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【新文速递】2024年7月20日复合材料SCI期刊最新文章

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今日更新:Composite Structures 2 篇,Composites Part A: Applied Science and Manufacturing 3 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇

Composite Structures

Creep resistance enhancement and modeling of 3D printed Polyetherimide/carbon black composites

Merve Karabal, Alptekin Yıldız

doi:10.1016/j.compstruct.2024.118398

3D打印聚醚酰亚胺/炭黑复合材料的抗蠕变增强和建模

This study investigates the potential of carbon black (CB) reinforcement to enhance the mechanical properties of high-performance Polyetherimide (PEI) compromised by Material Extrusion (MEX), making them comparable to those produced by conventional methods. PEI filaments with varying CB fractions (5 – 20 wt%) were produced, and creep test specimens were fabricated via MEX. A neat PEI hot-pressed specimen was also manufactured for comparison. The results demonstrated a 7% increase in ultimate tensile strength (UTS), alongside 14% decrement in creep strain with 5 wt% CB reinforcement, approaching the performance of conventionally manufactured neat PEI. Creep behavior was modeled using Burgers, Kelvin–Voigt, and Findley models, with Findley’s model proving effective in capturing instantaneous strain. Additionally, the Time-Temperature Superposition Principle (TTSP) was applied to develop creep master curves up to 10^9s. This study highlights the potential of CB as a cost-effective reinforcement material to improve the mechanical properties of 3D-printed high-performance polymers.

本研究探讨了碳黑(CB)增强材料在提高高性能聚醚酰亚胺(PEI)机械性能方面的潜力,这种材料通过材料挤压(MEX)制成,可与传统方法制成的材料相媲美。生产出了不同 CB 分数(5 - 20 wt%)的 PEI 长丝,并通过 MEX 制作了蠕变测试试样。同时还制作了一个纯 PEI 热压试样进行比较。结果表明,5 wt% CB 增强材料的极限拉伸强度 (UTS) 提高了 7%,蠕变应变降低了 14%,接近传统制造的纯 PEI 的性能。蠕变行为是通过伯格斯模型、开尔文-伏依格特模型和芬德雷模型来模拟的,其中芬德雷模型在捕捉瞬时应变方面被证明是有效的。此外,还应用时间-温度叠加原理 (TTSP) 开发了蠕变主曲线,最高可达 10^9s。这项研究凸显了 CB 作为一种具有成本效益的增强材料在改善 3D 打印高性能聚合物机械性能方面的潜力。


Effect of the level of anisotropy on the macroscopic failure of notched thin-ply laminates

Anatoli Mitrou, Albertino Arteiro, José Reinoso, Pedro P. Camanho

doi:10.1016/j.compstruct.2024.118407

各向异性水平对缺口薄板宏观破坏的影响

This work presents a detailed experimental study conducted for a range of different lay-ups using thin-ply carbon fiber reinforced polymer (CFRP) laminates. The selection of the laminates was performed relying on their level of anisotropy. The laminates vary from a quasi-isotropic (QI) laminate, which is weakly anisotropic, to a cross-ply (CP) laminate, which is strongly anisotropic. The laminates were tested in on-axis and off-axis open hole tension (OHT). The main objective was to observe the effect of the level of anisotropy of the laminate on the macroscopic failure and observed failure patterns. It is shown that, contrary to most existing observations so far, depending on the lay-up and consequently its level of anisotropy, open-hole, quasi-homogeneous thin-ply laminates do not necessarily exhibit a fiber dominated failure mode, but could develop sub-critical damage mechanisms in a large extent prior to ultimate failure, reminiscent of what is observed for standard-ply CFRP laminates.

这项工作提出了一个详细的实验研究进行了一系列不同的铺装使用薄层碳纤维增强聚合物(CFRP)层压板。层压板的选择取决于它们的各向异性水平。层压板从弱各向异性的准各向同性(QI)层压板到强各向异性的交叉层(CP)层压板不等。对层合板进行了轴向和离轴裸眼拉伸(OHT)测试。主要目的是观察层压材料各向异性水平对宏观破坏和观察到的破坏模式的影响。研究表明,与大多数现有的观察结果相反,到目前为止,取决于铺层及其各向异性水平,开孔、准均匀薄层层压板不一定表现出纤维主导的破坏模式,但在最终破坏之前,可能在很大程度上发展亚临界损伤机制,让人想起标准层CFRP层压板所观察到的情况。


Composites Part A: Applied Science and Manufacturing

Burst pressure prediction of cord-rubber composite structures using global-local nonlinear finite element analysis

Ahaan Bhosale, Rob Barendse, Boyang Chen, J.M.J.F. van Campen

doi:10.1016/j.compositesa.2024.108361

 

基于全局-局部非线性有限元分析的索-胶复合结构爆破压力预测

This study aims to develop a model to predict the burst pressure of a dry filament wound cord-rubber composite pressure vessel under hydrostatic internal pressurization using a submodelling based global-local FEA model. The model links the global displacements of a rebar-based model to obtain the local deformation state in a single rhomboidal representative volume. Emphasis is placed on capturing the local stress concentrations in the fibers due to the unique filament winding mosaic pattern. Fiber damage is included in the local model using a maximum principle strain criteria. Verification of the created model is done experimentally on industrially manufactured burst-test specimens. Measurements for displacement during the experiments are taken photographically, while the burst pressure is captured using a pressure transducer. The final error between the burst pressure of the samples and the experimental demonstrators is approximately 6.5%, a marked improvement over conventional models with truss and rebar elements as fibers.

采用基于子模型的全局-局部有限元分析方法,建立了干丝缠绕绳-橡胶复合材料压力容器在静水压下的破裂压力预测模型。该模型将钢筋模型的整体 位移联系起来,在单个菱形代表体中获得局部变形状态。由于独特的长丝缠绕马赛克图案,重点放在捕获纤维中的局部应力集中。采用最大主应变准则将纤维损伤纳入局部模型。在工业生产的爆炸试验试样上对所建立的模型进行了实验验证。在实验过程中,位移测量是通过摄影进行的,而爆破压力是通过压力传感器捕获的。试样的破裂压力与实验模型之间的最终误差约为6.5%,与以桁架和钢筋为纤维的传统模型相比有显著改善。


An integrated approach to analyzing matrix-crack-induced stiffness degradation and medium leakage in linerless composite vessels

Haitao Zhao, Mingqing Yuan, Yahui Peng, Xiaochu Gao, Li Tian, Boming Zhang, Chengcheng Zhang, Ji’an Chen

doi:10.1016/j.compositesa.2024.108364

无衬底复合材料容器中基体裂纹引起的刚度退化和介质泄漏的综合分析方法

This paper proposes an integrated analysis method for linerless composite vessels considering matrix-crack-induced stiffness degradation and permeation. Stiffness degradation models are obtained using machine learning regression, the data sets of which consist of finite element analysis (FEA) results and virtual samples. Then, the effective leakage conductance is obtained by using the linear elastic fracture mechanics and the micro-cracking leakage mechanism. The proposed integrated method is applied to analyze vessel structures designed by the grid theory, which has variable ply thicknesses and layup angles. Simulation results show that whether the structure at cryogenic temperature cracks and leaks more easily depends on its dimensions and stacking sequences.

