影响层压复合板在冲击力作用下反应性能的参数研究

用二维Lagrange二次单元及三维8结点非协调单元作为有限元分析的模型。研究了正交各向异性参数平面外刚度，跨高比等几何和材料参数对层压复合板在冲击荷载作用下动力反应的影响：分析了不同参数下层压复合板的破坏模式；讨论了二维有限元模型在计算层合板的力学性能时的适用范围。     

层状金属复合材料断裂和增韧机理的研究进展

层状金属复合材料在航天航空,汽车和核能领域发挥越来越重要的作用。对比于单一金属或合金,层状金属复合材料呈现出超高的强度、断裂韧性、延伸率和成型能力。综合介绍承载变形过程中层状金属复合材料各种力学性能,断裂行为和增韧机制。通过调控层状结构参数,复合材料可获得较高的性能指标,在宏观尺度下,界面结合状态和层厚尺度可有效地影响层状金属复合材料的断裂韧性和断后延伸率,这两种性能一般不符合混合法则,而层状金属复合材料的弹性行为、屈服强度和抗拉强度基本符合混合法则。在微观尺度下,层状金属复合材料的断裂行为和增韧机制会呈现明显的尺度效应。     

Effect of nano-silica modification on the tensile property of SMA/GF/CF/epoxy super hybrid woven fabric composites

Tensile properties of epoxy casts together with shape memory alloy (SMA), glass (GF) and carbon (CF) woven fabric reinforced epoxy matrix super hybrid composites were investigated, respectively. In order to enhance the mechanical strength of this advanced material, two categories of modifications including matrix blending and fiber surface coating by nano-silica were studied. Scanning electron microscopy (SEM) and fiber pull-out tests were adopted to complement the experimental results, respectively. Experimental results reveal that the toughness of epoxy matrix is enhanced significantly by adding 2wt% nano-silica. The failure mechanism of SMA reinforced hybrid composites is different from that of GF/CF/epoxy composites. Compared with the matrix modification, the fibers modified by coating nano-silica on the surface have better tensile performances. Moreover, the fiber pull-out test results also indicate that composites with fiber surface modification have better interfacial performances. The modification method used in this paper can help to enhance the tensile performance of the mentioned composite materials in real engineering fields.     

黄麻纤维/环氧树脂复合材料的力学性能

探讨了黄麻/环氧树脂复合材料板的制作方法,并对不同质量分数与长度的黄麻纤维增强的板材进行了拉伸及弯曲性能测试,采用扫描电镜观察了拉伸断面的微观形貌.讨论了纤维质量分数与长度对复合材料拉伸强度、拉伸模量、弯曲强度和弯曲模量的影响.实验结果表明,加入黄麻纤维有利于提升环氧树脂的拉伸和弯曲,纤维质量分数与长度对复合材料力学性...     

Damping properties of fly ash/epoxy composites

An inexpensive fly ash (FA), which is from a waste product, was employed to prepare fly ash/epoxy composites. The purpose of this study is to characterize the contributions of matrix viscoelasticity, hollow structure characteristic (porosity), and filler/matrix interface friction to the high vibration damping capacity of such composites. The damping properties of the composites were investigated in the temperature range of -40 to 150°C and in the frequency range of 10 to 800 Hz by using a tension-compression mode. The results indicate that the peak value of damping loss factor (tanδ) for the fly ash/epoxy composites can reach 0.70-0.90 in test specification, and the attenuation of damping loss factor is inconspicuous with increasing frequency. In addition, scanning electron microscope (SEM) was used to observe the morphology of the fly ash as well as its distribution in the matrix, which will help to analyze the effect of fly ash on the damping properties of the fly ash/epoxy composites.     

混杂方式对CF/GF/环氧混杂复合材料低速冲击性能的影响

针对复合材料抗低速冲击性能较差的不足,利用通用有限元软件ABAQUS建立了5种不同形式的混杂复合材料。利用基于刚度衰减的VUMAT子程序,对不同形式的混杂层合板进行了低速冲击仿真实验。结果表明:与纯碳纤维增强环氧树脂复合材料相比,玻璃纤维的添加可以提高材料的韧性,从而增加层合板的抗冲击性能;不同混杂方式的复合材料在承受冲击载荷时,吸收的能量不同,玻璃纤维靠近层合板表面铺设时吸收的能量最多,当玻璃纤维的布置靠近层合板上下表面时,材料的抗冲击性能提升最为明显。     

Influence of alumina addition on the optical property of zirconia/alumina composite dental ceramics

The influence of various alumina additions on the optical property of zirconia/alumina composite ceramics was investigated. The relative sintered densities, transmittances, color and the microstructure of the composite ceramics were studied. The experimental results showed that the relative sintered densities and transmittances decreased with alumina addition. The lightness increased obviously but the chroma change was small. Pure zirconia nanopowders sintered densely could obtain the relatively high transmittance, while the transmittance and the lightness of slight addition changed significantly. The zirconia/alumina composite ceramics with alumina addition less than 7.5wt% could achieve the relatively stable and reliable optical properties.     

