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【新文速递】2024年1月1日固体力学SCI期刊最新文章

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今日更新:Mechanics of Materials 1 篇,International Journal of Plasticity 2 篇,Thin-Walled Structures 1 篇

Mechanics of Materials

Effect of the sonic shock wave on void evolution in materials under irradiation

Ning Zhou, YinBo Zhu, HengAn Wu

doi:10.1016/j.mechmat.2023.104907

声波冲击波对辐照下材料空隙演变的影响

Understanding the void-cascade interaction is of great importance for clarifying the irradiation damage as a major challenge in nuclear industry, since it typically causes void annihilation or shrinkage, which greatly affects the swelling of irradiated materials. But the current understanding of it is extremely limited due to the neglect of the sonic shock wave. Herein, we take γ-U as the representative model due to the emergence of a violent sonic shock wave there. Molecular dynamics simulations are performed to explore the underlying mechanism of the sonic shock wave interacting with voids. It is firstly revealed that the sonic shock wave is essentially focusons along <111> crystal orientation family, attributed to the highest energy transfer efficiency along <111> in γ-U. These focusons can cause void annihilation or shrinkage via sliding, while thermal spikes only cause annihilation by covering voids. Combining these two factors, we propose a model to qualitatively epitomize the void-cascade interaction, in which the influence scope exhibits an intriguing anisotropic feature, overturning a long-accepted view that the void-cascade interaction is isotropic. This model is further generalized to other nuclear materials owing to the similar mechanism of the sonic shock wave. Moreover, we find distinct size effect of voids on void-cascade interaction. Thermal spikes hardly affect voids that are too large to be covered, while the sonic shock wave also causes visible shrinkage in large voids. The present work proves that the sonic shock wave has a non-negligible effect on void evolution, improving the fundamental understanding of void-cascade interaction in irradiated materials.

空隙-级联相互作用通常会导致空隙湮灭或收缩,从而极大地影响辐照材料的膨胀,因此了解空隙-级联相互作用对于澄清辐照损伤这一核工业领域的重大挑战具有重要意义。但由于忽视了声波冲击波,目前对它的认识极为有限。在此,我们以γ-U 为代表模型,因为那里出现了剧烈的声波冲击波。通过分子动力学模拟来探索声波冲击波与空隙相互作用的内在机理。研究首先揭示了声波冲击波本质上是沿 <111> 晶向系列的焦子,这归因于在 γ-U 中沿 <111> 晶向的能量传递效率最高。这些聚焦子可以通过滑动造成空隙湮灭或收缩,而热尖峰只能通过覆盖空隙造成湮灭。结合这两个因素,我们提出了一个模型来定性地表征空隙-级联相互作用,其中的影响范围呈现出令人感兴趣的各向异性特征,推翻了长期以来公认的空隙-级联相互作用各向同性的观点。由于音速冲击波的机制类似,这一模型还可进一步推广到其他核材料。此外,我们还发现空隙的大小对空隙-级联相互作用有明显的影响。热尖峰几乎不会影响大到无法覆盖的空隙,而声波冲击波也会导致大空隙的明显收缩。本研究证明了声波冲击波对空隙演变具有不可忽视的影响,从而提高了对辐照材料中空隙-级联相互作用的基本认识。


International Journal of Plasticity

Achieving exceptional work-hardening capability of additively-manufactured multiphase Fe-Mn alloys via multiple deformation mechanisms

Peifeng Liu, Qinyuan Huang, Quan Shan, Zengbao Jiao, Qingge Wang, Yang Ma, Runhua Zhou, Ian Baker, Hong Wu

doi:10.1016/j.ijplas.2023.103871

通过多种变形机制实现快速成型多相铁-锰合金的超强加工硬化能力

Laser-powder-bed-fusion (LPBF) fabricated Fe-Mn biodegradable alloys provide an attractive prospect for orthopedic applications due to their good tensile strength and high degradation rate. Nevertheless, the ε-martensite and heterogeneous microstructures produced by the LPBF processing often lead to premature failure of alloys. Herein, we report a LPBFed multiphase Fe-18Mn alloy (γ-austenite, ε-martensite, and α-ferrite) fabricated from pre-alloyed powders. After annealing at 650 °C, the alloy with a uniform microstructure displays a high 1 GPa tensile strength, a good fracture elongation of 16 %, and an extremely high work-hardening rate of 8500 MPa. The work-hardening rate is higher than that reported in most Fe-Mn steels and Fe-based high entropy alloys. The grain size of a few hundred nanometers provided the excess Gibbs free energy, resulting in an increase in the stacking fault energy (SFE) to 23.9 mJ/m2. The multiple deformation mechanisms, i.e., SFs, the martensitic transformation (γ → ε → α') and nano-deformation twins (DTs), were sequentially activated. We elucidate such unique work-hardening capability, originating from the interaction between the DTs, SFs and transformed martensite. Besides a high-density of dislocations were accumulated between parallel planar defects, the cooperative deformation of the soft and hard phases provided continuous hardening. Our findings highlight the exceptional work-hardening capability of additively-manufactured Fe-Mn alloys achieved by a multiphase material exhibiting multiple deformation mechanisms. The work also provides a straightforward approach for the development of stable-implanted Fe-based bone substitutes.

