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【新文速递】2024年7月7日固体力学SCI期刊最新文章

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

International Journal of Solids and Structures

Developing a scalable analytical framework for predicting the contact behavior of elastic rings against rigid surfaces

Zhipeng Liu, Jaehyung Ju

doi:10.1016/j.ijsolstr.2024.112967

开发可扩展的分析框架,用于预测弹性环与刚性表面的接触行为

An elastic ring interacting with rigid surfaces is a fundamental engineering challenge with vast practical implications in various disciplines. However, the exploration of closed-form solutions for this issue has been limited, and existing studies often present complex, numerically unstable solution methods influenced by specific boundary conditions. Furthermore, the lack of scalable design principles for the ring-in-contact scenario has hindered its broader application across different geometries and materials. This study introduces a streamlined analytical and numerical approach to predict the contact behavior of orthotropic rings against centrosymmetric rigid surfaces, encompassing both flat and curved surfaces. Our approach, which simplifies the closed-form solution for extensible Timoshenko curved beams coupled with a contact algorithm that prevents penetration, yields robust and accurate predictions of nonlinear contact behaviors in elastic rings, including deformation patterns, contact angles, stresses, and stiffness. Additionally, we present a design map that serves as a scalable guideline for engineering elastic rings in contact, facilitating the choice of geometry and materials, such as ring radius, thickness, and elastic moduli. This research enhances the theoretical underpinnings of elasticity concerning ring contact and expands the engineering viewpoint on designing elastic rings in various contact scenarios.

弹性环与刚性表面相互作用是一项基本的工程挑战,对各学科具有广泛的实际影响。然而,对这一问题的闭式求解方法的探索还很有限,现有的研究往往提出了受特定边界条件影响的复杂、数值不稳定的求解方法。此外,接触环缺乏可扩展的设计原则,阻碍了其在不同几何形状和材料中的广泛应用。本研究介绍了一种简化的分析和数值方法,用于预测各向同性环与中心对称刚性表面(包括平面和曲面)的接触行为。我们的方法简化了可伸展季莫申科曲线梁的闭式解法,并结合了防止穿透的接触算法,可对弹性环的非线性接触行为进行稳健而准确的预测,包括变形模式、接触角、应力和刚度。此外,我们还提出了一个设计图,作为工程设计接触弹性环的可扩展指南,便于选择几何形状和材料,如环半径、厚度和弹性模量。这项研究加强了弹性环接触的理论基础,并拓展了在各种接触情况下设计弹性环的工程视角。


Journal of the Mechanics and Physics of Solids

Quantifying 3D time-resolved kinematics and kinetics during rapid granular compaction, Part I: Quasistatic and dynamic deformation regimes

Sohanjit Ghosh, Mohmad M. Thakur, Ryan C. Hurley

doi:10.1016/j.jmps.2024.105765

量化快速颗粒压实过程中的三维时间分辨运动学和动力学,第一部分:准静态和动态变形机制

Impacts in granular materials occur over a velocity range of a few hundred m/s in manufacturing processes to several km/s during asteroid impacts. Different energy dissipation mechanisms are activated during impacts based on the kinetic energy of the impactor and the properties of the granular material. Material response during impact can be classified into two broad regimes – quasi-static and dynamic – characterized by the nature of grain and pore deformation and the deformation morphology of grain interfaces. In the quasi-static regime, all energy from the impactor is utilized in pore (or void) collapse, while in the dynamic regime, excess energy after pore closure leads to material melting or jetting and often to non-planar grain interfaces. To understand the transition between the quasi-static and dynamic regimes, in-situ measurements of temperature, local stresses, and porosity at the grain scale are critical but often not possible due to short timescales and inherent heterogeneity of granular materials. In this work, we use X-ray phase contrast imaging (XPCI) to visualize grain-scale deformation during rapid granular compaction and observe phenomena such as plastic flow-induced pore collapse, compaction wave propagation, and the morphology of the grain-grain interfaces. Alongside these experiments, we develop and validate a mesoscale numerical model that incorporates each sample’s microstructure and captures realistic plasticity and thermal effects. Using this validated model, we quantify the temperatures, pressures, and porosity as granular materials are compacted in both quasi-static and dynamic deformation regimes. By comparing our results with existing theoretical models, we find that the continuum definitions of quasi-static and dynamic regimes needs to be updated for a realistic heterogeneous granular media. Specifically, the two regimes can coexist in the same assembly of grains at different time instants due to spatial heterogeneity and rapid dissipation of impact energy away from the point of impact. Finally, we quantify the energies associated with different dissipation mechanisms for individual grains using coupled numerical and analytical techniques. Our methodology allows us to obtain full 3D kinematics and kinetics of rapidly compacted granular materials at both the mesoscale and the grain scale.

