今日更新:Composite Structures 7 篇,Composites Part B: Engineering 5 篇,Composites Science and Technology 1 篇
Numerical and mechanical analysis of laminated PA11/twill basalt composites with enhanced flame behavior
Ilaria Papa, Matteo Bruno, Francesco Napolitano, Luca Esposito, Valentina Lopresto, Pietro Russo
doi:10.1016/j.compstruct.2024.118123
增强火焰性能的PA11/斜纹玄武岩层压复合材料的数值与力学分析
The development of new material configuration is a challenge which requires different steps of characterization. From the mechanical characterization, which is the starting point to determine the application fields, until the evaluation of the safety aspects in case of human contact use or in vehicle and building interiors. Nowadays, the integration with the numerical simulation is strategically important to make a further step in the obtainment of a model for rapid prevision of the mechanical response in different components. In this research study is provided a complete characterization of new composite material constituted by PA11 resin with flame retardant and basalt twill; the mechanical properties are evaluated through flexural and impact tests, also the fire resistance is assessed through the flammability test. Then a numerical model for mechanical response simulation was developed and compared with experimental results. This is driven by the need to expand the comprehension on the damage mechanisms generated by low velocity impacts. The results show an excellent behavior of this composite, with high fire resistance and mechanical properties which suggest proper use in aircraft interiors. Moreover, the good correspondence between numerical and experimental results gives a model which is suitable to design other PA11/basalt composite workpieces.
新材料结构的开发是一个挑战,需要不同的表征步骤。从机械特性开始,这是确定应用领域的起点,直到评估人类接触使用或车辆和建筑物内部的安全方面。目前,将其与数值模拟相结合对于进一步获得快速预测不同部件力学响应的模型具有重要的战略意义。本研究提供了一种由PA11树脂与玄武岩斜纹布组成的新型阻燃复合材料的完整表征;通过弯曲试验和冲击试验对其力学性能进行了评定,并通过可燃性试验对其耐火性能进行了评定。建立了机械响应仿真的数值模型,并与实验结果进行了比较。这是由于需要扩大对低速撞击产生的损伤机制的理解。结果表明,该复合材料性能优异,具有较高的耐火性能和机械性能,适合用于飞机内饰。数值计算结果与试验结果吻合较好,该模型适用于其它PA11/玄武岩复合材料工件的设计。
Mesoscopic finite element modeling of biaxial non-crimp fabric including representative stitch pattern
Ruochen Zheng, Naim Naouar, Julien Colmars, Auriane Platzer, Bastian Schäfer, Fabrice Morestin, Luise Kärger, Philippe Boisse
doi:10.1016/j.compstruct.2024.118126
双轴不卷曲织物的细观有限元建模,包括代表性的针型
A comprehensive understanding of the mechanical properties of carbon fiber reinforcements is necessary to accurately simulate forming processes. The parametrization of macroscopic models requires extensive experimental characterization for different deformation modes. In order to reduce experimental effort, this work proposes a mesoscopic model of bi-axial non-crimp fabric (Bi-NCF) that can be used for virtual material characterization. The fiber yarns are considered as a continuous medium and modeled with solid elements, and their mechanical behavior is described by a hyperelastic constitutive law dedicated to anisotropic fibrous media. The stitches are modeled with 2-node beam elements. This model is developed based on precise geometry measurements obtained from X-ray tomography results. An additional stitch pre-tension step is incorporated in the model to improve contact and simulate the tension induced by the sewing process. Experimental Picture Frame Tests are used to validate the model at mesoscale, while experimental and numerical Bias-extension Tests demonstrate its potential to simulate larger scales and effectively predict local defects.
