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【新文速递】2023年11月12日复合材料SCI期刊最新文章

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今日更新:Composite Structures 4 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇

Composite Structures

Structural topology optimization of three-dimensional multi-material composite structures with finite deformation

Du Zongliang, Guo Yunhang, Liu Chang, Zhang Weisheng, Xue Riye, Guo Yilin, Tang Shan, Guo Xu

doi:10.1016/j.compstruct.2023.117692

有限变形三维多材料复合结构拓扑优化

In this work, an explicit three-dimensional (3D) topology optimization approach is presented for multi-material composite structures accounting the finite deformation effect. The proposed method employs different sets of 3D Moving Morphable Voids (MMVs) to identify each phase material, resulting in explicit geometric descriptions of the optimized composite structures and a reduction in the number of design variables. The decoupling between the topology description and finite element analysis of composite structures enables the removal of redundant degrees of freedom, thereby mitigating the convergence issue of finite deformation analysis caused by low-density elements and leading to significant computational savings. Numerical experiments of composite structures with two- and three-phase materials are optimized to validate the accuracy and efficiency of the proposed method. The results demonstrate that, under finite deformation, the distribution of each phase material in optimized 3D composite structures is significantly affected by the amplitude of external loads, and the optimized layout could be quite different from its counterpart under small deformation assumption.

在这项工作中,提出了一种考虑有限变形效应的多材料复合材料结构显式三维(3D)拓扑优化方法。该方法采用不同的3D移动可变形空洞(mmv)集 合来识别每个相材料,从而对优化后的复合材料结构进行明确的几何描述,减少了设计变量的数量。复合材料结构的拓扑描述与有限元分析之间的解耦能够消除冗余自由度,从而减轻由低密度单元引起的有限变形分析的收敛问题,从而显著节省计算量。通过两相和三相材料复合结构的数值实验,验证了该方法的准确性和有效性。结果表明,在有限变形条件下,优化后的三维复合材料结构中各相材料的分布受外载荷幅值的影响较大,且优化后的布局与小变形条件下的布局存在较大差异。


Bandgap regulations of longitudinal wave for a nonlinear metastructure isolator with high-static-low-dynamic stiffness

Chen Ning, Yang Zhichun, Zuo Ang, Jiang Pengfei, Jin Shikai, Xu Yanlong

doi:10.1016/j.compstruct.2023.117706

高静低动刚度非线性元结构隔振器纵波带隙规律

Linear structures are inherently difficult to exhibit mechanical properties with high-static-low-dynamic stiffness (HSLDS), which means that linear isolators with these structures struggle to have both high-quality load-bearing capacity and low-frequency isolation ability at the same time. To address this issue, we have designed a high-load-capacity local resonance (LR) nonlinear metastructure isolator for low-frequency vibration isolation of target objects. We reveal the regulation mechanism of longitudinal wave attenuation in such metastructures and conduct comparative study by finite element method (FEM) and experiments for a 3D printed prototype metastructure. The results show that in specific excitation frequencies, the LR nonlinear metastructure with a cantilever beam oscillator having a natural frequency of 11.7 Hz triggers a LR mechanism. Under the action of the nonlinear isolator, the vibration transmissibility is as low as 10% at the center frequency of the bandgap under the base excitation. Furthermore, the dispersion equation of such nonlinear metastructures is derived, and through the analysis of the regulation of bandgaps, the variation trend of the transmissibility of nonlinear metastructure isolators is effectively predicted. The calculation method and design idea of this metastructure isolators provide a new approach for vibration isolation.

线性结构本身就很难表现出高静低动刚度(HSLDS)的力学性能,这意味着这些结构的线性隔振器很难同时具有高质量的承载能力和低频隔振能力。为了解决这一问题,我们设计了一种高负载能力局部共振(LR)非线性元结构隔振器,用于目标物体的低频隔振。我们揭示了这种元结构中纵波衰减的调节机制,并通过三维打印原型元结构的有限元方法(FEM)和实验进行了对比研究。结果表明,在特定的激励频率下,具有固有频率为11.7 Hz的悬臂梁振子的LR非线性元结构触发LR机制。在非线性隔振器的作用下,在基极激励下,在带隙中心频率处,振动透射率低至10%。进一步推导了非线性元结构的色散方程,通过分析带隙的变化规律,有效地预测了非线性元结构隔振子的透射率变化趋势。这种元结构隔振器的计算方法和设计思想为隔振提供了一种新的途径。


