今日更新:Composite Structures 3 篇,Composites Part B: Engineering 2 篇,Composites Science and Technology 1 篇
Dynamic compression-shear ignition mechanism of Al/PTFE reactive materials
Hengheng Geng, Rui Liu, Yeping Ren, Pengwan Chen, Chao Ge, Haifu Wang
doi:10.1016/j.compstruct.2024.117908
Al/PTFE反应材料的动态压缩-剪切点火机理
Ignition of Al/PTFE reactive materials can occur under dynamic loading. The ignition mechanism involves a mechanical-thermal-chemical coupled process, which draws the attention of scientists and engineers. However, it is difficult to understand the mechanism, especially under complex loadings. In this paper, three different shapes of Al/PTFE sample, 0° cylinder, 30° oblique cylinder and 45° oblique cylinder, were designed. The dynamic ignition tests were carried out by Split Hopkinson Pressure Bar (SHPB). The deformation, damage and fracture process were analyzed. The mechanical response depended on the shape of the sample, which determined the dynamic compression-shear states, further it induced different ignition behavior. The energy absorption rate ignition criterion was proposed to take the place of the traditional strain rate ignition criterion. The new criterion could match the testing well. In addition, numerical simulation on SHPB was conducted. It verified that Johnson-Cook model would describe the dynamic behavior of Al/PTFE reactive materials. The damage and the fracture of Al/PTFE under dynamic compression-shear loading was quantified well, and further was related to the ignition behavior observed during the tests. Finally, the dynamic compression-shear ignition mechanism of Al/PTFE reactive materials was revealed.
铝/聚四氟乙烯反应材料在动载荷作用下会发生着火。引燃机理涉及一个机械-热-化学耦合过程,引起了科学家和工程师的关注。然而,很难理解其机理,特别是在复杂载荷下。本文设计了3种不同形状的Al/PTFE试样,分别为0°圆柱体、30°斜圆柱体和45°斜圆柱体。采用分离式霍普金森压杆(SHPB)进行了动态点火试验。对其变形、损伤和断裂过程进行了分析。试样的力学响应取决于试样的形状,这决定了试样的动态压剪状态,进而导致不同的着火行为。提出了能量吸收率点火判据,取代了传统的应变率点火判据。新的标准可以很好地与测试相匹配。此外,还对SHPB进行了数值模拟。验证了Johnson-Cook模型能够描述Al/PTFE反应材料的动力学行为。动态压剪载荷对Al/PTFE的损伤和断裂进行了较好的量化,并进一步与试验中观察到的着火行为有关。最后,揭示了Al/PTFE反应材料的动态压缩-剪切点火机理。
Characterizing Damage Patterns and Evolution in Multi-Hole GLARE Laminates under Tensile Load via Integrated AE and DIC Techniques
Y.X. Zheng, K.J. Hu, M. Zhang, J.X. Zhu, F.L. Zhao, W.Q. Han, Q.H. Shi, Z.L. Cao
doi:10.1016/j.compstruct.2024.117911
基于声发射和DIC集成技术表征拉伸载荷下多孔眩光层合板的损伤模式和演化
In this study, a combined numerical simulation and experimental approach was employed to investigate the mechanical behavior and damage mechanisms of multi-hole GLARE laminates with varying off-axis angles under static tensile loading. Digital image correlation techniques were used to monitor changes in the strain field near the open hole region. The acoustic emission parameters were used to recognize damage patterns and evolution. The progressive damage evolution processes of various GLARE components were investigated using a 3D finite element model (FEM) based on the Hashin strain criterion and cohesive zone modeling. The results indicate that GLARE experiences damage modes such as aluminum alloy breakage, matrix cracking, fiber/matrix debonding, delamination, and fiber breakage. The frequency ranges associated with the five damage modes are as follows: [0-50 kHz], [100-175 kHz], [175-220 kHz], [220-300 kHz], and [300-400 kHz]. The dominant damage mode throughout the tensile phase is matrix cracking, but the ultimate failure of the specimen is determined by aluminum alloy breakage and fiber breakage. In addition, increasing the off-axis angle of the multi-hole leads to a shift in the final failure mode from tensile-dominated to tensile shear-dominated, while also slightly reducing the overall initial stiffness of the specimen.
