纤维增强树脂基复合材料防弹性能影响因素及破坏机制

以超高分子量聚乙烯(Ultra High Molecular Weight Polyethylene,UHMWPE)纤维、S-玻璃纤维、芳纶1414纤维和杂环芳纶纤维增强聚烯烃(Polyolefin,PO)和水性聚氨酯(Waterborne Polyurethane,WPU)树脂,采用热压工艺制备正交单向无纬(UD)结构复合材料装甲板;通过装甲板弹道极限速度测试,研究了纤维增强树脂基复合材料装甲板防弹性能的影响因素;通过体视显微镜观察装甲板侵彻破坏形貌,分析了纤维增强树脂基复合材料的破坏机制。结果表明:UHMWPE纤维增强PO树脂基复合材料的防弹性能与UHMWPE纤维的强度和模量呈正相关,但纤维模量对复合材料防弹性能的影响随着纤维模量的增大而逐渐变弱;在WPU树脂体系下,四种纤维的防弹性能由高到低依次是UHMWPE纤维、杂环芳纶纤维、芳纶1414纤维、S-玻璃纤维;纤维增强树脂基复合材料装甲板中纤维破坏方式有迎弹面纤维被剪切冲塞、中部被纤维拉伸变形后剪切、背弹面纤维被拉伸断裂,中部纤维拉伸变形是消耗子弹动能的主要方式。     

弹道防护用超高分子量聚乙烯纤维增强热塑性树脂基复合材料的拉伸力学行为

以弹道防护用超高分子量聚乙烯(Ultra-high molecular weight polyethylene,UHMWPE)纤维增强热塑性树脂基复合材料作为研究对象,通过热压工艺制备单向正交结构的复合材料层压板。基于自主设计的拉伸试验装置,开展UHMWPE纤维增强热塑性树脂基复合材料在宏观尺度和准细观尺度上的面内拉伸试验,研究其面内拉伸力学性能及失效模式。研究结果显示：弹道防护用UHMWPE纤维增强热塑性树脂基复合材料在准细观尺度上的面内拉伸力学性能是其本征性能;随着偏轴角度的增加,拉伸断裂强度呈现指数型下降,这是由于失效模式由纤维的拉伸断裂破坏转变为纤维-树脂基体的界面破坏;此外,其在宏观尺度上的拉伸破坏强度比在准细观尺度上的拉伸断裂强度降低了50.52%,这是由于宏观尺度上的面内拉伸力学响应是其面内拉伸变形和层间分层破坏的耦合结果,即层压板的叠层效应。     

层间混杂复合材料装甲板防弹性能及其防弹机制

为研究层间混杂复合材料装甲板的防弹性能及其防弹机制,采用钢芯弹侵彻层间混杂复合材料装甲板。以超高分子量聚乙烯（Ultra high molecular weight polyethylene,UHMWPE）纤维、对位芳香族聚酰胺纤维作增强纤维,水性聚氨酯（Waterborne Polyurethane,WPU）树脂和环氧树脂（Epoxy resin,EP）作基体,采用热压工艺制备单向（Unidirectional,UD）结构的层间混杂复合材料装甲板。研究混杂比例、防弹面和树脂基体对混杂复合材料装甲板防弹性能的影响以及弹击后混杂复合材料装甲板的破坏形貌,分析混杂复合材料装甲板的防弹机制,并对复合材料装甲板的破坏机制进行了分析。结果表明:混杂复合材料装甲板的防弹性能优于其任一单一纤维复合材料装甲板;WPU的防弹性能要优于环氧树脂;以UHMWPE纤维复合材料充当防弹面时,混杂复合材料装甲板具有更好的防弹性能;纤维拉伸变形和装甲板分层是纤维复合材料装甲板主要的吸能方式。      

玄武岩纤维增强复合材料抗弹性能试验研究

摘要：为了研究玄武岩纤维增强复合材料的抗弹性能,利用不同树脂基体制作了玄武岩纤维增强复合材料靶板试件,进行了弹道测试。研究了玄武岩纤维增强复合材料的抗侵彻性能和典型破坏模式,并分析了不同树脂基体和不同铺层方式对靶板防弹效果的影响。研究表明,玄武岩纤维增强复合材料在受弹体侵彻时,主要呈现局部破坏,破坏形式是迎弹面的纤维剪切失效、背弹面的拉伸断裂失效。另外,根据轻型防护的要求,提出设计新型防护结构的思路。研究结果可以为轻型复合装甲设计提供参考。     