Simulation of failure behavior of 2.5D SiC/SiC variable thickness dovetail joint structures based on mesoscale model

Zhang Sheng, Liu Chenyang, Zhang Xu, Du Jinkang, Chen Qiang, Gao Xiguang, Song Yingdong

doi:10.1016/j.compstruct.2023.117716

基于中尺度模型的2.5D SiC/SiC变厚度燕尾接头破坏行为模拟

The application of ceramic matrix composites plays an important role in improving the performance of aero engines. However, mesoscopic aperiodicity causes excellent challenges for the performance analysis of ceramic matrix composite structures. It is no longer applicable to obtain the macroscopic properties of materials through experiments or RVE simulations for structural performance analysis. Here an attempt is made to develop a performance analysis method for mesoscopic aperiodic ceramic matrix composite structures based on mesoscale models and apply the method to the strength calculation of 2.5D SiC/SiC variable thickness dovetail joint structures. The established model reasonably approximates and accurately describes the structure’s real yarn geometries and orientations, reflecting the differences of yarn architectures in different regions. The yarn stress–strain curve is obtained through experiments, and the yarn constitutive model is established. The failure behavior of the 2.5D woven dovetail joint structure is simulated using the progressive damage analysis method and taking the yarn as the basic load-bearing unit. The simulated results are in good agreement with the experimental data in terms of failure load, load–displacement responses, macroscopic damage evolutions, and failure modes.

陶瓷基复合材料的应用对提高航空发动机的性能起着重要的作用。然而,介观非周期性给陶瓷基复合材料结构的性能分析带来了极大的挑战。通过实验或RVE模拟来获得材料的宏观性能已不再适用于结构性能分析。本文尝试建立一种基于细观尺度模型的介观非周期陶瓷基复合材料结构性能分析方法,并将该方法应用于2.5D SiC/SiC变厚度燕尾接头结构的强度计算。所建立的模型合理地逼近和准确地描述了结构的真实纱线几何形状和方向,反映了不同地区纱线结构的差异。通过实验得到了纱线的应力应变曲线,建立了纱线的本构模型。采用渐进式损伤分析方法,以纱线为基本承载单元,模拟了2.5维编织燕尾节点结构的破坏行为。在破坏荷载、荷载-位移响应、宏观损伤演化和破坏模式等方面,模拟结果与试验数据吻合较好。


A mechanical analysis of variable angle-tow composite plates through variable kinematics models based on Carrera’s unified formulation

Iannotta D.A., Giunta G., Montemurro M.

doi:10.1016/j.compstruct.2023.117717

基于Carrera统一公式的可变运动学模型对变角-拖曳复合材料板的力学分析

Variable Angle-Tow (VAT) laminates offer a promising alternative to straight fiber composites. By varying fibers orientation within the structure plane, ambitious design and performance goals can be achieved. However, the wider design space results in a more complex problem with more parameters to consider. Carrera’s Unified Formulation (CUF) has been used in previous works performing buckling, vibrational and stress analyses of VAT plates. Usually, one-dimensional (1D) CUF beam models are used, while two-dimensional (2D) plate models are obtained as a particular case of shells by considering a null curvature. In most cases, a linear law is considered to describe the variation of fibers orientation in the main plane of the structure. The purpose of this article is to extend the CUF 2D plate finite elements family to the mechanical analysis of composite laminated plate structures with curvilinear fibers. The main contribute consists in the development of a CUF FE model within the Reissner’s Mixed Variational Theorem (RMVT) context for an improved calculation of the out-of-plane stress components. Results show that RMVT can predict in-plane stresses and satisfy the though-the-thickness transverse stresses continuity due to inter-layer equilibrium. The accuracy of RMVT-based models is also investigated using two different approximation points distributions along the plates thickness.