颗粒材料的撞击速度范围从制造过程中的几百米/秒到小行星撞击时的几千米/秒。根据撞击器的动能和颗粒材料的特性,撞击过程中会启动不同的能量消散机制。撞击过程中的材料响应可分为准静态和动态两大类,其特征在于颗粒和孔隙变形的性质以及颗粒界面的变形形态。在准静态条件下,来自冲击器的所有能量都被孔隙(或空隙)塌陷所利用,而在动态条件下,孔隙闭合后的多余能量会导致材料熔化或喷射,通常会导致晶粒界面不平整。要了解准静态和动态状态之间的转变,对温度、局部应力和晶粒尺度的孔隙率进行现场测量至关重要,但由于时间尺度短和颗粒材料固有的异质性,这往往是不可能的。在这项工作中,我们利用 X 射线相衬成像 (XPCI) 对快速颗粒压实过程中的颗粒尺度变形进行可视化,并观察塑性流动引起的孔隙塌陷、压实波传播和颗粒-颗粒界面形态等现象。在进行这些实验的同时,我们还开发并验证了一个中尺度数值模型,该模型结合了每个样品的微观结构,并捕捉到了真实的塑性和热效应。利用这个经过验证的模型,我们对颗粒材料在准静态和动态变形状态下压实时的温度、压力和孔隙率进行了量化。通过将我们的结果与现有的理论模型进行比较,我们发现准静态和动态状态的连续定义需要针对现实的异质颗粒介质进行更新。具体来说,由于空间异质性和撞击能量在远离撞击点时的快速消散,这两种状态可以在不同的时间时刻共存于同一个颗粒集 合体中。最后,我们利用数值和分析耦合技术量化了与单个晶粒的不同耗散机制相关的能量。我们的方法使我们能够在中尺度和颗粒尺度上获得快速压实颗粒材料的全三维运动学和动力学。


International Journal of Plasticity

Operative slip systems and their critical resolved shear stresses in η-Fe2Al5 investigated by micropillar compression at room temperature

Zhenghao Chen, Tsukasa Horie, Xiaofeng Wang, Haruyuki Inui

doi:10.1016/j.ijplas.2024.104057

室温下通过微柱压缩研究η-Fe2Al5中的工作滑移系统及其临界解析剪应力

The plastic deformation behavior of single crystals of orthorhombic η-Fe2Al5 has been investigated by micropillar compression at room temperature as a function of crystal orientation and specimen size. Plastic flow is observed even at room temperature by the operation of six slip systems; (001)<010>, (001)<110>, (001)<130>, {2 2 ¯ 3}<110>, {311}< 1 ¯ 03> and {301}< 1 ¯ 03>. The CRSS values for the five identified slip systems are very high all in the range of 1.1∼1.5 GPa and do not vary much with specimen size. In the middle of the stereographic projection, the (001)<010>, (001)<110>, (001)<130> and {2 2 ¯ 3}[110] slip systems operate according to the relative Schmid factors with the similar CRSS values in the range of 1.08∼1.23 GPa. In orientations close to [001], the {311}< 1 ¯ 03> slip system as well as the {301}< 1 ¯ 03> slip system operate with a much higher CRSS values around 1.5 GPa, producing wavy slip traces due to the occurrence of frequent cross-slip among these slip planes. In orientations close to the [100]-[110]-[010] symmetry line, on the other hand, premature failure occurs without the operation of any slip systems, although, the Schmidt factor-wise, the {311}< 1 ¯ 03> and {301}< 1 ¯ 03> slip systems could operate. The selection of slip systems, their CRSS values and the possible dislocation dissociation modes are discussed based on the overlapped atomic volume that occurs during shear along the slip direction on the slip plane, taking into account the partial occupancies of Al atoms in the linear atomic chain along the orthorhombic c-axis direction.

通过微柱压缩研究了室温下正交η-Fe2Al5 单晶体的塑性变形行为与晶体取向和试样尺寸的关系。即使在室温下,通过六种滑移系统的操作也能观察到塑性流动:(001)<010>, (001)<110>, (001)<130>, {2 2 ¯ 3}<110>, {311}< 1 ¯ 03> 和 {301}< 1 ¯ 03>。五个已识别滑移系统的 CRSS 值都非常高,在 1.1∼1.5 GPa 范围内,且随试样尺寸变化不大。在立体投影的中间位置,(001)<010>、(001)<110>、(001)<130>和{2 2 ¯3}[110]滑移系统根据相对施密德因子运行,CRSS 值在 1.08∼1.23 GPa 范围内相似。在靠近[001]的方向上,{311}< 1 ¯ 03>滑移系统和{301}< 1 ¯ 03>滑移系统的CRSS值在1.5 GPa左右,由于这些滑移面之间经常发生交叉滑移,因此会产生波浪形滑移痕迹。另一方面,在靠近[100]-[110]-[010]对称线的方向上,虽然从施密特因子来看,{311}< 1 ¯ 03>和{301}< 1 ¯ 03>滑移系统可以工作,但在没有任何滑移系统工作的情况下会发生过早失效。根据沿滑移面上的滑移方向剪切时发生的重叠原子体积,并考虑到沿正菱形 c 轴方向线性原子链中铝原子的部分占有率,讨论了滑移系统的选择、其 CRSS 值和可能的位错解离模式。


