聚脲弹性体“三明治”夹层结构抗爆性能

聚脲弹性体具有良好的力学性能,为研究聚脲作为夹层时靶板的抗爆性能,运用数值模拟对该靶板在爆炸载荷作用下的动态响应过程进行研究,与裸钢板和表面喷涂聚脲弹性体钢板进行对比,主要分析了靶板的变形特点、吸能特性以及对冲击波的衰减;并分析了三明治靶板的面板、夹层、背板厚度变化时对靶板抗爆性能的影响,结果表明,聚脲弹性体能够提高钢板的抗爆性能,作为夹层时抗爆能力更佳;当聚脲夹层厚度为0,2,14,30 mm时,靶板的背压分别为81.78,46.37,7.58,2.28 MPa。三明治夹层结构的面板和背板需要有一定的强度来抵抗变形。     

聚脲涂覆钢板复合结构抗爆性能研究

为了研究聚脲涂覆钢板复合结构的抗爆性能，对其进行了不同涂层厚度和不同炸药量的爆炸加载试验。利用三维激光扫描仪对聚脲涂覆钢板复合结构试验前后的形貌进行扫描，得到复合结构的中心挠度变化特征；运用DH5960超动态应变仪对复合结构的应变以及冲击波超压特点进行分析，得到应变和冲击波比冲量随聚脲涂层厚度的变化规律。研究结果表明：在等厚度钢板、180 gTNT当量爆炸荷载下，聚脲涂层厚度在0～2.76 mm范围内增加时，挠度呈线性减小，应变峰值先增大后减小，靶后冲击波超压峰值先减小后增大，冲击波比冲量先增大后减小，并在涂层厚度为1.70 mm时达到最大值。因此选择合适的聚脲涂层厚度能有效提高复合结构的抗爆性能。     

喷涂聚脲弹性体抗爆抗冲击性能研究进展

以喷涂聚脲弹性体抗爆抗冲击性能研究为重点,从非建筑构件、建筑构件以及LS–DYNA有限元模拟三个方面,综述了喷涂聚脲弹性体在爆炸冲击载荷作用下的防护研究进展,简要介绍了喷涂聚脲弹性体的研究成果和实际应用情况,指出了喷涂聚脲弹性体在结构背面加固时突显出的优异抗爆性能和吸能效率,最后指出了喷涂聚脲弹性体抗爆抗冲击性能研究存在的问题以及今后的发展方向。     

喷涂聚脲弹性体及复合结构抗爆抗冲击性能研究进展

防护结构的抗爆抗冲击性能是生命安全的重要保障，材料和结构是提高防护性能的2种主要途径。喷涂聚脲弹性体凭借良好的力学性能和耗能特性被广泛运用于抗爆抗冲击防护领域。从喷涂聚脲弹性体的抗冲击性能出发，介绍了不同试验方法下喷涂聚脲弹性体优异的爆炸冲击防护性能，分析喷涂聚脲弹性体在不同应变率和环境下良好的适应性，发现涂层厚度和涂层构造会对材料抗冲击性能产生影响；从材料微观层面以及阻抗失配的角度综述了喷涂聚脲弹性体的抗冲击机理，最后阐述了抗冲击复合结构的耗能机理以及优化方法，指出了喷涂聚脲弹性体以及复合结构尚存在的部分问题以及发展方向。     

铝板——环氧树脂夹层结构抗爆性能数值模拟研究

运用大型有限元软件ANSYS/LS-DYNA,在相同的爆炸冲击波作用下,对掩蔽物上方铝板和含环氧树脂夹层的普通铝板两种防护结构的抗爆性能进行了数值模拟和对比分析,结果表明:有环氧树脂夹层的铝板结构的抗爆性能要优于无环氧树脂夹层的铝板,且抗爆性能随着环氧树脂夹层厚度的增加呈现出先增大后减小的趋势,为防护结构的研制提供了一定的参考。     

铝板‐‐环氧树脂夹层结构本构模型研究

运用大型有限元软件ANSYS/LS-DYNA,在相同的爆炸冲击波作用下,对掩蔽物上方含环氧树脂夹层铝板防护结构的抗爆性能进行了数值模拟,通过模拟结果,建立不同环氧树脂夹层厚度的复合结构的本构模型,为防护结构的工程实践提供了一定的参考。     