激光粉末床熔融(LPBF)制造的铁锰生物可降解合金具有良好的抗拉强度和较高的降解率,为矫形外科应用提供了诱人的前景。然而,LPBF加工过程中产生的ε-马氏体和异质微结构往往会导致合金过早失效。在此,我们报告了一种由预合金化粉末制成的 LPBFed 多相铁-18Mn 合金(γ-奥氏体、ε-马氏体和 α-铁素体)。在 650 °C 退火后,具有均匀微观结构的合金显示出较高的 1 GPa 抗拉强度、16 % 的良好断裂伸长率和 8500 MPa 的极高加工硬化率。该加工硬化率高于大多数铁锰钢和铁基高熵合金的加工硬化率。几百纳米的晶粒尺寸提供了过剩的吉布斯自由能,导致堆叠断层能(SFE)增加到 23.9 mJ/m2。多种变形机制,即 SFs、马氏体转变(γ → ε → α')和纳米变形孪晶(DTs)依次被激活。我们阐明了这种独特的加工硬化能力,它源于 DTs、SFs 和转化马氏体之间的相互作用。除了在平行平面缺陷之间积累了高密度位错之外,软硬相的协同变形还提供了持续硬化。我们的研究结果凸显了加成法制造的铁锰合金通过表现出多种变形机制的多相材料实现的卓越加工硬化能力。这项研究还为开发稳定的植入式铁基骨替代物提供了一种直接的方法。


Distinct avalanche dynamics detected in metallic glasses with high energy state revealing the crack-like shear banding mechanism

Kai Tao, Fucheng Li, Yanhui Liu, Eloi Pineda, Kaikai Song, Jichao Qiao

doi:10.1016/j.ijplas.2023.103873

在金属玻璃中探测到的高能态雪崩动力学揭示了类似裂纹的剪切带机制

When a sufficiently high stress is applied to a metallic glass, causing plastic deformation, the material undergoes structural reconfiguration through dissipative slip avalanche events that release local stresses. By utilizing isothermal annealing and cold rolling techniques to tune the energy levels of metallic glasses, it has been observed that structural rejuvenation is accompanied by structural relaxation, as evidenced by distinct changes in avalanche dynamics. We present detailed statistics of the avalanche dynamics during shear band formation in energy-tuned metallic glasses, ranging from structurally relaxed to rejuvenated states. By analyzing shear band characteristics and examining scaling exponents, avalanche durations, and stress relaxation rates, we can establish a connection between the local activation of shear transformation zones and the formation of macroscopic shear bands. The statistics of avalanche duration indicate that an increase in soft zones within metallic glasses can alleviate stress release and stabilize plastic flow, as evidenced by the characteristics of shear bands. We attribute the significant transition of serrated flow, observed at different energy levels (i.e., as-cast, relaxed, and rejuvenated states) to the variations in nucleation and multiplication of shear bands that originate from local weak spots. Analysis of the distinct avalanche dynamics suggests that in lower energy level metallic glasses, the nucleation and propagation of shear bands exhibit localized crack-like behavior, while in higher energy level metallic glasses, they display diffused crack-like characteristics. Indeed, our results strongly support that the decreased avalanches observed in the high energy level metallic glasses originate from the nucleation of numerous small shear bands, which directly compete with the propagation of the main local shear band. These findings deepen our fundamental understanding of the relationship between the microscopic mechanism of slip avalanche dynamics and shear banding, providing a pathway to control the plasticity of metallic glasses.

当对金属玻璃施加足够大的应力导致塑性变形时,材料会通过释放局部应力的耗散滑移雪崩事件进行结构重构。通过利用等温退火和冷轧技术调节金属玻璃的能级,我们观察到结构年轻化伴随着结构松弛,雪崩动力学的明显变化就是证明。我们介绍了能量调谐金属玻璃剪切带形成过程中雪崩动力学的详细统计数据,包括从结构松弛状态到年轻化状态。通过分析剪切带特征并研究缩放指数、雪崩持续时间和应力松弛率,我们可以建立剪切转换区局部激活与宏观剪切带形成之间的联系。雪崩持续时间的统计结果表明,金属玻璃内部软区的增加可以缓解应力释放并稳定塑性流动,剪切带的特征也证明了这一点。我们认为,在不同能级(即铸造态、松弛态和恢复态)下观察到的锯齿流的显著转变是由于局部薄弱点产生的剪切带的成核和增殖变化造成的。对不同雪崩动力学的分析表明,在低能级金属玻璃中,剪切带的成核和传播表现出局部裂纹状行为,而在高能级金属玻璃中,则表现出扩散裂纹状特征。事实上,我们的研究结果有力地证明,在高能级金属玻璃中观察到的雪崩现象的减少源于无数小剪切带的成核,这些剪切带与主要局部剪切带的传播直接竞争。这些发现加深了我们对滑动雪崩动力学微观机制与剪切带之间关系的基本理解,为控制金属玻璃的塑性提供了一条途径。