Thin-Walled Structures

Functionally graded foam materials for head impact protection

Shunfeng Li, Q.M. Li, Kwong Ming Tse, Tong Pang

doi:10.1016/j.tws.2024.112193

用于头部撞击保护的功能分级泡沫材料

Head injuries commonly result from impact accidents, underscoring the urgent requirement for enhanced helmet protection. Functionally graded foam (FGF) materials present promising avenues for augmenting the design of impact-attenuating liners in helmets, thereby mitigating head injuries. This study aims to investigate the performance of the FGF materials in protecting against head frontal impact and provide an effective optimization methodology to support the efficient and reliable design of the FGF materials. The foam finite element model was developed and coupled with a highly biofidelic head model to simulate the FGF-head frontal impact scenarios. A parametric study based on the coupled FGF-head model was conducted to explore the effects of the configuration parameters on the protection performance of the FGF materials. The study demonstrated that the negative-gradient FGF materials provide better head impact protection than the uniform density foam (UDF) and positive-gradient FGF materials, despite the potential disadvantage in energy absorption. A discrete optimization method based on the FGF-head model was developed and illustrated to efficiently achieve an optimized design for FGF protectability, thereby reducing the risk of head injuries. The optimized design reduced the Head Injury Criterion (HIC) value by 40.4% compared to the conventional UDF design, from 1660 to 990. Therefore, this study provides a further understanding and a new optimization insight into designing FGF materials to improve head impact protection.

撞击事故通常会导致头部受伤,因此迫切需要加强头盔保护。功能分级泡沫(FGF)材料为增强头盔内撞击衰减衬垫的设计,从而减轻头部伤害提供了广阔的前景。本研究旨在探讨泡沫塑料在保护头部免受正面撞击方面的性能,并提供有效的优化方法来支持泡沫塑料的高效可靠设计。该研究开发了泡沫有限元模型,并将其与高生物保真度的头部模型相结合,以模拟 FGF-头部正面撞击情景。在耦合 FGF 头部模型的基础上进行了参数研究,以探索配置参数对 FGF 材料防护性能的影响。研究表明,与均匀密度泡沫(UDF)和正梯度 FGF 材料相比,负梯度 FGF 材料在能量吸收方面具有潜在的劣势,但却能提供更好的头部撞击保护。基于 FGF-头部模型开发并说明了一种离散优化方法,可有效实现 FGF 保护性的优化设计,从而降低头部受伤的风险。与传统的 UDF 设计相比,优化设计将头部伤害标准(HIC)值降低了 40.4%,从 1660 降至 990。因此,这项研究为设计 FGF 材料以改善头部撞击保护提供了进一步的理解和新的优化见解。


Compressive behaviour and capacities of S690 high strength steel welded π-shaped and cruciform section stub columns

Qianzhi Chen, Lulu Zhang, Ou Zhao

doi:10.1016/j.tws.2024.112194

S690 高强度钢焊接π形和十字形截面支柱的抗压性能和承载能力

This paper reports experimental and numerical investigations into the cross-sectional behaviour and resistances of S690 high strength steel welded π-shaped and cruciform section stub columns under compression. An experimental investigation was firstly carried out on five S690 high strength steel welded π-shaped sections and five S690 high strength steel welded cruciform sections (covering both non-slender and slender sections) and included material tensile coupon tests, initial local geometric imperfection measurements and twenty stub column tests. The experimental investigation was supplemented by a numerical modelling investigation, where finite element models were firstly developed to simulate test structural responses and subsequently adopted to conduct parametric studies to generate further numerical data. On the basis of the obtained experimental and numerical data, the relevant design rules for high strength steel welded sections under compression, as set out in the European code, American specification and Australian standard, were assessed. The assessment results indicated that (i) the European code and American specification led to overall accurate and consistent cross-section compression resistance predictions for S690 high strength steel welded π-shaped sections, but provided slightly conservative and scattered resistance predictions for their cruciform section counterparts, and (ii) the Australian standard was accurate and consistent when used for non-slender S690 high strength steel welded π-shaped sections, but the design resistances were conservative and scattered for slender S690 high strength steel welded π-shaped sections as well as non-slender and slender S690 high strength steel welded cruciform sections.

本文报告了对 S690 高强度钢焊接 π 形截面和十字形截面桩柱在受压情况下的截面行为和阻力进行的实验和数值研究。首先对五个 S690 高强度钢焊接 π 形截面和五个 S690 高强度钢焊接十字形截面(包括非细长截面和细长截面)进行了实验研究,包括材料拉伸试样测试、初始局部几何缺陷测量和二十次存根柱测试。实验研究还辅以数值建模研究,首先开发了有限元模型来模拟试验结构响应,随后采用有限元模型进行参数研究,以生成进一步的数值数据。根据获得的实验和数值数据,对欧洲规范、美国规范和澳大利亚标准中规定的受压高强度钢焊接型材的相关设计规则进行了评估。评估结果表明:(i) 欧洲规范和美国规范对 S690 高强度钢焊接 π 形截面的横截面抗压性预测总体上准确且一致,但对十字形截面的抗压性预测略显保守且分散;以及 (ii) 澳大利亚标准对 S690 高强度钢焊接 π 形截面的横截面抗压性预测总体上准确且一致,但对十字形截面的抗压性预测略显保守且分散、(ii) 澳大利亚标准用于非细长 S690 高强度钢焊接 π 型截面时准确一致,但用于细长 S690 高强度钢焊接 π 型截面以及非细长和细长 S690 高强度钢焊接十字型截面时,设计阻力保守且分散。