全面了解碳纤维增强材料的力学性能是准确模拟成形过程的必要条件。宏观模型的参数化需要对不同的变形模式进行大量的实验表征。为了减少实验工作量,本工作提出了一种可用于虚拟材料表征的双轴无卷曲织物(Bi-NCF)的介观模型。将纤维纱线视为一种连续介质,用实体单元进行建模,用各向异性纤维介质的超弹性本构律描述纤维纱线的力学行为。缝线采用2节点梁单元建模。该模型是基于从x射线断层扫描结果中获得的精确几何测量而开发的。在模型中加入了一个额外的缝线预张力步骤,以改善接触并模拟缝制过程引起的张力。实验相框测试用于中尺度上验证模型,而实验和数值偏差扩展测试则证明了该模型具有模拟更大尺度和有效预测局部缺陷的潜力。
On characterization of transverse tensile properties of pultruded glass fiber-reinforced polymer (PGFRP) profiles based on non-standard short coupons
Yunhong Luo, Pan Zhang, Tao Yu
doi:10.1016/j.compstruct.2024.118128
基于非标准短条的拉挤玻璃纤维增强聚合物(PGFRP)型材横向拉伸性能表征
Pultruded glass fiber-reinforced polymer (PGFRP) profiles, manufactured via a pultrusion process, are increasingly used in civil engineering. However, due to the anisotropic nature, their transverse material properties are weaker than the longitudinal ones, necessitating robust material characterization methods for transverse properties. Commercially available PGFRP profiles often have insufficiently large cross-sections for standard-sized transverse tensile tests, prompting the need to investigate the effect of coupon size on transverse tensile properties and propose a feasible shorter coupon size. This paper therefore aims to examine the coupon-size effects and propose suitable short coupon geometries for transverse tensile tests. Standard material characterization tests were conducted on channel-section PGFRP profiles, followed by transverse tensile tests on six types of non-standard short coupons. The effects of coupon width and gauge length on transverse tensile properties were evaluated and compared across six aspects, with potential failure mechanisms further explored using finite element analysis (FEA). The paper concludes by proposing a feasible short coupon configuration for transverse tensile tests.
拉挤玻璃纤维增强聚合物(PGFRP)型材,通过拉挤工艺制造,越来越多地应用于土木工程。然而,由于其各向异性,其横向材料性能弱于纵向材料性能,因此需要对横向性能进行稳健的材料表征方法。商业上可用的PGFRP型材通常没有足够大的横截面进行标准尺寸的横向拉伸试验,这促使需要研究粘结层尺寸对横向拉伸性能的影响,并提出可行的更短的粘结层尺寸。因此,本文的目的是研究粘片尺寸效应,并提出适合横向拉伸试验的短粘片几何形状。对通道截面PGFRP型材进行了标准材料特性试验,然后对6种非标准短板进行了横向拉伸试验。从六个方面评估和比较了试件宽度和厚度对横向拉伸性能的影响,并利用有限元分析(FEA)进一步探讨了潜在的破坏机制。最后,提出了一种可行的横向拉伸试验短板结构。
Anisotropic failure analysis of 2.5-D braided composites under compression
Linlin Deng, Ziqing Hao, Hongjun Ke, Hairun Wang, George Kardomateas, Liu Liu
doi:10.1016/j.compstruct.2024.118130
2.5维编织复合材料压缩破坏的各向异性分析
2.5-D braided high-alumina fabric-reinforced silica matrix composite materials are being developed as functional structural composites with thermal load-bearing capacity for the top thin face sheet of an integrated thermal protection system (TPS). This study seeks to elucidate the mechanical behavior of a 2.5-D braided top face sheet composite material subjected to off-axis compression, while the sandwich TPS is under deflection caused by the bending moment resulting from the temperature gradient in the thickness direction and the aerodynamic pressure on the top face sheet panel. The effective compressive modulus and ultimate strength along the warp direction are significantly lower than those along the weft direction. Both decrease as the off-axis loading angle increases, indicating anisotropy. A nonlinear compressive stress–strain response with extensive damage along the warp yarn direction, while the weft yarn direction exhibits a quasi-linear response with minor damage before fracture. Within the framework of continuum damage mechanics, fiber kinking and transverse inter-fiber cracking of fiber bundles with the linear damage evolution law are all considered simultaneously for the progressive damage model. To account for the interaction between multiple damage mechanisms in the fiber yarn, a joint degradation induced by multiple damage mechanisms is first proposed. The analysis reveals that the anisotropy of failure under compression is primarily due to the warp fiber bundle’s much larger undulation than the weft fiber bundle, which causes severe bending-dominated damage. Using the calibrated model, the qualitative effects of material thickness and yarn geometry size on the compressive mechanical properties of materials are analyzed.
