碳纤维复合材料力学性能研究进展

目的 综述碳纤维复合材料这一热结构材料的力学性能研究进展，推进碳纤维复合材料的研制和应用。方法 采用文献调研法，梳理和汇总国内外有关碳纤维复合材料力学性能的研究内容，对二维复合材料、针刺复合材料及三维编织复合材料3种结构进行性能影响因素分析。结论 影响碳纤维复合材料静态和动态力学性能的因素主要有温度、应变率、密度等，提出应进一步开展碳纤维复合材料在多因素耦合及高温动态性能方面的研究。     

Dynamic caustics in unidirectional fiber-reinforced composites with mode I cracks: Experiment and numerical simulation

The stress singularities of a dynamic crack tip in orthotropic composites were studied through caustics. The parametric equations of the caustic and its initial curve surrounding the dynamic crack tip were derived through the elastic dynamic crack solutions of orthotropic composites and the basic principle of reflective caustics. Theoretical caustics and initial curves for three kinds of orthotropic composites were simulated, and the effects of crack velocity on the caustics and initial curves were analyzed. In comparison with numerical results, the dynamic caustic experiment was performed for dynamic cracks along the material axes in unidirectional, fiber-reinforced composites under drop-hammer, three-point-bend loading.     

CF/GF混杂增强环氧树脂复合材料的高载动态黏弹特性

采用高载动态热机械分析仪EPLEXOR500对T300/S-2混杂纤维增强环氧树脂复合材料的动态黏弹特性进行了分析, 考察了静态载荷、 动态载荷对其储能模量、 损耗模量和损耗角正切的影响, 并研究和对比了不同载荷水平下混杂比以及混杂方式对动态黏弹性参数的影响规律。结果表明: 不同混杂比复合材料的储能模量均随动态载荷的增大而降低, 随静态载荷的增大而增大, 损耗模量和损耗角正切则随两种载荷的增大而降低。高载荷下混杂复合材料的储能模量仍较好地符合"复合梁理论"。动载扫描模式下, 损耗角正切随混杂比的变化基本符合"混合定律", 夹芯混杂复合材料的储能模量远高于层间混杂复合材料, 且损耗角正切也比层间混杂时大; 但在静载扫描模式下则是层间混杂复合材料的损耗角正切更大。      

Internal friction and dynamic modulus of three-dimensional silicon carbide-matrix composites

The internal friction and dynamic modulus of 3D C/SiC and SiC/SiC composites were investigated by means of forced vibration at elevated temperatures from room temperature to 600 °C, and the relationship between the microstructural defects in the composites and the internal friction mechanism was also discussed. It was found that the microstructural defects, which are produced by the mismatch of the coefficient of thermal expansion (CTE) between the fiber and matrix, have an important effect on the internal friction behavior and dynamic modulus of 3D C/SiC and SiC/SiC composites. C/SiC composites have a higher internal friction and lower dynamic modulus than SiC/SiC composites in the same testing conditions because of the damage.     

Dynamic analysis of fibre breakage in single-and multiple-fibre composites

The dynamic effects associated with fibre breakage in single- and multiple-fibre composites were investigated using the finite element method. The goal of this work was to determine if the dynamic stresses differed significantly from the static stresses and, consequently, if dynamic effects were important in the prediction of subsequent fracture of the composite. For single-fibre composites, dynamic and static analyses were performed over a range of modulus values for epoxy matrices with a glass fibre to establish a range of the dynamic effects. The maximum dynamic stresses, spatial distribution of dynamic stresses, and corresponding times were evaluated. For multiple-fibre composites, the dynamic effects associated with single- and double-fibre breakage were investigated for a typical epoxy/glass composite and compared to the corresponding static problems.     

连续纤维增韧碳化硅基复合材料内耗特征及机制

采用强迫振动法研究了不同应变振幅下C/SiC和SiC/SiC复合材料从室温到600℃的内耗特征,并讨论了其内耗产生机制.结果表明,C/SiC复合材料内耗随温度升高先减小, 后增加,并在120℃附近达到最小值;SiC/SiC复合材料内耗随温度升高一直增加;C/SiC 复合材料具有比SiC/SiC复合材料更高的内耗水平和更低的动态模量;C/SiC和SiC/SiC复合材料内耗随应变振幅增加而减小,但动态模量和应变振幅无关.     