可变角束(VAT)层压板提供了一种有前途的替代直纤维复合材料。通过改变纤维在结构平面内的取向,可以实现雄心勃勃的设计和性能目标。然而,更宽的设计空间导致了更复杂的问题,需要考虑更多的参数。Carrera的统一公式(CUF)已在以前的工作中用于VAT板的屈曲,振动和应力分析。通常使用一维(1D) CUF梁模型,而考虑零曲率的壳的特殊情况下,得到二维(2D)板模型。在大多数情况下,考虑线性定律来描述纤维取向在结构主平面上的变化。本文的目的是将CUF二维板有限元族扩展到曲线纤维复合材料层合板结构的受力分析。主要贡献在于在Reissner的混合变分定理(RMVT)背景下开发了CUF有限元模型,用于改进面外应力分量的计算。结果表明,由于层间平衡,RMVT可以预测面内应力,并满足横向应力的纵贯连续性。利用两种不同的近似点沿板厚分布,研究了基于rmvt的模型的精度。


Composites Part A: Applied Science and Manufacturing

Displacement-reconstruction-realized components by structure-sensing integration via a hybrid 3D printing strategy

Tao Yin, Yu Peishi, Zhang Xin, Li Maoyang, Liu Tao, Zhao Junhua

doi:10.1016/j.compositesa.2023.107896

 

基于混合3D打印策略的结构传感集成实现位移重建组件

Realizing displacement reconstruction is one of the main goals of real-time intelligent monitoring systems, motivating a highly promising requirement for structure-sensing integration technology. To obtain displacement-reconstruction-realized components, the crucial challenges cover the whole process including sensor-layout design, sensor assembly and rapidly functional verification. Accordingly, a rapid iterative solution is proposed from sensor-layout optimization to structure-sensing integrated fabrication then to displacement-reconstruction realization. A sensor array is optimally designed with minimized unit number and simplified circuit layout to integrate on the surface of or embed into the structures. Then we combine the direct-ink-writing with fused deposition modeling, achieving hybrid 3D printing strategy to fabricate the structure-sensing integrated components within one step. The local strains of plates are detected by the sensors and their full-field displacements are then reconstructed without any loading information. This work provides insights into the design and fabrication of structure–function-integration structures or devices.

实现位移重建是实时智能监测系统的主要目标之一,这激发了对结构传感集成技术的高度发展需求。为了获得实现位移重建的元件,关键的挑战涵盖了整个过程,包括传感器布局设计,传感器组装和快速功能验证。据此,提出了从传感器布局优化到结构传感集成制造再到位移重建实现的快速迭代求解方法。以最小的单元数和简化的电路布局优化设计传感器阵列,使其集成在结构表面或嵌入结构中。然后,我们将直墨书写与熔融沉积建模相结合,实现了混合3D打印策略,在一步内制造出结构传感集成组件。传感器检测板的局部应变,然后在没有任何载荷信息的情况下重建板的全场位移。这项工作为结构-功能-集成结构或器件的设计和制造提供了见解。


Phosphonitrile-modified biomass multi-crosslinking strategy: Construction of flame retardant, smoke suppressive and antibacterial polyvinyl alcohol composites

Tan Wei, Gao Lixiao, Su Jingna, Zuo Chunlong, Ren Yuanlin, Liu Xiaohui

doi:10.1016/j.compositesa.2023.107897

 

磷腈改性生物质多交联策略:阻燃、抑烟、抗菌聚乙烯醇复合材料的构建

To solve the problems of flammability, large smoke production and easy breeding of bacteria, polyvinyl alcohol (PVA) was modified by a multi-crosslinking structure fabricated by hexachlorocyclotriphosphazene derivative (SHCP) and chitosan (CS) followed by copper ions chelation. In terms of flame retardancy, the peak heat release rate (PHRR) and total heat release (THR) of the modified PVA composites decreased by 52.38% and 24.22%, while the LOI value and char-forming ability were greatly improved. The total smoke production (TSP) of the treated sample decreased by 91.00%. Furthermore, the inhibition rate of modified PVA composites against E. coli and S. aureus was as high as 99.67% and 92.45%. The current work provided a sustainable and versatile advanced strategy for the design of environmentally friendly, and cost-effective flame retardant, smoke suppression and antibacterial PVA composites, which was expected to be applied in the packaging field.