2.5维编织高铝纤维增强二氧化硅基复合材料是一种具有热承载能力的功能性结构复合材料,可用于集成热防护系统(TPS)的顶部薄面板。本研究旨在阐明2.5维编织顶面板复合材料在离轴压缩下,夹层TPS在厚度方向温度梯度和顶面板气动压力引起的弯矩引起的挠曲作用下的力学行为。有效压缩模量和极限强度沿经纱方向显著低于沿纬纱方向。随着离轴加载角的增大,两者均减小,表明各向异性。断裂前沿经纱方向为非线性压应力-应变响应,损伤广泛;纬纱方向为准线性响应,损伤较小。在连续损伤力学的框架下,渐进损伤模型同时考虑了纤维束的纤维扭结和纤维束的横向纤维间开裂,并遵循线性损伤演化规律。为了考虑纤维纱线中多种损伤机制之间的相互作用,首次提出了由多种损伤机制引起的联合退化。分析表明,压缩破坏的各向异性主要是由于经纱纤维束的波动比经纱纤维束大得多,造成了严重的弯曲主导损伤。利用标定后的模型,分析了材料厚度和纱线几何尺寸对材料压缩力学性能的定性影响。
Flexible composite structure with customizable in-plane Poisson’s ratio under large deformation
Wenhao Zhao, Sanchun Lin, Shengjie Wang, Heng Yang, Jiaxing Wang, Hongshuai Lei
doi:10.1016/j.compstruct.2024.118127
大变形下面内泊松比可定制的柔性复合材料结构
Regulating the inherent Poisson's ratio of soft elastic materials under large deformation is important for their application in emerging fields, such as morphing structures and stretchable electronics. In this study, we selected a composite in which an auxetic honeycomb was embedded in a soft material to regulate the in-plane Poisson's ratio. Based on a cantilever beam model, a theoretical model was established to guide the design optimization of composite structures. The macroscopic constitutive relation and in-plane Poisson's ratio of the composite structures with different configurations were predicted by the theoretical model, which were consistent with the finite element analysis results. In the 30% strain range, the slope of the Poisson's ratio–strain curve decreases with an increase in the length of the inclined bar, and the in-plane Poisson's ratio increases with an increase in the angle between the transverse bar and the inclined bar. In addition, we propose an optimization design method with the in-plane Poisson's ratio as the objective function and then optimize and fabricate a skin structure with an in-plane Poisson's ratio of approximately zero for the morphing wings. The achievements of this study provide theoretical guidance for regulating the in-plane Poisson's ratio of thin flexible layers.
调节大变形软弹性材料的固有泊松比对于软弹性材料在变形结构和可拉伸电子等新兴领域的应用具有重要意义。在本研究中,我们选择了一种复合材料,在软材料中嵌入一个消声蜂窝来调节面内泊松比。基于悬臂梁模型,建立了指导复合材料结构设计优化的理论模型。理论模型预测了不同构型复合材料结构的宏观本构关系和面内泊松比,与有限元分析结果一致。在30%应变范围内,泊松比应变曲线的斜率随斜杆长度的增加而减小,面内泊松比随横杆与斜杆夹角的增加而增大。此外,提出了一种以面内泊松比为目标函数的优化设计方法,优化制作出了面内泊松比近似为零的变形翼蒙皮结构。研究成果为柔性薄层面内泊松比的调节提供了理论指导。
Linear static, geometric nonlinear static and buckling analyses of sandwich composite beams based on higher-order refined zigzag theory
Yu-Hsien Chen, Chung-De Chen
doi:10.1016/j.compstruct.2024.118131
基于高阶精细之字形理论的夹层组合梁线性静力、几何非线性静力及屈曲分析
This study aims at developing finite element formulations based on higher-order refined zigzag theory (HRZT) to analyze sandwich composite beams under linear static bending, geometric nonlinearity and buckling. In HRZT, the higher-order terms associated with average shear strain and rotation due to zigzag are added based on refined zigzag theory (RZT). In linear static bending analysis, both C0 and C1 elements are developed. For the C0 element, an extra node is used in order to eliminate shear locking. For geometric nonlinear static analysis, the two-node C0 element is developed to solve the bending response with lateral loading and buckling response. The numerical results are compared with those calculated by 2D exact solutions, analytical solutions of HRZT and 2D models using commercial software. Various beam theories such as first-order shear deformation theory (FSDT), higher-order shear deformation theory (HSDT), RZT, and other types of higher-order zigzag theory are also introduced for comparisons. Through comprehensive comparisons with existing works on FEM or zigzag theories, the HRZT beam elements developed in this study exhibit superior accuracy and are free from shear locking in linear static analysis. Furthermore, the study also demonstrates that these elements achieve high accuracy in geometric nonlinear analysis and buckling analysis.