本文提出了一种考虑基体裂纹引起的刚度退化和渗透的无衬底复合材料容器综合分析方法。采用机器学习回归方法建立了刚度退化模型,该模型的数据集由有限元分析结果和虚拟样本组成。然后,利用线弹性断裂力学和微裂纹泄漏机理得到有效泄漏电导。将该方法应用于网格理论设计的具有变层厚和变层角的船舶结构的分析。仿真结果表明,结构在低温下是否更容易开裂和泄漏取决于其尺寸和堆叠顺序。


Damage and failure mechanisms of hybrid carbon fiber and steel fiber reinforced polymer composites

Jan Rehra, Julia Jungbluth, Bilal Katri, Sebastian Schmeer, Martin Gurka, Frank Balle, Ulf P. Breuer

doi:10.1016/j.compositesa.2024.108366

混杂碳纤维与钢纤维增强聚合物复合材料的损伤破坏机理

Fiber-reinforced plastics (FRPs) are widely used due to their superior properties but often suffer from brittle failure and poor structural integrity under impact loads. Metal fiber hybrids (MFH) offer a solution, but understanding their structure–property relationships remains challenging. This research provides a comprehensive mechanical characterization of a stainless steel-carbon fiber hybrid (SCFRP) embedded in epoxy resin, with a particular focus on the failure mechanisms and their influences. Therefore, the mechanical properties of the material, as well as the propagation and damage of the fracture, are investigated. In addition, three main failure mechanisms are identified and analyzed. The failure mode of a SCFRP laminate can be influenced by its composition, architecture, and specimen size and result from a combination of the blast effect of the brittle failing carbon fibers, the magnitude of the associated damage, and the movement of the fracture gap formation initiated by the carbon fiber failure.

纤维增强塑料(frp)由于其优越的性能而被广泛使用,但在冲击载荷下往往存在脆性破坏和结构完整性差的问题。金属纤维混合材料(MFH)提供了一种解决方案,但了解它们的结构-性能关系仍然具有挑战性。本研究提供了不锈钢-碳纤维复合材料(SCFRP)在环氧树脂中的综合力学特性,特别关注其失效机制及其影响。因此,研究了材料的力学性能以及断口的扩展和损伤。此外,还对三种主要失效机制进行了识别和分析。SCFRP层合板的破坏模式受其成分、结构和试样尺寸的影响,并受脆性碳纤维破坏的爆炸效应、相关损伤的大小和碳纤维破坏引发的断裂间隙形成的运动的综合影响。


Composites Part B: Engineering

Interlayer Enhancement of 3D Printed CF/PLA Composites via Localized Microwave Welding and Annealing-Induced Crystallization

Hongfu Li, Yuxi Mu, Qi Wang, Diandian Cai, Yuan Zhang, Yu Luo, Jiang Liu, Jintong Liu, Kangmin Niu, Ying Wu, Yuzhan Li, Naisheng Jiang

doi:10.1016/j.compositesb.2024.111737

 

基于局部微波焊接和退火诱导结晶的3D打印CF/PLA复合材料层间增强研究

Interlayer defects and insufficient diffusion are detrimental to the structural integrity of 3D printed composites. This study introduces a facile approach to enhance the interlayer adhesion and structural integrity of 3D printed carbon fiber/polylactic acid (CF/PLA) composites, utilizing graphene-coated CF/PLA filaments for localized microwave welding and annealing-induced crystallization. This method promotes localized PLA melting at the interlayer interfaces, facilitating polymer diffusion and transcrystallization, which are crucial for effective interlayer repair and enhancement. The unique microwave dissipation properties of graphene ensure selective heating at the interlayer interfaces without largely affecting the intralayer CF, which is crucial for maintaining the overall structural integrity. Combining microwave welding with post-annealing treatment promotes transcrystalline growth at interlayer interfaces, which results in a 26.4% increase in 90° tensile strength of the 3D printed CF/PLA composites, demonstrating the effectiveness of our approach. These findings provide new insights into strategies for enhancing the mechanical properties of 3D printed carbon fiber thermoplastic composites through precise interlayer enhancement and interfacial defect repair.

层间缺陷和扩散不足会影响3D打印复合材料的结构完整性。本研究介绍了一种简单的方法来增强3D打印碳纤维/聚乳酸(CF/PLA)复合材料的层间附着力和结构完整性,利用石墨烯涂层CF/PLA长丝进行局部微波焊接和退火诱导结晶。该方法促进了PLA在层间界面的局部熔化,促进了聚合物的扩散和转结晶,这是有效修复和增强层间的关键。石墨烯独特的微波耗散特性确保了层间界面的选择性加热,而不会对层内CF产生很大影响,这对于保持整体结构完整性至关重要。结合微波焊接和后退火处理促进了层间界面的跨晶生长,使3D打印的CF/PLA复合材料的90°拉伸强度提高了26.4%,证明了我们方法的有效性。这些发现为通过精确的层间增强和界面缺陷修复来增强3D打印碳纤维热塑性复合材料的机械性能提供了新的见解。


Composites Science and Technology

Multifunctional Hierarchical Electronic Skins: Unveiling Self-Repairing Mechanisms and Advancements in Sensing and Shielding Performance

Muchao Qu, Linzhi Hu, Shunyin Wang, Hongji Chen, Guanda Yang, Dirk W. Schubert, Ri Chen, Fritjof Nilsson, Lei Han

doi:10.1016/j.compscitech.2024.110769

 

