中等原因,可能导致衬管出现椭圆缺陷。因此,本研究旨在分别建立薄壁椭圆形钢衬垫弹性屈曲和非弹性屈曲行为的系统解析模型和数值模型。引入容许径向位移函数来描述衬板的单瓣变形。应用薄壁壳理论和最小势能原理,建立了跟踪平衡路径的控制方程。建立了衬垫弹性屈曲和非弹性屈曲的二维有限元模型。弹性屈曲的解析解与文献中其他闭型解、数值结果和相应的试验结果吻合较好。最后,从椭圆度、非均匀衬管间隙、内压和衬管屈服强度等方面进行参数评价。




来源:复合材料力学仿真Composites FEM
ACTMechanicalMaxwellSystemInspire通用航空理论材料仿生控制试验管道
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首次发布时间:2024-11-27
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【新文速递】2024年10月17日复合材料SCI期刊最新文章

今日更新:Composite Structures 1 篇,Composites Part A: Applied Science and Manufacturing 4 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇Composite StructuresA novel cellular structure with center-symmetric cell walls for morphing applicationsDezhi Wu, Guang Yang, Jianguo Tao, Yue Wang, Hong Xiao, Hongwei Guodoi:10.1016/j.compstruct.2024.118644具有中心对称细胞壁的新型细胞结构用于变形应用Cellular structures are potential candidates for the supporting framework of flexible morphing skins. Unlike traditional zero Poisson’s ratio (ZPR) cellular structures with axisymmetric cell walls, this paper proposes a novel cellular structure with center-symmetric cell walls. The in-plane mechanical properties of this novel structure are explored through theoretical analysis and substantiated by both finite element simulations and experimental tests. Compared to the classic accordion honeycomb structure, the elastic modulus in the x-direction of the novel structure is reduced by an average of 58%, the strain amplification rate is increased by 122%, and the in-plane stiffness anisotropy is improved by 200%. These findings suggest that the proposed structure offers far superior stiffness anisotropy and large deformation potential, making it more suitable for morphing applications than the traditional ZPR cellular structures.细胞结构是柔性变形皮肤支持框架的潜在候选者。与传统的轴对称细胞壁零泊松比(ZPR)细胞结构不同,本文提出了一种中心对称细胞壁的新型细胞结构。通过理论分析探索了这种新型结构的面内力学性能,并进行了有限元模拟和实验验证。与经典手风琴蜂窝结构相比,该结构x方向弹性模量平均降低58%,应变放大率提高122%,面内刚度各向异性提高200%。这些发现表明,所提出的结构具有优越的刚度各向异性和大的变形潜力,使其比传统的ZPR细胞结构更适合变形应用。Composites Part A: Applied Science and ManufacturingIn-plane properties of an in-situ consolidated automated fiber placement thermoplastic compositeTimothy Yap, Nathaniel Heathman, Behrooz Shirani Bidabari, Emile Motta de Castro, Ali Tamijani, Amir Asadi, Mehran Tehranidoi:10.1016/j.compositesa.2024.108525原位固结自动铺放纤维热塑性复合材料的面内性能Automated fiber placement (AFP) has been employed to manufacture aerospace structures for decades, recently focusing on thermoplastic composites (TPC). The in-situ consolidation AFP of TPCs is pursued as an energy-efficient additive manufacturing (AM) approach for fabricating composite structures. This work compares the in-plane mechanical properties of in-situ consolidated coupons with those of compression molded counterparts to provide new insights into their failure mechanics and processing-structure relationships. Tensile and compressive properties along the fiber and transverse directions, in-plane shear properties, and short beam strength were measured for all samples. Failure modes and mechanics in tested coupons were related to AFP defects and processing, i.e., resultant crystallinities, fiber misalignment, matrix mechanical properties, porosity, and fiber–matrix interfacial strength. The findings of this study can be used to guide the manufacturing of future TPC structures and potentially open new avenues for applications where post-processing is not feasible or reduced mechanical performance is acceptable.