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【新文速递】2024年3月19日复合材料SCI期刊最新文章

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

Composite Structures

Important contributions of metal interfaces on their tribological performances: From influencing factors to wear mechanisms

Guoqing Zhang, Jun Tang, Kang Yang, Ruili Wang, Yang Chen, Yahui Xiong, Chao Wu, Zhenjie Li, Yaqiong Wang, Haibo Lin

doi:10.1016/j.compstruct.2024.118027

金属界面对其摩擦学性能的重要影响:从影响因素到磨损机制

Metallic materials have attracted the considerable attentions owing to their remarkable tribological potentials, rendering them indispensable in the fields of manufacturing, aerospace, medical, and daily life. In the future, their utilization is poised to extend into electronic devices, energy storage, sensors, catalysts and other realms in order to enhance performance metrics, bolster stability and reduce costs. Notwithstanding various research have been undertaken on metal-based composites, the important influencing factors and wear mechanisms of metal-base friction interfaces have not been comprehensively reviewed. Therefore, this review summarizes these main influencing factors (e.g., material properties, service conditions, additives and energy effects) on tribological behaviors of metal interfaces, subsequently generalizes their wear mechanisms such as abrasion, adhesion, corrosion and fatigue. Finally, their development prospects and difficulties of the interface tribology are discussed in detail, thereby providing the in-depth insight of these fields for enriching actual applications.

金属材料因其卓越的摩擦学潜力而备受关注,成为制造、航空航天、医疗和日常生活领域不可或缺的材料。未来,为了提高性能指标、增强稳定性和降低成本,它们的应用将扩展到电子设备、能量存储、传感器、催化剂和其他领域。尽管对金属基复合材料进行了各种研究,但尚未对金属基摩擦界面的重要影响因素和磨损机制进行全面综述。因此,本综述总结了金属界面摩擦学行为的主要影响因素(如材料特性、使用条件、添加剂和能量效应),并归纳了磨损、粘附、腐蚀和疲劳等磨损机理。最后,详细讨论了界面摩擦学的发展前景和难点,从而为丰富实际应用提供了深入的见解。


Composites Part A: Applied Science and Manufacturing

Properties of shape memory polyimide composites with continuous “brick-and-mortar” layered structure: High flame retardancy, ablation resistance, and high mechanical properties

Xiaofei Wang, Yang He, Xinli Xiao, Yanju Liu, Jinsong Leng

doi:10.1016/j.compositesa.2024.108151

 

具有连续 "砖墙 "层状结构的形状记忆聚酰亚胺复合材料的性能:高阻燃性、耐烧蚀性和高机械性能

Shape memory polymer (SMP) is a type of smart materials mostly working below 200 ℃, which is difficult to be applied in the ultra-high temperature, even 1000 ℃. Herein, we have prepared shape memory polyimide composites (SMPIC) inspired by nacre “brick-and-mortar” layered structure. The SMPIC has the flame-retardant grade of V0 and the limiting oxygen index of 53.1% when the flame retardants amount is 20%. Besides, it has excellent resistance to high temperature airflow erosion, and the mass ablation ratio is 0.0053 g/s. After rapid thermal processing at 1000 ℃, the mechanical strength is 100 MPa, and the strength retention ratio is 103.3%. Also, the simple actuator can overturn iron blocks that are more than 8 times of its own weight, thus, the smart composite has huge application prospects in the high temperature environment, such as active morphing re-entry parachute, which provides reference for lightweight smart structures.

形状记忆聚合物(SMP)是一种智能材料,大多在 200 ℃ 以下工作,很难在超高温甚至 1000 ℃ 下应用。在此,我们受珍珠岩 "砖墙 "层状结构的启发,制备了形状记忆聚酰亚胺复合材料(SMPIC)。SMPIC 的阻燃等级为 V0,当阻燃剂用量为 20% 时,其极限氧指数为 53.1%。此外,它还具有优异的抗高温气流侵蚀能力,质量烧蚀比为 0.0053 g/s。经过 1000 ℃ 快速热处理后,其机械强度为 100 兆帕,强度保持率为 103.3%。同时,简单的致动器就能掀翻自身重量 8 倍以上的铁块,因此,该智能复合材料在高温环境下具有巨大的应用前景,如主动变形再入伞,为轻质智能结构提供了参考。


Composites Part B: Engineering

Hygrothermal progressive damage in open-hole compression of composite laminates with aligned carbon nanotube interlaminar reinforcement studied by X-ray micro-computed tomography