玄武岩短纤维-芳纶浆粕/氯丁橡胶复合材料的制备与性能

以氯丁橡胶（CR）为基体,改性玄武岩短纤维（BSF）和芳纶浆粕（AP）作为增强相,制备了高强度、高模量的BSF-AP/CR复合材料,系统地研究了BSF和AP对BSF-AP/CR复合材料基本物理性能、动态力学性能和动刚度的影响。采用超声波辅助γ-氨丙基三乙氧基硅烷（KH550）对BSF进行了改性,通过FTIR测试显示KH550与BSF表面基团发生了反应。通过SEM观察发现,改性BSF与CR界面相容性较好,易于分散和取向,而AP锚固在CR基体中,取向度不如BSF高;随着BSF与AP质量比值减小,BSF-AP/CR复合材料的拉伸强度、拉断伸长率和屈挠性能降低,耐撕裂性能和耐磨性能变好。采用弹性体材料测试系统（MTS）测试复合材料的动刚度。结果表明,BSF与AP质量比越小,BSF-AP/CR复合材料的动刚度越大,说明AP对BSF-AP/CR复合材料动刚度贡献大。动态力学性能显示,AP用量越多,BSF-AP/CR复合材料的储能模量（G'）越高,Payne效应越明显,而阻尼因子越小,说明AP有良好的模量-滞后平衡效应。当BSF与AP质量比为10:10时,BSF-AP/CR复合材料的综合性能较好。      

Low-velocity impact and static behaviors of high-resilience thermal-bonding inter/intra-ply hybrid composites

This study prepared inter/intra-ply hybrid composites reinforced with sandwich-structure recycled Kevlar nonwoven/glass woven compound fabric. Negative-depth needle punching and thermal bonding were applied to strengthen the structure with two compound cover plies and a fluffy cushioning center ply. The effects of center ply areal density, needle punching depth, and fiber blending ratio on the static and dynamic impact resistance behaviors of the composites were investigated. The results indicated that areal density significantly influenced the static and dynamic impact behaviors, which were both enhanced by the promotion of thermal-bonding points. As the needle punching deepened, the static and dynamic puncture resistances represented opposite tendencies because of different failure mechanisms. Static friction was the dominant factor for static puncture resistance, whereas kinetic friction was the dominant factor for dynamic puncture resistance. A similar phenomenon was observed when fiber blending ratio was varied. In terms of the non-penetrating dynamic cushioning test, areal density was the most distinct influence factor on cushioning behavior and the hybrid composites sample with an areal density of 700 g/m² could eliminate up to 66.5% of the incident force. Therefore, the inter/intra-ply hybrid composites showed high impact resistance and excellent dynamic cushioning property.     

Effect of fabrication process on the microstructure and dynamic compressive properties of SiCp/Al composites fabricated by spark plasma sintering

The effect of fabrication process on the microstructure and dynamic properties of SiC_p/Al composites was studied in this paper. Pure Al matrix composites reinforced with 20 vol.% SiC particles were fabricated by spark plasma sintering, and the pre-blended powders were prepared by two different processes. One was to mix the powders in conical flask by using a mechanical stirrer, and the other was the mechanical alloying process by using a planetary ball mill. The sintering temperature was also explored. The conventional split Hopkinson pressure bar was used to test the dynamic properties of these composites. The results show that the sintering temperature significantly affects the consolidation of the composites. The composites, which have not been fully densified, have very loose microstructure and poor mechanical properties. Mechanical alloying process can improve the microstructure and mechanical properties of the composites. These composites are rate dependent, their strengths increase with increasing strain rates.     

二维C/SiC复合材料准静态和动态拉伸力学性能

采用分离式Hopkinson拉杆装置和电子万能试验机研究了二维C/SiC复合材料在4种应变率（0.001、0.010、90.000和350.000 s-1）下的拉伸力学性能,计算并验证了动态试验中的应力平衡状态;采用SEM分析了复合材料在不同应变率下的破坏断口和失效机制;建立了复合材料包含损伤和应变率相关的本构方程。结果表明:二维C/SiC复合材料的应力-应变曲线都表现出非线性的特征。随着应变率的增加,二维C/SiC复合材料的拉伸强度从204 MPa增加到270 MPa,增加了33%,这表明复合材料的拉伸强度具有较强的应变率敏感性。复合材料在准静态和动态加载下表现出不同的破坏模式是由材料内部界面行为的应变率效应造成的。      

Electrical properties and morphology of carbon black filled PP/EPDM blends: effect of selective distribution of fillers induced by dynamic vulcanization

The roles of dynamic vulcanization process in the electrical properties, morphology, and rheology of carbon black (CB)-filled polypropylene (PP)/ethylene–propylene-diene rubber (EPDM) blends have been investigated. With the addition of CB, the uncross-linked (TPE) and dynamically vulcanized (TPV) composites showed a notable difference in the electrical properties, which is mainly caused by different distributions of CB particles resulting from the dynamic vulcanization process. Particularly, it was found that the CB particles in the TPE composites tended to distribute in EPDM phase, whereas the CB particles in the TPV composites were almost located in the PP matrix. The rheological behavior of the TPE and TPV composites was significantly changed with the incorporation of CB particles. Due to the selective distribution caused by the dynamic vulcanization process, the formation of the conductive network for the TPE composites is caused by the double percolation effect, while for the TPV composite, the formation of the conductive network is caused by the excluded volume effect.     

