今日更新:Composite Structures 3 篇,Composites Part A: Applied Science and Manufacturing 2 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 1 篇
A two-layered cross-ply laminate model for a single-ply satin woven fabric composite under thermal loads
Jungwan Lee, Woo-seop Kim, Jung-soo Kim, Moon-kwang Um, Sang Woo Kim, Jin Woo Yi, Youngseok Oh, Seong Su Kim
doi:10.1016/j.compstruct.2024.118619
热载荷作用下单层缎面机织物复合材料的两层交叉层压模型
The dominant fiber direction of a single-ply satin woven fabric is different depending on whether it is the upper or lower side. This affects the thermal distortion of laminates and principal curvature directions. Therefore, we propose a two-layered cross-ply laminate model for a single-ply satin woven fabric composite to consider the dominant fiber directions. To verify our model, we derive analytical solutions of antisymmetric angle-ply laminates under thermal loads for the conventional and proposed models. By comparing the analytical solutions with experimental results of unidirectional and satin woven fabric composites, we confirm that the proposed model accurately predicts the principal curvature direction.
单股缎面机织物的主导纤维方向是不同的,取决于它是上侧还是下侧。这影响了层压板的热变形和主曲率方向。因此,我们提出了一种考虑主导纤维方向的单层缎面机织物复合材料的双层交叉层压模型。为了验证我们的模型,我们推导了传统模型和提出的模型在热载荷下的反对称角层合板的解析解。通过将解析解与单向和缎面机织物复合材料的实验结果进行比较,证实了所提出的模型能够准确地预测主曲率方向。
Phononic crystal-based acoustic demultiplexer design via bandgap-passband topology optimization
Yuhao Bao, Zhiyuan Jia, Qiming Tian, Yangjun Luo, Xiaopeng Zhang, Zhan Kang
doi:10.1016/j.compstruct.2024.118622
基于带隙通带拓扑优化的声子晶体声学解复用器设计
The wave demultiplexer, which selectively transports specific frequencies from incident waves, has garnered considerable interest for its applications across various engineering disciplines. This study introduces a new customizable design method for acoustic demultiplexers based on the topology optimization of phononic crystals (PnCs). To achieve an acoustic demultiplexer capable of filtering multiple frequencies, a topological design model for PnCs that simultaneously considers bandgaps and passbands is proposed. By assembling the optimized PnCs within the structure, the demultiplexer can separate sound waves of different frequencies into distinct output channels. In the optimization model, an objective function based on transmission rates is proposed to determine whether specific frequencies fall within the specified bandgap or passband. To solve this complex topology optimization problem, the Kriging-based material-field series expansion (KG-MFSE) approach is used to describe the material distribution and optimization of PnCs. The designed PnC unit cells can be directly integrated into the demultiplexer without requiring additional space. Based on specified combinations of passbands and bandgaps, different PnCs are designed to realize a programmable acoustic demultiplexer capable of filtering various sound waves. Numerical analyses demonstrate that the constructed acoustic demultiplexer effectively separates the specified frequencies. Finally, experimental validation of the 3D printed acoustic demultiplexer model confirms the effectiveness of the proposed optimization method.