Reed Kopp, Xinchen Ni, Pontus Nordin, Per Hallander, Linnéa Selegård, Brian L. Wardle

doi:10.1016/j.compositesb.2024.111391

利用 X 射线显微计算机断层扫描技术研究带有对齐碳纳米管层间增强层的复合材料层板在开孔压缩过程中的湿热渐进损伤

Hierarchical nanoengineered composite laminates were created with through-thickness-aligned carbon nanotube (CNT) reinforcement of unidirectional carbon (micro) fiber/epoxy laminae in their failure-prone interlaminar regions, forming a multiscale “nanostitched” architecture. Motivated by previous mechanical enhancements for similar nanostitched laminates in ambient environments, hygrothermal effects on the 3D strengthening and toughening mechanisms of nanostitched laminates are investigated here for the first time, focusing on standard open-hole compression (OHC) testing of quasi-isotropic laminates. We report that the hygrothermal conditions of −55 °C/DRY and 100 °C/DRY correspond to ultimate strength increases of 2.6% and 5.9%, respectively, for nanostitched laminates over the baseline; and, room temperature/50% relative humidity (RT/50% RH) and 100 °C/wet conditions exhibit no change in ultimate strength, suggesting correlation of positive nanostitch effects with increased polymer brittleness. Subsequently, damage progression in step-wise interrupted OHC loading for selected hygrothermal conditions (RT/50% RH and 100 °C/DRY) was performed in coordination with high-resolution ex situ X-ray micro-computed tomography for various load steps up to 98% of failure load. No clear differences due to nanostitch in the damage progression are found up to 98% of ultimate strength, suggesting that the reinforcement effect is associated with interlaminar strength at ultimate load, and not pre-ultimate damage. This study contributes first insights from high-resolution experimental mapping of nanostitched composite progressive damage subjected to hygrothermal conditions that may guide and inform mechanical enhancement approaches and improved progressive damage models. Future work is suggested to expand the environmental conditions considered, as well as visualize progressive damage nearer to failure to identify nanostitch effects on complex multimodal failure.

在单向碳(微)纤维/环氧层压板的易失效层间区域,采用贯通对齐的碳纳米管(CNT)对单向碳(微)纤维/环氧层压板进行加固,形成多尺度的 "纳米缝合 "结构,从而制造出分层纳米工程复合层压板。受先前类似纳米缝合层压板在环境中的力学增强效果的启发,我们在此首次研究了湿热对纳米缝合层压板三维增强和增韧机制的影响,重点是准各向同性层压板的标准开孔压缩(OHC)测试。我们发现,在-55 °C/DRY和100 °C/DRY的湿热条件下,纳米缝合层压板的极限强度比基线分别提高了2.6%和5.9%;而在室温/50%相对湿度(RT/50% RH)和100 °C/湿条件下,极限强度没有变化,这表明纳米缝合的正效应与聚合物脆性的增加有关。随后,在选定的湿热条件(RT/50% RH 和 100 °C/DRY)下,通过高分辨率原位 X 射线显微计算机断层扫描,对各种负载阶跃(最高达失效负载的 98%)进行了分步间断 OHC 负载的损伤进展。在达到极限强度的 98% 时,未发现纳米缝在损伤发展过程中产生明显差异,这表明加固效应与极限载荷时的层间强度有关,而不是与终极损伤前有关。这项研究首次通过高分辨率实验绘制了纳米缝合复合材料在湿热条件下的渐进损伤图,为机械增强方法和改进的渐进损伤模型提供了指导和信息。建议今后的工作扩大考虑的环境条件,并在接近失效时对渐进损伤进行可视化,以确定纳米缝合对复杂的多模态失效的影响。



来源:复合材料力学仿真Composites FEM
ACTMechanicalAdditiveInspireSTEPS疲劳复合材料航空航天电子材料多尺度
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首次发布时间:2024-11-13
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【新文速递】2024年3月26日复合材料SCI期刊最新文章

