首页/文章/ 详情

【新文速递】2024年1月2日复合材料SCI期刊最新文章

16天前浏览449

今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 1 篇

Composite Structures

A bistable impact resistant sandwich carbon-fibre reinforced core

Francesco Flora, Marco Boccaccio, Fulvio Pinto, Michele Meo

doi:10.1016/j.compstruct.2023.117865

双稳态抗冲击夹层碳纤维增强内核

The interest of aerospace and automotive fields in the improvement of energy absorption properties of composite materials has stimulated researchers to design new typologies of cores of sandwich-structures under impact events. In this work, a sandwich structure based on pre-stressed bistable carbon fibre composite core is proposed. The core, named Circular Prestressed Carbon Core (CPCC), takes advantage of the asymmetric fibres orientation and the bistability-concept to enhance energy dissipation and reduce the damage extension during impacts. The impact campaign was conducted both experimentally and numerically to analyse the mechanical properties of the core and to study the contribution of the residual stresses. Experimental results were compared with an aerospace-grade aluminium honeycomb-core and a not-prestressed version of the core. Results proved its unique impact characteristics, showing, an improvement of the maximum-force up to 171% and 23% in comparison with aluminium honeycomb and not-prestressed CPCC, respectively. The specific properties of the CPCC were considerably higher than the aluminium sandwich, with peak force values up to +75%, displacement reduced up to -71%, and non-destructive evaluation (NDE) test showed a reduction of the projected damaged area by ∼20%. These results demonstrates that the CPCC structure constitutes a novel high-performance sandwich core for improved impact resistance.

航空航天和汽车领域对提高复合材料能量吸收性能的关注,激发了研究人员在冲击事件下设计新型夹层结构芯材的热情。本研究提出了一种基于预应力双稳态碳纤维复合材料芯材的夹层结构。这种芯材被命名为环形预应力碳纤维芯材(CPCC),它利用非对称纤维取向和双稳态概念来增强能量耗散并减少冲击过程中的破坏扩展。为了分析芯材的机械性能并研究残余应力的作用,我们通过实验和数值方法进行了冲击试验。实验结果与航空航天级铝蜂窝芯材和非预应力型芯材进行了比较。结果表明,与铝蜂窝芯和无预应力 CPCC 相比,CPCC 具有独特的冲击特性,最大力分别提高了 171% 和 23%。CPCC 的特殊性能大大高于铝夹层,其峰值力可达到 +75%,位移可减少到 -71%,无损评价(NDE)测试显示,投影损坏面积减少了 ∼ 20%。这些结果表明,CPCC 结构是一种新型的高性能夹层芯材,可提高抗冲击性能。


Low-velocity impact response of the post-buckled FG-MEE plate resting on visco-Pasternak foundation: Magneto-electro-mechanical effects-based interaction analysis

Lizhi Li, Lu Nie, Yiru Ren

doi:10.1016/j.compstruct.2023.117869

粘滞-帕斯捷尔纳克地基上的后扣式 FG-MEE 板的低速冲击响应:基于磁机电效应的相互作用分析

Revealing the coupling of nonlinear behavior and the magneto-electro-mechanical effects in the impact responses of post-bucked magneto-electro-elastic structures contributes to the intelligent development of aircraft structural systems. The low-velocity impact responses of the post-buckled functional gradient magneto-electro-elastic(FG-MEE) plate resting on visco-Pasternak foundation are investigated. In the framework of the von Kármán-type nonlinear model considering post-buckling configurations, the low-velocity impact dynamics model of the post-buckled FG-MEE plate is constructed. The two-step perturbation method is developed to obtain the post-buckling equilibrium path induced by the magneto-electro-mechanical effects. Further, the higher-order form of the two-step perturbation method-Galerkin integral method is proposed for the post-buckled FG-MEE plate resting on visco-Pasternak foundation, acquiring the high-order truncated solutions of displacement, electric potential, and magnetic potential. Ultimately, the snap-through phenomenon of the post-buckled FG-MEE plate under low-velocity impact is captured, and the variation in the degree of coupling between nonlinear behavior and the magneto-electro-mechanical effects is systematically revealed.