多功能分层电子皮肤:揭示自我修复机制和传感和屏蔽性能的进展

In light of advancements in electronic skins (E-skins), their application in extreme environments poses significant challenges. Inspired by real human skin, we have developed a hierarchical structured electronic skin that utilizes flexible carbon fiber fabric as a framework. Copper nanoflakes and embedded sensors function as the neural layer, while Ethylene Vinyl Acetate acts as the dermal layer, and Polytetrafluoroethylene is employed as the epidermal layer. The reported E-skin demonstrates outstanding flexibility, excellent heat resistance, robust mechanical properties (fracture strength of 1600 MPa, Young's modulus approximately 3.8 GPa), exceptional bending /compression strain performance, excellent hydrophobicity (water contact angle of 120°), effective electromagnetic shielding performance (approximately 45dB total shielding effectiveness for X-band), and electromagnetic wave absorption capability. Additionally, this E-skin possesses self-healing properties, capable of restoring to its original hydrophobic state within 30 seconds under a 9V voltage through the Joule heating effect, complemented by corresponding theoretical and mathematical modeling. This E-skin introduces a novel, environmentally friendly, and operationally simple strategy for enhancing the extreme environment resistance and durability of flexible devices.

鉴于电子皮肤(e -skin)的进步,它们在极端环境中的应用提出了重大挑战。受真实人体皮肤的启发,我们开发了一种分层结构的电子皮肤,利用柔性碳纤维织物作为框架。铜纳米片和嵌入式传感器作为神经层,乙烯醋酸乙烯作为真皮层,聚四氟乙烯作为表皮层。所报道的E-skin具有出色的柔韧性、优异的耐热性、强大的机械性能(断裂强度为1600 MPa,杨氏模量约为3.8 GPa)、优异的弯曲/压缩应变性能、优异的疏水性(水接触角为120°)、有效的电磁屏蔽性能(x波段的总屏蔽效率约为45dB)和电磁波吸收能力。此外,该E-skin具有自愈特性,能够在9V电压下通过焦耳热效应在30秒内恢复到原来的疏水状态,并辅以相应的理论和数学模型。这种E-skin引入了一种新颖、环保、操作简单的策略,以增强柔性设备的极端环境抗性和耐用性。


Stiffness-Switchable Hydrogel Composite for Transformable Exo-Suit

Yu Zhu, Meng-Ting Xu, Zhen-Hua Tang, Feng Chen, De-Yang Wang, Yuan-Qing Li, Shao-Yun Fu

doi:10.1016/j.compscitech.2024.110763

 

可变形宇航服的刚度可切换水凝胶复合材料

Transformable exo-suits, which are soft and wearable under normal conditions and could increase stiffness dramatically on demand, are significant in personal protection and robotics and also a dream of science-fiction fans. Herein, an ideal candidate material based on a carbon fabric reinforced thermal-hardening hydrogel (CFRTH) composite is proposed for developing transformable exo-suits. The introduction of carbon fabric significantly enhances the mechanical performance of thermal-hardening hydrogel, and empowers the CFRTH composite with an active, rapid and repeatable stiffness switchability. At ambient temperature, the CFRTH composite developed is soft and wearable with excellent flexibility and shape adaptability, while the composite becomes hard and rigid instantaneously as temperature rises. The flexural modulus of the CFRTH composite increases from 2.3 MPa to 539.7 MPa (about 232 times) by applying an electro-thermal stimulus, which endows the composite with good energy absorption/dissipation performance. Compared with the untransformed CFRTH composite, the transformed CFRTH composite under the electro-thermal stimulus exhibits 200% improvement in the peak force attenuation ratio under dropping ball test, 137% enhancement in withstanding puncture energy under penetration test, and 6 to 1 layer penetration depth reduction under knife stab. Finally, the transformable CFRTH composite demonstrates a high effectiveness in egg and glass protection from the impact of steel ball. This study offers a novel and versatile strategy for developing transformable exo-suits which have wearable conformability under normal circumstances and exhibit enhanced stiffness and impact protection performance on-demand through an electro-thermal stimulus.

可变形的外服在正常条件下柔软可穿戴,并可根据需要大幅增加硬度,在个人防护和机器人领域具有重要意义,也是科幻爱好者的梦想。本文提出了一种基于碳织物增强热硬化水凝胶(CFRTH)复合材料的理想候选材料,用于开发可变形的外露服。碳织物的引入显著提高了热硬化水凝胶的机械性能,并使CFRTH复合材料具有主动、快速和可重复的刚度切换性。在室温下,CFRTH复合材料柔软耐磨,具有良好的柔韧性和形状适应性,但随着温度的升高,复合材料瞬间变硬变刚性。经电热刺 激后,CFRTH复合材料的抗弯模量由2.3 MPa提高到539.7 MPa(约232倍),具有良好的吸耗能性能。与未转化CFRTH复合材料相比,经热处理后的CFRTH复合材料在落球试验下的峰值力衰减比提高了200%,在侵彻试验下的抗穿刺能量提高了137%,在刀刺作用下的侵彻深度降低了6∶1层。最后,可变形CFRTH复合材料在钢球冲击下对鸡蛋和玻璃的保护效果非常好。这项研究提供了一种新颖和通用的策略来开发可变形的外骨骼服,这种外骨骼服在正常情况下具有可穿戴性,并通过电热刺 激显示出增强的刚度和冲击保护性能。


A Multifunctional Heterogeneous Structure Inspired by Shell Brick-Mud Structure: Balancing Noise Reduction and Mechanical Performance

Zhenglei Yu, Lixin Chen, Chaolei Zhang, Haojie Chi, Binkai Guo, Yanan Yang, Ruiyao Liu, Renlong Xin, Ping Liang, Zezhou Xu, Yunting Guo, Zhihui Zhang, Luquan Ren, Chunling Mao

doi:10.1016/j.compscitech.2024.110765

 

受壳砖泥结构启发的多功能异质结构:平衡降噪与力学性能

Electric armoured vehicles, which are crucial for strategic operations, must possess superior mechanical properties and noise reduction to maintain normal functionality. However, achieving high energy absorption and noise reduction performance simultaneously is challenging with a single uniform material or structure. This study introduces heterogeneous structures with metal lattice skeletons filled with polymer materials. The skeleton, known as the bionic mantis shrimp structure (BMS), is filled with polyurethane and epoxy. Impedance tube experiments revealed that the sound absorption coefficients of Heterostructure-polyurethane foam (HS-PU) and Heterostructure-epoxy (HS-EP) are significantly higher than BMS. HS-PU achieved an average sound insulation of 33.6 dB, marking a 739% improvement over BMS. Compression tests show that polymer filling can inhibit the destructive collapse of BMS and enhance its mechanical performance. HS-EP exhibits specific strength and specific energy absorption values of 57 MPa/(g·cm-3) and 30.75 J/g, respectively, representing an increase of 67.6% and 315% compared to BMS. Additionally, as the volume fraction of BMS increased in the heterogeneous structure, the elastic modulus and compressive strength increase while the specific energy absorption decreased. This research suggest that the design of metal/polymer heterogeneous structures offers a promising approach for developing high-strength and noise-reducing protective structures.