自动纤维铺放技术(AFP)已经应用于航空航天结构制造几十年了,最近的重点是热塑性复合材料(TPC)。原位固结复合材料是一种高效节能的增材制造(AM)方法。这项工作比较了原位固结板与压缩成型板的平面内力学性能,为其破坏机制和加工-结构关系提供了新的见解。测试了所有样品沿纤维方向和横向的拉伸和压缩性能、面内剪切性能和短梁强度。试样中的失效模式和力学与AFP缺陷和加工有关,即结晶度、纤维错位、基体力学性能、孔隙率和纤维-基体界面强度。这项研究的结果可用于指导未来TPC结构的制造,并可能为后处理不可行的应用或降低机械性能可接受的应用开辟新的途径。Bearing performance and progressive failure analysis of bolted joint in 3D printed pseudo-woven CFRP composite with fibre steeringAonan Li, Haoqi Zhang, Dongmin Yangdoi:10.1016/j.compositesa.2024.1085263D打印纤维转向伪编织CFRP复合材料螺栓连接承载性能及渐进失效分析This study investigates the bearing failure process of 3D printed pseudo-woven carbon fibre reinforced polymer (CFRP) composite joints, with a particular focus on the damage mechanisms influenced by steered fibres. A multiscale finite element model employing LaRC05 failure criteria is developed and validated against the experimental load–displacement curves and micro-computed microtomography (CT) images of four distinct cases. The model clearly demonstrates the critical importance of maintaining fibre continuity around the bolt hole, as this significantly influences the ability to reduce stress concentrations caused by the direct bearing loads from the bolt. Moreover, the model reveals that fibre steering can substantially improve the composite joint’s performance. This enhancement is achieved by adjusting the level of shear-induced damage propagation in individual filaments. The results demonstrate the potential and capability of the model to capture individual filament behaviour for the failure analysis of 3D printed composites, achieving good correlations with experimental measurements and observations, in terms of failure modes and load-bearing capacities.本文研究了3D打印伪编织碳纤维增强聚合物(CFRP)复合材料接头的承载破坏过程,重点研究了定向纤维对其损伤机制的影响。采用LaRC05失效准则建立了一个多尺度有限元模型,并根据实验载荷-位移曲线和四种不同情况的微计算机微断层扫描(CT)图像进行了验证。该模型清楚地表明,保持螺栓孔周围纤维的连续性至关重要,因为这极大地影响了降低由螺栓直接承载载荷引起的应力集中的能力。此外,该模型还表明,纤维转向可以显著提高复合材料接头的性能。这种增强是通过调整单个细丝中剪切引起的损伤传播水平来实现的。结果表明,该模型具有捕获单个细丝行为的潜力和能力,可用于3D打印复合材料的失效分析,在失效模式和承载能力方面,与实验测量和观察结果具有良好的相关性。The moisture absorption of additively manufactured short carbon fibre reinforced polyamideYingwei Hou, Ajit Panesardoi:10.1016/j.compositesa.2024.108528增材制造短碳纤维增强聚酰胺的吸湿性能Polymer composites are commonly exposed to moisture and undergo reductions in mechanical properties. It is challenging to describe the moisture absorption dynamics of 3D printed parts due to manufacture-induced microstructures. This work investigates the moisture absorption of printed short carbon fibre reinforced polyamide (SFRP) with varied microstructures and its impact on mechanical properties. The printed SFRP have inferior microstructures and diffusivity increases with the number of interlayer interfaces by up to 119%, which is 258% higher than that of compression moulded composite. The yield stress and tensile modulus of SFRP decrease by up to 59% and 79%, respectively. This deterioration is irreversible and more significant than injection moulded samples as the microstructure is permanently degraded by moisture. Additionally, the shear moduli of printed polyamide and SFRP decrease by up to 63% and 74%, respectively. The results are crucial for prediction, evaluation, and maintenance of 3D printed applications in humid conditions.聚合物复合材料通常暴露在潮湿中,机械性能会降低。由于制造诱导的微结构,描述3D打印部件的吸湿动力学具有挑战性。本文研究了不同微观结构的印刷短碳纤维增强聚酰胺(SFRP)的吸湿性能及其对力学性能的影响。