采用数值模拟与实验相结合的方法,研究了不同离轴角的多孔眩光层压板在静态拉伸载荷作用下的力学行为和损伤机理。利用数字图像相关技术监测裸眼区域附近应变场的变化。利用声发射参数识别损伤模式和演化过程。采用基于Hashin应变准则和黏聚区建模的三维有限元模型,研究了不同眩光组件的渐进损伤演化过程。结果表明,眩光材料经历了铝合金断裂、基体开裂、纤维/基体脱粘、分层和纤维断裂等损伤模式。与五种损伤模式相关的频率范围如下:[0-50 kHz], [100-175 kHz], [175-220 kHz], [220-300 kHz]和[300-400 kHz]。拉伸阶段的主要破坏方式是基体断裂,但最终破坏是由铝合金断裂和纤维断裂决定的。此外,增加多孔离轴角会导致最终破坏模式从拉伸为主转变为拉伸剪切为主,同时也会使试件的整体初始刚度略有降低。
Auxetic Composite Absorbers based on foam-filled chiral frames for energy absorption in localized impact
Chuanqing Chen, Alessandro Airoldi, Antonio Maria Caporale, Giuseppe Sala, Xiaochun Yin
doi:10.1016/j.compstruct.2024.117916
基于泡沫填充手性框架的消声复合材料局部冲击吸能研究
In this paper, an innovative concept is proposed, based on the hexachiral auxetic frames filled with foams with enhanced energy absorption capabilities. Numerical assessments of the composite foam-filled auxetic absorbers, of pure foam blocks and unfilled auxetic frames for metallic and polymeric material combinations were accomplished considering a case of localized impact. The energy absorbed by the composite absorbers are found superior to the sum of the energies absorbed by constituent elements tested separately with clear advantages also at the level of the specific energy absorbed per unit mass. The interactions between the two constituents are analyzed and discussed. An experiment considering a 3D-printed polymeric hexachiral frame filled with open-cell soft polyurethane foam under localized impact is conducted to validate the numerical approach. Eventually, a parametric sensitivity study is conducted numerically to illustrate the effects of geometrical parameters on the energy absorption capacity. Overall, the results confirm the potential and the great design flexibility of the concept, provides the guidelines to design advanced energy absorbing system, underlies the importance of the combination between the frame and foam properties and the effect of the main geometrical parameters on the performance.
在此基础上,提出了一种具有增强吸能能力的泡沫填充六手性减振框架的创新概念。考虑局部碰撞情况,对金属和高分子材料组合的泡沫填充消声吸波器、纯泡沫块和未填充消声框架进行了数值评估。发现复合吸收剂吸收的能量优于单独测试的组成元素吸收的能量总和,在单位质量吸收的比能量水平上也具有明显的优势。分析和讨论了这两种成分之间的相互作用。以开孔软质聚氨酯泡沫塑料填充的3d打印聚合物六手体框架为研究对象,进行了局部冲击实验,验证了数值方法的有效性。最后,进行了参数敏感性数值研究,以说明几何参数对能量吸收能力的影响。总体而言,结果证实了这一概念的潜力和巨大的设计灵活性,为设计先进的吸能系统提供了指导,揭示了框架和泡沫性能之间结合的重要性以及主要几何参数对性能的影响。
Towards sustainable reprocessable structural composites: Benzoxazines as biobased matrices for natural fibers
Guillem Seychal, Louis Van Renterghem, Connie Ocando, Leila Bonnaud, Jean-Marie Raquez
doi:10.1016/j.compositesb.2024.111201
迈向可持续的可再加工结构复合材料:苯并恶嗪作为天然纤维的生物基基质
In this work, we synthesized and investigated three fully biobased benzoxazine matrices containing exchangeable ester bonds for natural fiber composites. The thermoset properties were investigated and the transesterification behavior was assessed. The obtained polymers show high tunability. Using isosorbide as the starting building block, the thermoset exhibits a glass transition of 130 °C, a tensile modulus of 2.5 GPa, and thermal stability leading to degradation occurring after 270 °C with 31% char at 800 °C. All formulations stress relax under catalyst-free conditions within an hour with properties recovery superior to 80%. Finally, flax composites were manufactured. We highlight strong affinities between the matrices and the fibers through high mechanical performances with a modulus over 30 GPa and stress at break of 400 MPa in the longitudinal direction. 5 GPa modulus and 47 MPa stress at break were found in the transverse direction. Excellent fire retardancy properties, with self-extinguishment and UL-94 V1 classification were obtained for the isosorbide-based/flax composite. The obtained composites were able to be welded with comparable results to glued ones, paving the way to processable laminates and stable cured prepreg perfectly suited for transportation-engineered applications.