在后扣式磁电弹性结构的冲击响应中揭示非线性行为与磁电力学效应的耦合,有助于飞机结构系统的智能化发展。本文研究了位于粘滞-帕斯捷尔纳克地基上的后扣式功能梯度磁电弹性(FG-MEE)板的低速冲击响应。在考虑后屈曲配置的 von Kármán 型非线性模型框架内,构建了后屈曲 FG-MEE 板的低速冲击动力学模型。通过两步扰动法获得了由磁电效应引起的后屈曲平衡路径。此外,还提出了两步扰动法的高阶形式--Galerkin 积分法,用于支撑在粘滞-帕斯捷尔纳克地基上的后屈曲 FG-MEE 板,获得了位移、电动势和磁动势的高阶截断解。最终,捕捉到了后折叠 FG-MEE 板在低速冲击下的快穿现象,并系统地揭示了非线性行为与磁机电效应之间耦合度的变化。


Nonlinear isogeometric analysis of axially functionally graded graphene platelet-reinforced composite curved beams

Yanan Liang, Shijie Zheng, Hongtao Wang, Dejin Chen

doi:10.1016/j.compstruct.2023.117871

轴向功能分级石墨烯血小板增强复合材料曲线梁的非线性等几何分析

The linear and nonlinear isogeometric finite element models of an axially functionally graded graphene platelet-reinforced composite (AFG-GPLRC) curved beam are established within the framework of the third-order shear deformation beam theory (TSDT) and von-Kármán’s nonlinear geometric relation. The AFG-GPLRC curved beams can be seen as composite structures in which the graphene platelets (GPLs) are continuously distributed in the matrix along the length direction of the curved beam according to different patterns. The modified Halpin-Tsai parallel model and the rule of mixture are implemented to predict the effective Young’s modulus and mass density as well as Poisson’s ratio, respectively. Hamilton's principle, TSDT, and von-Kármán’s strain-displacement relation are combined to derive the governing partial differential equation of motion and corresponding boundary conditions. Furthermore, the Non-Uniform Rational B-splines (NURBS)-based isogeometric analysis (IGA) approach together with a direct iterative technique are utilized to solve the nonlinear governing equation. The accuracy and efficiency of the proposed IGA framework are confirmed by comparing corresponding numerical solutions with other available results. The parametric investigations, such as the curved beam’s geometric parameters, boundary conditions, and GPL’s distribution patterns, on the nonlinear bending and vibration responses of the AFG-GPLRC curved beams are carried out by some illustrative examples.

在三阶剪切变形梁理论(TSDT)和 von-Kármán 非线性几何关系的框架内,建立了轴向功能分级石墨烯血小板增强复合材料(AFG-GPLRC)曲线梁的线性和非线性等几何有限元模型。AFG-GPLRC 曲线梁可以看作是一种复合结构,其中石墨烯平板(GPLs)沿着曲线梁的长度方向以不同的模式连续分布在基体中。采用改进的 Halpin-Tsai 平行模型和混合规则分别预测有效杨氏模量和质量密度以及泊松比。结合汉密尔顿原理、TSDT 和 von-Kármán 的应变-位移关系,推导出支配运动的偏微分方程和相应的边界条件。此外,还利用基于非均匀有理 B-样条曲线(NURBS)的等几何分析(IGA)方法和直接迭代技术来求解非线性控制方程。通过将相应的数值解与其他可用结果进行比较,证实了所提出的 IGA 框架的准确性和效率。通过一些示例对 AFG-GPLRC 曲线梁的非线性弯曲和振动响应进行了参数研究,如曲线梁的几何参数、边界条件和 GPL 的分布模式。


An efficient surrogate model for damage forecasting of composite laminates based on deep learning

Guowen Wang, Laibin Zhang, Shanyong Xuan, Xin Fan, Bin Fu, Xiao Xue, Xuefeng Yao

doi:10.1016/j.compstruct.2023.117863

基于深度学习的复合材料层压板损伤预测高效替代模型

In this paper, full-field damage forecasting of a laminated composite structure subjected to different low velocity impact (LVI) conditions is realized through the proposed surrogate model, named VQ-SM. First, an efficient surrogate modelling method is proposed based on the advanced Vector Quantised-Variational AutoEncoder (VQ-VAE) proposed by DeepMind. Second, numerical simulation based on the progressive damage model of composite laminates is performed to obtain the training dataset. After training, the performance of VQ-SM is evaluated compared to the surrogate model without a representation learning process. The results show that VQ-SM has better performance with high-precise and good robustness, trained on the small dataset. Finally, the impact damage field of composite laminates is analyzed based on the surrogate model. The proposed surrogate modelling method provides not only the full-field damage forecast model for composite structures, but also an efficient method of improving the performance of the “generative” surrogate model.