为解决聚乙烯醇(PVA)易燃、产烟大、易滋生细菌等问题,采用六氯环三磷腈衍生物(SHCP)与壳聚糖(CS)复合制备多交联结构对聚乙烯醇(PVA)进行了铜离子螯合改性。在阻燃性方面,改性后的PVA复合材料的峰值放热率(PHRR)和总放热率(THR)分别降低了52.38%和24.22%,LOI值和成炭能力均有较大提高。处理后样品的总产烟量(TSP)降低了91.00%。改性PVA复合材料对大肠杆菌和金黄色葡萄球菌的抑制率分别高达99.67%和92.45%。本研究为设计环保、高性价比的阻燃、抑烟、抗菌聚乙烯醇复合材料提供了一种可持续、通用的先进策略,有望在包装领域得到应用。


Surface waviness of continuous fiber-reinforced thermosets – Experimental and numerical studies considering the viscoelasticity of the resin

Lorenz N., Hennes P., Fischer K., Hopmann Ch.

doi:10.1016/j.compositesa.2023.107895

连续纤维增强热固性材料的表面波纹度。考虑树脂粘弹性的实验和数值研究

This contribution aims to understand surface waviness formation during cooling and post-curing of glass fiber-reinforced plastics (GFRP). GFRP plates were manufactured by resin transfer molding (RTM). Part surface waviness is determined by tactile contour measuring at ambient temperature up to 1008h after initial cooling. Additionally, the manufactured plates were exposed to elevated post-curing temperatures to study the influence of resins’ viscoelasticity on their surface waviness. In parallel, the curing and post-curing processes were analyzed using a cure- and temperature-dependent viscoelastic simulation model. The experimental results of this work capture the influence of the resin’s viscoelastic behavior on the surface waviness at ambient and temperatures. The numerical results show a satisfactory agreement with experimental values. Surface waviness amplitude increases up to 25% for the applied post-curing cycle. The results of the present work underline the importance of the resin’s temperature-dependent viscoelasticity on the process-related formation of surface waviness.

这一贡献旨在了解玻璃纤维增强塑料(GFRP)在冷却和后固化过程中的表面波纹形成。采用树脂传递模塑(RTM)法制备玻璃钢板材。零件表面波纹度是在初始冷却后1008h的环境温度下通过触觉轮廓测量确定的。此外,将制备的板材暴露在较高的固化后温度下,研究树脂的粘弹性对其表面波纹度的影响。同时,利用依赖于固化和温度的粘弹性模拟模型对固化和后固化过程进行了分析。本工作的实验结果捕捉到树脂的粘弹性行为对环境和温度下表面波纹的影响。数值计算结果与实验值吻合较好。在应用后固化周期时,表面波纹幅度增加到25%。本工作的结果强调了树脂的温度依赖粘弹性在表面波纹的工艺相关的形成的重要性。


Composites Part B: Engineering

Morphological characteristics of spray dried cellulose nanofibers produced using various wood pulp feedstocks and their effects on polypropylene composite properties

Hwang Sungjun, Han Yousoo, Gardner Douglas J.

doi:10.1016/j.compositesb.2023.111093

不同木浆原料制备的喷雾干燥纤维素纳米纤维的形态特征及其对聚丙烯复合材料性能的影响

Bleached Kraft pulp (BKP), unbleached Kraft pulp (UKP), and old corrugated cardboard pulp (OCC) are excellent feedstock sources for producing CNF suspensions manufactured by a mechanical disk refining process. The CNF drying operation should be performed to produce dry powders that can be compounded into thermoplastic matrices, and spray drying is fast, simple, cost-effective, and scalable. Among several spray-drying techniques, the pilot scale-rotary disk atomizer has many advantages, including large capacities, drying efficiency, and less feed blockage. In this study, BKP, UKP, and OCC pulps fibrillated to 90 % and 100 % fines levels were spray-dried using a pilot-scale rotary disk atomizer. The high-quality micrometer scale, round-shaped powders were produced from all feedstock sources, and a smaller particle size powder was produced with the higher fibrillated pulps. The spray-dried cellulose nanofibrils (SDCNFs) were compounded into a polypropylene (PP) matrix as a reinforcing material, and maleic anhydride-grafted polypropylene (MAPP) was used as a coupling agent. A masterbatch was used for the optimal dispersion and distribution of SDCNFs and MAPP in the PP matrix. It was concluded that the tensile and flexural properties increased as the particle size of SDCNFs increased, and the impact strength increased as the particle size decreased. The tensile strength, tensile modulus, flexural strength, flexural modulus, and impact strength increased by up to 29 %, 66 %, 15 %, 27 %, and 11 % respectively, compared to the neat PP after adding 10 wt% of SDCNFs with MAPP to the PP matrix.