打印后的SFRP具有较差的微观结构,其扩散系数随着层间界面数量的增加而提高了119%,比压缩成型复合材料提高了258%。SFRP的屈服应力和拉伸模量分别降低了59%和79%。这种劣化是不可逆的,并且比注射成型样品更重要,因为微观结构被水分永久劣化。此外,打印聚酰胺和SFRP的剪切模量分别下降了63%和74%。研究结果对于潮湿条件下3D打印应用的预测、评估和维护至关重要。Translaminar fracture in (non–)hybrid thin-ply fibre-reinforced composites: An in-depth examination through a novel mini-compact tension specimen compatible with microscale 4D computed tomographySina AhmadvashAghbash, Guillaume Broggi, Abdullah Aydemir, Alexios Argyropoulos, Joël Cugnoni, Véronique Michaud, Mahoor Mehdikhani, Yentl Swolfsdoi:10.1016/j.compositesa.2024.108529(非)混杂薄层纤维增强复合材料的跨层断裂:通过与微尺度4D计算机断层扫描兼容的新型微型紧凑型拉伸试样进行深入检查Translaminar fracture toughness is pivotal for notch sensitivity and damage tolerance of fibre-reinforced composites. Hybridisation offers a promising pathway for enhancing this parameter in thin-ply composites. Three novel mini-compact tension specimen geometries were investigated for their competence in microscale characterisation of translaminar fracture using in-situ synchrotron radiation computed tomography (SRCT). Only “mini-protruded” design resulted in stable crack propagation with adequate crack increments. Based on this design, five baseline and hybrid cross-ply configurations incorporating low- and high-strain carbon fibres were studied. Crack propagation in low- and high-strain baseline configurations was stable. For interlayer and intrayarn fibre-hybrid configurations, a correlation between load–displacement curves and delamination is observed. The SRCT data confirmed that 90° ply-blocks cushion the interaction between 0° plies, enabling independent fracture. Additionally, crack fronts in 90° plies advance further than those in 0° plies. Moreover, mechanical interlocking and bundle bending within 0° plies serve as supplementary mechanisms for energy dissipation.跨层断裂韧性是影响纤维增强复合材料缺口敏感性和损伤容限的关键因素。杂化为提高薄层复合材料的这一参数提供了一条很有前途的途径。利用原位同步辐射计算机断层扫描(SRCT)技术,研究了三种新型的微型紧致拉伸试样几何形状在跨椎板断裂微尺度表征中的能力。只有“微突出”设计导致裂纹扩展稳定且有足够的裂纹增量。基于这种设计,研究了包含低应变和高应变碳纤维的五种基线和混合交叉层配置。在低应变和高应变基线配置下,裂纹扩展是稳定的。对于层间和层内纤维混杂结构,观察到载荷-位移曲线与分层之间的相关性。SRCT数据证实,90°层段缓冲了0°层段之间的相互作用,实现了独立压裂。此外,90°层的裂缝前缘比0°层的裂缝前缘超前得多。此外,机械联锁和0°层内的束弯曲是能量耗散的补充机制。Composites Part B: EngineeringA New Path Planning Strategy Driven by Geometric Features and Tensile Properties for 3D Printing of Continuous Fiber Reinforced Thermoplastic CompositesWang Gongshuo, Wang Fuji, Guan Shouyan, Rao Fu, Wang Hongquan, Lei Yajingdoi:10.1016/j.compositesb.2024.111885 基于几何特征和拉伸性能的连续纤维增强热塑性复合材料3D打印路径规划策略Three-dimensional (3D) printing technology for continuous fiber reinforced thermoplastic composites (C-FRTP), capable of rapid manufacturing of lightweight components with intricate geometric features, has emerged as one of the most promising technologies in the field of advanced composite manufacturing. Path planning is a crucial step for determining the fabrication quality of C-FRTP components. In this study, we proposed a new 3D printing path planning strategy driven by the geometric features and tensile properties of C-FRTP components. This strategy employed the properties of the Euler graph to generate the continuous full-field filling paths, ensuring the geometric features of the target components. The intersections were scattered along the printing path to enhance the tensile strength. The feasibility and advantages of the new path planning strategy were validated by comparative experiments with