电动装甲车对战略作战至关重要,必须具有卓越的机械性能和降噪能力,以保持正常的功能。然而,用单一的均匀材料或结构同时实现高能量吸收和降噪性能是具有挑战性的。本研究引入了金属晶格骨架填充高分子材料的非均相结构。这种被称为仿生螳螂虾结构(BMS)的骨架由聚氨酯和环氧树脂填充。阻抗管实验表明,异质结构聚氨酯泡沫(HS-PU)和异质结构环氧树脂(HS-EP)的吸声系数显著高于BMS。HS-PU实现了33.6 dB的平均隔声,比BMS提高了739%。压缩试验表明,聚合物填充可以抑制BMS的破坏性坍塌,提高其力学性能。HS-EP的比强度和比能吸收值分别为57 MPa/(g·cm-3)和30.75 J/g,比BMS分别提高了67.6%和315%。此外,随着BMS在非均相结构中的体积分数的增加,弹性模量和抗压强度增加,而比能吸收降低。该研究表明,金属/聚合物非均相结构的设计为开发高强度、低噪声的防护结构提供了一条有前途的途径。


Highly Durable Hollow Sandwich MXene/h-AgNWs/ANF Composite Films for Exceptional Electromagnetic Interference Shielding Performance

Fan Xie, Qiaoling Liu, Xiyi Dai, Haitao Wei, Zhaoqing Lu

doi:10.1016/j.compscitech.2024.110766

 

高度耐用的中空夹层MXene/h-AgNWs/ANF复合薄膜具有卓越的电磁干扰屏蔽性能

Multi-functional electromagnetic interference (EMI) shielding materials are crucial for advanced electronic devices, requiring low thickness, exceptional shielding performance, and stability, especially in extreme conditions. In this study, the hollow sandwich MXene/h-AgNWs/ANF (AMAgMA) composite films were fabricated via template sacrificing method and layer-by-layer vacuum assisted filtration. Specifically, the hollow MXene was created using PMMA as the template, together with AgNWs for the conductive layer, while ANF provided stability and high temperature resistance as the protective layer. The optimized EMI shielding efficiency (SE) reached 88.2 dB for a film thickness of 93 μm, with an SSE/t value of 18160 dB·cm2·g–1, which was attributed to the hollow structure and continuous double conductive network design. Remarkably, EMI SE of the films maintained even after 70 days of exposure to oxidation, acid, alkali, salt, and ultrasonic treatment thanks to the sandwich design. Additionally, the composite films displayed excellent heat transfer and thermal stability (530 oC), alongside notable flame retardancy and self-extinguishing properties. The superior EMI shielding performance and stability in extreme environments suggest a promising application potential in advanced electronics.

多功能电磁干扰(EMI)屏蔽材料对于先进的电子设备至关重要,它要求低厚度、卓越的屏蔽性能和稳定性,特别是在极端条件下。本研究采用模板牺牲法和逐层真空辅助过滤法制备了中空夹层MXene/h-AgNWs/ANF (AMAgMA)复合薄膜。具体来说,中空MXene是用PMMA作为模板,用AgNWs作为导电层,而ANF作为保护层提供稳定性和耐高温性。当膜厚为93 μm时,优化后的电磁干扰屏蔽效率SE达到88.2 dB, SSE/t值为18160 dB·cm2·g-1,这主要归功于中空结构和连续双导电网络设计。值得注意的是,由于夹层设计,即使经过70天的氧化、酸、碱、盐和超声波处理,薄膜的EMI SE仍然保持不变。此外,复合膜表现出优异的传热性能和热稳定性(530℃),以及显著的阻燃性和自熄性。优越的电磁干扰屏蔽性能和在极端环境下的稳定性表明其在先进电子领域具有广阔的应用潜力。




来源:复合材料力学仿真Composites FEM
ACTMechanicalInspireMAGNETDeform断裂复合材料非线性通用船舶电子焊接裂纹理论爆炸材料机器人试验
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【新文速递】2024年7月22日复合材料SCI期刊最新文章