今日更新:Composite Structures 11 篇Composite StructuresDynamic response of magneto-electro-elastic composite plates lying on visco-Pasternak medium subjected to blast loadQuoc-Hoa Pham, Van Ke Tran, Phu-Cuong Nguyendoi:10.1016/j.compstruct.2024.118054位于粘滞-帕斯捷尔纳克介质上的磁弹性复合板在爆炸荷载作用下的动态响应This is the first endeavor to present a finite element approach to predict free oscillation and transient characteristics of magneto-electro-elastic (MEE) composite rectangular and elliptical plates resting on the visco-Pasternak medium in a hygro-thermal environment subjected to blast load. The variation of electric and magnetic potentials along the thickness direction of the MEE plate is determined via the Maxwell equation and magneto-electric boundary condition. The governing equations of motion for the MEE plate are obtained using refined higher-order shear plate theory and Hamilton's principle. Stiffness matrices, mass matrices, damping matrices, and force vectors of the plate are derived using a four-node quadrilateral element with eight degrees of freedom per node approximated using C1-order non-conforming Hermite and Lagrange functions. In addition, the Navier close-form solutions for rectangular plates with simply supported boundary conditions are used as a useful comparison tool for the numerical solutions. Dynamic response results of plates were obtained using Newmark's direct integration written by Matlab's programming. The accuracy of the method is verified through numerical comparison with confidence statements. The results show that the applied magnetic and electric potential highly inspires the transient responses. These results can be used in vibration control studies of structures and structures subjected to explosive or low-velocity impact loads.这是首次提出一种有限元方法,用于预测磁电弹性(MEE)复合矩形板和椭圆板的自由振荡和瞬态特性,这些复合矩形板和椭圆板位于承受爆炸荷载的湿热环境中的粘滞-帕斯捷尔纳克介质上。电势和磁势沿 MEE 板厚度方向的变化是通过麦克斯韦方程和磁电边界条件确定的。利用精炼的高阶剪切板理论和汉密尔顿原理获得了 MEE 板的支配运动方程。板的刚度矩阵、质量矩阵、阻尼矩阵和力矢量是使用四节点四边形元素推导出来的,每个节点有八个自由度,使用 C1 阶非符合赫米特函数和拉格朗日函数进行近似。此外,还使用了具有简单支撑边界条件的矩形板的纳维耶近似形式解作为数值解的有用比较工具。利用 Matlab 编程编写的纽马克直接积分法获得了板的动态响应结果。通过与置信度声明进行数值比较,验证了该方法的准确性。结果表明,外加磁势和电动势对瞬态响应有很大影响。这些结果可用于受爆炸或低速冲击载荷作用的结构和构造物的振动控制研究。An aero-structure-acoustics evaluation framework of wind turbine blade cross-section based on Gradient Boosting regression treeGuangxing Guo, Weijun Zhu, Zhenye Sun, Shifeng Fu, Wenzhong Shen, Jiufa Caodoi:10.1016/j.compstruct.2024.118055基于梯度提升回归树的风力涡轮机叶片横截面气动-结构-声学评估框架Under the rapid development of wind turbines, the rotor size has substantially increased in recent years. To meet the key design criteria, finding a trade-off between aerodynamic, structure and noise (ASN) impact becomes a challenging problem. The blade cross-section is the basic element of the blade, its outer contour is the airfoil profile that produces aerodynamic loads as well as noise, and the inner part is the supporting composite material that provides enough stiffness to balance the loads. Modifying local blade sections can adjust the rotors’ overall performance. However, in the work of blade-combined ASN optimization, the iterative process using traditional numerical simulation methods becomes extremely heavy. In this study, a sustainable database is created based on a large number of calculations of aerodynamic, structural and noise attributes at various cross-sections. Then a platform named AFML (Airfoil machine learning) for simultaneously predicting the comprehensive performance of the cross-section is constructed by using the integrated Gradient Boosting Regression Tree algorithm. Results show that the prediction accuracy of AFML is acceptable even for unseen inflow conditions. By calling the pre-trained AFML, ASN data of the cross-section can be immediately obtained, and the blade shape and inner structure can be updated quickly.近年来,随着风力涡轮机的快速发展,其转子尺寸也大幅增加。为了满足关键的设计标准,如何在空气动力、结构和噪声(ASN)影响之间找到平衡点成为一个具有挑战性的问题。