波解复用器选择性地从入射波中传输特定频率,由于其在各种工程学科中的应用而引起了相当大的兴趣。提出了一种基于声子晶体拓扑优化的声学解复用器定制设计方法。为了实现能够过滤多个频率的声学解复用器,提出了一种同时考虑带隙和通带的pnc拓扑设计模型。通过在结构内装配优化后的pnc,解复用器可以将不同频率的声波分离到不同的输出通道中。在优化模型中,提出了一个基于传输速率的目标函数来确定特定频率是否落在指定的带隙或通带内。为了解决这一复杂的拓扑优化问题,采用基于kriging的材料场级数展开(KG-MFSE)方法来描述pnc的材料分布和优化。所设计的PnC单元可以直接集成到解复用器中,而不需要额外的空间。基于特定的通带和带隙组合,设计了不同的pnc来实现能够过滤各种声波的可编程声学解复用器。数值分析表明,所设计的声解复用器能有效地分离指定频率。最后,对3D打印声复用器模型进行了实验验证,验证了所提优化方法的有效性。
Novel pre-folded lattice metamaterial for two-stage deformation and variable Poisson’s ratio properties under quasi-static compression
Wenyou Zha, Weikai Shi, Yongtao Yao, Yanju Liu
doi:10.1016/j.compstruct.2024.118623
准静态压缩下具有两阶段变形和变泊松比特性的新型预折叠晶格超材料
When honeycomb structures are compressed in the axial direction, they are prone to high crushing loads and structural instability. Folded structures with origami ideas can overcome this defect. In this work, a novel pre-folded lattice metamaterial is proposed, with notable energy absorption capacity and vibration isolation properties. The geometry of the structure is described, and a theoretical model of the deformation platform at various stages is established. The compression and energy absorption properties of the structure are evaluated by compression experiments and finite element simulations. The findings indicate that the structure has two smooth and stable platform stages under quasi-static compression. This feature effectively avoids the initial crushing force of compression energy. It possesses a bistable property during the structural deformation process in the first stage. In the meantime, the compression deformation has the characteristic of variable Poisson’s ratio. Furthermore, the vibration modes and vibration isolation capacity of the variable folding angle are investigated as well. Pre-folded lattice metamaterial with 49.1° exhibits the broadest vibration isolation region across the 0–500 Hz spectrum. This work can provide a novel perspective for the integrated design of structural load-bearing and vibration isolation functions.
蜂窝结构在轴向受压时,容易产生较大的破碎载荷和结构失稳。采用折纸思想的折叠结构可以克服这一缺陷。本文提出了一种新型的预折叠晶格超材料,具有显著的吸能和隔振性能。描述了结构的几何形状,建立了各阶段变形平台的理论模型。通过压缩实验和有限元模拟对结构的压缩性能和吸能性能进行了评价。结果表明,在准静态压缩作用下,该结构具有两个光滑稳定的平台阶段。这一特点有效地避免了压缩能的初始破碎力。在第一阶段的结构变形过程中,它具有双稳性。同时,压缩变形具有变泊松比的特征。此外,还研究了变折叠角结构的振动模态和隔振能力。49.1°的预折叠晶格超材料在0-500 Hz频谱上表现出最宽的隔振区域。本研究为结构的承载与隔振功能的一体化设计提供了新的思路。
The microstructure, mechanical properties and tribological behaviors of YB2C2 reinforced Cu matrix composites prepared by spark plasma sintering
Hao Zhang, Yueming Li, Zikuan Xu, Ying Fu, Meishuan Li, Guorui Zhao, Jixin Chen
doi:10.1016/j.compositesa.2024.108500
放电等离子烧结制备YB2C2增强Cu基复合材料的显微组织、力学性能和摩擦学性能
The first ternary layered ceramic reinforced copper matrix composites, Cu-xYB2C2 (x = 0, 5, 10, 20 vol%) composites without interfacial reaction were successfully fabricated by spark plasma sintering at 950 °C. Microstructures, phase compositions, mechanical properties and tribological behaviors of Cu-YB2C2 composites were investigated. The results indicated that Cu-YB2C2 composites had good chemical compatibility. Compared with pure copper, the hardness, tensile strength and wear resistance of Cu-YB2C2 composites were all significantly improved. Cu-10 vol% YB2C2 composites exhibited the highest tensile strength and the best tribological performance, with an ultimate tensile strength of 203 ± 2 MPa and a wear rate of (3.1 ± 0.4) × 10−8 mm3/mm. The wear mechanism changed from adhesive wear to a combination of adhesive wear and abrasive wear with the addition of YB2C2, while surface oxidation and fatigue were also present in all tribosystems. Cu-YB2C2 composites have application prospects in electrical contacts and aerospace fields.