今日更新:Composite Structures 6 篇,Composites Part A: Applied Science and Manufacturing 1 篇,Composites Part B: Engineering 1 篇,Composites Science and Technology 4 篇Composite StructuresThermal buckling of variable stiffness composite laminates using high order plate finite elementsF. Bracaglia, R. Masia, A. Pagani, E. Zappino, E. Carreradoi:10.1016/j.compstruct.2024.118393用高阶板有限元分析变刚度复合材料层合板的热屈曲This paper proposes a study on the thermal buckling of Variable Angle Tow (VAT) composite plates using high-order theories. Here, the governing equations are derived via the principle of virtual work. Under the assumption of linear pre-buckling, the stability problem is reduced to a linear eigenvalue analysis considering proportional geometric stiffness. In contrast, a constant thermal load is assumed to be known along the plate thickness, and the uncoupled thermo-mechanical formulation is used, where the thermal effects are described as external loads. The plate is discretized using the Finite Element Method (FEM) and high-order theories are developed using the Carrera Unified Formulation (CUF). Using the CUF, the equations are expressed as an invariant of the plate theory approximation order. Therefore, Equivalent Single Layer (ESL) and Layer-Wise (LW) models can be easily implemented. Several geometries and lamination cases are considered for verification purposes, including different side-to-thickness ratios and fiber orientations, which result in various anisotropy effects. In addition, the effect of changing constraints and materials is evaluated. Particular attention is paid to the effect of the structural theory approximation on the evaluation of the thermal buckling load. It is shown that the correct evaluation is highly dependent on the edge-to-thickness ratio and on the anisotropy given by both the fiber orientation and the material properties. As a final remark, sensitivity analysis and best fibre angle solutions are discussed to highlight the importance of the LW modelling approach.本文采用高阶理论对变角Tow复合材料板的热屈曲进行了研究。本文利用虚功原理推导了控制方程。线性的假设下前挠曲,稳定性问题是减少到一个线性特征值分析考虑几何刚度成比例。相反,假设沿板厚已知恒定的热负荷,并使用不耦合的热-机械公式,其中热效应被描述为外部负荷。采用有限元法对板进行离散化,采用Carrera统一公式建立了高阶理论。利用CUF,将方程表示为板理论近似阶的不变量。因此,等效单层(ESL)和分层(LW)模型可以很容易地实现。为了验证目的,考虑了几种几何形状和层压情况,包括不同的边厚比和纤维取向,这些都会导致不同的各向异性效应。此外,还评估了约束条件和材料变化的影响。特别注意了结构理论近似对热屈曲载荷评估的影响。结果表明,正确的评价高度依赖于边厚比和纤维取向和材料性能所给出的各向异性。最后,讨论了灵敏度分析和最佳纤维角解,以突出LW建模方法的重要性。Topological design of soft substrate acoustic metamaterial for mechanical tuning of sound propagationYan Li, Xiaopeng Zhang, Qiming Tian, Yangjun Luodoi:10.1016/j.compstruct.2024.118399用于声音传播机械调谐的软基声学超材料拓扑设计The design of tunable acoustic waves is crucial in phononic crystals (PnCs), as acoustic waves exhibit continuous variation across diverse frequency ranges in practical applications. While there have been research efforts on tunable PnCs, existing design strategies predominantly rely on predetermined topology and scatterer shapes based on empirical experience. This reliance poses challenges in ensuring customized and reversible tuning of the bandgap. In this work, we present a customized tunable PnC design model and solution strategy based on soft substrates, which enables reversible tuning of a specific frequency/order bandgap. The designed structure consists of a soft substrate and crystalline columns dispersed in the soft substrate and air. The relative positions of the scatterers in the air are changed by stretching the substrate, thereby realizing the modulation of sound propagation. Since soft materials have both material nonlinearities and complex geometrical variations that are difficult to obtain design sensitivity information, the material-field series expansion topology optimization approach is employed to achieve custom tunable design of the bandgap. The paper presents simulation-based analyses and experimental verification of the customized bandgap opening and closing. The results demonstrate a close alignment between theoretical predictions of propagation curves and experimental findings. This concurrence serves as evidence that the soft-substrate PnC, derived through topology optimization, effectively facilitates the adjustment of bandgaps of arbitrary orders and enables switching between various acoustic functions.可调谐声波的设计在声子晶体(pnc)中是至关重要的,因为声波在实际应用中在不同的频率范围内表现出连续的变化。虽然对可调谐pnc进行了研究,但现有的设计策略主要依赖于基于经验经验的预定拓扑和散射体形状。这种依赖在确保定制和可逆调谐带隙方面提出了挑战。在这项工作中,我们提出了一种基于软基板的定制可调谐PnC设计模型和解决策略,它可以对特定频率/阶带隙进行可逆调谐。所设计的结构由软基板和分散在软基板和空气中的结晶柱组成。通过拉伸基片来改变散射体在空气中的相对位置,从而实现声音传播的调制。针对软质材料具有材料非线性和复杂几何变化难以获得设计灵敏度信息的特点,采用材料场串联展开拓扑优化方法实现带隙的自定义可调设计。本文对自定义的带隙开闭进行了仿真分析和实验验证。结果表明,理论预测的传播曲线与实验结果非常吻合。这种一致性证明,通过拓扑优化得到的软基板PnC有效地促进了任意阶带隙的调整,并实现了各种声学功能之间的切换。Theoretical study on the bond performance of CFRP-to-steel single-lap shear tests with multiple debonding defectsHugo C. Biscaia, Pedro Coelho, Fábio Conde, Tommaso D’Antinodoi:10.1016/j.compstruct.2024.118406含多剥离缺陷的cfrp -钢单搭接剪切试验粘结性能的理论研究The amount of research on the external bonding of Carbon Fiber Reinforced Polymers (CFRP) to degraded structures has increased recently. The adhesive is the weakest element of the joint and the bonding of the adherends is critical for the efficiency of the joint. Therefore, the influence of multiple debonding defects on CFRP-to-steel joints has still not been correctly quantified nor fully understood. For this reason, the current work proposes a new numerical strategy that allows for studying the influence of multiple debonding defects when a brittle and ductile adhesive is used. A new nonlinear bond-slip relationship is used and four different ratios between the debonded and the bonded area (η) are assumed: 0%, 25%, 50%, and 75%. The proposed model is based on the Finite Difference Method (FDM) and validation is carried out with a commercial Finite Element Method (FEM) package. The load-slip curves allowed for observing that the proposed FDM and the FEM are consistent and both revealed degradation of the load capacity of the joints with the increase of η. Moreover, by adopting a displacement control at the CFRP-free end, a snap-through and snap-back phenomenon are observed in the specimens with a localized debonding defect.