Thin-Walled Structures

Wave propagation in beams with functionally graded porosity distribution under highly transient axial and transverse impacts

M. Heshmati, S.K. Jalali, N.M. Pugno

doi:10.1016/j.tws.2023.111548

在高瞬态轴向和横向冲击下,具有功能分级孔隙分布的梁中的波传播

Recent advances in the manufacturing process provide a possibility of fabricating a new generation of porous materials denoted by functionally graded porous materials (FGPM). This paper aims to present a time domain analysis of wave propagation through the porous structures with functionally graded porosity distribution, which has not been completely studied before. For this purpose, the beams with different functionally graded porosity distributions subjected to both axial and transverse tip impact loads with a high-frequency content are investigated. The shear deformable cantilevered functionally graded porous beams with various porosity distributions through the beam thickness are studied. The governing differential equations are derived using the Hamiltonian principle based on the Timoshenko beam theory. A locking-free first-order shear deformable beam element is used to derive the finite element formulation of the equations. The Newmark time integration method is used to perform a time domain analysis of the equations of motion and to investigate the transient response of the beams. The axial and transverse wave propagation characteristics through functionally graded (FG) porous beams are found using time domain analysis of the results. Deflection and velocity time histories of the tip and each point of the beam, reflection time, and variation of support reactions are obtained. The influences of the porosity magnitude and porosity distribution on the wave propagation characteristics and overall time responses are investigated. The results reveal that porosity distribution has a significant effect on the wave amplitude, wave speed, and reflection from the boundary. Also, this study can help in a better understanding of porous structures' behavior subjected to high-transient impact loads in different engineering applications.

制造工艺的最新进展为制造新一代多孔材料提供了可能,这种材料被称为功能分级多孔材料(FGPM)。本文旨在对波在具有功能分级孔隙率分布的多孔结构中的传播进行时域分析,而这在以前还没有过完整的研究。为此,本文研究了具有不同功能分级孔隙率分布的横梁,这些横梁同时承受轴向和横向尖端高频冲击载荷。研究了在梁厚度上具有不同孔隙率分布的可剪切变形悬臂功能分级多孔梁。基于季莫申科梁理论,利用哈密顿原理推导出了控制微分方程。无锁定一阶剪切变形梁元素用于推导方程的有限元公式。采用纽马克时间积分法对运动方程进行时域分析,并研究梁的瞬态响应。通过对结果进行时域分析,发现了穿过功能分级(FG)多孔梁的轴向和横向波传播特性。得出了梁顶端和各点的挠度和速度时间历程、反射时间以及支撑反作用力的变化。研究了孔隙率大小和孔隙率分布对波传播特性和整体时间响应的影响。结果表明,孔隙率分布对波幅、波速和边界反射有显著影响。此外,这项研究还有助于更好地理解多孔结构在不同工程应用中承受高瞬态冲击载荷时的行为。



来源:复合材料力学仿真Composites FEM
ACTAdditiveDeform断裂ADSUG铸造裂纹理论材料分子动力学控制
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首次发布时间:2024-11-05
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【新文速递】2024年1月2日复合材料SCI期刊最新文章

今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Science and Technology 1 篇Composite StructuresA bistable impact resistant sandwich carbon-fibre reinforced coreFrancesco Flora, Marco Boccaccio, Fulvio Pinto, Michele Meodoi: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 analysisLizhi Li, Lu Nie, Yiru Rendoi: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 beamsYanan Liang, Shijie Zheng, Hongtao Wang, Dejin Chendoi: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&#39;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 learningGuowen Wang, Laibin Zhang, Shanyong Xuan, Xin Fan, Bin Fu, Xiao Xue, Xuefeng Yaodoi: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 &quot;生成式 &quot;代用模型性能的有效方法。Finite element analysis of the influence of dowel angle on CFRP anchorsJosé Luis Jiménez, Hernán Santa Maríadoi: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 PrestressingChristopher Jenkins, Matthew J. Donough, B. Gangadhara Prustydoi: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 ManufacturingRecent advances in thermal-conductive insulating polymer composites with various fillersQingguo Chen, Kailun Yang, Yu Feng, Liang Liang, Minghe Chi, Zhonghua Zhang, Xuesong Chendoi: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 modelManish Kumar, Supratik Mukhopadhyaydoi: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 interleavesOthman Laban, Garth Pearce, Jin Zhang, Mohammad S. Islam, Luke P. Djukicdoi: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 TechnologySelf-constructed strategy-based reinforcement LSTM approach for fiber-reinforced polymer non-linear degradation performance analysisZhicen Song, Yunwen Feng, Cheng Lu, Jiaqi Liu, Weihuang Pandoi: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&#39; 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

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