玻纤/环氧树脂复合材料非线性粘弹性响应

为研究玻璃纤维增强环氧树脂基复合材料的非线性粘弹性响应,采用Schapery模型描述复合材料的非线性粘弹性,并在不同应力水平下分别对[90]₁₆横向试样和[±45]_4S面内剪切试样开展拉伸蠕变-回复试验. 根据试验观察到的残余粘塑性应变现象,在Schapery模型中引入粘塑性应变分量,提出一种基于解析法的非线性参数辨识方法,获得了Schapery非线性参数g₀, g₁, g₂和a_σ随应力的变化规律. 结果表明:当施加的横向拉伸应力大于横向拉伸强度的53%,面内剪切应力大于剪切强度的31%时,玻纤/环氧复合材料表现出明显的非线性粘弹性;横向上,非线性参数g_0T和g_2T与应力无关,g_1T随应力线性增加,a_σT随应力线性降低;面内剪切方向上,非线性参数g_0S和g_2S随应力呈指数增加,g_1S随应力线性增加,a_σS则随应力线性降低. 与传统的非线性参数辨识方法相比,所提出的参数辨识方法能方便准确地获取非线性参数随应力的变化规律.      

Low velocity impact response and energy absorption behavior on glass fibre reinforced epoxy composites

A study was undertaken to determine the effects of several key geometry influencing factors on the impact response and energy absorption behavior of the glass fibre reinforced epoxy composites at low and intermediate energies.The energy-balance model was employed for characterising the energy absorption behavior and it depends strongly on the plate diameter and thickness.In addition,the damage vs.energy and force maps is effective in monitoring damage growth within the composite panel.The response of the composite laminate configurations characterized by different stacking sequences subjected to low velocity impacts with different impact energies have also been studied to estimate the damage initiation of composites.     

碳/环氧面内准各向三维复合材料的动态压缩性能

利用置换法三维织物非织造技术结合树脂传递模塑(RTM)工艺,制备了碳/环氧面内准各向三维复合材料和三维正交复合材料.采用岛津万能材料试验机和分离式霍普金森压杆(SHPB)测试系统,对复合材料进行了面内和厚度方向的准静态及动态压缩性能试验,研究了碳/环氧面内准各向三维复合材料不同应变率下的压缩应力-应变关系以及破坏模式.对比分析结果表明:无论面内还是厚度方向,碳/环氧面内准各向三维复合材料的压缩性能都是应变率敏感的,并且其破坏应力和应变的应变率敏感程度大于三维正交复合材料;在面内和厚度方向准静态压缩载荷作用下,面内±45°纱线有效地抑制了面内准各向三维复合材料剪切带的形成和扩展,使得脆性破坏形貌更加均匀;随着应变率增加,面内准各向三维复合材料面内方向以剪切破坏为主,断口比三维正交复合材料粗糙,厚度方向二者破坏模式相同.     

Retraction Note: Analytical investigations and fuzzy logic-based modeling of the impact resistance of aluminum-epoxy laminated composites

Science China Technological Sciences - This article has been retracted. Please see the retraction notice for more detail: https://doi.org/10.1007/s11431-021-1775-1     

层合结构复合材料振动特性研究进展

对国内外层合结构复合材料振动特性研究进展进行了系统论述,详细介绍了研究涉及的理论分析方法及试验测试技术,并对层合结构复合材料振动特性研究在损伤检测、结构设计等领域的实际应用进行了总结.进而提出需要进一步做好夹芯层合结构振动特性的研究、改进试验方法和测试手段以提高振动测量的精度;并对损伤破坏或缺陷引起的振动特性改变机理进行了探索.     