本研究旨在开发基于高阶精炼之字形理论(HRZT)的有限元公式,以分析线性静态弯曲、几何非线性和屈曲情况下的夹层复合梁。在 HRZT 中,与平均剪切应变和人字形旋转相关的高阶项是在精炼人字形理论(RZT)的基础上添加的。在线性静态弯曲分析中,开发了 C0 和 C1 元素。对于 C0 元素,为了消除剪切锁定,使用了一个额外的节点。在几何非线性静态分析中,开发了双节点 C0 元素来解决带有横向载荷的弯曲响应和屈曲响应。数值结果与二维精确解、HRZT 分析解以及使用商业软件的二维模型计算的结果进行了比较。此外,还引入了各种梁理论,如一阶剪切变形理论(FSDT)、高阶剪切变形理论(HSDT)、RZT 和其他类型的高阶之字形理论进行比较。通过与现有有限元理论或之字形理论著作的综合比较,本研究开发的 HRZT 梁元素表现出更高的精度,并且在线性静力分析中不会出现剪切锁定。此外,研究还证明,这些元素在几何非线性分析和屈曲分析中也能达到很高的精度。
Impact resistance of assembled plate-lattice auxetic structures
Wei-Jing Wang, Wei-Ming Zhang, Meng-Fu Guo, Hang Yang, Li Ma
doi:10.1016/j.compstruct.2024.118132
拼装板-格结构的抗冲击性能
Auxetic materials are attracting increasing interest due to their extraordinary or even abnormal mechanical properties. Different from the traditional truss-lattice structures, this paper proposes a series of novel auxetic plate-lattice structures with an excellent auxetic effect. Utilizing a dual-materials glue-free assembly design involving hyperelastic and plastic materials, these plate-lattices exhibit numerous advantages such as disassembly, assembly, replacement, recyclability, reusability, excellent energy absorption, high specific stiffness, and impact resistance performances. Quasi-static/dynamic tests and simulations are conducted to assess mechanical properties, including elastic constants, deformation modes, and mechanical responses. Simultaneously, the effect of the principal geometric parameter, concave angle, on the structural response was analyzed with various impact velocities. Findings suggest that the concave angle influences the structural elastic constants under compressive loading. The stress–strain response exhibits a distinct dual-plateau phenomenon. Taking the A65 (concave angle is 65°) configuration as an example, the stress on the second plateau is approximately 2.7 times that of the first plateau, significantly enhancing the structure's energy absorption capability. Under dynamic impact loadings, different configurations and varying impact velocities affect the structure's energy absorption performance. This paper introduces a series of assemblable plate-lattice structures with an auxetic effect, offering design insights and guidance tailored to the convenient transportation, unconventional structures, and rapid assembly needs of lightweight, impact-resistant mechanical metamaterials.
