今日更新:Composite Structures 5 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Science and Technology 2 篇
SIMP Phase-field topology optimisation framework to maximise fracture resistance in FGMs
Pavan Kumar Asur Vijaya Kumar, Pengfei Li, Jose Reinoso, Qi Chang He, Julien Yvonnet, Marco Paggi
doi:10.1016/j.compstruct.2023.117750
SIMP 相场拓扑优化框架,最大限度提高 FGM 的抗断裂性
In this study, we explore the use of SIMP topology optimization and the phase field approach to fracture to maximize fracture resistance in functionally graded materials (FGMs) in the presence of a second phase. We derive a mathematical formulation using a consistent derivation of the second law of thermodynamics to maximize the external work under the constraints of volume fraction. We also demonstrate that, for every distribution of the density function, the topology optimization problem Γ−Converges. We highlight the significant difference between the fracture resistance in FGMs and homogeneous materials. We investigate the crack propagation path along with the optimum topology for the FGM under different grading profiles, elastic mismatch ratio, strength mismatch ratio, and inclusion mismatch ratio. We present several numerical examples to demonstrate the predictive capability of the presented model. A comparison between the initial design guess and the final optimized design is also provided for each example, to further assess the model’s capability.
在本研究中,我们探讨了如何利用 SIMP 拓扑优化和相场断裂法,在存在第二相的功能分级材料 (FGM) 中实现断裂阻力最大化。我们利用热力学第二定律的一致推导得出了一个数学公式,即在体积分数的约束下最大化外部功。我们还证明,对于密度函数的每一种分布,拓扑优化问题Γ-收敛。我们强调了 FGM 与均质材料在抗断裂性方面的显著差异。我们研究了不同级配剖面、弹性错配比、强度错配比和包容错配比条件下 FGM 的裂纹传播路径和最佳拓扑结构。我们列举了几个数值示例来证明所提出模型的预测能力。我们还对每个实例的初始设计猜测和最终优化设计进行了比较,以进一步评估模型的能力。
Hybrid Deep Convolutional Networks for the Autonomous Damage Diagnosis of Laminated Composite Structures
Muhammad Muzammil Azad, Heung Soo Kim
doi:10.1016/j.compstruct.2023.117792
用于层状复合结构自主损伤诊断的混合深度卷积网络
This article presents a robust autonomous damage diagnosis method using hybrid deep convolutional networks for the damage diagnosis of laminated composite structures. Inspired by the potential of deep learning models to autonomously extract deep discriminative features and machine learning models that provide better diagnosis on limited data, the current research integrates deep convolutional networks, namely convolutional neural networks (CNN) and convolutional autoencoder (CAE), with support vector machines (SVM) to build hybrid damage detection models. The proposed hybrid models incorporate the advantages of both convolutional operations to extract deep features, and SVM to diagnose using limited feature data. The proposed hybrid models are validated using random vibrational signals for one healthy and two delamination states of laminated composites. The results showed improved damage detection performance compared to the conventional methods, with lower computational costs. Additionally, the hybrid methods autonomously extracted deep discriminative features, eliminating the need for manual damage-sensitive feature extraction.
本文针对层状复合材料结构的损伤诊断,提出了一种使用混合深度卷积网络的鲁棒自主损伤诊断方法。受深度学习模型在自主提取深度判别特征和机器学习模型在有限数据上提供更好诊断的潜力的启发,目前的研究将深度卷积网络(即卷积神经网络(CNN)和卷积自动编码器(CAE))与支持向量机(SVM)集成在一起,以建立混合损伤检测模型。所提出的混合模型结合了卷积运算和 SVM 的优点,前者可提取深度特征,后者可利用有限的特征数据进行诊断。针对层状复合材料的一种健康状态和两种分层状态,使用随机振动信号对所提出的混合模型进行了验证。结果表明,与传统方法相比,损伤检测性能提高了,计算成本降低了。此外,混合方法还能自主提取深度判别特征,从而无需手动提取损伤敏感特征。
Probabilistic aeroelastic analysis of high-fidelity composite aircraft wing with manufacturing variability
Michael McGurk, Olivia Stodieck, Jie Yuan
doi:10.1016/j.compstruct.2023.117794
具有制造变异性的高保真复合材料飞机机翼的概率气动弹性分析
Safety margins of aerospace structures can be improved through altering the laminate parameters of composite materials to increase flutter and divergence velocities. Existing work demonstrates the impact of material uncertainties on low-fidelity structural models that are not sufficient to represent realistic aircraft designs. A gap exists in quantifying laminate parameter uncertainties on aeroelasticity for high-fidelity three-dimensional composite structures in realistic tailored designs. This paper puts forward an efficient methodology for uncertainty quantification on the aeroelastic characteristics of three-dimensional composite structures using FE-based parametric composite models and advanced Kriging surrogate models. The methodology is tested on both low and high fidelity case studies to represent the composite wing structure. Similarities between the case studies are observed in the coefficient of variance of all hard flutter modes being within 0.15-1.4% of each other. The difference was found for divergence and soft flutter velocities where the coefficient of variance could be over ten times higher in the high fidelity case. Global sensitivity results revealed similar physical behavior cases can be produced from both studies at early design stages.