本文通过所提出的代用模型(VQ-SM),实现了不同低速冲击(LVI)条件下层状复合材料结构的全场损伤预测。首先,基于 DeepMind 提出的先进矢量量化变异自动编码器(VQ-VAE),提出了一种高效的代用建模方法。其次,基于复合材料层压板的渐进损伤模型进行数值模拟,获得训练数据集。训练完成后,将 VQ-SM 的性能与没有表征学习过程的代用模型进行比较评估。结果表明,在小数据集上训练的 VQ-SM 性能更好,具有高精度和良好的鲁棒性。最后,基于代用模型分析了复合材料层压板的冲击损伤场。所提出的代用建模方法不仅提供了复合材料结构的全场损伤预测模型,还提供了提高 "生成式 "代用模型性能的有效方法。


Finite element analysis of the influence of dowel angle on CFRP anchors

José Luis Jiménez, Hernán Santa María

doi:10.1016/j.compstruct.2023.117866

锚栓角度对 CFRP 锚固件影响的有限元分析

In current retrofitting design guidelines, carbon fiber reinforced polymer (CFRP) anchors are recognized as an efficient and minimally invasive approach to delaying delamination. Recent research has demonstrated the capability of Finite Element Method (FEM) models to accurately reproduce the behavior of experimentally tested CFRP anchors. Among the various design parameters of CFRP anchors, the dowel angle is one of the least studied, yet it is a crucial factor. There is limited experimental data available for this parameter and there are no numerical models focused on its influence on anchor behavior. This article reports the results of a comprehensive three-dimensional FEM model for CFRP anchors, with a particular emphasis on varying dowel angles. The model accuracy is verified against direct shear joint tests drawn from the literature, including aspects such as the maximum load, load-slip curves, and the distribution of strains along the CFRP. Subsequently, the model is used to conduct a sensitivity analysis of the dowel angle in conjunction with other important parameters for the design of CFRP anchors. These parameters are the length of the CFRP ply behind the anchor, the number of anchors within the joint, the fiber content, and the depth of the dowel. The results obtained from the modeling show an important influence of the dowel angle on the effective use of carbon fibers and the enhancement of joint strength. By offering insights into the interactions between the dowel angle and other design parameters, this research contributes information that can guide the development of design guidelines for the optimization of CFRP anchor systems.

在目前的改造设计指南中,碳纤维增强聚合物(CFRP)锚固件被认为是一种高效、微创的延迟分层方法。最近的研究表明,有限元法(FEM)模型能够准确再现经实验测试的 CFRP 锚固件的行为。在 CFRP 锚固件的各种设计参数中,榫头角度是研究最少的参数之一,但它却是一个关键因素。有关该参数的实验数据非常有限,也没有数值模型重点研究其对锚固行为的影响。本文报告了 CFRP 锚栓综合三维有限元模型的结果,特别强调了不同的榫头角度。根据文献中的直接剪切连接试验验证了模型的准确性,包括最大载荷、载荷-滑移曲线以及沿 CFRP 的应变分布等方面。随后,利用该模型结合 CFRP 锚固件设计中的其他重要参数,对镙栓角度进行了敏感性分析。这些参数包括锚固件后面 CFRP 层的长度、连接处的锚固件数量、纤维含量和榫头深度。建模结果表明,镙栓角度对有效使用碳纤维和提高连接强度有重要影响。通过深入了解榫销角度和其他设计参数之间的相互作用,这项研究提供的信息可以指导 CFRP 锚固系统优化设计指南的制定。


Mould Free Laminated Composites Using Eccentric Fibre Prestressing

Christopher Jenkins, Matthew J. Donough, B. Gangadhara Prusty

doi:10.1016/j.compstruct.2023.117867

使用偏心纤维预应力的无模层压复合材料

Mould free fibre reinforced composites are an emerging manufacturing process that allows for complex shapes to be produced, independently from complex moulding. Previous examples demonstrated reconfiguration through thermal stresses induced by an asymmetrical stacking sequence within a laminate. However, asymmetry within the laminate can adversely influence the stiffness and geometric coupling which results in heavier structures. This paper presents eccentric prestressing as a novel method to produce more structurally efficient mould free laminated composites. Euler-Bernoulli beam theory and finite element methods were employed to predict the strain and deformation of laminated composites with selective fibre prestress. The internal and external strains were measured with chirped fibre bragg grating sensors, and surface mounted strain gauges respectively to validate the numerical and analytical predictions where a difference of 3.13% was reported. Finally, a comparative study was conducted to show the benefits of eccentric prestress over asymmetric 4D printed laminates.