聚脲基体复合材料抗爆耐冲击性能研究进展

随着聚脲基体复合材料在结构防护领域的大量应用,其抗爆耐冲击性能获得广泛研究。本文基于聚脲基体复合材料在结构防护领域的研究现状,介绍了聚脲材料作为高聚物弹性体的抗爆性能,综述了聚脲-纤维复合材料的研究进展,阐述了聚脲材料抗冲击性能机理。指出聚脲作为高聚物弹性体对防护结构具有较好的抗冲击防护效果,可与纤维组成高强度、高弹性模量和可吸收爆炸冲击能量的复合材料,在防护结构抗爆炸毁伤领域具有可观前景。     

喷涂型抗爆聚脲高应变率力学性能及其涂层钢板爆炸模拟研究

为研究爆炸冲击荷载作用下喷涂型抗爆聚脲 MS-1对钢板的防护性能,对 MS-1进行了高速拉伸实验,研究了其在高应变率下的力学性能;运用 ANSYS/LS-DYNA有限元软件对 MS-1涂层钢板进行接触式爆炸模拟实验,获得小当量 TNT炸药作用下钢板的宏观破坏模式、位移变形和涂层能量传递规律;根据数值模拟的结果分析了 MS-1涂层对钢板的抗爆耗能机理。结果表明： MS-1具有良好的应变率效应,随应变率的提高其自身的力学性能也不断增强;相较于空白钢板,背爆面喷涂 MS-1涂层的钢板破坏程度减弱, 2 mm、4 mm和 8 mm涂层钢板中心点最大位移分别降低 14. 34%、 47. 01%和 49. 4%,MS-1涂层可以高效地将爆炸冲击能量转化为涂层自身的内能和动能,通过自身拉伸变形进行吸能和耗能。     

接触爆炸作用下抗爆型喷涂聚脲防护钢筋混凝土板爆炸试验和数值模拟

为研究接触爆炸荷载作用下Qtech T26抗爆型喷涂聚脲(T26聚脲)防护钢筋混凝土板(RC板)的抗爆性能和损伤机制,对有无T26聚脲防护RC板进行爆炸试验,通过扫描电子显微镜(SEM)对T26聚脲防护RC板的典型损伤区域进行微观分析。基于T26聚脲力学性能及爆炸试验建立有限元模型进行数值模拟,并与试验结果进行对比。研究结果表明：T26聚脲与RC板界面附着较好,可以抵抗界面拉伸波的作用,并实现对RC板损伤和变形的抑制;RC板在大当量爆炸荷载作用下的损伤以冲切破坏为主,T26聚脲宏观及微观损伤特点均表明背爆面变形起始位置为RC板冲切变形边缘区域,且会由于应变率效应发生脆性开裂;结合有限元模拟与爆炸试验,T26聚脲可以提高RC板的抗爆性能,并通过材料的高强、高韧、高阻尼特性实现10 kg TNT接触爆炸作用零破片的防护目标,在爆炸防护领域具有重要工程应用价值。     

固支矩形钢板近距爆炸的毁伤特性

为掌握金属平板结构在近距爆炸载荷下的毁伤特性,以四边固支矩形钢板为对象,开展了柱形TNT装药近距爆炸毁伤试验,根据试验结果划分了钢板的3种毁伤模式:塑性大变形毁伤、临界起裂毁伤和花瓣状破口毁伤,建立了不同毁伤模式下的理论计算和数值模型,并分析了药量、爆距及钢板厚度对其近距爆炸毁伤特性的影响。结果表明,钢板的塑性最大变形随装药质量增加而增加,随爆距增加而减小;钢板的临界起裂毁伤形式为平行于长边的Ⅰ字形裂纹;爆距保持不变时,钢板的最大破口毁伤直径与药量为正相关,2000g药量时的最大破口直径为1000g药量时的1.18倍;相同药量时,随着爆距的增加,钢板最大破口直径呈先增大后减小的趋势,药量为500g和1000g时,最佳毁伤爆距分别为4cm和5cm。     