增塑型材料因其特殊甚至异常的力学性能而受到越来越多的关注。与传统的桁架-晶格结构不同,本文提出了一系列具有良好减震效果的新型板-晶格减震结构。利用双材料无胶组装设计,包括超弹性和塑料材料,这些板晶格具有许多优点,如拆卸,组装,更换,可回收性,可重复使用,出色的能量吸收,高比刚度和抗冲击性能。进行准静态/动态测试和模拟,以评估机械性能,包括弹性常数,变形模式和机械响应。同时,分析了不同冲击速度下,主要几何参数凹角对结构响应的影响。结果表明,在压缩载荷作用下,凹角会影响结构的弹性常数。应力应变响应表现出明显的双平台现象。以A65(凹角为65°)结构为例,第二平台的应力约为第一平台的2.7倍,结构的吸能能力显著增强。在动冲击载荷作用下,不同的结构形式和不同的冲击速度会影响结构的吸能性能。本文介绍了一系列具有辅助效应的可组装板-晶格结构,为轻量化、抗冲击的机械超材料的运输便利、非常规结构和快速装配需求提供了设计见解和指导。
Quantitative assessment of whether phosphorus-based flame retardants are optimizing or degrading the fire hazard of aircraft carbon fiber/epoxy composites
Bin Zou, Ziyan Qian, Zixuan Zhang, Weiyi Xing, Shangshang Zhong, Jiajun Li, Fukai Chu, Yongchun Kan, Jie Chen, Yuan Hu
doi:10.1016/j.compositesb.2024.111413
磷系阻燃剂是否优化或降低飞机碳纤维/环氧复合材料的火灾危险性的定量评估
Fire hazards are a primary concern in aircraft accidents, and controlling combustible materials is pivotal in managing cabin fire risks. This work aims to elucidate the impact of widespread measures that introduce phosphorus-based flame retardants (PFRs) on the fire safety of carbon fiber epoxy composites (CF/EP). Firstly, the hazardous indicators for flame retardant CF/EP composites exhibit two categories of optimization and degradation, which are caused by the intrinsic feature, pyrolysis characteristics and chemical valence states of PFRs. Secondly, the fire hazards of composites are assessed by fusing the analytic network process and information weights guided by Nash Equilibrium theory. The method combines the merits of subjective and objective weights from dimensions of intrinsic hazards, interrelationships and data dispersion of indicators. Finally, the assessed fire hazard rankings under 35 and 65 kW/m2 both are EP > CF/EP16%DOPO-HQ > CF/EP > CF/EP7%DPO. In conclusion, DOPO-HQ (+1) primarily increases the fire hazard of CF/EP due to gas-phase flame-retardant effects, while DPO (+3) predominantly reduces the fire hazard of CF/EP by contributing to condensed-phase effects. This work highlights the contradictory effects of PFRs on the fire safety of CF/EP composites due to structure and thermal stability. The proposed ANP and IW hybridization method provides a theoretical foundation for selecting flame retardants and assessing material fire hazards comprehensively.