Numerical investigation and design methods of the local buckling of WAAM stainless steel circular hollow section stub columns

Yanan Huang, Lu Yang, Meiyu Liu, Kelong Xu

doi:10.1016/j.tws.2024.112195

WAAM 不锈钢圆形空心截面支柱局部屈曲的数值研究和设计方法

3D printing is an advanced technology that has been used in biomedical and automotive engineering, and has raised a significant response in civil engineering. Wire and arc additive manufacturing (WAAM), a metal 3D printing technology, has prospective applications in steel construction because it can fabricate large-scale structural members at an acceptable cost and manufacturing efficiency. Fundamental studies are still urgently needed to realise its engineering application. However, due to the irregular geometric features, limited studies on the structural performance of WAAM components, particularly the numerical studies, have been carried out. To this end, a numerical investigation on the local buckling of WAAM stainless steel circular hollow section (CHS) stub columns under axial compression has been conducted and presented herein. The finite element (FE) models were established and validated against the existing experimental research. Parametric studies were subsequently carried out to broaden the cross-sectional resistance data pool using the developed FE models. The applicability of the cross-section design provisions specified in EN 1993-1-4:2006+A2:2020, ANSI/AISC 370-21 and the continuous strength method (CSM) for the design of WAAM CHS was evaluated according to the experimental and FE results. Furthermore, a modified design method with improved accuracy was suggested.

3D打印是一种先进技术,已在生物医学和汽车工程领域得到应用,并在土木工程领域引起了巨大反响。线弧增材制造(WAAM)是一种金属3D打印技术,在钢结构领域具有广阔的应用前景,因为它可以以可接受的成本和制造效率制造大型结构件。要实现其工程应用,仍迫切需要进行基础研究。然而,由于其不规则的几何特征,对 WAAM 构件结构性能的研究,尤其是数值研究十分有限。为此,本文对 WAAM 不锈钢圆形空心截面 (CHS) 存根柱在轴向压缩下的局部屈曲进行了数值研究。根据现有的实验研究建立并验证了有限元 (FE) 模型。随后进行了参数研究,以利用开发的 FE 模型扩大横截面阻力数据池。根据实验和 FE 结果,评估了 EN 1993-1-4:2006+A2:2020、ANSI/AISC 370-21 和连续强度法 (CSM) 中规定的截面设计条款对 WAAM CHS 设计的适用性。此外,还提出了一种精度更高的改进设计方法。




来源:复合材料力学仿真Composites FEM
ACTAdditiveSystemDeform非线性UDF汽车增材ADS焊接理论材料试验曲面
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【新文速递】2024年7月8日复合材料SCI期刊最新文章