漂白硫酸盐纸浆(BKP),未漂白硫酸盐纸浆(UKP)和旧瓦楞纸板纸浆(OCC)是生产CNF悬浮液的优良原料,由机械圆盘精炼过程制造。CNF干燥操作应执行以生产可复合成热塑性基质的干燥粉末,喷雾干燥快速,简单,具有成本效益和可扩展性。在几种喷雾干燥技术中,中试规模旋转圆盘雾化器具有容量大、干燥效率高、进料堵塞少等优点。在这项研究中,BKP, UKP和OCC纸浆纤原化到90% %和100% %的细粉水平,使用中试规模的旋转圆盘雾化器喷雾干燥。所有原料均可制得高质量的微米级圆形粉体,高纤原化浆可制得小粒度粉体。将喷雾干燥的纤维素纳米原纤维(SDCNFs)复合成聚丙烯(PP)基体作为增强材料,以马来酸酐接枝聚丙烯(MAPP)作为偶联剂。采用母粒对SDCNFs和MAPP在PP基质中的分散和分布进行了优化。结果表明,SDCNFs的拉伸和弯曲性能随粒径的增大而增大,冲击强度随粒径的减小而增大。在PP基体中加入10 wt%的MAPP后,与纯PP相比,拉伸强度、拉伸模量、弯曲强度、弯曲模量和冲击强度分别提高了29 %、66 %、15 %、27 %和11 %。


Composites Science and Technology

Interfacial thermal conduction mechanism of polypyrrole/carbon nanotube composites

Zou Hanying, Feng Yanhui, Tang Xiaolong, Zhang Xinxin, Qiu Lin

doi:10.1016/j.compscitech.2023.110346

 

聚吡咯/碳纳米管复合材料界面热传导机理研究

The excellent properties of carbon nanotube (CNT) make it possible for CNT-based materials to have both high thermal conductivity and high electrical conductivity. However, the weak coupling between the CNTs results in these properties far below expectations, which seriously hinders the application of CNT-based materials. The approaches to improve the electrical conductivity or the thermal conductivity are usually considered separately, but the heat generated by low resistance at high frequencies cannot be ignored and both of them need be focused. Loading polypyrrole (PPy) into the grooves between CNTs is a common method to improve electrical conductivity of CNT-based materials, which may also increase thermal conductivity through its polymer characters. This work finds that PPy fills the space of the grooves between CNTs, acts as the role of thermal transport relay, and builds a more stable heat transfer channel. And the PPy also resonates with carbon atoms, results in the phonon mode variation and interfacial phonon mismatch level change. The interfacial thermal conduction of CNTs significantly improves up to 202 %. This provides new design ideas for advanced CNT-based electronic devices.

碳纳米管的优异性能使碳纳米管基材料具有高导热性和高导电性成为可能。然而,碳纳米管之间的弱耦合导致这些性能远低于预期,这严重阻碍了碳纳米管基材料的应用。提高电导率的方法和提高导热性的方法通常是分开考虑的,但在高频下低电阻产生的热量是不可忽视的,两者都需要关注。在碳纳米管之间的沟槽中加载聚吡咯(PPy)是提高碳纳米管基材料导电性的常用方法,也可能通过其聚合物特性提高导热性。本研究发现,PPy填充了CNTs之间的凹槽空间,起到了热传递中继的作用,建立了更稳定的传热通道。PPy还与碳原子发生共振,导致声子模式的变化和界面声子失配水平的变化。CNTs的界面热传导率显著提高202%。这为基于碳纳米管的先进电子器件提供了新的设计思路。