聚脲弹性体/纤维增强树脂基复合材料抗冲击性能研究

玻璃纤维增强树脂基复合材料在使用过程中极易受到外力冲击,造成复合材料结构破坏,严重威胁其安全使用寿命。研究了聚脲弹性体涂层对玻璃纤维增强乙烯基树脂复合材料抗冲击性能的影响。通过简支梁摆锤冲击试验和光学显微镜对前涂覆(FCGF)、后涂覆(BCGF)及未涂覆(NCGF)试样进行对比测试。研究结果表明,聚脲弹性体涂层的弹性形变和断裂破坏能够大幅增加冲击能耗,提高整体的冲击强度。当试样聚脲涂层厚度相同时,前涂覆(FCGF)试样聚脲弹性体冲击后并未完全断裂,主要依靠弹性形变吸收冲击能量,起缓冲减震作用;后涂覆(BCGF)试样聚脲弹性体发生断裂破坏能够消耗更多的冲击能量,其整体结构破坏最小,冲击强度更高。     

Comparison of foam core sandwich panel and through‐thickness polymer pin–reinforced foam core sandwich panel subject to indentation and flatwise compression loadings

Through‐thickness polymer pin–reinforced foam core sandwich (FCS) panels are new type of composite sandwich structure as the foam core of this structure was reinforced with cylindrical polymer pins, which also rigidly connect the face sheets. These sandwich panels are made of glass fiber–reinforced polyester face sheets and closed‐cell polyurethane foam core with cylindrical polymer pins produced during fabrication process. The indentation and compression behavior of these sandwich panels were compared with common traditional sandwich panel, and it has been found that by reinforcing the foam core with cylindrical polymer pins, the indentation strength, energy absorption, and compression strength of the sandwich panels were improved significantly. The effect of diameter of polymer pins on indentation and compression behavior of both sandwich panels was studied and results showed that the diameter of polymer pins had a large influence on the compression and indentation behavior of through‐thickness polymer pin–reinforced FCS panel, and the effect of adding polymer pins to FCS panel on indentation behavior is similar to the effect of increasing the thickness of face sheet. The effect of strain rate on indentation behavior of FCS panel and through‐thickness polymer pin–reinforced FCS panel were studied, and results showed that both types of composite sandwich panels are strain rate dependent structure as by increasing strain rate, the indentation properties and energy absorption properties of these structures are increased. POLYM. COMPOS., 37:612–619, 2016. © 2014 Society of Plastics Engineers     

Synthesis and strengthened microwave absorption properties of three-dimensional porous Fe3O4/graphene composite foam

The three-dimensional porous Fe₃O₄/graphene composite foam as a new kind of absorbing composite with electrical loss and magnetic loss was successfully synthesized by a facile method. Fe₃O₄ was evenly attached on structure of graphene sheets which overlapped with each other to form three-dimensional porous graphene foam. The results revealed that when the mass ratio of graphene oxide (GO) and Fe₃O₄ was 1:1, the Fe₃O₄/graphene composite foam possessed the best absorption properties: the minimum reflection loss was up to ??45.08?dB when the thickness was 2.5?mm and the bandwidth below ??10?dB was 6.7?GHz when the content of the composite foam absorbents was just 8%. The micron-sized three-dimensional porous structure provided more propagation paths, enhancing the energy conversion of incident electromagnetic waves. The addition of Fe₃O₄ contributed to improving the impedance matching performance and magnetic loss. The three-dimensional porous Fe₃O₄/graphene composite foam was a kind of high-efficiency wave absorber, providing a new idea for the development of microwave absorbing materials.     

Gradient dielectric constant sandwich-structured BaTiO3/PMMA nanocomposites with strengthened energy density and ultralow-energy loss

High energy storage density with low-energy loss polymer films are essential for high-performance electric devices. To avoid the high-energy loss of utilizing nonlinear polymer materials, a sandwich nanostructure comprising a linear polymer poly(methyl methacrylate) (PMMA) matrix embedded with a high dielectric constant BaTiO₃ (BT) interlayer and poly(vinylidene fluoride) (PVDF) binder was constructed using a solution casting strategy. This structural design takes advantage of each component in the composite. The good dispersion of BT particles in the binder, which was incorporated between PMMA, enabled a high dielectric constant and fewer defects. Additionally, the excellent film formation ability of the PVDF binder guarantees the uniform thickness and stable structure of the BT mid-layer, and good miscibility between PVDF and PMMA enhanced the interaction between each layer. Interestingly, since the dielectric constant of PVDF was between BT fillers and PMMA, a dielectric gradient distribution mitigated the local electric field concentration, as proven by the simulation results. Consequently, a low-loss linear PMMA composite film exhibited satisfying breakdown strength and excellent discharged energy density, which were 25% and 460% higher than those of pristine PMMA, respectively.     