叶片横截面是叶片的基本要素,其外部轮廓是产生气动载荷和噪声的机翼轮廓,内部则是提供足够刚度以平衡载荷的支撑复合材料。对叶片局部进行修改可以调整转子的整体性能。然而,在叶片组合 ASN 优化工作中,使用传统数值模拟方法的迭代过程变得异常繁重。在本研究中,基于对不同截面的气动、结构和噪声属性的大量计算,创建了一个可持续数据库。然后,利用集成梯度提升回归树算法构建了一个名为 AFML(机翼机器学习)的平台,用于同时预测横截面的综合性能。结果表明,AFML 的预测精度是可以接受的,即使是在不可见的流入条件下。通过调用预训练的 AFML,可以立即获得横截面的 ASN 数据,并快速更新叶片形状和内部结构。Behavior and design of functionally graded concrete subject to triple impacts of the shaped charge, projectile penetration and explosionXuexiang Yin, Jianzhong Lai, Longyu Du, Jiehang Zhou, Ningyu Kangdoi:10.1016/j.compstruct.2024.118061受定型装药、射弹穿透和爆炸三重影响的功能级配混凝土的行为和设计The present issue is how to improve the concrete structure to resist multiple impacts of the tandem warhead. This study developed an approach to design a functionally graded concrete (FGC) structure with fiber-graded (FG) and centralized high-strength aggregates (CHSA) to address this issue. The enhancement of the FG and CHSA in the concrete structure was verified by static mechanical performance tests and dynamic compressive simulation. The behavior of the FGC structure subject to the tandem warhead was investigated by the experimental and numerical dynamic destructive tests, including three stages: shaped charge, projectile penetration and explosion. There are three types of targets, including ultra-high-performance concrete (UHPC), ceramic aggregate reinforced (CAR) FGC and steel aggregate reinforced (SAR) FGC. The results showed that the SAR-FGC had the best multiple-impact resistance in concrete structures. The blocking effect to impact waves was improved by increasing the wave impedance of the anti-penetration layer. Energy absorption was increased by 7 times through the combined action of functional structures to ameliorate damage distribution. The triple destruction depth of it was reduced by 36% compared to UHPC. According to the Forrestal empirical equation, a penetration depth model was proposed for the FGC with jet damage.目前的问题是如何改进混凝土结构,以抵御串联弹头的多次撞击。为解决这一问题,本研究开发了一种方法来设计一种含有纤维级配(FG)和集中高强度骨料(CHSA)的功能级配混凝土(FGC)结构。通过静态力学性能测试和动态抗压模拟,验证了 FG 和 CHSA 在混凝土结构中的增强作用。通过实验和数值动态破坏试验研究了 FGC 结构在串联弹头作用下的行为,包括三个阶段:定型装药、弹丸穿透和爆炸。目标有三种类型,包括超高性能混凝土(UHPC)、陶瓷骨料加固(CAR)FGC 和钢骨料加固(SAR)FGC。结果表明,SAR-FGC 在混凝土结构中具有最佳的抗多重冲击能力。通过增加抗穿透层的波阻抗,提高了对冲击波的阻挡效果。通过功能结构的联合作用,能量吸收提高了 7 倍,从而改善了破坏分布。与超高强度混凝土相比,其三重破坏深度减少了 36%。根据福雷斯塔尔经验方程,提出了具有喷射破坏的 FGC 的穿透深度模型。Connectivity patterns in lead-free piezocomposites: A critical analysis for 0-3 and 1-3 configurationsFrancisco J. Cañamero, Federico C. Buroni, Luis Rodríguez-Temblequedoi:10.1016/j.compstruct.2024.118062无铅压电复合材料中的连接模式:0-3 和 1-3 配置的关键分析In the quest for eco-friendly alternatives within materials science, the development of sustainable and non-toxic piezoelectric composites is of utmost importance. This study undertakes a computational exploration to elucidate the influence of phase connectivity on the engineering performance of lead-free piezocomposites. Employing a combination of analytical and numerical methodologies, we critically evaluated various figures of merit across different microstructural configurations, juxtaposing these findings with traditional lead zirconate titanate (PZT)-based materials. Our analysis considers 0-3 and 1-3 connectivity patterns, incorporating active phases in the form of spherical particles and cylindrical fibers. We also examine the impact of carbon nanotubes (CNTs) in enhancing the polymeric matrix, which introduces the potential for network percolation and further mechanical and electrical property optimization. The study yields pivotal insights into the phase connectivity of lead-free piezocomposites, with direct implications for their application in sensing, actuating, and energy harvesting domains. We ascertain that the electromechanical performance of these composites is contingent upon the connectivity pattern and the proportion of active phase. Notably, the KNNS-BNZH & Polyethylene composite