溶剂法回收玻璃纤维/环氧复合材料的试验研究

为了解决现有化学回收法技术不适用于热固化体系的问题,采用溶剂法从玻璃纤维／环氧复合材料成功回收了玻璃纤维．在90℃的8mol／L分解液作用下,12h即可将复合材料中的环氧树脂基体分解为低分子含苯环有机物,回收到外观清洁的玻璃纤维．当分解温度为90℃,酸液浓度为8mol／L,投料比为6g：100mL时,回收纤维的单丝拉伸强度损失为5．2％．以分解时间、回收纤维强度损失为考查指标,利用正交实验法对分解条件进行优化,得到各因素的影响次序：浓度为最重要因素、温度次之、投料比影响最小．     

Study on T700/cyanate/PS/epoxy composites with ex-situ toughening technique

Composites were prepared with polysulfone through ex-situ toughening technique. The dynamic parameters of cyanate/epoxy resin were studied by differential scanning calorimetric（DSC） analysis and dynamic mechanical analysis（DMA）. Microstructual toughening mechanism was studied through scanning electron microscopy（SEM）. The particle microstructure in interlaminar region of composites toughened through ex-situ toughening technique revealed that a reaction induced phase decomposition and phase inversion happened in the interlaminar region. The thermosetting particles were surrounded by the PS phase, which could signifi cantly improve the delamination resistance of composites. The compression after impact（CAI） can be signifi cantly improved from 180 MPa to 260 MPa by using ex-situ toughening while the mechanical properties are not affected.     

Conductive behaviors of carbon nanofibers reinforced epoxy composites

By means of ultrasonic dispersion, carbon nanofibers reinforced epoxy resin composite was prepared in the lab, the electrical conductivity of composite with different carbon nanofibers loadings were studied, also the voltage-current relationship, resistance-temperature properties and mechano-electric effect were investigated. Results show that the resistivity of composite decreases in geometric progression with the increasing of carbon nanofibers, and the threshold ranges between 0.1 wt%-0.2 wt%. The voltage-current relationship is in good conformity with the Ohm＇s law, both positive temperature coefficient and negative temperature coefficient can be found at elevated temperature. In the course of stretching, the electrical resistance of the composites increases with the stress steadily and changes sharply near the breaking point, which is of importance for the safety monitor and structure health diagnosis.     

PTFE基金属复合材料的摩擦磨耗性能研究

用热啧涂法在低碳钢基体上分别形成Al Bronze和Mo薄膜,再通过热烧结的方法在薄膜表面沉积PTFE层,制备了一种PTFE基金属复合材料.通过Type32型摩擦磨损试验机考察了样品在干摩擦条件下的磨耗性能,用光学显微镜观察了实验过程中样品表面形貌变化.结果表明,由AlBronze喷涂形成的PTFE基金属复合材料的磨耗性能优于由Mo复合形成的复合材料,这可通过XRD分析其过程中发生的物理化学变化来解释.     

非傅立叶模型层状复合陶瓷结构热传导分析

用非傅立叶热传导模型分析层状复合陶瓷结构的温度场,并与单热涂层结构的结果进行比较,同时进一步研究了夹层热物理性能参数对温度场的影响。研究表明：夹层可以有效地减缓内部结构的温度变化,夹层热物理性能参数（如：松弛时间、声速）对结构层的温度场有明显影响。     

C／T iO 2复合材料的制备及光催化性能的研究

采用溶胶-凝胶法制得了C/TiO2复合光催化剂,并采用X射线衍射（XRD）﹑扫描电子显微镜（ SEM ）﹑紫外光谱等方法对复合材料进行了表征。以1-萘胺-4-偶氮对苯磺酸为模型化合物评价了C/TiO2复合材料的光催化性能,考察了降解时间、初始浓度和催化剂投加量等因素对降解率的影响。研究表明,在1-萘胺-4-偶氮对苯磺酸初始浓度为2×10-5 mol/L,催化剂投加量为1．0 g/L时,光催化反应5 h后,1-萘胺-4-偶氮对苯磺酸的降解率达到85．41％。     

PBT／CNTs复合材料的制备及其导电性能

采用熔融共混法制备聚对苯二甲酸丁二醇酯（PBT）／碳纳米管（CNTs）复合材料,研究了不同分散工艺处理的原生CNTs和不同CNTs质量分数对复合材料表面电阻的影响。利用扫描电镜观察了处理后CNTs的分布状态和PBT／CNTs复合材料的微观形貌。结果表明：球磨分散使CNTs有更好的分散效果并更好地提高了复合材料的导电率;随着CNTs质量分数的不断增加,复合材料的表面电阻呈不断下降的趋势,导电阀值出现在CNTs质量分数约为4％时。     

SiCp/Cu复合材料高温抗氧化性能研究

采用粉末冶金方法制备了SiCp/Cu复合材料,研究了复合材料在恒温氧化和循环氧化条件下的抗氧化性能。结果表明：在400—700℃时,SiCp/Cu复合材料具有比纯铜优良的抗氧化性能;在温度一定的条件下,SiC体积分数为20%时,复合材料的抗氧化性能最好;在循环氧化条件下,随着氧化时间延长,复合材料氧化增重率逐渐增大,而且呈现近抛物线变化规律;对相同SiC颗粒含量的SiCp/Cu复合材料,SiC颗粒越细,试样的抗氧化性能越好。