在这项工作中,我们合成并研究了三种含交换酯键的全生物基苯并恶嗪基天然纤维复合材料。对其热固性进行了研究,并对其酯交换行为进行了评价。所得聚合物具有较高的可调性。使用异山梨酯作为起始构件,热固性材料表现出130°C的玻璃化转变,拉伸模量为2.5 GPa,热稳定性导致270°C后发生降解,800°C下炭化31%。在无催化剂条件下,所有配方在1小时内应力松弛,性能恢复优于80%。最后,制备了亚麻复合材料。我们通过高力学性能(模量超过30 GPa,纵向断裂应力为400 MPa)突出了基质和纤维之间的强亲和力。横向模量为5 GPa,断裂应力为47 MPa。结果表明,异山梨酯基/亚麻复合材料具有良好的自熄性和UL-94 V1级阻燃性能。所获得的复合材料能够焊接,其结果与粘合的结果相当,为可加工的层压板和稳定的固化预浸料铺平了道路,非常适合运输工程应用。
Engineered nanocomposites through embedding of smaller “organic inorganic” nanoparticles in thermoplastic Poly(2-Vinylpyridine) polymer matrix
Sanju Gupta, Alex Henson
doi:10.1016/j.compositesb.2024.111207
通过在热塑性聚(2-乙烯基吡啶)聚合物基体中嵌入更小的“有机无机”纳米颗粒来设计纳米复合材料
Polymer nanocomposites (PNCs) are significant for modern and future applications owing to their multifunctionality promoted by morphology and tailored interfaces between the constituents. However, ‘forward’ engineered polymer (host) composites with smaller size nanoparticles (guest) providing desired properties remains challenging as they depend upon nanoparticles aggregation, size, shape, and loading (volume or weight) fraction. This study strategically designs and develops PNCs comprising thermoplastic poly (2-vinylpyridine) (P2VP) polymer matrix impregnated with spherical polyhedral oligomeric silsesquioxane (N-POSS) nanoparticles (diameter ∼2–5 nm) and anisotropic planar nitrogenated graphene nanoribbons (GNR, strip width ∼5–10 nm) commensurate with polymer chain radius of gyration, Rg, (or segment length ∼1.5 nm) and comparable energy scales of electrostatic interaction and attractive hydrogen bonding. We investigated static and dynamic structure and thermophysical properties to correlate with interfacial regions and the results are compared with larger graphene oxide (GO, lateral dimension ∼100–200 nm) nanosheets and silica (SiO2, ∼25–50 nm) particles. While electron microscopy revealed nanoparticle distribution, the lattice bonding, conjugation length, and mechanical properties are determined from micro-Raman spectroscopy and atomic force microscopy, respectively. The differential scanning calorimetry provided a measure of glass transition temperature, Tg, with positive shift of ∼10–18 °C with nanoparticles loading indicating strength of structural relaxation/chain rigidity behavior and thermogravimetric analysis displayed increased thermal stability and conductivity (decreased interfacial resistance). We also measured temperature dependent dc electrical conductivity and dielectric relaxation spectroscopy gaining insights into percolation and dynamic interfacial layer. This study signified understanding of interactions and interfacial regions, key element to demystify the microscopic structure-property relationships.