demonstrates exceptional potential in 1-3 configurations, while the BTO & PVDF composite distinguishes itself with superior dielectric and piezoelectric responses across varying volume fractions. The strategic infusion of CNTs into the PDMS matrix emerges as a significant enhancer of electromechanical attributes, albeit with performance improvements that are specific to the type of coefficient and CNT concentration. This investigation underscores the nuanced interplay between composite design and microstructural attributes, reinforcing the critical role these factors play in the advancement of effective and eco-conscious piezoelectric materials.在材料科学领域寻求生态友好型替代品的过程中,开发可持续且无毒的压电复合材料至关重要。本研究进行了计算探索,以阐明相连通性对无铅压电复合材料工程性能的影响。我们结合分析和数值方法,对不同微结构配置的各种性能指标进行了严格评估,并将这些结果与传统的锆钛酸铅(PZT)基材料进行了对比。我们的分析考虑了 0-3 和 1-3 连接模式,并结合了球形颗粒和圆柱形纤维形式的活性相。我们还研究了碳纳米管(CNT)在增强聚合物基体方面的影响,这为网络渗透和进一步优化机械和电气性能带来了可能性。这项研究对无铅压电复合材料的相连通性提出了重要见解,并对其在传感、致动和能量收集领域的应用产生了直接影响。我们确定,这些复合材料的机电性能取决于连接模式和活性相的比例。值得注意的是,KNNS-BNZH 和聚乙烯复合材料在 1-3 种配置中表现出非凡的潜力,而 BTO 和聚偏二氟乙烯复合材料则在不同体积分数下表现出卓越的介电和压电响应。将 CNT 战略性地注入 PDMS 基体可显著增强机电属性,尽管性能的提高取决于系数类型和 CNT 浓度。这项研究强调了复合材料设计与微结构属性之间微妙的相互作用,强化了这些因素在开发高效、具有生态意识的压电材料中的关键作用。Modeling dynamic crush behavior of carbon fiber reinforced polymer composite structures using MAT213R.T. Haluza, R.K. Goldberg, T.M. Ricks, J.M. Pereira, K.L. Koudela, C.E. Bakisdoi:10.1016/j.compstruct.2024.118063使用 MAT213 模拟碳纤维增强聚合物复合材料结构的动态挤压行为Modeling crushing of carbon fiber reinforced polymer (CFRP) composites is challenging, and current simulation methodologies involve tuning of non-physical parameters. MAT213, a next-generation material model, has advanced functionality to better simulate dynamic impact loading. The objective of the present investigation is to evaluate the potential for using MAT213 to simulate dynamic crushing of CFRPs. Two sets of simulations were performed: one for calibration based on a set of coupon-level experiments and another for prediction of the response of structural elements. Simulations involving dynamic crushing of flat specimens were iteratively run to calibrate model parameters. The calibration demonstrated that MAT213 could produce a simulated force–displacement response within experimental scatter. The simulated failure morphology was also comparable to the experiments. After successful calibration, predictive simulations of dynamic crushing of C-channel shaped specimens were completed using a simulated crash sled test rig and two pairs of impactor mass/velocity conditions. The simulated force–displacement curve in the crash sled simulations for the lower-velocity condition fell within the experimental scatter, but the stable crush force was underpredicted by 27 % in the higher-velocity simulations. Better correlation in the lower-velocity test condition likely results from the calibration condition being a similar velocity to the lower-velocity crash sled condition.碳纤维增强聚合物(CFRP)复合材料的挤压建模具有挑战性,目前的模拟方法涉及非物理参数的调整。新一代材料模型 MAT213 具有先进的功能,可以更好地模拟动态冲击载荷。本研究旨在评估使用 MAT213 模拟 CFRP 动态挤压的潜力。我们进行了两组模拟:一组是基于一组试样级实验的校准,另一组是用于预测结构元素的响应。通过反复运行涉及平面试样动态挤压的模拟来校准模型参数。校准结果表明,MAT213 可以在实验散度范围内产生模拟的力-位移响应。模拟的破坏形态也与实验结果相当。校准成功后,使用模拟碰撞雪橇试验台和两对撞击器质量/速度条件,完成了 C 形通道试样动态挤压的预测模拟。在低速度条件下,撞击橇模拟的力-位移曲线在实验散点范围内,但在高速模拟中,稳定挤压力被低估了 27%。较低速度测试条件下的相关性更好,可能是因为校准条件与较低速度的碰撞雪橇条件速度相似。An evaluation of large diameter through-thickness metallic pins in compositesGeoffrey Neale, Vinodhen Saaran, Monali Dahale, Alex Skordosdoi:10.1016/j.compstruct.2024.118066对复合材料中大直径穿透厚度金属销钉的评估There is increasing demand for functional through-thickness reinforcement (TTR) in composites using elements whose geometry exceeds limitations of existing TTR methods like tufting, stitching, and z-pinning. Recently, static insertion of large diameter TTR pins into heated prepreg stacks has proven a feasible and robust reinforcement process capable of providing accurate TTR element placement with low