无模纤维增强复合材料是一种新兴的制造工艺,它可以生产出复杂的形状,而不需要复杂的模具。以往的实例表明,层压板内不对称的堆叠顺序会产生热应力,从而导致重新配置。然而,层压板内的不对称会对刚度和几何耦合产生不利影响,从而导致结构更重。本文将偏心预应力作为一种新方法,用于生产结构效率更高的无模层压复合材料。采用欧拉-伯努利梁理论和有限元方法来预测带有选择性纤维预应力的层状复合材料的应变和变形。分别使用啁啾纤维布拉格光栅传感器和表面安装应变仪测量内部和外部应变,以验证数值预测和分析预测,结果显示两者相差 3.13%。最后,还进行了一项比较研究,以显示偏心预应力对不对称 4D 印刷层压板的益处。


Composites Part A: Applied Science and Manufacturing

Recent advances in thermal-conductive insulating polymer composites with various fillers

Qingguo Chen, Kailun Yang, Yu Feng, Liang Liang, Minghe Chi, Zhonghua Zhang, Xuesong Chen

doi:10.1016/j.compositesa.2023.107998

含各种填料的导热绝缘聚合物复合材料的最新进展

Development of polymer-based composites with excellent thermal conductivity and electrical insulation properties is a hot research topic, because more and more electrical devices with high energy/power density need thermal conductive electrical insulation systems. Polymers generally own lower thermal conductivity, and the composites filled with thermally conductive fillers is a common method for preparing high thermal conductivity composites. However, large amounts of fillers always result in decreasing of electrical insulation properties in the composites. Morphology control of the filler, complete core-shell structure, and core-shell-like structure fillers can achieve optimization of thermal conductivity and electrical insulation properties in filled composites. This work covers how to obtain a reasonable balance of thermal conductivity and electrical insulation properties in filled composites from the filler chosen of view. Recent advances in new thermally conductive fillers are summarized, to provide a reference for the application of high thermal conductivity composites in the electrical insulation field.

由于越来越多的高能量/功率密度电气设备需要导热电气绝缘系统,因此开发具有优异导热性能和电气绝缘性能的聚合物基复合材料是一个热门研究课题。聚合物的导热系数通常较低,而在复合材料中填充导热填料是制备高导热复合材料的常用方法。然而,大量填充物总是会导致复合材料的电气绝缘性能下降。填料的形态控制、完整的核壳结构和类核壳结构填料可以实现填充复合材料导热性能和电绝缘性能的优化。本研究从填料的角度探讨了如何在填充复合材料中获得导热性和电气绝缘性的合理平衡。总结了新型导热填料的最新进展,为高导热复合材料在电气绝缘领域的应用提供参考。


Efficient modelling of progressive damage due to quasi-static indentation on multidirectional laminates by a mesh orientation independent kinematically enriched continuum damage model

Manish Kumar, Supratik Mukhopadhyay

doi:10.1016/j.compositesa.2023.108002

通过与网格方向无关的运动学富集连续损伤模型,对多向层压板上的准静态压痕造成的渐进损伤进行高效建模

This work proposes a computationally efficient high-fidelity modelling framework for analysis of damage in composites subjected to quasi-static indentation. A ply-by-ply modelling approach is adopted, and a new semi-discrete continuum damage model is used for intra-ply cracking that allows for cracks to grow independent of the ply mesh pattern. This feature greatly simplifies the meshing effort since the requirement of a ply-oriented mesh and imposition of tie constraints at mesh-mismatched ply interfaces is eliminated. The model is further enhanced to realise kinematic interactions between the cracked and uncracked material domains at the constitutive level. Inter-ply delamination is simulated using cohesive elements. Through a challenging problem of static indentation on a quasi-isotropic laminate, it is shown that the model can capture solution-dependent multiple discrete ply cracks and detailed crack-delamination interaction, but with reduced computational time and complexity, compared to a reference model with ply-oriented mesh and pre-seeded cracks at known locations.

本研究提出了一种计算高效的高保真建模框架,用于分析复合材料在准静态压痕作用下的损伤。采用了逐层建模方法,并针对层内开裂采用了一种新的半离散连续损伤模型,该模型允许裂纹独立于层间网格模式生长。这一特点大大简化了网格划分工作,因为无需采用面向层的网格,也无需在网格不匹配的层界面上施加绑扎约束。该模型得到了进一步增强,在构成层面上实现了开裂材料域和未开裂材料域之间的运动相互作用。使用内聚元素模拟了层间分层。通过一个具有挑战性的准各向同性层压板静态压痕问题,表明该模型可以捕捉与求解相关的多离散层状裂纹和详细的裂纹-分层相互作用,但与采用面向层状网格并在已知位置预埋裂纹的参考模型相比,计算时间和复杂性都有所降低。


A comparative study of the cryogenic performance of CFRP composites with polyethersulfone/epoxy blends and electrospun polyethersulfone interleaves