different printing paths. The results indicated that the new strategy not only achieved the geometric features of the target components but significantly enhanced their tensile strength. Using the printing path generated by the new path planning strategy, the tensile strength of specimens featuring mounting holes reached 349.4 MPa, which was only about 4.1% lower than the tensile strength of continuous fibers at straight paths. Compared to the existing contour-parallel path, the new strategy in this work improved the tensile properties by about 40.9%. The new path planning strategy proposed in this study shows great potential to design and fabricate C-FRTP components with enhanced mechanical properties for practical applications.连续纤维增强热塑性复合材料(C-FRTP)的三维(3D)打印技术能够快速制造具有复杂几何特征的轻质部件,已成为先进复合材料制造领域最有前途的技术之一。路径规划是决定C-FRTP构件制造质量的关键步骤。在这项研究中,我们提出了一种新的3D打印路径规划策略,该策略由C-FRTP部件的几何特征和拉伸性能驱动。该策略利用欧拉图的特性生成连续的全场填充路径,保证了目标部件的几何特征。在打印路径上分散交点以提高拉伸强度。通过不同打印路径的对比实验,验证了新路径规划策略的可行性和优越性。结果表明,新策略既能满足目标部件的几何特征,又能显著提高目标部件的抗拉强度。采用新路径规划策略生成的打印路径,安装孔试件的抗拉强度达到349.4 MPa,仅比连续纤维在直线路径下的抗拉强度低4.1%左右。与现有的轮廓平行路径相比,新策略的拉伸性能提高了约40.9%。本研究提出的新的路径规划策略在设计和制造具有增强机械性能的C-FRTP部件的实际应用中具有很大的潜力。Composites Science and TechnologyMultiscale study of interfacial properties of carbon fiber reinforced polyphthalazine ether sulfone ketone resin matrix compositesZhenyu Qian, Tianqi Zhu, Xingyao Liu, Xinyu Fan, Zhongwei Yan, Xigao Jian, Jian Xudoi:10.1016/j.compscitech.2024.110906 碳纤维增强聚酞醚砜酮树脂基复合材料界面性能的多尺度研究In view of the limitations of traditional research tools on interfacial failure mechanisms in fiber/PPESK composites, this work proposes a multiscale research tool to carry out an in-depth study of the interfacial behavior between fibers and matrix. Based on microdroplet debonding tests, at the mesoscopic scale, the influence of residual thermal stress on the interface damage mode is explored through finite element (FEM) simulations. The evolution mechanism of composite material interfaces in spatial and temporal dimensions is examined based on changes in interfacial stress distribution, energy dissipation, and damage morphology during the debonding process, which can be summarized as follows: accompanied by elastic-plastic deformation and friction effects, the progressive process from localized to complete failure presents a dominant Type II damage mode at the interface. To further explore the interface failure mechanism at the molecular level, an interface model of CF/PPESK composite materials was established using molecular dynamics (MD) method. By monitoring the atom movement trend, the "fiber-matrix displacement synergistic effect" in the interfacial shear damage process was revealed, thereby establishing a multiscale mapping relationship of composite material interface. Based on this, the combination of FEM and MD was utilized to investigate the interface damage process of composite materials under different service conditions and to reasonably predict the initiation and expansion of microcracks. This study provides a pioneering perspective on interface damage research in composite materials with a "top-down" multiscale approach.鉴于传统研究工具对纤维/PPESK复合材料界面破坏机制的局限性,本工作提出了一种多尺度研究工具,以深入研究纤维与基体之间的界面行为。基于微液滴脱粘试验,在细观尺度上,通过有限元模拟探讨了残余热应力对界面损伤模式的影响。基于剥离过程中界面应力分布、能量耗散和损伤形态的变化,考察复合材料界面在时空维度上的演化机制,可归纳为:伴随着弹塑性变形和摩擦作用,界面从局部破坏到完全破坏的渐进过程以II型损伤模式为主;为了在分子水平上进一步探讨界面破坏机理,采用分子动力学(MD)方法建立了CF/PPESK复合材料的界面模型。