通过改变复合材料的层压参数来提高扑翼和发散速度,可以改善航空航天结构的安全裕度。现有工作证明了材料不确定性对低保真结构模型的影响,而低保真结构模型不足以代表现实的飞机设计。在量化高保真三维复合材料结构的层状参数不确定性对现实定制设计的气动弹性的影响方面还存在差距。本文利用基于 FE 的参数化复合材料模型和先进的 Kriging 代理模型,提出了一种对三维复合材料结构的气动弹性特性进行不确定性量化的有效方法。该方法在代表复合材料机翼结构的低保真和高保真案例研究中进行了测试。案例研究的相似之处在于所有硬扑翼模式的方差系数都在 0.15-1.4% 之间。不同之处在于发散和软扑翼速度,高保真情况下的方差系数可能高出 10 倍以上。全局灵敏度结果表明,在早期设计阶段,两种研究都能产生类似的物理行为案例。
Stability and load carrying capacity of thin-walled composite columns with square cross-section under axial compression
Patryk Rozylo, Hubert Debski
doi:10.1016/j.compstruct.2023.117795
方形截面薄壁复合材料柱在轴向压缩下的稳定性和承载能力
The study aimed to analyse the stability and load-carrying capacity of compressed thin-walled composite columns subjected to axial compression. The subject of the survey was composite columns with closed square cross-sections made of carbon-epoxy composite. Different lay-ups of the composite material characterised the test specimens - several cases of lay-ups were considered. The application of the subject of the research is closely related to the use of these elements as load-carrying elements of aerospace and building structures. The requirements for such structures are closely related to the provision of a large reserve of load-carrying capacity after buckling. Experimental testing was carried out using a universal testing machine and other testing techniques, where acoustic emission, an optical deformation measurement system, and a digital microscope, among others, were used. Numerical simulations using the finite element method were carried out parallel to the experimental studies. In the case of FEA simulations, original numerical models were developed considering known failure models of the composite material. For both empirical studies and FEM simulations, an in-depth analysis of the buckling and post-buckling states was carried out, considering the failure phase of the composite material. The novelty of the present work was the development of original FEM models, allowing faithful reproduction of experimental studies conducted on physical models, as well as the use of research methods to determine the load-carrying capacity of composite structures.
该研究旨在分析受轴向压缩的薄壁复合材料柱的稳定性和承载能力。调查对象是由碳-环氧复合材料制成的具有封闭方形截面的复合材料柱。复合材料的不同铺设方式决定了试样的特性--考虑了多种铺设方式。研究课题的应用与将这些元件用作航空航天和建筑结构的承重元件密切相关。对此类结构的要求与屈曲后提供大量承载能力储备密切相关。实验测试使用了万能试验机和其他测试技术,包括声发射、光学变形测量系统和数码显微镜等。在进行实验研究的同时,还使用有限元法进行了数值模拟。在有限元模拟中,根据已知的复合材料失效模型开发了原始数值模型。在经验研究和有限元模拟中,考虑到复合材料的失效阶段,对屈曲和屈曲后状态进行了深入分析。本研究的新颖之处在于开发了原始有限元模型,从而忠实地再现了在物理模型上进行的实验研究,并利用研究方法确定了复合材料结构的承载能力。
On the nonlinear dynamics of a multi-scale flexoelectric cylindrical shell
Ashgar Faramarzi Babadi, Krzysztof Kamal Żur, Yaghoub Tadi Beni
doi:10.1016/j.compstruct.2023.117741
论多尺度柔电圆柱壳的非线性动力学
The flexoelectric property shows the relationship between the strain gradient and the electric polarization and has a significant effect on static and dynamic responses of structures at small scales such as micro and nano. Nowadays, experimental studies for intelligent/composite ultra-small mechanical systems are complex, challenging, and in most cases still impossible, especially for nonlinear dynamic behavior analysis. For the first time, this study presents an advanced and complex generalized model for the nonlinear vibrations of a piezo-flexoelectric mechanical system based on a cylindrical shell. It should be noted, that the formulated boundary value problem is generalized, well-posed, and can be applied to the system at micro and nano scales. Hamilton's variational principle as well as assumptions of the first-order shear deformation theory (FSDT) and reformulated flexoelectric theory were used to derive equations of motion of the multi-scale intelligent shell system. To introduce nonlinear effects, von-Kármán strains are applied. Appropriate classical and non-classical mechanical/electric boundary conditions as well as higher-order forces and moments are determined to fully close the formulated problem. The Galerkin method combined with the GDQM, supported by the displacement control strategy and the weighted residual method, have been used to discretize and solve the nonlinear governing equations of the shell with different boundary conditions. Good convergence between the current results and the results from previous studies for simpler cases of the shell was proved. Furthermore, the results showed that geometric ratios of the structure, gradation of material properties, thickness of the flexoelectric layers, and the size effect parameter significantly influence the nonlinear frequency of the structure under the direct flexoelectric effect.