近年来,对碳纤维增强聚合物(CFRP)与降解结构外键合的研究越来越多。胶粘剂是接头最薄弱的环节,胶粘剂的粘结对接头的工作效率至关重要。因此,多重脱粘缺陷对cfrp -钢连接的影响还没有得到正确的量化和充分的认识。因此,目前的工作提出了一种新的数值策略,允许研究脆性和延性粘合剂使用时多重脱粘缺陷的影响。采用一种新的非线性粘结-滑移关系,并假设脱粘与粘结面积(η)的比值为0%、25%、50%和75%。所提出的模型基于有限差分法(FDM),并使用商业有限元方法(FEM)软件包进行了验证。从载荷-滑移曲线可以看出,所提出的FDM和FEM是一致的,都显示了节点的承载能力随着η的增加而退化。此外,通过在无cfrp端进行位移控制,在具有局部脱粘缺陷的试件中观察到弹穿和弹回现象。Comparative study on the impact behaviors of CFWST columns reinforced with steel spiral and tubeXia Yang, Jiu-Yuan Wang, Yu Chen, Geng-chen Wudoi:10.1016/j.compstruct.2024.118408钢管与螺旋钢加固CFWST柱冲击性能对比研究To obtain superior corrosion resistance and impact resistance, as well as good economic benefits, two new types of composite structure called as steel tube internally-reinforced concrete-filled weathering steel tube (STRCFWST) and steel spiral internally-reinforced concrete-filled weathering steel (SSRCFWST) columns are proposed and compared in terms of their impact resistance in this paper. Eleven impact tests were conducted and three parameters comprising steel spiral diameter, wall thicknesses of outer and inner steel tube were considered to evaluate their influences on the lateral impact behaviors. Results show the presence of inner steel tube and reinforcement cage significantly enhances the impact resistance while slightly decreases the energy absorption capacity. Increasing inner steel tube wall thickness helps to improve the impact resistance, however the contribution is not so good as that produced by increasing the outer steel tube wall thickness, whilst varying steel spiral diameter almost has no impact. Numerical models were developed by ABAQUS/Explicit and verified via the test, based on which the full-range behaviors of STRCFWST, SSRCFWST and unreinforced concrete-filled weathering steel tube (CFWST) columns under impact loading were compared and discussed. It is demonstrated that steel tube and reinforcement cage provide little confinement on concrete infill under impact. With the same internal steel ratio, inner steel tube makes a greater contribution to sectional bending moment resistance and energy absorption as compared to the reinforcement cage.为了获得优异的耐腐蚀和抗冲击性能以及良好的经济效益,本文提出了钢管内筋混凝土填充耐候钢(STRCFWST)和钢螺旋内筋混凝土填充耐候钢(SSRCFWST)两种新型组合结构,并对其抗冲击性能进行了比较。进行了11次冲击试验,考虑了钢螺旋直径、外、内钢管壁厚3个参数对横向冲击行为的影响。结果表明,内钢管和钢筋笼的存在显著提高了结构的抗冲击能力,但对结构的吸能能力略有降低。增加内管壁厚度有助于提高抗冲击能力,但贡献不如增加外管壁厚度,而改变钢螺旋直径几乎没有影响。采用ABAQUS/Explicit软件建立数值模型并进行试验验证,在此基础上对STRCFWST、SSRCFWST和无筋耐候钢钢管混凝土柱在冲击荷载作用下的全工况性能进行了比较和讨论。结果表明,钢管和钢筋笼对混凝土充填体在冲击作用下的约束作用较小。在相同的内钢比下,内钢管对截面抗弯矩和吸能的贡献大于钢筋笼。Influence of rate effects on delamination: From Crack Leap Shear tests to low-velocity impactsMaxime Pouliquen, Olivier Allix, Roland Ortiz, Juan Pedro Berro Ramirezdoi:10.1016/j.compstruct.2024.118409速率效应对分层的影响:从裂纹跳跃剪切试验到低速冲击This paper is devoted to the study of different aspects of rate effects in the case of delamination. Two rate dependent cohesive zone models are compared for which the shear rate dependency is identified using Crack Leap Shear experiments. For both models, the key factor appears to be the evolution of the critical energy release rate as function of the crack opening. Moreover, if for very low velocity (1 m/s) rate effects can be neglected, it is not the case for quite low velocity (10 m/s). In the case of a 16 plies quasi-isotropic plate for the size and the shape of the delamination are significantly influenced by the rate effects.本文致力于研究分层情况下速率效应的不同方面。比较了两种速率相关的黏聚带模型,并利用裂缝跃进剪切实验识别出剪切速率相关。对于这两种模型,关键因素似乎是临界能量释放率随裂纹开度的变化。此外,如果对于非常低的速度(1m /s)速率效应可以忽略不计,那么对于非常低的速度(10m /s)就不是这样了。在16层准各向同性板的情况下,分层的大小和形状受到速率效应的显著影响。An explicit finite element discrete crack analysis of open hole tension failure in compositesK. Tian, J. Zhi, V.B.C. Tan, T.E. Taydoi:10.1016/j.compstruct.2024.118411复合材料开孔拉伸破坏的显式有限元离散裂纹分析Developing efficient, robust methods for predicting the progressive failure of carbon fiber composites under tension is essential for optimal design, balancing weight reduction, damage tolerance, and service life. Implicit finite element (FE) methods struggle with the complex interplay of failure mechanisms, leading to a heavy reliance on costly, time-consuming experimental testing. This study introduces a novel explicit algorithm designed for laminate-level mesh models, capable of simulating cohesive cracks without predefined paths. Utilizing an explicit finite element software approach, our method effectively addresses convergence issues associated with the non-linear and unstable nature of composite failures during quasi-static loading. Contrasting with implicit FE method, this mesh-independent approach is both practical and numerically robust. The algorithm’s performance, tested on carbon-fiber reinforced composites with varying ply configurations [45_2 /-45_2]s, [45n/90n/-45n/0n]s and [45/90/-45/0]ns (n=1/2/4/8), demonstrates improved simulation accuracy and efficiency over implicit FE methods, aligning well with prior experimental and simulation data. This advancement offers a promising solution for accurately simulating and understanding the complex failure behavior of these composites.开发高效、可靠的方法来预测碳纤维复合材料在拉力作用下的渐进失效,对于优化设计、平衡减重、损伤容限和使用寿命至关重要。隐式有限元 (FE) 方法难以应对复杂的失效机制相互作用,导致严重依赖昂贵、耗时的实验测试。本研究介绍了一种专为层状网格模型设计的新型显式算法,能够模拟无预定路径的内聚裂纹。