采用火花等离子烧结技术,在950 ℃下制备了第一个无 界面反应的三元层状陶瓷增强铜基复合材料Cu-xYB2C2 (x = 0,5,10,20 vol%)。研究了Cu-YB2C2复合材料的显微组织、相组成、力学性能和摩擦学行为。结果表明,Cu-YB2C2复合材料具有良好的化学相容性。与纯铜相比,Cu-YB2C2复合材料的硬度、抗拉强度和耐磨性均有显著提高。Cu-10 卷% YB2C2复合材料表现出最高的抗拉强度和最好的摩擦学性能,极限抗拉强度203 ±2 MPa和磨损率(3.1 ±0.4 ) × 10−8 mm3 /毫米。随着YB2C2的加入,磨损机制从黏着磨损转变为黏着磨损和磨粒磨损的结合,同时在所有摩擦系统中也存在表面氧化和疲劳。Cu-YB2C2复合材料在电接触和航空航天领域具有广阔的应用前景。
Structure and process optimization and performance analysis of carbon fiber composite industrial robot big arm
Zhang Rongtao, Meng Zhuo, Cai Gaowei, Sun Zhijun, Zhang Yujing
doi:10.1016/j.compositesa.2024.108495
碳纤维复合材料工业机器人大臂结构工艺优化及性能分析
Lightweighting of the industrial robot can improve the load-to-weight ratio and increase the robot’s movement speed and accuracy. The structure and molding process of the big arm are optimized to reduce weight and enhance performance. The structural optimization changes the metal flange’s fixation method from adhesive bonding to direct pre-embedding, reducing the positioning error of the metal flange. A new molding process has changed the preparation method of the preform from triaxial braiding to a braiding-layering-winding form, enhancing the big arm’s overall performance. The numerically computed braiding trajectory is mapped onto the finite element model to analyze the stiffness and modal of the big arm. Experimental results demonstrate a 23 % reduction in big arm’s weight and a 3.81 % decrease in robot deformation. The fundamental frequencies of the two arms before and after optimization are 490 Hz and 563 Hz, respectively. The optimized arm is less prone to resonance.
工业机器人的轻量化可以提高机器人的载重比,提高机器人的运动速度和精度。对大臂的结构和成型工艺进行了优化,减轻了重量,提高了性能。通过结构优化,将金属法兰的固定方式由胶粘接改为直接预埋,减小了金属法兰的定位误差。一种新的成型工艺将预制件的制备方法从三轴编织改为编织-分层-缠绕形式,提高了大臂的整体性能。将数值计算得到的编织轨迹映射到有限元模型上,分析大臂的刚度和模态。实验结果表明,大臂的重量减少了23% %,机器人的变形减少了3.81 %。优化前后两臂的基频分别为490 Hz和563 Hz。优化后的手臂不容易产生共振。
Intelligent fatigue damage tracking and prognostics of composite structures utilizing raw images via interpretable deep learning
P. Komninos, A.E.C. Verraest, N. Eleftheroglou, D. Zarouchas
doi:10.1016/j.compositesb.2024.111863
利用可解释深度学习的原始图像对复合材料结构进行智能疲劳损伤跟踪和预测
In recent years, prognostics gained attention in various industries by optimizing maintenance, boosting operational efficiency, and preventing costly downtime. Central to prognostics is the Remaining Useful Life (RUL), representing the critical time before system failure. Deep learning advancements facilitate RUL forecasting by extracting features from diverse data formats such as time series, images, or sequences thereof, in one, two, or three dimensions, respectively. Yet, predicting RUL from image sequences often relies heavily on resource-intensive techniques like digital image correlation, complicating data acquisition. To address challenges with high-dimensional data and unreliable models, this study introduces ISTRUST, an innovative Transformer-based architecture. ISTRUST (Interpretable Spatiotemporal TRansformer for Understanding STructures) tackles the dual challenges posed by high-dimensional data and the black-box nature of existing models. Leveraging Transformers’ attention mechanism, ISTRUST breaks down the spatiotemporal domain, effectively realizing interpretable RUL predictions under uncertainty using only sparse raw image sequences as input. Evaluated on fatigue-loaded composite samples showcasing crack propagation, ISTRUST interprets the relation between cracks and RUL via the attention mechanism. The results substantiate its capacity to interpret and clarify instances in which predictions may exhibit variability in accuracy. Through the attention mechanism, a strong correlation between the model’s spatiotemporal focus and the RUL predictions is established, making it, to the best of our knowledge, the first model to provide interpretable stochastic RUL predictions directly from sequential images of this nature.