火灾危险是飞机事故的首要问题,控制可燃材料是管理客舱火灾风险的关键。本工作旨在阐明引入磷基阻燃剂(PFRs)的广泛措施对碳纤维环氧复合材料(CF/EP)防火安全的影响。首先,阻燃CF/EP复合材料的危险指标呈现出两类优化和降解,这是由阻燃材料的内在特性、热解特性和化学价态决定的。其次,以纳什均衡理论为指导,融合分析网络过程和信息权重,对复合材料的火灾危险性进行评估;该方法从指标的内在危害、相互关系和数据离散度等方面综合了主客观权重的优点。35 kW/m2和65 kW/m2以下的火灾危险性排序为:EP > CF/EP16%DOPO-HQ > CF/EP > CF/EP7%DPO。综上所述,DOPO-HQ(+1)主要通过气相阻燃作用增加CF/EP的火灾危险性,而DPO(+3)主要通过促进凝聚相阻燃作用降低CF/EP的火灾危险性。这项工作强调了由于结构和热稳定性,PFRs对CF/EP复合材料防火安全性的矛盾影响。提出的ANP和IW杂交方法为阻燃剂的选择和材料火灾危险性的综合评估提供了理论基础。
Bonding Strength Enhancement of a 30wt.%GF/PET–2024 Aluminium Alloy Joint by Synergistic Action of Multi-scale Mechanical Interlocking and Multiplex H-Bonding
Shumei Lou, Baojia Cheng, Leyao Xu, Ben Ma, Haoyu Wang, Lina Lu, Xiping Li
doi:10.1016/j.compositesb.2024.111437
提高30wt的粘接强度。GF/ PET-2024铝合金多尺度机械联锁与多重h键协同作用接头
In this study, micro-scale cellular and nano-scale labyrinth structures were obtained on the surface of A2024 aluminium alloy adherends through ultrasonic-aided corrosion using an FeCl3 etchant solution to significantly enhance the mechanical interlock of it and a 30 wt.% glass-fibre-enhanced polyethylene terephthalate substrate. The tensile shear strength of the 30wt.% GF/PET–A2024 joint was increased to 31.84 MPa. The subsequent treatment of an appropriate amount of KH-892/PVA transformed the surface of the aluminium alloy from hydrophobic to hydrophilic to significantly improve its wettability. Furthermore, this treatment generated multiplex hydrogen bonding of O-H…O…H-N at the interface, further improving the tensile shear strength of the joint up to 50.94 MPa, which is significantly higher than the values obtained using exiting methods. The tensile shear tests of a ring-shaped insulator specimen according to GB 7251-87 verified the improved fracture work equation herein and the bonding strength enhancement of the 30wt.%GF/PET–A2024 aluminium alloy joint treated by ultrasonic-aided corrosion with an FeCl3 etchant solution and pre-coating of an appropriate amount of KH-892/PVA.
在本研究中,采用FeCl3蚀刻液对A2024铝合金粘附体表面进行超声辅助腐蚀,获得了微尺度的细胞和纳米尺度的迷宫结构,显著增强了A2024铝合金与30% wt.%玻璃纤维增强聚对苯二甲酸乙二醇酯基板的机械联锁。拉伸剪切强度30wt。% GF/ PET-A2024接头增大到31.84 MPa。后续处理适量的KH-892/PVA使铝合金表面由疏水性转变为亲水性,润湿性显著提高。此外,该处理在界面处形成了O- h…O…H-N的多重氢键,进一步提高了接头的抗拉剪切强度,达到50.94 MPa,显著高于现有方法。按照GB 7251-87标准对环形绝缘子试样进行了拉伸剪切试验,验证了改进后的断裂功方程和30wt的粘结强度提高。采用FeCl3蚀刻液和预涂适量KH-892/PVA对%GF/ PET-A2024铝合金接头进行超声辅助腐蚀处理。
Enhancement of strength-ductility synergy in high-strength metastable β-titanium alloys through boron microalloying
Dingxuan Zhao, Keer Li, Jixiong Liu, Rui Li, Wei Chen, Jinyu Zhang, Xiaoxiang Wang, Jian Wang, Jun Sun
doi:10.1016/j.compositesb.2024.111449
硼微合金化增强高强度亚稳β-钛合金的强度-延展性协同作用
Metastable β-titanium (Ti) alloys have always attracted great attention due to the available ultra-high strength via precipitation strengthening, while they often succumb to a strength-ductility trade-off known as improving strength but degrading ductility. In this study, we exploit a novel strategy to address the issue in Ti-6Cr-5Mo-5V-4Al (Ti6554) high-strength metastable β-Ti alloy through the trace boron addition. It is found that an ultra-high strength ∼1600 MPa with elongation of ∼9 % is synchronously achieved with the addition of minor boron, corresponding to a ∼7 % increase in strength and ∼70 % improvement in ductility compared to the boron-free counterpart. Microstructural characterizations manifest that boron addition promotes almost complete transformation from abnormal β-grain region to normal β-grain region, which possesses better deformation accommodation capacity at the aged state. Meanwhile, TiB whiskers are produced and adhered by a layer of αs-film, creating a sandwiched structure architected by TiB whisker/αs-film/ the aged β-matrix. This unique structure not only effectively retards the deteriorative development of highly localized deformation propagating from the the aged β-matrix, but also sufficiently activates dislocation slip within TiB whiskers. These findings demonstrate a counterintuitive result that TiB intermetallic compound well-known as the susceptive brittleness can be harnessed in ductilizing materials, and also provide a practical strategy for enhancing plasticity of high-strength Ti alloys by microalloying design.