利用显式有限元软件方法,我们的方法能有效解决与准静态加载期间复合材料失效的非线性和不稳定性相关的收敛问题。与隐式有限元方法相比,这种与网格无关的方法既实用又具有数值稳定性。该算法在不同层配置 [45_2/-45_2]s、[45n/90n/-45n/0n]s 和 [45/90/-45/0]ns(n=1/2/4/8)的碳纤维增强复合材料上进行了性能测试,结果表明,与隐式 FE 方法相比,该算法提高了模拟精度和效率,与之前的实验和模拟数据非常吻合。这一进步为准确模拟和理解这些复合材料的复杂失效行为提供了一种有前途的解决方案。Composites Part A: Applied Science and ManufacturingA new modified direct method for determining the mode I delamination traction-separation lawA.B. de Moraisdoi:10.1016/j.compositesa.2024.108365一种新的改进的直接法确定I型分层牵引分离规律A new equation was developed for the crack-tip separation in the double cantilever beam (DCB) specimen, which has been standardised for mode I delamination of composites. The very simple closed-form equation is based on a pseudo-elastic beam model and on the effective crack concept. Moreover, it only requires the common load–displacement data up to crack initiation and easy to obtain elastic moduli. Strain-energy release rate versus crack-tip separation curves can then be differentiated for obtaining the tractions, as in the classical direct method. Numerical results for piecewise linear traction-separation laws (TSL) showed good accuracy of strain-energy release rate versus crack-tip separation curves predicted. Application to two carbon/epoxy materials gave very promising TSL results, including cohesive strengths similar to transverse tensile strengths and post-peak steep traction decreases.建立了双悬臂梁(DCB)试样裂纹尖端分离的新方程,并对该方程进行了标准化处理。非常简单的封闭形式方程是基于伪弹性梁模型和有效裂缝的概念。该方法只需要裂纹起裂前的常用荷载-位移数据,且弹性模量易于获得。然后,与经典的直接法一样,可以区分应变-能量释放率与裂纹尖端分离曲线,以获得牵引力。分段线性牵引分离律(TSL)的数值结果表明,所预测的应变能释放率与裂纹尖端分离曲线具有较好的准确性。应用于两种碳/环氧树脂材料的TSL结果非常有希望,包括与横向拉伸强度相似的内聚强度和峰后陡峭牵引力下降。Composites Part B: EngineeringDesign optimization of advanced tow-steered composites with manufacturing constraintsChuan Luo, Federico Ferrari, James K. Guestdoi:10.1016/j.compositesb.2024.111739具有制造约束的先进牵引复合材料的设计优化Tow steering technologies, such as automated fiber placement, enable the fabrication of composite laminates with curvilinear fiber, tow, or tape paths. Designers may therefore tailor tow orientations locally according to the expected local stress state within a structure, such that strong and stiff orientations of the tow are (for example) optimized to provide maximal mechanical benefit. Tow path optimization can be an effective tool in automating this design process, yet has a tendency to create complex designs that may be challenging to manufacture. In the context of tow steering, these complexities can manifest in defects such as tow wrinkling, gaps, overlaps. In this work, we implement manufacturing constraints within the tow path optimization formulation to restrict the minimum tow turning radius and the maximum density of gaps between and overlaps of tows. This is achieved by bounding the local value of the curl and divergence of the vector field associated with the tow orientations. The resulting local constraints are effectively enforced in the optimization framework through the Augmented Lagrangian method. The resulting optimization methodology is demonstrated by designing 2D and 3D structures with optimized tow orientation paths that maximize stiffness (minimize compliance) considering various levels of manufacturing restrictions. The optimized tow paths are shown to be structurally efficient and to respect imposed manufacturing constraints. As expected, the more geometrical complexity that can be achieved by the feedstock tow and placement technology, the higher the stiffness of the resulting optimized design.拖曳导向技术,如自动纤维放置,可以制造具有曲线纤维、拖曳或胶带路径的复合材料层压板。因此,设计人员可以根据结构中预期的局部应力状态在局部定制拖缆方向,例如,拖缆的强和硬方向被优化以提供最大的机械效益。拖径优化是实现设计过程自动化的一种有效工具,但它往往会产生复杂的设计,这可能对制造构成挑战。在拖曳转向的情况下,这些复杂性可以表现在缺陷,如拖曳起皱,缝隙,重叠。在这项工作中,我们在牵引路径优化公式中实施制造约束,以限制最小牵引转弯半径和最大牵引间隙和重叠密度。这是通过约束与两个方向相关的向量场的旋度和散度的局部值来实现的。通过增广拉格朗日方法在优化框架中有效地实现了局部约束。通过设计具有优化的两种方向路径的2D和3D结构,从而在考虑各种制造限制的情况下最大化刚度(最小化顺应性),从而证明了所得到的优化方法。优化后的两条路径在结构上是有效的,并且尊重强加的制造约束。正如预期的那样,原料束和放置技术可以实现的几何复杂性越高,优化设计的刚度就越高。Composites Science and TechnologyCharacterization on fibre kinking fracture of laminated composites under combined compression and shear at high loading rateRui He, Longfei Cheng, Yidi Gao, Hao Cui, Yulong Li, Jianhu Liudoi:10.1016/j.compscitech.2024.110770 高加载速率下压剪复合材料纤维扭结断裂特性研究This paper presented a novel method to characterize the fracture toughness and cohesive law of laminated composites under combined compression and shear at high loading rate. Compact compression specimens with off-axis fibres which introduce the in-plane shear stresses were conducted on the uniaxial bidirectional electromagnetic Hopkinson bar system and the displacement field and strain field were recorded by the high-speed camera for the digital image correlation analysis and J-integral calculation. The results reveal that the in-plane shear stresses bring the increase of fracture toughness at crack initiation and propagation and advance the damage initiation of the specimens. The fracture surfaces indicate that the shear stresses cause the fibre bundles' shear failure during the formation of the kink band, accompanied by more energy dissipation with the increase of off-axis angle.提出了一种表征高加载速率下压剪复合层合材料断裂韧性和粘聚规律的新方法。在单轴双向电磁霍普金森杆体系上进行了带离轴纤维且引入面内剪应力的致密压缩实验,利用高速摄像机记录了位移场和应变场,进行了数字图像相关分析和j积分计算。结果表明:面内剪应力增加了裂纹萌生和扩展时的断裂韧性,促进了试样的损伤萌生;断裂面表明,在扭结带形成过程中,剪切应力导致纤维束发生剪切破坏,随离轴角的增大,能量耗散增大。