今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 5 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇Composite StructuresAnalysis of laminated shells using pseudospectrals and the Reissner-Mixed Variational TheoremS.C.F. Fernandes, J. Cuartero, A.J.M. Ferreiradoi:10.1016/j.compstruct.2024.118341利用伪谱和赖斯纳-混合变分定理分析层叠壳体In this paper, we combine the Carrera’s Unified Formulation CUF and a pseudospectral technique for predicting the static deformations and free vibrations behaviour of thin and thick cross-ply laminated shells. For the first time, the Reissner-Mixed Variational Theorem is used together with pseudospectrals to achieve a highly accurate technique. The accuracy and efficiency of this numerical technique for static and vibration problems are demonstrated through numerical examples.在本文中,我们将卡雷拉统一公式 CUF 与伪谱技术相结合,用于预测薄层和厚层交叉层叠壳体的静态变形和自由振动行为。我们首次将赖斯纳混合变分定理与伪谱技术结合使用,从而实现了高精度技术。该数值技术在静态和振动问题上的准确性和效率通过数值示例得到了证明。Tailoring band gap properties of curved hexagonal lattices with nodal cantileversShuvajit Mukherjee, Marcus Maeder, Milan Cajić, Felix Kronowetter, Sondipon Adhikari, Steffen Marburgdoi:10.1016/j.compstruct.2024.118342用节点悬臂调整曲面六边形晶格的带隙特性Metamaterials find applications across diverse domains such as electromagnetics, elasticity, and acoustics by creating band gaps. Lattice-based metamaterials also exhibit band gaps, which have a great potential to influence engineering design in vibration and noise reduction problems. The geometry of the repetitive unit cell in the lattice plays a crucial role in diversifying the location and number of stop bands across the frequency range. One of the key hurdles is devising unit cell architectures that can effectively suppress vibrations across diverse frequency ranges. This work proposes an innovative two-dimensional hexagonal lattice with tailored band gap characteristics through curved beam members and auxiliary cantilever beams at the nodes. We have thoroughly explored the impact of various design parameters on dispersion characteristics, wave directionality through iso-frequency contours of dispersion surfaces, and the transmission loss considering finite lattice. The investigation demonstrates an improvement in band gap characteristics, indicating the generation of more band gaps across the entire frequency range and the widening of the same. This study has the potential to serve as a future benchmark in the development of lattice-based elastic/acoustic metamaterials, particularly for addressing vibration reduction challenges at user-defined frequencies.超材料通过产生带隙在电磁学、弹性和声学等不同领域都有应用。基于晶格的超材料也表现出带隙,在影响减震降噪问题的工程设计方面具有巨大潜力。晶格中重复单元的几何形状在使整个频率范围内的阻带位置和数量多样化方面起着至关重要的作用。其中一个关键障碍是设计出能够在不同频率范围内有效抑制振动的单元格结构。这项研究提出了一种创新的二维六边形晶格,通过弯曲的梁构件和节点处的辅助悬臂梁来定制带隙特性。我们深入探讨了各种设计参数对色散特性的影响、通过色散面等频等值线得出的波方向性,以及考虑到有限晶格的传输损耗。研究结果表明,带隙特性得到了改善,表明在整个频率范围内产生了更多带隙并扩大了带隙。这项研究有望成为未来开发基于晶格的弹性/声学超材料的基准,特别是在解决用户定义频率的减振难题方面。TRC truss – Proof of concept by experimental investigationDor Simon, Alva Peled, Yiska Goldfelddoi:10.1016/j.compstruct.2024.118361TRC 桁架--通过实验研究验证概念The study develops textile-reinforced concrete (TRC) trusses, reinforced with 3D textiles. It is argued that, by taking advantage of textiles’ ability to conform to complex shapes and their corrosion resistance, TRC truss structures enable a substantial reduction in material and weight through efficient load transfer mechanisms. An experimental investigation explores the design methodology and manufacturing possibilities, as well as the macro-structural response and the cracking and failure mechanisms under flexural loading. Additionally, the study investigates the effects of various reinforcement layouts associated with different anchoring feasibilities and reinforcement ratios on the structural performance.It was found that TRC trusses maintain their structural performance compared to full cross-sectional rectangular TRC beams while achieving significant material savings and weight reduction (about 50 %). It was also found that effective anchoring is a dominant parameter governing structural response. Results from this study highlight the high potential of TRC trusses as a sustainable alternative for structural components.该研究开发了用三维纺织品加固的纺织品加固混凝土(TRC)桁架。研究认为,通过利用纺织品适应复杂形状的能力及其耐腐蚀性,TRC 桁架结构可以通过有效的荷载传递机制大幅减少材料和重量。实验研究探讨了设计方法和制造可能性,以及宏观结构响应和弯曲加载下的开裂和破坏机制。此外,研究还探讨了与不同锚固可行性和加固比相关的各种加固布局对结构性能的影响。研究发现,与全截面矩形 TRC 梁相比,TRC 桁架在保持其结构性能的同时,还能显著节省材料和减轻重量(约 50%)。研究还发现,有效锚固是影响结构响应的主要参数。这项研究的结果凸显了 TRC 桁架作为可持续结构部件替代材料的巨大潜力。