insertion forces and lower tow damage compared with existing methods for similar element sizes (>1mm diameter) like post-cure drilling. Local mechanical performance and failure mechanics of these pinned laminates are reported here. Laminates with a single statically inserted pins (1.2, 1.5, and 2.0 mm) can mostly retain their in-plane integrity alongside a local improvement in mode I delamination toughness in carbon fibre-benzoxazine laminates. Tensile strength is mostly unaffected by the pins resulting from delamination suppression, whereas there is up to a doubling of Young’s modulus. Compressive strength is significantly diminished (up to 42 %) in pinned laminates. Interlaminar toughness is improved, and peak toughness is pushed ahead of the crack as pin diameter increases. The lack of significant deterioration in in-plane tensile properties in pinned laminates produced using static insertion can expand the range and forms of materials that can be inserted compared to existing TTR.在复合材料中使用几何形状超出现有 TTR 方法(如簇绒、缝合和 Z 形钉)限制的元素进行功能性穿厚加固(TTR)的需求日益增长。最近,将大直径 TTR 销钉静态插入加热的预浸料堆栈已被证明是一种可行且稳健的加固工艺,与现有的类似元件尺寸(直径大于 1 毫米)的方法(如固化后钻孔)相比,它能以较低的插入力和较低的丝束损伤提供精确的 TTR 元件位置。本文报告了这些销钉层压板的局部机械性能和失效力学。使用单个静态插入销钉(1.2、1.5 和 2.0 毫米)的层压板大多能保持面内完整性,同时还能局部改善碳纤维-苯并恶嗪层压板的模式 I 分层韧性。拉伸强度基本不受分层抑制所产生的销钉的影响,而杨氏模量则增加了一倍。针 刺层压板的抗压强度明显下降(最多 42%)。层间韧性得到改善,随着销钉直径的增加,峰值韧性被推到裂缝之前。与现有的 TTR 相比,使用静态插入技术生产的插针层压板的面内拉伸性能没有明显下降,这可以扩大可插入材料的范围和形式。Analysis of doubly curved laminated composite shells using hybrid-Trefftz finite element model based on a high order shear deformation theorySubhasankar Dwibedi, M.C. Raydoi:10.1016/j.compstruct.2024.118070利用基于高阶剪切变形理论的混合特雷弗茨有限元模型分析双曲面层压复合材料壳体Static analysis of doubly curved laminated composite shells with rectangular plan form has been carried out using a novel hybrid Trefftz finite element (HTFE) model. A typical higher order shear deformation theory (HSDT) has been used for describing the kinematics of deformations delineating both internal and auxiliary displacement fields. This HSDT allows to derive the system of governing partial differential equations of the single layer equivalent to the element domain. The characteristic functions forming the exact solutions of these homogenous governing equilibrium equations are used as the Trefftz functions. A key aspect of our HTFE strategy is its efficiency in bypassing the use of particular solution of the governing equations. Validation against the exact solutions reveals the precision of this novel HTFE model. The versatility of the Trefftz functions allows them to accommodate a spectrum of geometric configurations, ranging from standard to complex polygonal HTFE designs. The HTFE model for the doubly curved composite shells employing the HSDT marks a significant advancement in the analysis of doubly curved spherical, paraboloid and hyperboloid cross-ply and antisymmetric angle-ply shells.采用新型混合特雷弗茨有限元(HTFE)模型对矩形平面的双曲面层压复合材料壳体进行了静态分析。典型的高阶剪切变形理论(HSDT)被用于描述内部和辅助位移场的变形运动学。该 HSDT 可以推导出与元素域等效的单层偏微分方程系统。形成这些同源控制平衡方程精确解的特征函数被用作特雷弗茨函数。我们的 HTFE 策略的一个关键方面是它能有效地绕过使用治理方程的特定解。根据精确解法进行的验证揭示了这种新型 HTFE 模型的精确性。Trefftz 函数的多功能性使其能够适应从标准到复杂多边形 HTFE 设计的各种几何配置。采用 HSDT 的双曲面复合材料壳体 HTFE 模型标志着在分析双曲面球形、抛物面和双曲面交叉层和非对称角层壳体方面取得了重大进展。Experimental study on the fire resistance of all-composite and hybrid web-core sandwich panels for building floorsM. Proença, M. Garrido, J.R. Correia, J. Sena-Cruzdoi:10.1016/j.compstruct.2024.118071建筑楼板用全复合材料和混合腹板夹芯板的耐火性能实验研究Fibre-reinforced polymer (FRP) composites and polymeric foams used in construction are susceptible to elevated temperatures, but little is known about the behaviour of composite sandwich panels under fire exposure. This paper presents an experimental study on the fire resistance of web-core composite sandwich panels with polyurethane foam infill for building floors. Two panel variants were considered: (i) an all-composite panel, with glass-FRP (GFRP) face sheets and webs; and (ii) a hybrid panel, with an additional fibre reinforced concrete (FRC) top layer. Five full-scale specimens were loaded in a four-point bending configuration, subjected to a constant service load, and subsequently exposed to a standard fire (ISO 834) on their bottom face. The effectiveness of passive fire protection systems, consisting of calcium silicate boards installed either adherent to the panels or forming an air cavity, was assessed. The following features were investigated: (i)temperature progression across the thickness of the panels, (ii)their mechanical response, (iii)failure modes, and (iv)fire resistance. The results obtained indicate that despite the vulnerability of composite sandwich panels to fire, relatively high fire resistances of 44 min and 49 min were obtained for the unprotected web-core all-composite and hybrid variants, respectively. The failure mechanism of the sandwich panels generally involved local compression and in-plane shear failure of the webs. The use of suitable passive fire protections provided significant fire resistance increases of at least 45 min (adherent) and 60 min (with air cavity), allowing to exceed the 90 min threshold.建筑中使用的纤维增强聚合物(FRP)复合材料和聚合泡沫很容易受到高温的影响,但人们对复合夹芯板在火灾中的表现却知之甚少。本文介绍了一项关于带有聚氨酯泡沫填充物的建筑地板用腹板芯复合夹芯板耐火性的实验研究。研究考虑了两种板材变体:(i) 全复合板,包括玻璃纤维增强塑料(GFRP)面板和腹板;(ii) 混合板,包括额外的纤维增强混凝土(FRC)顶层。对五个全尺寸试样进行了四点弯曲加载,使其承受恒定的使用荷载,随后在试样底面进行了标准火灾(ISO 834)试验。评估了被动防火系统的有效性,该系统由安装在面板上的硅酸钙板或形成气腔的硅酸钙板组成。对以下特征进行了研究:(i) 板材厚度上的温度变化;(ii) 板材的机械反应;(iii) 失效模式;(iv) 耐火性。研究结果表明,尽管复合夹芯板易受火灾影响,但无保护腹板芯全复合材料和混合变体的耐火度相对较高,分别为 44 分钟和 49 分钟。夹芯板的破坏机理一般涉及腹板的局部压缩和平面剪切破坏。使用适当的被动防火保护措施可显著提高防火性能,至少可提高 45 分钟(粘附)和 60 分钟(带气腔),从而超过 90 分钟的临界值。Controllable and scalable gradient-driven optimization design for two-dimensional metamaterials based on Deep learningLi Xiao, Zhigang Cao, Haoran Lu, Yuanqiang Caidoi:10.1016/j.compstruct.2024.118072基于深度学习的二维超材料可控、可扩展梯度驱动优化设计A novel gradient-driven rapid optimization design method based on deep learning is proposed to design two-dimensional irregular elastic metamaterial (EMM). We develop a design network comprising a conditional topology generator (TG) and a bandgap predictor (BGP). TG is applied to controllably generate candidate topological structures with geometric constraints, while BGP serves as a surrogate model linking EMM structures with their bandgaps. Utilizing automatic differentiation techniques, the error gradients of design variables are computed on the design network and then passed to gradient-driven optimization algorithms to optimize the design variables until the target bandgap is achieved. The design variables in optimization algorithm are independent of the network’s input features, allowing adaptation to changes in design factors without retraining the network, thereby providing scalability. The testing results demonstrate that the proposed method can efficiently and rapidly design EMM structures, exhibiting significant consistency with target bandgaps. Further comparative analysis reveals that the irregular topological structures enable bandgap broadening, generation of new bandgaps, and band flattening. The proposed method demonstrates significant feasibility and efficiency in the design of irregular EMM structures, and offers practical controllability and scalability.我们提出了一种基于深度学习的梯度驱动快速优化设计方法,用于设计二维不规则弹性超材料(EMM)。我们开发了一个由条件拓扑生成器(TG)和带隙预测器(BGP)组成的设计网络。条件拓扑生成器用于可控地生成具有几何约束的候选拓扑结构,而带隙预测器则用作连接 EMM 结构及其带隙的代理模型。利用自动微分技术,在设计网络上计算设计变量的误差梯度,然后将其传递给梯度驱动优化算法,以优化设计变量,直至达到目标带隙。优化算法中的设计变量与网络的输入特征无关,因此无需重新训练网络即可适应设计因素的变化,从而提供了可扩展性。测试结果表明,所提出的方法可以高效、快速地设计 EMM 结构,并与目标带隙表现出明显的一致性。进一步的比较分析表明,不规则拓扑结构能够拓宽带隙、产生新带隙和实现带平坦化。所提出的方法证明了设计不规则 EMM 结构的显著可行性和效率,并提供了实用的可控性和可扩展性。