来源:复合材料力学仿真Composites FEM
ACTMechanicalSystemDeform振动复合材料非线性电路拓扑优化通用航空电子ADS材料试验
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【新文速递】2023年10月25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 1 篇Mechanics of MaterialsEmbedding strain-rate sensitivities of multiple deformation mechanisms to predict the behavior of a precipitate-hardened WE43 alloy under a wide range of strain ratesWeiss Jacob, Su Yanqing, McWilliams Brandon A., Beyerlein Irene J., Knezevic Markodoi:10.1016/j.mechmat.2023.104843嵌入多种变形机制的应变速率敏感性,预测沉淀硬化的 WE43 合金在各种应变速率下的行为A rare earth Mg alloy, WE43, exhibits high strength, good ductility, low anisotropy, and moderately high strain rate sensitivity. As such, the alloy is a viable candidate for high strain rate applications. In this work, a comprehensive set of mechanical and microstructure data recorded during quasi-static, high strain rate split Hopkinson bar (SHB), and impact tests on specimens of WE43 Mg alloy reported in (Savage et al., 2020b) is simulated and interpreted using an advanced Taylor-type crystal plasticity finite element (T-CPFE) model. The T-CPFE model is formulated physically to embed two sources of strain-rate sensitivities inherent to each slip and twinning mode in WE43, one that occurs under constant structure and another that affects structure evolution. The model parameters are established for the alloy by achieving agreement in the stress-strain response and microstructure evolution under quasi-static and SHB tests. Density functional theory calculations of anti-phase boundary (APB) energy are carried out to explain origins of the unusually large initial slip resistance for basal dislocations, which shear precipitates in the alloy. The initial slip resistances of the prismatic and pyramidal dislocations are, instead, rationalized by Orowan looping around precipitates. After calibration and validation, the model is shown to successfully predict WE43 response at much larger strain rates than those used for model calibration. Specifically, mechanical response, specimen geometry changes, twin volume fractions, and texture evolution are predicted for different orientations of the Taylor cylinders. Details of the modeling framework, comparison between simulation and experimental results, and insights from the results are presented and discussed.稀土镁合金 WE43 具有高强度、良好的延展性、低各向异性和适度的高应变速率敏感性。因此,该合金是高应变速率应用的可行候选材料。在这项工作中,使用先进的泰勒型晶体塑性有限元(T-CPFE)模型模拟和解释了(Savage 等人,2020b)中报道的 WE43 镁合金试样在准静态、高应变率分裂霍普金森棒(SHB)和冲击试验中记录的一整套机械和微观结构数据。T-CPFE 模型通过物理方法制定,嵌入了 WE43 中每种滑移和孪晶模式固有的应变速率敏感性的两个来源,一个是在恒定结构下发生的,另一个是影响结构演变的。通过在准静态和 SHB 试验下应力-应变响应和微观结构演变的一致性,为合金建立了模型参数。对反相边界(APB)能量进行了密度泛函理论计算,以解释合金中剪切析出的基底位错的初始滑移阻力异常大的原因。棱柱位错和金字塔位错的初始滑移阻力则是通过析出物周围的奥罗万循环而得到合理解释的。经过校准和验证,该模型可以成功预测 WE43 在比用于模型校准的应变速率大得多的应变速率下的响应。具体来说,预测了泰勒圆柱体不同方向的机械响应、试样几何形状变化、孪晶体积分数和纹理演变。本文介绍并讨论了建模框架的细节、模拟与实验结果的比较以及从结果中获得的启示。International Journal of PlasticityTwo-dimensional evolution of temperature and deformation fields during dynamic shear banding: In-situ experiments and modelingZeng Qinglei, Chen Manxi, Yu Xiaoqi, Qi Wei, Zhu Shengxin, Yang Heng, Chen Hao-Sendoi:10.1016/j.ijplas.2023.103782动态剪切成带过程中温度场和变形场的二维演变:现场实验与建模Adiabatic shear band (ASB) is a significant failure mechanism observed in metals and alloys under impact loading. Though ASB formation has been widely assumed to be a one-dimensional thermo-mechanically-coupled instability problem, it is crucial to recognize that adiabatic shear banding is essentially a two-dimensional propagating event in space. However, it is challenging to perform in-situ characterization of temperature-deformation fields during ASB formation due to the extremely small spatial and temporal scales involved. To obtain the two-dimensional features of ASB evolution, a newly developed plane-array infrared imaging system and microspeckle-based digital image correlation (DIC) technique are synchronized with the Kolsky bar