Composites Part A: Applied Science and ManufacturingPaper fiber-reinforced polypropylene composites from nonwoven preforms: A study on compression molding optimization from a manufacturing perspectiveCecile A. Grubb, David J. Keffer, Christopher D. Webb, Marton Kardos, Hendrik Mainka, David P. Harperdoi:10.1016/j.compositesa.2024.108339无纺布预制件中的纸纤维增强聚丙烯复合材料:从制造角度优化压缩成型的研究This work optimizes compression molding manufacturing for wet-formed nonwoven paper and polypropylene fiber mats. A central composite designed experiment investigated the effects of fiber reinforcement concentration, compression molding temperature, pressure, and time on composite laminate performance. We assess the composites’ density, panel thickness, water uptake, flexural behavior, and Izod impact strength. Models predicted and optimized composite performance using objective function analysis with penalties applied for undesirable conditions, such as processing time or low reinforcement concentration. Paper fiber content has the largest impact on composite properties, followed by processing time, molding pressure, and temperature. Composite optimization depends on penalty conditions; low fiber content penalties favor low fiber content panels with short processing times, while high fiber content penalties favor high fiber content panels with long processing times. This work suggests that molding composites with a greater fraction of renewable feedstock requires a commensurate increase in processing intensity.这项研究优化了湿成型无纺纸和聚丙烯纤维毡的压缩成型制造工艺。中心复合设计实验研究了纤维增强浓度、压缩成型温度、压力和时间对复合材料层压板性能的影响。我们评估了复合材料的密度、板材厚度、吸水率、弯曲性能和伊佐德冲击强度。模型通过目标函数分析预测并优化了复合材料的性能,并对加工时间或低增强浓度等不良条件进行了惩罚。纸纤维含量对复合材料性能的影响最大,其次是加工时间、成型压力和温度。复合材料的优化取决于惩罚条件;低纤维含量惩罚有利于加工时间短的低纤维含量面板,而高纤维含量惩罚有利于加工时间长的高纤维含量面板。这项研究表明,使用更多的可再生原料模塑复合材料需要相应增加加工强度。Fabrication of a high-temperature resistant and water-soluble sizing agent to significantly improve the interfacial properties of carbon fiber reinforced epoxy compositesBaowei Qiu, Youquan Ling, Xiwen Gu, Lei Wang, Fei Chen, Shengtai Zhou, Huawei Zou, Mei Liangdoi:10.1016/j.compositesa.2024.108344 制备耐高温水溶性施胶剂,显著改善碳纤维增强环氧树脂复合材料的界面性能Applying suitable sizing agents is effective in improving the interfacial performance of carbon fiber reinforced composites (CFRPs). However, the poor thermal stability of conventional epoxy-based sizing agent limits their application at elevated temperatures for preparing advanced CFRPs. The question could lead to interfacial damage of composites at high temperatures, thus deteriorating their mechanical properties. In this work, diethanolamine (DEA) was selected to modify E51 resin to obtain a high-temperature resistant sizing agent (E51@DEA). The decomposition temperature of E51@DEA was 320 °C, which was 140 °C higher than that of E51. Furthermore, the resultant composites treated by E51@DEA 2 % showed robust interfacial performance (ILSS = 74.2 MPa, IFSS = 100.70 MPa), which was both increased by about 25 % compared to unmodified samples. In addition, the modified fiber could completely retain their interfacial reinforcement after treatment at 300 °C for 4 h. The prepared composites combined excellent thermal and interfacial properties, further expanding the application range of CFRPs.使用合适的施胶剂可以有效改善碳纤维增强复合材料(CFRP)的界面性能。然而,传统环氧基施胶剂的热稳定性较差,限制了它们在高温下制备先进 CFRP 的应用。这一问题可能会导致复合材料在高温下发生界面破坏,从而降低其机械性能。本研究选用二乙醇胺(DEA)对 E51 树脂进行改性,从而获得一种耐高温施胶剂(E51@DEA)。E51@DEA 的分解温度为 320 ℃,比 E51 高 140 ℃。此外,经 2 % E51@DEA 处理的复合材料显示出良好的界面性能(ILSS = 74.2 MPa,IFSS = 100.70 MPa),与未改性样品相比,界面性能均提高了约 25%。此外,在 300 °C 下处理 4 小时后,改性纤维可完全保持其界面加固性能。所制备的复合材料兼具优异的热性能和界面性能,进一步扩大了 CFRP 的应用范围。Influence of Flow-Induced crystallization and morphology on mechanical behavior in long discontinuous glass fiber polyamide compositesSiavash Sattar, Jimesh Bhagatji, Mohammad Nazmus Saquib, Diego Pedrazzoli, Mingfu Zhang, Sergey G. Kravchenko, Oleksandr G. Kravchenkodoi:10.1016/j.compositesa.2024.108353流动诱导结晶和形态对长非连续玻璃纤维聚酰胺复合材料机械行为的影响This study investigates the combined flow-induced crystallization in the polymer and fiber reorientation during compression molding of a long discontinuous glass fiber polyamide (PA) 6 composite. The composite is molded from an organosheet (a semi-finished pre-impregnated mat); the composite anisotropic tensile properties are evaluated as a function of polymer crystalline morphology and fiber orientation state, both controlled by the extent of material flow in the mold. To study these effects, the full mold coverage and partial center charge of organosheet (OS)-80 %, 60 %, 50 %, and 40 % were compression molded to cause varying anisotropic material flow. Tensile specimens were cut out from the molded plates in the flow and transverse direction and tested to compare their effective tensile properties (modulus and strength). The flow-induced morphological changes in a