通过对原子运动趋势的监测,揭示了界面剪切损伤过程中的“纤维-基质位移协同效应”,从而建立了复合材料界面的多尺度映射关系。在此基础上,采用有限元法和模态分析相结合的方法,研究了复合材料在不同使用条件下的界面损伤过程,合理预测了微裂纹的萌生和扩展。本研究为复合材料界面损伤研究提供了一个“自上而下”的多尺度方法。Composite Janus film based on the synergistic interactions of π-π stacking and dynamic covalent bond toward direction recognition sensingYang Bai, Guoliang Yang, Zhong Jing, Boyuan Zhang, Xinrui Li, Guiqiang Feidoi:10.1016/j.compscitech.2024.110913 基于π-π堆叠和动态共价键协同作用的方向识别传感复合Janus膜Although flexible strain sensors have made important advancements recently, most of them are unable to recognize the direction of motion, which greatly limits their application in fields such as human-machine interaction. This paper presents the fabrication of a bilayer asymmetric composite film that exhibits Janus dual-sided characteristics and interfacial properties. Specifically, the two sides possess different chemical compositions and surface features. The strong π-π stacking interaction between carbon nanotubes (CNTs) and pyrene enables a tight coating on the surface of poly(glycidyl propyl urethane) (PGPU), resulting in excellent sensing capabilities and electromagnetic shielding properties for the composite material. This composite film can effectively monitor the amplitude and direction of motion. Firstly, pyrene-grafted polyurethane (PGPU) was synthesized including on dynamic covalent bonds. The tensile strength of different samples can reach up to 19.69 MPa, and the strain at break is up to 501.95%. Furthermore, PGPU/CNTs conductive composite films were fabricated by spray-coating carbon nanotubes (CNTs) onto PGPU, and the pyrene units in PGPU can effectively interact with CNTs via π-π stacking, ensuring that stable adhesion of CNTs layer during long-term usage. Due to the dynamic covalent bonds and hydrogen bonds inside PGPU, PGPU and PGPU/CNTs both exhibit well-performed self-healing capability. Notably, the Janus structure of PGPU/CNTs can adjust the positive and negative values of relative resistance based on stretchable and compressive status of CNTs layer. Thus, PGPU/CNTs are directionally sensitive and self-healing flexible wearable sensor, which might apply in human-machine interaction field.虽然柔性应变传感器近年来取得了重要的进展,但它们大多无法识别运动方向,这极大地限制了它们在人机交互等领域的应用。本文介绍了一种具有双面特性和界面特性的双层非对称复合膜的制备方法。具体来说,两面具有不同的化学成分和表面特征。碳纳米管(CNTs)和芘之间的强π-π堆叠相互作用使得聚甘油三酯(PGPU)表面具有紧密的涂层,从而使复合材料具有优异的传感能力和电磁屏蔽性能。这种复合薄膜可以有效地监测运动的幅度和方向。首先合成了含动态共价键的芘接枝聚氨酯(PGPU)。不同试样的抗拉强度可达19.69 MPa,断裂应变可达501.95%。此外,通过在PGPU上喷涂碳纳米管(carbon nanotubes, CNTs)制备了PGPU/CNTs导电复合膜,PGPU中的芘单元可以通过π-π堆叠与CNTs有效相互作用,保证了长期使用过程中CNTs层的稳定粘附。由于PGPU内部的动态共价键和氢键,PGPU和PGPU/CNTs都表现出良好的自愈能力。值得注意的是,PGPU/CNTs的Janus结构可以根据CNTs层的可拉伸和压缩状态调节相对阻力的正负值。因此,PGPU/CNTs是一种方向敏感、自修复的柔性可穿戴传感器,有望应用于人机交互领域。Experimental and Numerical Investigations on the Tensile Response of Pin-Loaded Carbon Fibre Reinforced Polymer StrapsDanijela Stankovic, James R. Davidson, Valentin Ott, Luke A. Bisby, Giovanni P. Terrasidoi:10.1016/j.compscitech.2024.110915 引脚加载碳纤维增强聚合物带拉伸响应的实验与数值研究Carbon fibre reinforced polymer (CFRP) pin-loaded looped straps are increasingly being used in a range of structural load-bearing applications, notably for bridge hanger cables in network arch rail and highway bridges. The static performance of such CFRP straps is investigated through experimental and numerical analyses. Finite element (FE) models based on both one-eighth and half pin-strap assembly geometries