Artificial neural network prediction of transverse modulus in humid conditions for randomly distributed unidirectional fibre reinforced composites: A micromechanics approachK. Aghabalaei Baghaei, S.A. Hadighehdoi:10.1016/j.compstruct.2024.118073人工神经网络预测随机分布单向纤维增强复合材料在潮湿条件下的横向模量:微观力学方法This paper proposes an innovative micromechanics-based artificial neural network (ANN) method to efficiently investigate the transverse modulus of unidirectional fibre/epoxy composites under humid conditions. In this research, a novel approach is developed to establish relations between the geometrical, mechanical, and environmental properties of the microstructure and the material’s performance under transverse tension. A framework is developed to artificially generate periodic representative volume elements (RVEs) while taking into account the interphase region between fibre and matrix. The RVEs are analysed by the finite element method to obtain the transverse moduli of composites. Two-point correlation functions and principal component analysis techniques are applied to extract and compress statistical information from microstructure images. A database establishment framework is developed to create three batches of data with 1000, 2000, and 3000 sizes. An ANN-based prediction framework is developed by integrating 10-fold cross validation and Bayesian optimisation to optimise the neural network architecture and establish an efficient structure-property linkage under the influence of humid conditions. The prediction results demonstrate the efficiency of ANN in mapping microstructural data to effective transverse modulus. A parametric study by ANN reveals the role of microstructure geometrical features and humid environmental parameters on the transverse performance of the composite.本文提出了一种基于微机械学的创新型人工神经网络(ANN)方法,用于有效研究单向纤维/环氧复合材料在潮湿条件下的横向模量。在这项研究中,开发了一种新方法来建立微结构的几何、机械和环境属性与材料在横向拉伸下的性能之间的关系。在考虑到纤维与基体之间的相间区域的同时,还开发了一个框架来人为生成周期性的代表性体积元素(RVE)。通过有限元法对 RVE 进行分析,从而获得复合材料的横向模量。应用两点相关函数和主成分分析技术从微观结构图像中提取和压缩统计信息。开发了一个数据库建立框架,以创建 1000、2000 和 3000 大小的三批数据。通过整合 10 倍交叉验证和贝叶斯优化,开发了基于神经网络的预测框架,以优化神经网络结构,并在潮湿条件影响下建立有效的结构-属性联系。预测结果表明了神经网络在将微观结构数据映射到有效横向模量方面的效率。利用神经网络进行的参数研究揭示了微观结构几何特征和潮湿环境参数对复合材料横向性能的影响。3D compression-twist lattice metamaterials for surface reconfigurability of future architectureHan Yan, Yi Zhang, Xing Chi Teng, Wei Zhong Jiang, Yi Min Xie, Wen Wang Wu, Wei Qiu Chen, Chuan Zeng Zhang, Xin Rendoi:10.1016/j.compstruct.2024.118075用于未来建筑表面可重构性的三维压缩扭转晶格超材料Metamaterials refer to a class of materials with special properties, whose characteristics mainly come from the microstructures designed artificially. Among them, those metamaterials with tunable shape and mechanical properties under external stimuli provide a new inspiration for the design of the multifunctional structures. This work deals with the three-dimensional (3D) compression-twist lattice metamaterials, studies the surface reconfigurability under external forces, and reveals the torsion-bending coupling (TBC) effect of the special metamaterials. To explain the main characteristics of the TBC effect, the deformation mechanism of the metamaterials is analyzed. Combining the finite element method (FEM) and the spherical fitting algorithm, the relationship between the bending angle and the load of the metamaterials after deformation is analyzed and verified by experiments. Finally, a metamaterial module that could be freely transformed between planar and spherical surfaces is envisaged. A faster and greener solution is proposed for the construction of curved surfaces of engineering structures in the future, which promotes the subsequent applications of metamaterials to engineering practice.超材料是指一类具有特殊性能的材料,其特性主要来自人工设计的微结构。其中,在外部刺 激下具有可调形状和机械特性的超材料为多功能结构的设计提供了新的灵感。本研究以三维压缩扭转晶格超材料为对象,研究其在外力作用下的表面可重构性,并揭示特殊超材料的扭转弯曲耦合(TBC)效应。为了解释 TBC 效应的主要特征,分析了超材料的变形机理。结合有限元法(FEM)和球形拟合算法,分析了超材料变形后的弯曲角度与载荷之间的关系,并通过实验进行了验证。最后,设想了一种可在平面和球面之间自由转换的超材料模块。这为未来建造工程结构的曲面提出了一个更快、更环保的解决方案,从而促进了超材料在工程实践中的后续应用。来源:复合材料力学仿真Composites FEM

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