molded composite at the glass fiber bundle microstructure scale and polymer crystalline phases nano-structure were characterized using optical microscopy and X-ray diffraction, respectively. These morphological changes contributed to the significant change in the tensile strength and modulus; a combined experimental/numerical simulation framework was used to segregate the relative contribution of each factor. Experimentally, the tensile modulus increased in the flow direction from 9.6GPa to 14.9GPa for the specimens produced by full mold coverage and OS-50 % coverage mold, respectively. The tensile strength increased from 162 MPa to 254 MPa for the full and OS-60 % mold coverage. On the contrary, the strength and modulus in the transverse direction to the flow showed a significant drop to 35 MPa and 3GPa, respectively, which was attributed to reduced fiber alignment and anisotropy in the PA6 matrix.本研究探讨了在压缩成型长间断玻璃纤维聚酰胺(PA)6 复合材料的过程中,聚合物中的流动诱导结晶和纤维重新取向的综合作用。该复合材料由有机片材(半成品预浸渍毡)模塑而成;复合材料的各向异性拉伸性能作为聚合物结晶形态和纤维取向状态的函数进行了评估,而聚合物结晶形态和纤维取向状态均受模具中材料流动程度的控制。为了研究这些影响,对有机片材 (OS) 的全模具覆盖率和部分中心电荷 - 80%、60%、50% 和 40% 进行了压缩成型,以产生不同的各向异性材料流动。从模塑板上沿流动方向和横向切割出拉伸试样并进行测试,以比较其有效拉伸性能(模量和强度)。使用光学显微镜和 X 射线衍射分别表征了模塑复合材料在玻璃纤维束微观结构尺度和聚合物结晶相纳米结构尺度上由流动引起的形态变化。这些形态变化导致了拉伸强度和模量的显著变化;采用实验/数值模拟相结合的框架来分离各因素的相对贡献。实验结果表明,全模具覆盖和 OS-50 % 覆盖模具生产的试样在流动方向上的拉伸模量分别从 9.6GPa 增加到 14.9GPa。模具全覆盖和 OS-60 % 覆盖率生产的试样的拉伸强度从 162 兆帕增加到 254 兆帕。相反,流向横向的强度和模量却显著下降,分别为 35 兆帕和 3GPa, 这归因于 PA6 基体中纤维排列和各向异性的减少。Thermoviscoelastic modelling of highly reactive thermoset resins for liquid moulding applicationsLeonardo Barcenas, Loleï Khoun, Pascal Hubertdoi:10.1016/j.compositesa.2024.108350用于液体成型应用的高活性热固性树脂的热变弹性建模This paper presents a methodology for developing thermo-mechanical properties model for highly reactive resins and its use for Resin Transfer Moulding process (RTM) modelling and prediction of residual stresses. Cure Hardening Instantaneously Linear Elastic (CHILE), and Thermoviscoelastic (TVE) models, were implemented to analyze the mechanical behaviour of the resin. Simulation of the RTM process was developed and applied to a representative curved plate geometry. An integral approach was considered where the degree of cure gradient, generated during the filling stage due to the reactivity of the resin, was implemented as initial condition of the stress-deformation process simulation. The validation process included fabricating experimental parts with the representative geometry. The degree of cure variation of highly reactive thermosets during injection caused a significant effect on the final shape of the parts. These effects were captured by the simulations, where the TVE model showed a more accurate prediction of the part distortion.本文介绍了一种开发高活性树脂热机械性能模型的方法,并将其用于树脂传递模塑工艺(RTM)建模和残余应力预测。采用固化硬化瞬时线性弹性模型(CHILE)和热变形弹性模型(TVE)来分析树脂的机械性能。对 RTM 过程进行了模拟,并将其应用于具有代表性的曲面板几何形状。考虑了一种整体方法,将填充阶段由于树脂反应性而产生的固化梯度作为应力-变形过程模拟的初始条件。验证过程包括制造具有代表性几何形状的实验部件。高活性热固性树脂在注塑过程中的固化程度变化对零件的最终形状有显著影响。模拟捕捉到了这些影响,其中 TVE 模型对零件变形的预测更为准确。Silicone elastomer dielectric composites by introducing novel O-MMT@TiO2 nanoparticles for energy harvesting applicationTao Yang, Chongyang Wang, Ling Liu, Liqun Zhangdoi:10.1016/j.compositesa.2024.108351 引入新型 O-MMT@TiO2 纳米粒子的硅树脂弹性体介电复合材料的能量采集应用Dielectric elastomers have attracted attention in emerging advanced electromechanical applications. However, how to simultaneously improve the dielectric constant and the breakdown strength of dielectric composite needs to be solved. In this paper, we propose a new strategy to anchor TiO2 nanoparticles onto organically modified montmorillonite (O-MMT) nanoplatelets through dehydration reaction to synthesize a novel filler O-MMT@TiO2. Then, the O-MMT@TiO2 is incorporated into methyl vinyl silicone rubber (MVSR) matrix to obtain O-MMT@TiO2/MVSR dielectric composites. Comparing with the composites by direct mixing of TiO2 and O-MMT in MVSR (O-MMT/TiO2/MVSR), O-MMT@TiO2/MVSR composites significantly increase mechanical and dielectric and energy storage properties. 30 wt% O-MMT@TiO2/MVSR composite achieves the highest energy storage density of 118.65 kJ/m3, which is 142.9 % higher than that of 15 wt%O-MMT/15 wt%TiO2/MVSR (48.84 kJ/m3). This study offers an effective method for the preparation of high-performance dielectric elastomer materials, which can be exploited for the energy harvesting application.介电弹性体在新兴的先进机电应用中备受关注。然而,如何同时提高介电复合材料的介电常数和击穿强度仍是一个亟待解决的问题。本文提出了一种新策略,即通过脱水反应将 TiO2 纳米颗粒锚定在有机改性蒙脱石(O-MMT)纳米颗粒上,合成新型填料 O-MMT@TiO2。然后,将 O-MMT@TiO2 加入甲基乙烯基硅橡胶(MVSR)基体中,得到 O-MMT@TiO2/MVSR 介电复合材料。与在 MVSR 中直接混合 TiO2 和 O-MMT 的复合材料(O-MMT/TiO2/MVSR)相比,O-MMT@TiO2/MVSR 复合材料显著提高了机械性能、介电性能和储能性能。