were modelled. The resulting strains, stresses, and applied loads were compared against experimental data obtained using Digital Image Correlation, Distributed Fibre Optic Sensing (DFOS), and Fibre Bragg Grating (FBG) Sensing. The FE models effectively captured local strain distributions around the vertex area, close to the pin ends of the straps, as well as in the mid-shaft region, and aligned reasonably with experimental observations. The half FE model accurately predicted the overall strain distribution when compared to DFOS data; however, higher strain magnitudes (by 0.45-10.2%) and larger strain reductions were observed in some locations. Regarding failure loads, the FE models agreed well with Schürmann's analytical solution and the maximum stress criterion, exhibiting less than 2.5% deviations from the experimental data. Furthermore, the predicted onset of strap failure (by delamination) in the half model agreed with experimental values, with a maximum variance of 9.2%.碳纤维增强聚合物(CFRP)销加载环带越来越多地应用于一系列结构承重应用,特别是在网络拱轨道和公路桥梁的桥吊索中。通过试验和数值分析研究了碳纤维布带的静力性能。基于八分之一和二分之一针带装配几何形状的有限元模型进行了建模。将得到的应变、应力和施加的载荷与使用数字图像相关、分布式光纤传感(DFOS)和光纤布拉格光栅(FBG)传感获得的实验数据进行比较。有限元模型有效地捕获了顶点区域周围、靠近吊带销端以及中轴区域的局部应变分布,与实验观测值吻合较好。与DFOS数据相比,半有限元模型更准确地预测了整体应变分布;然而,在某些位置观察到更高的应变大小(0.45-10.2%)和更大的应变减小。在破坏荷载方面,有限元模型与sch<s:1> rmann解析解和最大应力准则吻合较好,与试验数据偏差小于2.5%。此外,在半模型中,预测的皮带失效(由分层)开始与实验值一致,最大方差为9.2%。Hollow core-shell structure Fe3O4@Polypyrrole composites for enhanced electromagnetic wave absorptionJiang Guo, Yukun Sun, Xu Li, Shaohua Xi, Mohamed M. Ibrahim, Hua Qiu, Gaber A.M. Mersal, Zeinhom M. El-Bahy, Vignesh Murugadoss, Waras Abdul, Fujian Zhou, Juanna Ren, Zhanhu Guo, Jianfeng Zhudoi:10.1016/j.compscitech.2024.110917 中空核壳结构Fe3O4@Polypyrrole增强电磁波吸收复合材料Due to the rapid development of electronic devices, the electromagnetic pollution has become increasingly serious. Developing electromagnetic wave absorption (EWA) materials with lightweight, strong absorption capacity and wide effective absorption bandwidth (EAB) becomes a research hotspot. In this work, the hollow-Fe3O4@polypyrrole (HFO@PPy) composites with core-shell structure were successfully synthesized by in situ polymerization method. The electromagnetic parameters could be adjusted by controlling the content of HFO in HFO@PPy. In addition, HFO@PPy composites show both dielectric and magnetic losses. The synergistic effect of both two losses contributes to an enhanced electromagnetic attenuation. The enhanced impedance matching is achieved by the composition (HFO and PPy) and designed unique structure (core-shell and hollow structure). The maximum reflection loss (RL) and EAB are -52.01 dB and 2.72 GHz at 3.1 mm for 60.0 wt% HFO@PPy composites. Therefore, by reasonably regulating the component content and optimizing the structural design, the EWA performance of HFO@PPy composites could be effectively improved, providing a significant inspiration for fabrication of microwave absorbers.由于电子设备的快速发展,电磁污染日益严重。开发重量轻、吸收能力强、有效吸收带宽宽的电磁波吸收材料成为研究热点。本文采用原位聚合法制备了具有核壳结构的hollow-Fe3O4@polypyrrole (HFO@PPy)复合材料。通过控制HFO@PPy中HFO的含量,可以调节电磁参数。此外,HFO@PPy复合材料同时显示介电和磁损耗。这两种损耗的协同效应有助于增强电磁衰减。通过HFO和PPy组成和独特的结构(核壳和空心结构)实现了增强的阻抗匹配。60.0 wt% HFO@PPy复合材料在3.1 mm处的最大反射损耗(RL)和EAB分别为-52.01 dB和2.72 GHz。因此,通过合理调节组分含量和优化结构设计,可有效提高HFO@PPy复合材料的EWA性能,为微波吸收材料的制造提供重要启示。来源:复合材料力学仿真Composites FEM

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