含碳纤维格栅结构吸波复合材料的实验研究

本文研究了碳纤维频率选择表面(FSS)结构在雷达吸波复合材料的应用,考察碳纤维结构的尺寸及其在吸波材料中的位置,并首次探讨了不同形式的碳纤维FSS结构组合形式对吸波复合材料的影响.实验结果表明,在不添加任何吸波剂的情况下引入碳纤维FSS结构可提高材料的吸波性能.碳纤维结构的尺寸及其在吸波材料中的位置均对材料的吸波性能有不同程度的影响.含两层碳纤维结构材料的吸波性能要优于含单层碳纤维结构的复合材料.     

喷涂聚脲弹性体混凝土试件在不同环境下抗冻融循环试验研究

简述了喷涂聚脲弹性体的应用优点,并做了喷涂聚脲弹性体混凝土试件在不同环境下抗冻融循环实验。结果表明,喷涂聚脲弹性体对混凝土的保护是非常有效的,在混凝土保护中将会得到更为广泛的应用。     

填料对聚脲弹性体防滑耐磨性能的影响

本文采用喷涂聚脲弹性体技术制备防滑耐磨型聚脲弹性体.通过摩擦、磨耗、硬度、拉伸和动态力学性能(DMTA)测试以及SEM观察,研究了一定添加量的复合填料对聚脲弹性体性能的影响,并对比添加填料前后材料性能的变化.分析了填料对聚脲弹性体性能的影响机理.结果表明,填料的加入对聚脲弹性体的摩擦系数、耐磨性能有一定程度的提高,但由于聚脲交联密度下降,填料与基体间的界面结合较弱、分布不均匀,导致聚脲弹性体的硬度、拉伸性能和耐热性能略有下降.     

聚脲涂层对储油罐耐冲击性影响的研究

为避免储油罐发生意外碰撞造成巨大损失，考察了新型聚脲防护涂层对油罐车储油罐破坏变形的防护作用。通过储油罐耐冲击实验，分析了不同涂覆方式对聚脲复合涂层耐冲击性的影响，最后通过 LS-DYNA有限元模拟进行验证。结果表明：相比无涂层防护，聚脲涂层对储油罐具有良好的耐冲击防护效果，涂覆聚脲试样比无涂层试样最大变形位移减少了 18. 3 mm。在相同涂层厚度情况下， 2 mm Q190m和 2 mm Q413m聚脲复合涂层耐冲击效果最优，适合作为储油罐的防护涂层。     

Broadband electromagnetic wave absorption of Ni0.5Zn0.5Nd0.04Fe1.96O4 ferrites modified by nano-silver particles

Ferrite materials have the potential to become excellent absorbing materials due to their high magnetic loss and good impedance matching. However, the disadvantages of high density and lack of dielectric loss capability limit its application. Herein, we used the citric acid sol-gel method and the self-propagating combustion method to prepare neodymium-doped nickel-zinc ferrite (NZNF), then the target effect of Sn²⁺ and an improved electroless silver plating process was used to plate a layer composed of silver nanoparticles (Ag NPs) with strong dielectric loss on the NZNF, and a magnetic/dielectric composite material (NZNF@Ag) with a heterogeneous structure was prepared. The number and particle size of Ag NPs on the surface of NZNF can be precisely controlled, thereby greatly enhancing the dielectric loss capability with little impact on the magnetic loss. The huge difference in conductivity between conductors and semiconductors promotes the occurrence of polarization at the heterogeneous interface and significantly enhances the electromagnetic wave absorption ability of the composite material. In the 2–18 GHz frequency band, the best sample can obtain an effective bandwidth of 6.82 GHz when the matching thickness is 2.1 mm. Combining conductors with semiconductor materials to obtain significantly enhanced interfacial polarization provides a new idea for improving the performance of wave absorbing materials.