system. By incorporating interrupted tests, “quasi-synchronous” characterization of temperature-deformation-microstructure evolution during ASB formation in hat-shaped specimens of Ti-6Al-4V is achieved. A phase-field model incorporating energy-based shear banding criteria and independently calibrated model parameters is established to simulate the dynamic shear failure process, which is demonstrated to be able to well reproduce experimentally observed temperature and deformation evolution. Based on experimental characterization and simulation results, the two-dimensional features and thermo-mechanical aspects of ASB formation are presented. Energy dissipation of shear banding is estimated based on the measured temperature field, demonstrating good agreement with the calibrated values in the phase-field model. The “propagation” and “percolation” modes along the band are analyzed, which can be predicted by the introduction of a shear band process zone. The influences of thermal and microstructural softening on shear failure are also clarified through a comprehensive analysis of temperature and microstructure evolution.绝热剪切带(ASB)是金属和合金在冲击载荷作用下出现的一种重要失效机制。尽管人们普遍认为 ASB 的形成是一个一维热机械耦合不稳定问题,但必须认识到绝热剪切带基本上是一个二维空间传播事件。然而,由于涉及的空间和时间尺度极小,在 ASB 形成过程中对温度-形变场进行现场表征具有挑战性。为了获得 ASB 演化的二维特征,新开发的平面阵列红外成像系统和基于微斑的数字图像相关(DIC)技术与 Kolsky bar 系统同步进行。通过结合间断试验,实现了对 Ti-6Al-4V 帽形试样 ASB 形成过程中温度-变形-微结构演变的 "准同步 "表征。建立了一个相场模型,其中包含基于能量的剪切带标准和独立校准的模型参数,用于模拟动态剪切破坏过程,该模型能够很好地再现实验观察到的温度和变形演变。基于实验表征和模拟结果,介绍了 ASB 形成的二维特征和热力学方面。根据测量的温度场估算了剪切带的能量耗散,结果表明与相场模型中的校准值十分吻合。分析了沿带的 "传播 "和 "渗流 "模式,这些模式可以通过引入剪切带过程区来预测。此外,还通过对温度和微结构演变的全面分析,阐明了热软化和微结构软化对剪切破坏的影响。Thin-Walled StructuresFiber orientation and boundary stiffness optimization of laminated cylindrical shells with elastic boundary for maximum the fundamental frequency by an improved sparrow search algorithmChen Yugeng, Wang Qingshan, Zhong Rui, Shi Xianjie, Qin Bindoi:10.1016/j.tws.2023.111299用改进的麻雀搜索算法优化具有弹性边界的层叠圆柱壳的纤维方向和边界刚度,以获得最大基频In this paper, a multivariate improved sparrow search algorithm (MCSSA) is proposed for maximizing the fundamental frequency of composite laminated cylindrical shells and preventing vibrational resonance. The mathematical model for analyzing the fundamental frequency of composite laminated cylindrical shells in free vibration is established based on the first-order shear deformation theory (FSDT). A fundamental frequency optimization model for composite laminated cylindrical shells with elastic boundary is formulated, considering the influence of fiber orientation and boundary stiffness, with the objective of maximizing the fundamental frequency. In the optimization process, in response to the shortcomings of the sparrow search algorithm, Piecewise Linear Chaotic Map (PWLCM), tracking learning strategy, opposition-based learning strategy (OBL) and elite retention strategy are introduced for improvement to obtain the MCSSA with better overall performance for model optimization. The effectiveness and applicability of the algorithm improvements are demonstrated by comparing MCSSA with the whale optimization algorithm (WOA), sparrow search algorithm (SSA), and pelican optimization algorithm (POA) using 13 standard test functions and 2 composite laminated cylindrical shell cases. The numerical calculation results show that the shells optimized with MCSSA have higher fundamental frequency. MCSSA is an effective candidate for solving such problems.本文提出了一种多变量改进麻雀搜索算法(MCSSA),用于最大化复合材料层压圆柱壳的基频并防止振动共振。基于一阶剪切变形理论(FSDT),建立了分析自由振动中复合材料层压圆柱壳基频的数学模型。考虑到纤维取向和边界刚度的影响,建立了具有弹性边界的复合材料层压圆柱壳的基频优化模型,目标是使基频最大化。在优化过程中,针对麻雀搜索算法的缺点,引入了片断线性混沌图(PWLCM)、跟踪学习策略、基于对立面的学习策略(OBL)和精英保留策略进行改进,得到了整体性能更好的 MCSSA,用于模型优化。通过使用 13 个标准测试函数和 2 个复合层压圆柱壳案例,比较 MCSSA 与鲸鱼优化算法(WOA)、麻雀搜索算法(SSA)和鹈鹕优化算法(POA),证明了算法改进的有效性和适用性。数值计算结果表明,采用 MCSSA 算法优化的壳体具有更高的基频。MCSSA 是解决此类问题的有效候选算法。来源:复合材料力学仿真Composites FEM

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