由于可通过沉淀强化获得超高强度,可代谢β-钛(Ti)合金一直以来都备受关注,但它们往往会受到强度-韧性权衡的影响,即在提高强度的同时降低韧性。在本研究中,我们采用了一种新颖的策略,通过痕量添加硼来解决 Ti-6Cr-5Mo-5V-4Al (Ti6554) 高强度隐晶β-Ti 合金中的这一问题。研究发现,与不含硼的合金相比,添加微量硼后可同步达到 1600 兆帕的超高强度和 9 % 的伸长率,相当于强度提高了 7 %,延展性提高了 70 %。微观结构特征表明,硼的添加几乎促进了异常β晶粒区向正常β晶粒区的完全转变,而正常β晶粒区在老化状态下具有更好的变形容纳能力。与此同时,TiB 晶须产生并被一层 αs 薄膜粘附,从而形成了一种由 TiB 晶须/αs 薄膜/老化的 β 基质构成的夹层结构。这种独特的结构不仅能有效延缓从老化的β基质传播的高度局部变形的劣化发展,还能充分激活 TiB 晶须内的位错滑移。这些发现证明了一个反直觉的结果,即众所周知的易脆性 TiB 金属间化合物可以在延展材料中得到利用,同时也为通过微合金化设计增强高强度钛合金的塑性提供了一种实用策略。
Effect of microscale C–S–H on the properties of Portland cement and hydration kinetics analysis at different curing temperatures
Kang Li, Huajun Zhu, Zuhua Zhang, Zheyu Zhu, Zhifeng Yin, Qisheng Wu, Zhonghua Li
doi:10.1016/j.compositesb.2024.111461
微尺度C-S-H对硅酸盐水泥性能的影响及不同养护温度下水化动力学分析
Microscale calcium–silicate–hydrate (C–S–H) is easily accessible and readily storable, enabling a cleaner production process of cement-waste grinding and simple chemical synthesis technology. However, the temperature effects of microscale C–S–H require further exploration. In this study, we evaluated the impact of microscale C–S–H admixture on the properties of Portland cement at different curing temperatures. Microscale C–S–H can not only increase the early strength of cement pastes, but also achieve high strength in the long term. Adding microscale C–S–H to cement can effectively reduce the apparent activation energy Ea of hydration products and accelerate the reaction of C3S and C2S with water and form more hydration products. At a curing temperature of 10 oC, the microscale C–S–H increased the 1 d compressive strength by 70.0% and shortened the hydration induction period by 1.2 h. Microscale C–S–H also increased the 12 h hydration degree by 38.1%. Microscale C–S–H promoted the formation of CH and xonotlite-like C–S–H and changed the composition of hydrates, although the effects diminished with increasing curing temperature. This paper offers theoretical and fundamental data on the usage of microscale C–S–H as an admixture in cement-based materials.