30 wt% O-MMT@TiO2/MVSR 复合材料的储能密度最高,达到 118.65 kJ/m3,比 15 wt%O-MMT/15 wt%TiO2/MVSR 的储能密度(48.84 kJ/m3)高出 142.9%。这项研究为制备高性能介电弹性体材料提供了一种有效的方法,可用于能量收集应用。Composites Part B: EngineeringAn experimental and analytical study of mode I fracture and crack kinking in thick adhesive jointsAli Shivaie Kojouri, Javane Karami, Kalliopi-Artemi Kalteremidou, Jialiang Fan, Akash Sharma, Anastasios P. Vassilopoulos, Veronique Michaud, Wim Van Paepegem, Danny Van Hemelrijckdoi:10.1016/j.compositesb.2024.111695厚粘合剂接头 I 型断裂和裂缝扭结的实验和分析研究This study investigates the fracture behavior of thick adhesive joints manufactured with composite adherends and bonded with an epoxy-based structural adhesive common to the wind turbine industry. For that purpose, double cantilever beam specimens with an adhesive thickness of approximately 10 mm and different pre-crack lengths are manufactured and tested under mode I loading. Analytical approaches are compared to assess the energy release rate, including the simple beam theory, modified beam theory, compliance calibration method, and beam on an elastic and elastic-plastic foundation. In order to evaluate the applicability of the analytical approaches, an in-situ measurement method based on Digital Image Correlation is also employed to determine the energy release rate of the thick adhesive joints. The crack propagation angle is determined theoretically using the second-order crack kinking theory. A good correlation is observed between the theoretical predictions and experimental results. Furthermore, it is demonstrated that due to the T-stress, the crack tends to deviate from the middle of the joint and propagate towards the interface. By comparing different data reduction methods to evaluate the energy release rate of thick adhesive joints, recommendations for their fracture analysis are made, pinpointing the beam on an elastic and elastic-plastic foundation as the most suitable model.本研究探讨了用复合材料粘合剂制造并用风力涡轮机行业常用的环氧基结构粘合剂粘合的厚粘合接头的断裂行为。为此,制作了粘合剂厚度约为 10 毫米、预裂缝长度不同的双悬臂梁试样,并在模式 I 载荷下进行了测试。比较了评估能量释放率的分析方法,包括简单梁理论、修正梁理论、顺应性校准方法以及弹性和弹塑性基础上的梁。为了评估分析方法的适用性,还采用了基于数字图像相关性的现场测量方法来确定厚粘合剂接头的能量释放率。裂缝扩展角是利用二阶裂缝扭结理论从理论上确定的。理论预测与实验结果之间存在良好的相关性。此外,实验还证明,由于 T 形应力的作用,裂纹倾向于偏离接头中部并向界面方向扩展。通过比较不同的数据还原方法来评估厚粘接接头的能量释放率,为其断裂分析提出了建议,并指出弹性和弹塑性基础上的梁是最合适的模型。Composites Science and TechnologyBending shape memory properties and multi-scale viscoelastic behaviors of knitted-fabric reinforced polymer compositesYing Huang, Haipeng Ren, Yang Liu, Weilin Xu, Wei Zhaodoi:10.1016/j.compscitech.2024.110747 针织织物增强聚合物复合材料的弯曲形状记忆特性和多尺度粘弹性行为Knitted fabrics with easily deformable loop structure have the potential in the development of shape memory polymeric composites with large recovery deformations. The knitted fabric reinforced shape memory epoxy polymer composites (SMPC) were prepared in this work. The effects of loop densities, orientations and bending radii on shape memory properties of SMPC were investigated. The shape fixity ratio and shape recovery ratio of SMPC subjected to U-shaped bending radius of 5 mm are above 98%. The shape recovery force of SMPC can reach up to 5.9 N. The thermodynamic properties of SMP were also characterized to obtain mechanical parameters and a user-defined material subroutine (UMAT) of shape memory epoxy polymer (SMEP) was written. Based on viscoelastic theory and the multi-scale geometrical structures, the macroscopic homogeneous thermodynamic model and mesoscopic thermodynamic model of knitted fabric reinforced SMPC were established to study the macro-scale stress distribution and meso-scale deformation evolution during shape memory process, respectively. The neutral surface position of SMPC during bending deformation is offset inner. The unique anisotropic loop structure of knitted fabric determines the shape memory behavior of the SMPC. Finally, micro-CT characterizations of knitted fabric reinforced SMPC were conducted to further understand the loop deformation mechanism during shape memory process. This study will provide important theoretical and technical support for large deformation structure design and deformation prediction of smart composites.具有易变形环状结构的针织物具有开发具有大恢复变形的形状记忆聚合物复合材料的潜力。本研究制备了针织物增强环氧聚合物形状记忆复合材料(SMPC)。研究了环密度、取向和弯曲半径对 SMPC 形状记忆性能的影响。在半径为 5 毫米的 U 形弯曲条件下,SMPC 的形状固定率和形状恢复率均在 98% 以上。还对 SMP 的热力学性质进行了表征,以获得力学参数,并编写了形状记忆环氧聚合物(SMEP)的用户自定义材料子程序(UMAT)。基于粘弹理论和多尺度几何结构,建立了针织物增强 SMPC 的宏观均匀热力学模型和中观热力学模型,分别研究了形状记忆过程中的宏观应力分布和中观变形演化。在弯曲变形过程中,SMPC 的中性面位置为内偏移。针织物独特的各向异性环状结构决定了 SMPC 的形状记忆行为。最后,对针织物增强的 SMPC 进行了显微 CT 表征,以进一步了解形状记忆过程中的环变形机制。这项研究将为智能复合材料的大变形结构设计和变形预测提供重要的理论和技术支持。来源:复合材料力学仿真Composites FEM

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