挠电特性显示了应变梯度与电极化之间的关系,对微米和纳米等小尺度结构的静态和动态响应具有重要影响。目前,智能/复合超小型机械系统的实验研究非常复杂、具有挑战性,在大多数情况下仍无法进行,尤其是非线性动态行为分析。本研究首次针对基于圆柱形壳体的压电柔电机械系统的非线性振动提出了一个先进而复杂的通用模型。值得注意的是,所提出的边界值问题是广义的、求解良好的,可应用于微米和纳米尺度的系统。汉密尔顿变分原理以及一阶剪切变形理论(FSDT)和重构柔电理论的假设被用来推导多尺度智能壳系统的运动方程。为了引入非线性效应,应用了 von-Kármán 应变。确定了适当的经典和非经典机械/电气边界条件以及高阶力和力矩,以完全解决所提出的问题。在位移控制策略和加权残差法的支持下,Galerkin 方法与 GDQM 相结合,用于离散化和求解具有不同边界条件的壳体非线性控制方程。对于较简单的壳体,目前的结果与之前的研究结果具有良好的收敛性。此外,研究结果表明,结构的几何比率、材料特性的等级、挠电层的厚度以及尺寸效应参数对直接挠电效应下结构的非线性频率有显著影响。
Ultra-tough architected adhesive joints for integrated composite processing and bonding
Charline van Innis, Michal K. Budzik, Thomas Pardoen
doi:10.1016/j.compositesa.2023.107949
用于集成复合材料加工和粘接的超强结构胶粘剂接头
Deployment of advanced polymer-based composites in critical structures requires, among others, breakthroughs in adhesive bonding solutions. Indeed, available methods suffer from limited fracture toughness of adhesives and from time-consuming bonding processes. Here, we demonstrate a novel concept of architected thermoplastic joints with exceptional fracture resistance larger than 5000 J/m2 (4267±846 J/m2), fully integrated with the composite resin transfer molding process, hence simultaneously targeting both limitations. This extreme toughness is activated through controlled 3D printed hollow pattern within a Nylon bondline. A synergetic combination of plastic dissipation, crack deflection, branching and arrest is tuned by changing the pattern characteristics. Three failure regimes are unraveled through fractographic analyses and finite element models. A stress-at-a-distance fracture criterion, identified for each constituent, quantitatively predicts the toughness variations along the crack path. This approach, amenable to dissimilar bonding between metals and composites, paves the road towards novel and higher performance structures and manufacturing approaches.
在关键结构中使用先进的聚合物基复合材料需要在粘合剂粘接解决方案方面取得突破。事实上,现有的方法存在粘合剂断裂韧性有限和粘合过程耗时的问题。在这里,我们展示了一种新颖的热塑性塑料接头设计理念,这种接头具有大于 5000 J/m2 (4267±846 J/m2)的超强断裂韧性,并与复合树脂传递成型工艺完全集成,从而同时解决了这两个局限性。这种极强的韧性是通过在尼龙粘合线内控制三维打印中空图案来实现的。通过改变图案特征,可对塑性耗散、裂纹偏转、分支和断裂进行协同组合。通过断裂分析和有限元模型揭示了三种破坏机制。为每种成分确定的距离应力断裂标准可定量预测裂纹路径上的韧性变化。这种方法适用于金属和复合材料之间的异种粘接,为新型高性能结构和制造方法铺平了道路。
Enhanced design of dual dynamic cross-linked rubber composites: Achieving self-healing and recyclability through imine and metal-ligand bonding
Lingfeng Cui, Guanyue Zeng, Xin Li, Feng Bian, Yuzhu Xiong
doi:10.1016/j.compscitech.2023.110382
增强双动态交联橡胶复合材料的设计:通过亚胺和金属配体键合实现自愈合和可回收性
The quest to confer self-healing and recyclable properties to conventional rubber is a prominent research area in the rubber industry. This study presents the novel construction of a self-healing and recyclable rubber composite by employing imine bond and Cu2+-imine cross-linking the polybutadiene rubber matrix and Cu2+-imidazole groups cross-linking at the silica-rubber interface. The introduction of imine bonded cross-linked imparts high elasticity to the rubber, while the Cu2+-imidazole complex serves as a bridge, enhancing the interfacial interaction between the silica and rubber matrix. The Cu2+-N (Cu2+-imidazole and Cu2+-imine) complexes not only improves silica dispersion but also acts as a sacrificial unit, thereby enhancing the mechanical properties of the rubber composites. The addition of 0.2 mmol anhydrous copper (II) chloride (CuCl2) results in a significant increase in tensile strength and Young's modulus of the samples (1.04 and 3.91 MPa), with improvements of 181 % and 407 %, respectively, compared to the pure samples. Additionally, the highly dynamic nature of the imine bond and the Cu2+-N (Cu2+-imidazole and Cu2+-imine) complexes imparts excellent self-healing and recyclable properties to the material, exhibiting repair efficiency and recycling recovery of up to 90 % (tensile strength). Therefore, this work opens a new avenue for the design and development of self-healing, recyclable rubber composites.