聚合物纳米复合材料(pnc)由于其形态和成分之间的定制界面而具有多功能性,在现代和未来的应用中具有重要意义。然而,采用更小尺寸纳米颗粒(客体)的“正向”工程聚合物(主体)复合材料提供所需的性能仍然具有挑战性,因为它们取决于纳米颗粒的聚集、尺寸、形状和负载(体积或重量)分数。本研究战略性地设计和开发了pnc,包括热塑性聚(2-乙烯基吡啶)(P2VP)聚合物矩阵,其中浸染了球形多面体低聚硅氧烷(N-POSS)纳米颗粒(直径~ 2-5 nm)和各向异性平面氮化石墨烯纳米带(GNR,条带宽度~ 5 - nm),与聚合物链的旋转半径Rg(或片段长度~ 1.5 nm)相当,并具有可比较的静电相互作用和吸引氢键的能量尺度。我们研究了与界面区域相关的静态和动态结构以及热物理性质,并将结果与较大的氧化石墨烯(GO,横向尺寸~ 100-200 nm)纳米片和二氧化硅(SiO2, ~ 25-50 nm)颗粒进行了比较。电子显微镜显示了纳米颗粒的分布,微拉曼光谱和原子力显微镜分别测定了晶格键、共轭长度和力学性能。差示扫描量热法提供了玻璃化转变温度Tg的测量值,其正位移为~ 10-18 °C,纳米颗粒加载表明结构松弛/链刚性行为的强度,热重分析显示热稳定性和导电性增加(界面阻力降低)。我们还测量了温度相关的直流电导率和介电弛豫光谱,从而深入了解渗透和动态界面层。这一研究对了解相互作用和界面区域是揭开微观结构-性质关系的关键因素。
Efficient degradation of amine cured epoxy resin via the cleavage of C-N bond by amphiphilic dodecylbenzenesulfonic acid
Chizhou Wang, Ning Zhang, Shaodi Wu, Weijie Wang, Peng Zhao, Shiyu Jia, Yongqin Qi, Xianglin Hou, Xiaojing Cui, Tiansheng Deng
doi:10.1016/j.compscitech.2024.110442
两亲性十二烷基苯磺酸裂解C-N键高效降解胺固化环氧树脂
Amine-cured epoxy resin (EP) is often compounded with carbon fiber (CF) used for wind power blades due to its excellent performance. However, the insolubility and infusibility of service-life-expired carbon fiber reinforced epoxy resin (CFREP) hinder its sustainable recycling. We reported a new strategy for efficient degradation of EP and CFREP with 0.5 mol% amphiphilic dodecylbenzenesulfonic acid (DBSA) in aqueous system. It was found that the strong lipophilicity of DBSA accelerated its enrichment on EP surface, and further promoted the diffusion of DBSA and H2O to the resin bulk phase. As a result, the degradation ratio of the EP powder reached 100 % at 190 °C only in 10 h. The characterization of FT-IR and NMR proved that the degradation mechanism of EP was the selective cleavage of C-N bond catalyzed by H+. The resin degradation products (RDP) containing active hydrogen were used to prepare polyurethane (PU) with good mechanical properties. This method achieves complete recycling of waste CFREP in aqueous systems.
胺固化环氧树脂(EP)由于其优异的性能,常与碳纤维(CF)复合用于风力发电叶片。然而,碳纤维增强环氧树脂(CFREP)的不溶性和可灌注性阻碍了其可持续回收利用。本文报道了用0.5 mol%两亲性十二烷基苯磺酸(DBSA)在水溶液中高效降解EP和CFREP的新策略。发现DBSA的强亲脂性加速了其在EP表面的富集,进一步促进了DBSA和H2O向树脂体相的扩散。结果表明,在190 ℃下,仅10 h, EP粉末的降解率就达到了100% %。FT-IR和NMR表征证明了EP的降解机制是h +催化C- n键的选择性裂解。采用含活性氢的树脂降解产物(RDP)制备了具有良好力学性能的聚氨酯(PU)。该方法实现了水系统中废弃CFREP的完全回收。