近年来,通过优化维护、提高运营效率和防止代价高昂的停机时间,预测技术在各个行业受到了关注。预测的核心是剩余使用寿命(RUL),表示系统故障前的关键时间。深度学习的进步通过从不同的数据格式(如时间序列、图像或其序列)中分别提取一维、二维或三维的特征,促进了RUL预测。然而,从图像序列预测RUL通常严重依赖于资源密集型技术,如数字图像相关,使数据采集复杂化。为了应对高维数据和不可靠模型的挑战,本研究引入了基于transformer的创新架构isttrust。isttrust(可解释时空转换器,用于理解结构)解决了高维数据和现有模型的黑箱特性带来的双重挑战。利用变形金刚的注意力机制,isttrust分解了时空域,仅使用稀疏的原始图像序列作为输入,有效地实现了不确定性下可解释的规则预测。通过对疲劳加载的复合材料试样进行裂纹扩展评估,istust通过注意机制解释了裂纹与RUL之间的关系。结果证实了其解释和澄清预测可能表现出准确性变化的实例的能力。通过注意机制,建立了模型的时空焦点与RUL预测之间的强相关性,使其成为据我们所知的第一个直接从这种性质的序列图像中提供可解释的随机RUL预测的模型。
Atomic force microscopy-based nanoindentation technique for characterizing the transverse and shear moduli of flax fibers
P.V. Divakarraju, V. Pandurangan, M. Nithyadharan
doi:10.1016/j.compscitech.2024.110890
基于原子力显微镜的表征亚麻纤维横向模量和剪切模量的纳米压痕技术
Experimentally evaluating the elastic properties of flax fibers is challenging due to their complex hierarchical structure, and a standard test procedure for measuring their transverse and shear moduli is currently not reported in the literature. Hence, this study presents an atomic force microscopy (AFM) based nanoindentation technique to evaluate the transverse and shear moduli of flax fiber. A high-precision focused ion beam (FIB)-milling process was used to fabricate a flat surface for indentation along the longitudinal fiber cross-section of the fiber and transverse fiber cross-section by polishing the unidirectional (UD) lamina in order to evaluate the indentation modulus. Further, Swanson’s numerical contour approach was adopted to evaluate the elastic properties of the fiber from the measured indentation modulus. The accuracy of the experimentally obtained fiber properties is verified by using it in a micromechanics model for predicting the elastic properties of the UD lamina and comparing it with experimental results reported in the literature.
由于其复杂的层次结构,实验评估亚麻纤维的弹性特性具有挑战性,并且测量其横向和剪切模量的标准测试程序目前尚未在文献中报道。因此,本研究提出了一种基于原子力显微镜(AFM)的纳米压痕技术来评估亚麻纤维的横向和剪切模量。采用高精度聚焦离子束(FIB)铣削工艺,通过对单向(UD)薄片进行抛光,沿光纤的纵向纤维截面和横向纤维截面加工出一个平面进行压痕,以评估压痕模量。此外,采用Swanson数值轮廓法从实测压痕模量评价纤维的弹性性能。通过将实验所得的纤维性能用于预测UD层弹性性能的微观力学模型,并与文献报道的实验结果进行比较,验证了实验所得纤维性能的准确性。