Othman Laban, Garth Pearce, Jin Zhang, Mohammad S. Islam, Luke P. Djukic

doi:10.1016/j.compositesa.2023.108000

聚醚砜/环氧混合物和电纺聚醚砜交织物 CFRP 复合材料低温性能比较研究

Thermoslastic-modifers are used to enhance the fracture toughness of epoxy resins for cryogenic applications. This study presents a comparative analysis of the cryogenic performance of laminated fibre-reinforced composites, focusing on two different toughening approaches: interleaving electrospun polyethersulfone (PES) veils or epoxy/PES blends with varying PES loadings. In casted epoxy/PES blends, the particulate phase structure was formed with a PES content of 2.5-10 phr, transitioning to a co-continuous structure beyond 10 phr. Electrospun PES interleaves effectively enhanced interlaminar fracture toughness at both 293 and 77 K by 76% and 48%, respectively. These improvement levels achieved were comparable to those of laminates toughened with 7.5 phr PES/epoxy blend. The results presented suggest that interleaving composite laminates offers great potential in enhancing the durability of cryogenic tanks while being seamlessly integrated into manufacturing processes.

热塑性改性剂可用于增强环氧树脂在低温应用中的断裂韧性。本研究对层状纤维增强复合材料的低温性能进行了比较分析,重点关注两种不同的增韧方法:交错电纺聚醚砜(PES)纱或不同 PES 负载的环氧树脂/PES 混合物。在浇注环氧树脂/聚醚砜混合物中,聚醚砜含量为 2.5-10 phr 时会形成颗粒相结构,超过 10 phr 时会过渡到共连续结构。电纺聚醚砜交织层在 293 K 和 77 K 条件下分别有效提高了 76% 和 48% 的层间断裂韧性。这些改善水平与使用 7.5 phr PES/epoxy 混合材料增韧的层压板相当。研究结果表明,交错复合材料层压板在提高低温罐耐久性方面具有巨大潜力,同时可无缝集成到制造工艺中。


Composites Science and Technology

Self-constructed strategy-based reinforcement LSTM approach for fiber-reinforced polymer non-linear degradation performance analysis

Zhicen Song, Yunwen Feng, Cheng Lu, Jiaqi Liu, Weihuang Pan

doi:10.1016/j.compscitech.2023.110414

 

基于自构建策略的增强 LSTM 方法,用于纤维增强聚合物非线性降解性能分析

The performance degradation of fiber-reinforced polymer (FRP) is a typical sequential data with a highly non-linear evolution pattern. In this study, a Self-constructed strategy-based reinforcement LSTM approach (short for SCRLA) is proposed to self-accommodate the non-linear sequential data, reduce modeling burden, and improve generalization ability. SCRLA incorporates Bayesian algorithms introducing the uncertainty of hyperparameter optimization by a probabilistic distribution of implicit objectives and self-constructed a high-dimensional, reinforced machine model that can learn and predict non-linear representations. In the case study, the datasets with different properties (one consisting of finite element analysis (FEA) results and one of real experimental (EXP) data) are selected to verify the validity of the degradation performance predictions. It is shown that the reinforced LSTM based on SCRLA is more suitable for the non-linear degradation performance analysis of FRP, especially with higher prediction accuracy for EXP data. The establishment of the approach and model provides a feasible idea and framework for the prediction of composites' sequential performance.

纤维增强聚合物(FRP)的性能退化是一种典型的序列数据,具有高度非线性的演化模式。本研究提出了一种基于自构造策略的强化 LSTM 方法(简称 SCRLA),以自适应非线性序列数据,减轻建模负担,提高泛化能力。SCRLA 采用贝叶斯算法,通过隐含目标的概率分布引入超参数优化的不确定性,自建了一个高维强化机器模型,可以学习和预测非线性表征。在案例研究中,选择了不同性质的数据集(一个是有限元分析(FEA)结果,一个是实际实验(EXP)数据)来验证退化性能预测的有效性。结果表明,基于 SCRLA 的增强型 LSTM 更适合玻璃钢的非线性降解性能分析,尤其是 EXP 数据的预测精度更高。该方法和模型的建立为复合材料的连续性能预测提供了可行的思路和框架。



来源:复合材料力学仿真Composites FEM
MeshingACTMechanicalSystemMarc振动断裂复合材料非线性航空航天汽车电力裂纹参数优化理论化机材料控制试验
著作权归作者所有,欢迎分享,未经许可,不得转载
首次发布时间:2024-11-05
最近编辑:16天前
Tansu
签名征集中
获赞 3粉丝 0文章 690课程 0
点赞
收藏
作者推荐