高温处理对碳/碳复合材料摩擦学性能影响

研究了高温处理对化学气相沉积碳/碳(简称C/C)复合材料摩擦磨损性能的影响,分析了经过不同温度处理的试样的刹车力矩-刹车时间曲线.结果表明:随着处理温度的升高,C/C复合材料的干态平均动摩擦系数由大变小,湿态平均动摩擦系数及干态平均静摩擦系数由小变大.经过2500℃处理的C/C材料,不仅刹车过程平稳,湿态平均动摩擦系数衰减少,而且磨损率小.当刹车比压和能载增加时,经过不同温度处理的四种试样干态及湿态平均动摩擦系数均相应下降.     

动态冲击损伤对炭/炭复合材料压缩行为的影响

本文在利用split Hopkinson pressure bar装置对碳毡增强的炭/炭(C/C)复合材料进行动态冲击损伤的基础上,利用CSS44000电子万能试验机测定了其冲击后的压缩性能,探讨了动态冲击损伤对C/C复合材料横向压缩破坏行为的影响。研究结果表明:C/C复合材料具有较强的抗动态冲击损伤能力;未受冲击损伤复合材料的压缩破坏具有剪切失效特征,而冲击损伤后其压缩破坏具有剪切与分层失效特征。     

Thermal and dynamic mechanical analysis of polystyrene composites reinforced with short sisal fibres

The thermal behaviour of polystyrene composites reinforced with short sisal fibres was studied by means of thermogravimetric and dynamic mechanical thermal analysis. The thermal stability of the composites was found to be higher than that of sisal fibre and the PS matrix. The effects of fibre loading, fibre length, fibre orientation and fibre modification on the dynamic mechanical properties of the composites were evaluated. Fibre modifications were carried out by benzoylation, polystyrene maleic anhydride coating and acetylation of the fibre and the treatments improved the fibre-matrix adhesion. PS/sisal composites are thermally more stable than unreinforced PS and sisal fibre. The addition of 10% fibre considerably increases the modulus but the increase is found to level off at higher fibre loadings. The T_g values of the composites are lower than that of unreinforced PS and may be attributed to the presence of some residual solvents in the composites entrapped during the composite preparation. The treated-fibre composites show better properties than those of untreated-fibre composites. The Arrhenius relationship has been used to calculate the activation energy of the glass transition of the composites. A master curve is constructed based on time-temperature superposition principle.     

Morphological,thermal and dynamic mechanical properties of Cathay poplar/organoclay composites prepared by in situ process

In order to improve the thermal stability and dynamic mechanical properties of Cathay poplar (Populus cathayana Rehd.) wood, a kind of organoclay, that is, organo-montmorillonite (OMMT), was introduced into its structure via an in situ process by sequentially impregnating poplar wood with sodium-montmorillonite (Na-MMT, in concentrations of 1.0%, 2.0%, and 4.0%) and didecyldimethylammonium chloride (DDAC, in a concentration of 2.0%). Consequently, the wood/organoclay composites were prepared. The X-ray diffraction (XRD), scanning electron microscopy coupled with energy dispersed X-ray analysis (SEM-EDXA) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the morphological and chemical alterations of the composites. Also the effects of clay type and concentrations on the thermal stability and dynamic mechanical properties of the composites were studied. The results showed that didecyldimethylammonium ions were intercalated into the galleries of Na-MMT through cation exchange, partially separating the silicate layers. Thereafter, the inorganic Na-MMT transformed to OMMT during the in situ synthesis process, and the latter was successfully intercalated into the wood cell wall. The thermal degradation was alleviated in the wood/clay composites, among which the wood/OMMT composites exhibited the best thermal stability. According to dynamic mechanical analysis (DMA) results, the wood/OMMT composites showed an enhancement in energy storage and a diminution in energy dissipation compared to other groups. The improvements in the thermal stability and dynamic mechanical properties of the composites became more significant with the increasing clay content.     