超高分子量聚乙烯纤维/水性聚氨酯复合材料层压板抗软钢芯弹侵彻性能及其损伤机制

选用碳纳米粒子(CNPs)原位改性和未改性的超高分子量聚乙烯(UHMWPE)纤维作为增强纤维,水性聚氨酯(WPU)作为树脂基体,采用缠绕-复合-热压工艺制备单向(UD)正交结构的UHMWPE纤维/WPU复合材料层压板。基于X射线计算机断层扫描(CT)技术,研究UHMWPE纤维/WPU复合材料层压板在7.62 mm×39 mm软钢芯弹以弹速为(720±10) m/s侵彻下的弹道响应。结果表明,UHMWPE纤维的CNPs原位改性提高了CNPs-UHMWPE纤维/WPU复合材料层压板抗单发侵彻性能,但会降低其抗多发打击的能力。对于未被穿透的层压板,其被侵彻过程可分为三个阶段,依次为剪切冲塞、断裂破坏和剩余子层的塑性变形,且每个阶段的厚度比依次为11.51%、44.40%和44.09%;层压板的分层响应主要发生在第二阶段,并集中在弹着点附近;每发弹丸侵彻导致层压板的破坏区域包含在以弹着点为圆心、直径约为70 mm的圆内。      

高强型聚酰亚胺纤维增强热塑性树脂基复合材料防弹性能研究

采用S35高强型聚酰亚胺(PI)纤维作为增强体，热塑性树脂作为基体，采用热压工艺制备了织物结构和正交单向无纬(UD)结构复合材料靶板，通过弹道极限速度测试和背部变形测试，研究了增强体结构和界面结合强度对PI纤维增强热塑性树脂基复合材料防弹性能的影响。结果表明：高强型聚酰亚胺纤维表现出了优异的防弹性能；UD结构靶板更适用于防铅芯弹；织物结构靶板更适用于防破片；当界面剥离强度由5.45N/cm提高到26.44N/cm时，剥离后界面处的纤维表面形貌的破坏程度逐渐增加。当侵彻体为5.6g铅芯弹时，随着界面剥离强度的提高，复合材料靶板的防弹性能呈现出先提高后降低的趋势；并且靶板的背部变形逐渐减小，进一步证明了界面结合强度对复合材料靶板防弹性能的影响。     

弹道防护用先进复合材料弹道响应的研究进展

本文对弹道防护用先进复合材料的弹道响应研究及其在工程领域的应用现状进行了综述。首先,基于工程应用研究的试验结果,对超高分子量聚乙烯(UHMWPE)纤维、对位芳香族聚酰胺(PPTA)纤维、芳Ⅲ纤维、聚对苯撑苯并双噁唑(PBO)纤维和聚酰亚胺(PI)纤维等高性能纤维的防弹性能及其复合材料在弹道防护工程领域的应用现状进行了概述,近年来先进复合材料的防弹性能随着纤维力学性能的突破而逐渐提高;其次,讨论了先进复合材料弹道响应的影响因素及其作用机制,发现先进复合材料的塑性拉伸变形是其抵挡弹丸侵彻的主要防弹机制;最后,对弹道防护用先进复合材料的研究方向进行了展望。      

芳纶纤维复合材料界面粘结性能研究

为了改善芳纶纤维复合材料的界面粘结性能,从自制树脂基体入手,针对芳纶纤维的结构特点,合成了一种新型树脂(AFR)作为基体,制备了芳纶/AFR复合材料.通过宏观力学、微观力学以及接触角测试等方法研究了AFR树脂与芳纶纤维之间的界面粘结性能.结果表明:AFR树脂对芳纶纤维的浸润性好,单丝拔出强度高,复合材料的横向拉伸强度及层间剪切强度高,这说明芳纶纤维与AFR树脂之间具有良好的界面粘结性能.     

单宁酸协同改性超高分子量聚乙烯纤维与环氧树脂复合材料

将单宁酸共混改性的环氧树脂与单宁酸-金属Na~+络合改性超高分子量聚乙烯(UHMWPE)纤维进行复合,从而改善了UHMWPE纤维与环氧树脂的界面强度,提高了纤维增强复合材料的整体性能。改性后纤维表面的单宁酸与树脂基体中的单宁酸在界面处形成"桥联"作用。单宁酸共混改性环氧树脂是为了在环氧树脂中引入羟基以增强其力学强度。结果表明,当单宁酸在环氧树脂中的负载量为1%时,树脂基体的拉伸强度、弯曲强度达到最大值,分别为55.41 MPa, 74.24 MPa,与纯环氧树脂相比分别提高了67.5%和63.5%。同时界面剪切强度达到2.22 MPa,与原复合材料相比提高了64.8%。纵向纤维束使环氧树脂复合材料的拉伸强度增加到89.52 MPa,弯曲强度达到118.82 MPa,与纯复合材料相比,分别提高了120.2%,47.3%。通过扫描电镜图分析可以得出,纤维增强复合材料的破坏方式为黏接剂破坏。     

超高分子量聚乙烯纤维增强防弹复合材料研究进展

介绍了超高分子量聚乙烯(UHMWPE)纤维的特点、种类及编织结构,分析了UHMWPE纤维复合材料的防弹机理,总结了UHMWPE纤维的编织结构、树脂基体性能、界面性能等因素对防弹性能的影响,归纳了UHMWPE纤维防弹复合材料的优缺点,并对UHMWPE纤维复合材料的发展进行了展望。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.