【新文速递】2023年12月24日固体力学SCI期刊最新文章

今日更新:Mechanics of Materials 1 篇,International Journal of Plasticity 1 篇,Thin-Walled Structures 4 篇Mechanics of MaterialsTopological boundary states in micropolar gyroelastic continuaMohamed Shaat, Xin-Lin Gaodoi:10.1016/j.mechmat.2023.104902微波陀螺弹性连续体中的拓扑边界态The study of topology in elastic media has been primarily focused on achieving non-trivial topological states in discrete elastic lattices through active or chiral microscopic interactions. Realization of such topological states in continuous elastic media remains largely unexplored. In this study, a new continuum theory of micropolar gyroelasticity is developed and applied to attain non-trivial topological boundary states in elastic continua. According to the new theory, an elastic continuum is composed of elastically interacting micro-volume elements that can translate and rotate and are connected at their mass centers to gyroscopes, which contribute to the linear and orbital angular momenta but not to the spin angular momentum of the continuum. By applying this micropolar gyroelasticity theory to elastic media with both periodic and finite domains, the emergence of topological boundary states in 2D micropolar gyroelastic continua is demonstrated. Through using the Floquet–Bloch method for periodic domains, the bulk-boundary correspondence is analytically established, and the emergence of non-trivial topological bulk states characterized by Mexican-hat band structures is observed. In addition, by employing an asymptotic analytical model based on the extended Bloch theorem and performing numerical analyses of micropolar gyroelastic continua with finite domains of different geometries, it is shown that the non-trivial Mexican-hat band structure is associated with and provides protection for topological boundary states confined at the boundaries. Finally, the application of the newly developed micropolar gyroelasticity theory to Zinc-blende structured materials (including ZnTe, GaP, InP and ZnS) reveals that the emergence of the topological boundary states in an elastic continuum is not triggered solely by the gyroscopic effect but also depends on the material properties of the micropolar continuum. This study provides new insights into extending notions and methods of topology to analyze elastic continua, paving the way for the practical implementation of topological mechanical systems in various engineering applications.弹性介质拓扑学的研究主要集中在通过主动或手性微观相互作用在离散弹性晶格中实现非三维拓扑状态。在连续弹性介质中实现这种拓扑状态在很大程度上仍未得到探索。在本研究中,我们提出了一种新的微极性陀螺弹性连续理论,并将其应用于在弹性连续体中实现非三维拓扑边界态。根据新理论,弹性连续体由弹性相互作用的微体积元素组成,这些元素可以平移和旋转,并在其质心处与陀螺仪相连,陀螺仪对连续体的线性角动量和轨道角动量有贡献,但对自旋角动量没有贡献。通过将这种微陀螺弹性理论应用于具有周期性和有限域的弹性介质,证明了二维微陀螺弹性连续体中拓扑边界态的出现。通过对周期性域使用 Floquet-Bloch 方法,分析建立了体-界对应关系,并观察到以墨西哥帽带结构为特征的非三维拓扑体态的出现。此外,通过采用基于扩展布洛赫定理的渐近分析模型,并对具有不同几何形状的有限畴的微极陀螺弹性连续体进行数值分析,证明了非微观墨西哥帽带结构与限制在边界的拓扑边界态相关,并为其提供保护。最后,将新开发的微波陀螺弹性理论应用于锌蓝晶结构材料(包括 ZnTe、GaP、InP 和 ZnS),发现在弹性连续体中拓扑边界态的出现并非仅由陀螺效应引发,还取决于微波连续体的材料特性。这项研究为扩展拓扑学的概念和方法以分析弹性连续体提供了新的见解,为拓扑机械系统在各种工程应用中的实际实现铺平了道路。International Journal of PlasticityA dislocation-density-based crystal plasticity model for FCC nanocrystalline metals incorporating thermally-activated depinning from grain boundariesJonathan Cappola, Jian Wang, Lin Lidoi:10.1016/j.ijplas.2023.103863基于位错密度的面心立方纳米晶金属晶体塑性模型,其中包含晶界热激活去氧化作用A novel dislocation-density-based crystal plasticity model for nanocrystalline face-centered cubic metals is developed based on the thermally-activated mechanism of dislocations depinning from grain boundaries. Dislocations nucleated from grain boundary dislocation sources are assumed to be the primary carriers of plasticity in the nanocrystals. The evolution of the dislocation density thereby involves a competition between the nucleation of dislocations from grain boundary defect structures, such as ledges, and the absorption of dislocations into the grain boundary via diffusion processes. This model facilitates the simulation of plastic deformation in nanocrystalline metals, with consideration of the initial microstructure resulting from a particular processing method, to