微尺度硅酸钙水合物(C-S-H)易于获取和储存,可实现水泥废料研磨的清洁生产工艺和简单的化学合成技术。然而,微尺度 C-S-H 的温度效应需要进一步探索。在这项研究中,我们评估了微尺度 C-S-H 掺合料在不同固化温度下对硅酸盐水泥性能的影响。微尺度 C-S-H 不仅能提高水泥浆的早期强度,还能获得长期高强度。在水泥中添加微尺度 C-S-H 可以有效降低水化产物的表观活化能 Ea,加速 C3S 和 C2S 与水的反应,形成更多的水化产物。在固化温度为 10 oC 时,微尺度 C-S-H 使 1 d 抗压强度提高了 70.0%,水化诱导期缩短了 1.2 h。微尺度 C-S-H 促进了 CH 和类 xonotlite C-S-H 的形成,并改变了水合物的组成,但随着固化温度的升高,其效果会减弱。本文提供了微尺度 C-S-H 用作水泥基材料外加剂的理论和基础数据。
TGACharacterization of Multidirectional Carbon-nanotube-yarn/bismaleimide Laminates Under Tensile Loading
Britannia Vondrasek, Cecil Evers, Claire Jolowsky, Gregory M. Odegard, Zhiyong Liang, Michael Czabaj
doi:10.1016/j.compositesb.2024.111465
拉伸载荷下多向碳纳米管-纱/双马来酰亚胺复合材料的tga表征
Unidirectional, cross-ply, and quasi-isotropic composite laminates are made from continuous carbon nanotube (CNT) yarns with bismaleimide (BMI) resin. The laminates are highly graphitic and have low resin content. Elastic modulus and strength of CNT/BMI laminates and IM7/8552 carbon-epoxy laminates are measured using a scaled-down tensile test method. For CNT/BMI laminates, the variation in the measured tensile modulus is high and the laminates fail in a more gradual manner than IM7/8552 laminates. Microscopy of the failed specimens indicates that intra-yarn splitting is a common feature in all CNT/BMI laminates tested. The results of this investigation will inform the development of CNT yarn reinforced composites for structural applications.
用碳纳米管(CNT)纱线和双马来酰亚胺(BMI)树脂制备了单向、交叉和准各向同性复合层压板。层压板的石墨含量高,树脂含量低。采用按比例缩小的拉伸试验方法测量了CNT/BMI层压板和IM7/8552碳-环氧层压板的弹性模量和强度。对于CNT/BMI层压板,测量的拉伸模量变化很大,层压板比IM7/8552层压板以更渐进的方式失效。显微镜检查失败的样品表明,纱线内分裂是所有CNT/BMI层压板测试的共同特征。该研究结果将为碳纳米管纱增强复合材料的结构应用提供参考。
A highly efficient self-consistent clustering analysis method with field refinement capability for the mesoscale damage behavior of 3D woven composites
Siyang Wu, Licheng Guo, Zhixing Li, Tao Zheng, Jinzhao Huang, Xiaojian Han, Fenghao Jia, Shihan Man
doi:10.1016/j.compscitech.2024.110609
三维编织复合材料细观损伤行为的高效自洽聚类分析方法
To effectively balance the accuracy and efficiency in solving high-dimensional damage problems, a self-consistent clustering analysis framework with field refinement capability (RESCA) incorporating a mesoscale damage model, is developed to investigate the mesoscale failure behavior of 3D woven composites (3DWCs). The RESCA method includes three stages: offline stage, online stage and field refinement stage integrating damage information. In the third stage, a damage-related field refinement framework is proposed to achieve cluster-based field dehomogenization and efficiently reconstruct the voxel-based field information. The results indicate that the RESCA method can accurately predict the local stress concentration, the voxel-based damage field distribution and the damage accumulation process, which are not available with the traditional SCA method. Importantly, the RESCA method can improve the computational efficiency by 25∼55 times compared to the finite element analysis (FEA) method. The RESCA method has double advantages in the efficiency and accuracy for the damage analysis of 3DWCs.
为了有效地平衡高维损伤问题的准确性和效率,开发了一个包含细观损伤模型的自一致聚类分析框架(RESCA)来研究三维编织复合材料(3DWCs)的细观破坏行为。RESCA方法包括三个阶段:离线阶段、在线阶段和集成损伤信息的现场精细化阶段。第三阶段,提出损伤相关场细化框架,实现基于聚类的场去均匀化,有效重构基于体素的场信息。结果表明,RESCA方法可以准确预测局部应力集中、基于体素的损伤场分布和损伤累积过程,这是传统SCA方法所无法实现的。重要的是,与有限元分析(FEA)方法相比,RESCA方法可以将计算效率提高25 ~ 55倍。RESCA方法在三维结构损伤分析中具有效率和精度双重优势。