UFPR含量对PP/UFPR复合材料动态和瞬态流变行为的影响

研究了超细全硫化粉末橡胶(UFPR)的含量在0%～70%(质量分数,下同)变化时,PP/UFPR复合材料的动态及瞬态流变行为的变化规律。结果表明,当UFPR含量低于15%时,复合材料的流变性质与PP基体类似,但材料非均相性随UFPR含量逐渐增加而增加;当UFPR的含量超过25%时,复合材料的储能模量(G′)出现"第二平台",表明材料内部类网络结构形成;当UFPR含量增至50%和70%时,复合材料的G′失去频率(ω)依赖性,呈现出典型的橡胶特征。     

纳米石墨/天然橡胶复合材料的应力软化与动态性能

以不同尺寸的纳米石墨为原料,制备了纳米石墨/天然橡胶(NR)复合材料.研究不同尺寸(30、80、150 nm)的纳米石墨对复合材料的应力软化效应(Mullins效应)、Payne效应、动态生热和损耗因子的影响.结果表明:随着纳米石墨尺寸的增大,纳米填料对纳米石墨/NR复合材料体系的补强作用明显,应力软化效应增大、动态损耗因子增加,但Payne效应降低;纳米石墨/NR复合材料动态损耗因子越大,其动态生热越高;动态生热还与填料粒子网络形成紧密相关.SEM观察及Payne效应分析结果表明:采用不同尺寸的纳米石墨材料填充天然橡胶,大尺寸石墨在橡胶基体中易于分散均匀,片层的聚集程度小,而小尺寸纳米片层表现出较明显的团聚.     

单向帘线增强橡胶复合材料在周期载荷下的动态粘弹性

研究了橡胶复合材料的疲劳行为，发现：橡胶复合材料在疲劳过程中具有明显的非线性粘弹性，材料的动态粘弹性在疲劳初期和末期表现出不同的趋势，与其他脆性复合材料不同，橡胶复合材料在疲劳过程中伴有较高的热生成，橡胶复合材料的滞后损失愈大，实际热生成温度愈高，其疲劳寿命降低愈明显。     

Ti基非晶合金及其SiC陶瓷骨架复合材料动态压缩力学行为研究

为了验证Ti基非晶合金和陶瓷两种材料三维连通网状结构的复合优势,制备出具有优良抗冲击性能的复合材料,本文采用铜模吸铸法制备了Ti基非晶合金,并用渗流铸造法制备出孔隙率分别为30.86%、18.14%和15.28%的Ti基非晶合金/SiC陶瓷骨架复合材料。采用X射线衍射仪对纯Ti基非晶合金以及SiC陶瓷骨架复合材料进行相分析,确认了试件材料的非晶状态;在不同应变速率下,用分离式霍普金森压杆(SHPB)实验装置对试样进行室温轴向动态压缩力学性能测试,并利用能谱型场发射扫描电镜(SEM)等设备观察了试件的微观组织和断面特征,对比分析了Ti基非晶合金和SiC陶瓷骨架复合材料的动态压缩力学性能和失效机理。研究表明,Ti基非晶合金/SiC陶瓷骨架复合材料内部的微裂纹最初萌生于应力集中的两相界面处,并在SiC相内部或两相界面处扩展,继续加载,SiC相失效后,Ti基非晶合金相在远超过其动态压缩强度的应力下迅速失效,复合材料整体失效。SiC相内的断裂形貌主要有微裂纹与解理台阶,Ti基非晶合金相内的断裂形貌有脉状花样、多重脊状条带、蜂窝状花样与光滑无特征区,其中以光滑无特征区为主。复合材料的抗压强度随Si...     

Dynamic properties of pultruded natural fibre reinforced composites using Split Hopkinson Pressure Bar technique

The paper presents results on dynamic mechanical properties of jute, and kenaf fibre reinforced composites at various strain rates using compression Split Hopkinson Pressure Bar technique. The stress–strain curves for both pultruded natural fibre reinforced composites at strain rates of nearly 1400 s⁻¹ are illustrated and then compared with statically determines stress–strain curve (1.0 × 10⁻³ s⁻¹). Results show that the strain rate does affect the value of dynamic compressive properties of both pultruded natural fibre composites. Higher dynamic compression modulus and 2.5% flow stress were recorded for higher strain rates as compared to lower strain rate over the range of strain rates investigated. Under dynamic loading, jute fibre reinforced composites recorded the highest value of dynamic response in terms of compression modulus, 2.5% flow stress and compressive strength than that of kenaf fibre reinforced composites. In addition, kenaf fibre reinforced composites is more severely damaged as compared to jute fibre reinforced composites for all tested strain rate.