be computed as a direct result of dislocation-mediated plasticity only. The exclusion of grain boundary-mediated plasticity mechanisms in the formulation of the crystal plasticity model allows for the exploration of the fundamental role dislocations play in nanocrystalline plasticity. The combined effect of average grain size, grain size distribution shape, and initial dislocation density on the mechanical performance and strain-rate sensitivity are explored with the model. Further, the influence of the grain boundary diffusivity on post-yielding strain-hardening behavior is investigated to discern the impact that the choice of processing route has on the resulting deformation response of the material.基于晶界位错降解的热激活机制,为纳米晶面心立方金属建立了一种基于位错密度的新型晶体塑性模型。假定从晶界位错源成核的位错是纳米晶体塑性的主要载体。因此,位错密度的演化涉及晶界缺陷结构(如台阶)中的位错成核与通过扩散过程吸收到晶界中的位错之间的竞争。该模型有助于模拟纳米晶金属的塑性变形,考虑到特定加工方法产生的初始微观结构,只计算位错介导塑性的直接结果。在制定晶体塑性模型时排除晶界介导的塑性机制,可以探索位错在纳米晶塑性中的基本作用。该模型探讨了平均晶粒尺寸、晶粒尺寸分布形状和初始位错密度对机械性能和应变速率敏感性的综合影响。此外,还研究了晶界扩散性对屈服后应变硬化行为的影响,以了解加工路线的选择对材料变形响应的影响。Thin-Walled StructuresNonlinear Forced Vibrations of Functionally Graded Three-phase Composite Cylindrical Shell Subjected to Aerodynamic Forces, External Excitations and Hygrothermal EnvironmentT. Liu, H.Y. Zheng, W. Zhang, Y. Zheng, Y.J. Qiandoi:10.1016/j.tws.2023.111511受空气动力、外部激励和湿热环境影响的功能分级三相复合圆柱壳体的非线性受迫振动In this paper, the new functionally graded three-phase composite cylindrical shell is assumed as a common structure in the carrier rocket in the future, and we creatively study the nonlinear forced vibration of this cylindrical shell considering the interaction of different factors in the complex operating environment, including the aerodynamic forces, external excitations, and hygrothermal environment. Based on the first-order shear deformation theory, Von-Karman geometric nonlinear theory, and Hamilton's principle, we derive the nonlinear partial differential equations of motion of the functionally graded three-phase composite cylindrical shell. Considering the axisymmetry of the perfect circular shell, there is a 1:1 internal resonance between the conjugate modes of this cylindrical shell. On this basis, the nonlinear forced vibration of the cylindrical shell is investigated by a combination of Galerkin's method and the pseudo-arc length continuation method. Matcont toolbox can directly solve the ordinary differential equations to obtain the nonlinear frequency response curves. The method can effectively obtain both stable and unstable solutions, avoiding the mathematical difficulties encountered in the formulation process, and facilitating the study of the effects of parametric variables on the resonance response in complex environments. The results show that the variation of material parameters and the complex environment have important effects on the nonlinear resonance response of functionally graded three-phase composite cylindrical shell.本文将新型功能分级三相复合材料圆柱壳体假定为未来运载火箭的常用结构,考虑到复杂工作环境中不同因素的相互作用,包括空气动力、外部激励和湿热环境,创造性地研究了该圆柱壳体的非线性受迫振动。基于一阶剪切变形理论、冯-卡曼几何非线性理论和汉密尔顿原理,我们推导出了功能分级三相复合圆柱壳的非线性偏微分运动方程。考虑到完美圆壳的轴对称性,该圆柱壳的共轭模之间存在 1:1 的内部共振。在此基础上,结合 Galerkin 方法和伪弧长延续方法研究了圆柱壳的非线性受迫振动。Matcont 工具箱可以直接求解常微分方程,从而得到非线性频率响应曲线。该方法能有效地得到稳定解和不稳定解,避免了公式化过程中遇到的数学困难,便于研究参数变量对复杂环境下共振响应的影响。结果表明,材料参数的变化和复杂环境对功能分级三相复合材料圆柱壳的非线性共振响应有重要影响。The added mass of a biaxial tensioned membrane in still airShaochen Yang, Bing Zhao, Wujun Chendoi:10.1016/j.tws.2023.111531静止空气中双轴拉伸薄膜的附加质量It is well known that added mass significantly impacts the vibration of membrane structures in still air. Numerous theoretical, numerical, and experimental studies have been conducted on the added mass of axial tensioned membranes. However, the added mass of biaxial tensioned membranes subjected to different tensile forces in two directions in still air remains unclear. Therefore, this study focuses on investigating the added mass of biaxial tensioned membranes in still air. Firstly, this paper proposes a simplified theoretical model for the added mass of biaxial tensioned membranes in still air based on the energy conservation law. To validate the accuracy of the proposed