Investigation on Thermal Conductivities of Plain-woven Carbon/Phenolic and Silica/Phenolic Composites at High Temperature: Theoretical Prediction and ExperimentYifan Wang, Qiuyu Wang, Shuangyu Lv, Bowen Zuo, Lei Chen, Taofeng Cao, Chen Chen, Wen-Quan Taodoi:10.1016/j.compscitech.2024.110771 炭/酚醛和硅/酚醛复合材料高温热导率研究:理论预测与实验Phenolic resin-based ablation materials have found widespread applications in the aerospace industry. The prediction of their thermal conductivity is of paramount importance for the optimization and evaluation for thermal protection systems. However, there is rarely reported thermal conductivity performance of phenolic composites during ablation processes. Therefore, this investigation theoretically predicts the dynamic response of thermal conductivity at high temperatures for plain-woven carbon/phenolic and high silica/phenolic composites. By combining the progressive cubic ablation model with existing composite material property formulas, a multiscale prediction model for effective thermal conductivity is developed. The thermal performance of the resin matrix, reinforcing fibers, yarns, and overall fabric composites is calculated. Additionally, mesoscale representative volume elements are implemented to investigate the overall heat transfer characteristics of carbon/phenolic and high-silica/phenolic composites, including temperature and heat flux distributions. Moreover, both composites thermal conductivities are measured in the range from 298 K to 473 K. The proposed prediction model demonstrates good reliability, with average deviations of 3.76% and 7.36% compared to finite element analysis results and experimental data, respectively.酚醛树脂基烧蚀材料在航空航天工业中有着广泛的应用。其导热系数的预测对于热防护系统的优化和评价具有至关重要的意义。然而,在烧蚀过程中,酚醛复合材料的导热性能却鲜有报道。因此,本研究从理论上预测了普通编织碳/酚醛和高硅/酚醛复合材料在高温下导热系数的动态响应。将渐进立方烧蚀模型与现有的复合材料性能公式相结合,建立了复合材料有效导热系数的多尺度预测模型。计算了树脂基体、增强纤维、纱线和整体织物复合材料的热性能。此外,采用中尺度代表性体积元来研究碳/酚醛和高硅/酚醛复合材料的整体传热特性,包括温度和热流密度分布。此外,两种复合材料的热导率在298 ~ 473 K范围内进行了测量。该预测模型具有良好的可靠性,与有限元分析结果和实验数据相比,平均偏差分别为3.76%和7.36%。Fully 3D printed functional PDMS composites with designable structures and performancesYi An, Wenhao Wang, Renyi Cheng, Chenglin Li, Jiaming Liu, Hong Xu, Xiaoli Wang, Daming Wu, Jingyao Sundoi:10.1016/j.compscitech.2024.110773 全3D打印功能PDMS复合材料具有可设计的结构和性能Three-dimensional (3D) printing, as a layer-to-layer additive manufacturing technology, has received widespread attention for excellent designability. However, as for direct ink writing (DIW), current printing level is difficult to achieve high-precision printing of thermoset composites of different compositions. Therefore, fully 3D printing based on thermoset composites with high designability is proposed. The intralayer and interlayer of structure and materials prepared by this method are designable, and layer thicknesses as well as inter-layer patterns are adjustable. In this work, alumina (Al2O3) and short carbon fiber (SCF) are used as thermally conductive fillers, polydimethylsiloxane (PDMS) is conducted as thermoset matrix. Benefit from the high designability of our method, a series of Al2O3/SCF/Al2O3 (ASA) and SCF/Al2O3/SCF (SAS) composite samples with sandwich structures are fabricated and compared. The different materials and structural designs of these composite samples give them completely different properties in terms of thermal, electromagnetic shielding, and mechanical properties, making it possible to create customized designs for different scenarios. Taking thermal management materials (TMMs) as an example, we use this method to prepare ASA and SAS composites with sandwich structure, thermal conductivity of A40S30A40 and S30A40S30 reached 1.00 W/(m·K) and 1.55 W/(m·K) respectively. In all, customized and multifunctional applications make PDMS composites have a widespread prospect.三维打印作为一种层对层增材制造技术,因其优异的可设计性而受到广泛关注。然而,对于直墨书写(DIW),目前的印刷水平很难实现不同成分热固性复合材料的高精度印刷。因此,提出了基于高可设计性热固性复合材料的全3D打印技术。用该方法制备的结构和材料的层内和层间是可设计的,层厚度和层间图案是可调节的。本文采用氧化铝(Al2O3)和短碳纤维(SCF)作为导热填料,聚二甲基硅氧烷(PDMS)作为热固性基体。利用该方法的高可设计性,制备了一系列具有夹层结构的Al2O3/SCF/Al2O3 (ASA)和SCF/Al2O3/SCF (SAS)复合样品并进行了比较。这些复合材料样品的不同材料和结构设计使其在热、电磁屏蔽和机械性能方面具有完全不同的性能,从而可以针对不同的场景创建定制设计。以热管理材料(TMMs)为例,利用该方法制备了具有夹层结构的ASA和SAS复合材料,A40S30A40和S30A40S30的导热系数分别达到1.00 W/(m·K)和1.55 W/(m·K)。总之,定制化和多功能的应用使得PDMS复合材料具有广泛的应用前景。Microscopic damage behavior in CFRP cross-ply laminates at cryogenic temperatureKazuyoshi FUJISHIRO, Toshio OGASAWARA, Koki MIZUTANI, Hisashi KUMAZAWA, Takahira AOKIdoi:10.1016/j.compscitech.2024.110774 低温下CFRP交叉层合板的微观损伤行为For the practical use of cryogenic propellant tanks made of CFRP laminates, experimental elucidation of the laminates’ microstructural damage propagation behavior at cryogenic temperatures is important. This paper presents a newly developed tensile test rig that enables in-situ observation of microscopic damage using an optical microscope at cryogenic temperatures using a Gifford–McMahon refrigerator. In-situ observations of microscopic damage under uniaxial tensile loading were done at room temperature (290 K, 17 °C) and at 30 K (-243 °C) on cross-ply thin-layer CFRP specimens of three kinds with different 90° layer thicknesses. The results demonstrated that the crack propagation behavior is independent of temperature, that the matrix crack density is higher, and that the onset of matrix crack initiation strain is lower at 30 K than at 290 K. Furthermore, the thermal strain within 90° layer at 30 K and 290 K was estimated using finite element analyses (FEA). The FEA results suggest that the decrease in onset strain of matrix crack initiation at 30 K is mainly attributed to the increase in the thermal strains within the 90° layer.为了实际应用碳纤维复合材料制成的低温推进剂储罐,对复合材料在低温下的微结构损伤扩展行为进行实验研究具有重要意义。本文介绍了一种新开发的拉伸试验台,该试验台使用Gifford-McMahon冰箱在低温下使用光学显微镜对微观损伤进行原位观察。在室温(290 K, 17°C)和30 K(-243°C)条件下,对三种不同90°层厚的交叉铺层CFRP薄层试样进行了单轴拉伸加载下的微观损伤现场观察。结果表明:裂纹扩展行为与温度无关,基体裂纹密度较高,30k时基体裂纹起裂应变小于290k;此外,利用有限元分析(FEA)估算了30 K和290 K时90°层内的热应变。有限元分析结果表明,30k时基体裂纹起裂应变的减小主要是由于90°层内热应变的增大。来源:复合材料力学仿真Composites FEM

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