赋予传统橡胶自愈合和可回收特性是橡胶行业的一个突出研究领域。本研究通过采用亚胺键和 Cu2+-imine 交联聚丁二烯橡胶基体,以及 Cu2+-imidazole 基团交联白炭黑-橡胶界面,提出了自愈合和可回收橡胶复合材料的新型结构。亚胺键交联的引入为橡胶带来了高弹性,而 Cu2+-imidazole 复合物则起到了桥梁的作用,增强了白炭黑与橡胶基体之间的界面相互作用。Cu2+-N(Cu2+-咪唑和 Cu2+-亚胺)复合物不仅能改善白炭黑的分散性,还能作为牺牲单元,从而提高橡胶复合材料的机械性能。添加 0.2 mmol 的无水氯化铜(II)(CuCl2)后,样品的拉伸强度和杨氏模量显著增加(1.04 和 3.91 兆帕),与纯样品相比,分别提高了 181 % 和 407 %。此外,亚胺键和 Cu2+-N(Cu2+-咪唑和 Cu2+-亚胺)复合物的高动态性质赋予了材料优异的自愈和可回收特性,显示出高达 90% 的修复效率和回收率(拉伸强度)。因此,这项工作为设计和开发自愈合、可回收的橡胶复合材料开辟了一条新途径。
UHMWPE fibers reinforced gradient structure to break the thermal-dielectric-mechanical trade-off in high filled polyethylene
Lin Pan, Yongliang Wang, Chunfeng Wang, Zhidong Han
doi:10.1016/j.compscitech.2023.110375
超高分子量聚乙烯纤维增强梯度结构,打破高填充聚乙烯的热-电-机械平衡
In view of the diversified demands for thermal management materials in soaring developments of electrical systems, the high thermally conductive composites often suffer from their poor mechanical properties and electrical insulation. Targeting at enhancing simultaneous thermal conductivity, dielectric and mechanical properties, the fibers reinforced gradient structured polyethylene-based composites consisting of ultrahigh molecular weight polyethylene (UHMWPE) fiber layer and hybrid-filled layer are proposed and successfully prepared by simple overlapping-hot pressing. The fibers collaborated with gradient arrangement of hybrid-filled layer in modulating the temperature, electric and stress field distribution. The resultant as-designed composites exhibit excellent thermal conductivity of 0.91 W/(m·K), ultrahigh tensile strength of 104.7 MPa and superior breakdown strength of 161.5 kV/mm, which are increased by 18%, 1374% and 37% than those of the homogeneous composites, respectively. This work provides a new strategy for manufacturing high-performance polymer-based composites.
鉴于电气系统的飞速发展对热管理材料的多样化需求,高导热复合材料往往存在机械性能和电气绝缘性能差的问题。为了同时提高热导率、介电性能和机械性能,我们提出了由超高分子量聚乙烯(UHMWPE)纤维层和混合填充层组成的纤维增强梯度结构聚乙烯基复合材料,并通过简单的重叠热压工艺成功制备了这种复合材料。纤维与混合填充层的梯度排列共同调节了温度、电场和应力场的分布。所制备的复合材料具有 0.91 W/(m-K)的优异热导率、104.7 MPa 的超高拉伸强度和 161.5 kV/mm 的超强击穿强度,分别比均质复合材料提高了 18%、1374% 和 37%。这项工作为制造高性能聚合物基复合材料提供了一种新策略。