model, a modal testing system for a rectangular membrane is designed to identify the frequencies of biaxial tensioned membranes in still air. In the experimental system, the utilization of a laser displacement sensor array is to obtain the time-displacement information of observation points. Then, a combination of Fast Fourier Transform (FFT) and Stochastic Subspace Identification (SSI) methods is employed for modal identification. Comparative analysis between the experimental and theoretical model results demonstrates an excellent agreement in frequencies. Additionally, the proposed added mass model is closer to the experimental added mass than other models, with a maximum deviation of only 4.77%. This research provides a reference for the study of the impact of air on the ground vibration of membranes.众所周知,附加质量对静止空气中膜结构的振动有很大影响。关于轴向拉伸膜的附加质量,已经进行了大量的理论、数值和实验研究。然而,在静止空气中受到两个方向不同拉伸力的双轴拉伸膜的附加质量仍不清楚。因此,本研究将重点放在研究静止空气中双轴拉伸膜的附加质量上。首先,本文基于能量守恒定律,提出了静止空气中双轴拉伸膜附加质量的简化理论模型。为了验证所提模型的准确性,本文设计了一个矩形膜的模态测试系统,以确定静止空气中双轴张拉膜的频率。在实验系统中,利用激光位移传感器阵列获取观测点的时间位移信息。然后,结合快速傅立叶变换(FFT)和随机子空间识别(SSI)方法进行模态识别。实验结果与理论模型结果的对比分析表明,两者在频率上非常一致。此外,与其他模型相比,所提出的附加质量模型更接近于实验附加质量,最大偏差仅为 4.77%。这项研究为研究空气对膜材地面振动的影响提供了参考。A simple SIF determination method for cracked orthotropic cylindrical shell by means of stress ratioRong Li, Shuai Bai, Meng Yang, Bin Liang, Ke-jun Hudoi:10.1016/j.tws.2023.111532利用应力比确定开裂正交圆柱壳 SIF 的简单方法A convenient and universal calculation method for stress intensity factor (SIF) in cracked orthotropic cylindrical shell under diverse loadings is described. The present expressions are derived from traditional classical numerical method and simplified by extracting and eliminating the complex but regular parameters. A simple relation between SIF and crack tip stress from finite element method (FEM) is constructed by means of reference problem and unknown problem, then a simple SIF formulation can be realized and the impact of material orthotropy is considered. The feasibility and advantages of present study are proved to be analyzed by comparing against published results.本文介绍了在不同载荷作用下,开裂的正交圆柱壳体应力强度因子(SIF)的一种方便通用的计算方法。本表达式源自传统的经典数值方法,并通过提取和消除复杂但规则的参数进行了简化。通过参考问题和未知问题,构建了有限元法(FEM)中 SIF 与裂纹尖端应力之间的简单关系,从而实现了简单的 SIF 公式,并考虑了材料正交性的影响。通过与已发表的结果进行对比分析,证明了本研究的可行性和优势。Study on stability of H-type section aluminum alloy perforated members under axial compression and eccentric compression around weak axisWenyuan Kong, Hang Yang, Liang Zhou, Zhiquan Xing, Yu Chen, Wei Chen, En Lindoi:10.1016/j.tws.2023.111533H 型截面铝合金穿孔构件在轴向压缩和围绕弱轴的偏心压缩条件下的稳定性研究Aluminum alloy components have the advantages of light weight, high strength, favorable machinability, and good acid corrosion resistance, which can greatly reduce maintenance costs and easy to make the structures with beautiful appearance. Based on the shortcomings of existing research fields, the stability of H-type section 6082-T6 aluminum alloy perforated members under axial compression and eccentric compression around weak axis is studied by combining experimental and numerical simulation methods in this paper. The test results of aluminum alloy members under axial compression and aluminum alloy members under eccentric compression around weak axis with different web opening numbers, opening diameters, slenderness ratios and eccentric distances are analyzed. The verified finite element model is used to carry out the extensive parameter analysis focusing on the key variables. Based on the test and numerical simulation results of the stability bearing capacity of 134 members, the design methods for H-type section aluminum alloy perforated members under axial compression and eccentric compression are proposed and evaluated by reference to the existing specification.铝合金构件具有重量轻、强度高、可加工性好、耐酸腐蚀性好等优点,可大大降低维护成本,且易于制作成外形美观的结构。基于现有研究领域的不足,本文采用实验和数值模拟相结合的方法,研究了 H 型截面 6082-T6 铝合金穿孔构件在轴向压缩和绕弱轴偏心压缩下的稳定性。分析了不同腹板开孔数、开孔直径、细长比和偏心距的铝合金构件在轴向压缩和绕弱轴偏心压缩下的试验结果。利用经过验证的有限元模型对关键变量进行了广泛的参数分析。根据 134 个构件的稳定承载力试验和数值模拟结果,提出了轴向压缩和偏心压缩条件下 H 型截面铝合金穿孔构件的设计方法,并参照现有规范进行了评估。来源:复合材料力学仿真Composites FEM

未登录
还没有评论
课程
培训
服务
行家
VIP会员 学习 福利任务 兑换礼品
下载APP
联系我们
帮助与反馈