Compressive mechanical properties of closed-cell aluminum foam–polymer composites

The compressive mechanical properties of two kinds of closed-cell aluminum foam–polymer composites (aluminum–epoxy, aluminum–polyurethane) were studied. The nonhomogeneous deformation features of the composites are presented based on the deformation distributions measured by the digital image correlation (DIC) method. The strain fluctuations rapidly grow with an increase in the compressive load. The uneven level of the deformation for the aluminum–polyurethane composite is lower than that for the aluminum–epoxy composite. The region of the preferentially fractured aluminum cell wall can be predicted by the strain distributions in two directions. The mechanical properties of the composites are investigated and compared to those of the aluminum foams. The enhancement effect of the epoxy resin on the Young’s modulus, the Poisson’s ratio and the compressive strength of the aluminum foams is greater than that of the polyurethane resin.     

多孔ZnO/羟基磷灰石生物复合材料的制备与性能

利用放电等离子烧结技术制备多孔ZnO/羟基磷灰石（HA）生物复合材料,研究不同纳米ZnO含量对ZnO/HA复合材料微观结构、孔隙特征、力学性能、矿化和降解性能的影响。结果表明:烧结后ZnO/HA复合材料主要由HA相和ZnO相组成;随着ZnO含量提高,多孔ZnO/HA复合材料孔隙率缓慢增大,抗压强度略有减小,弹性模量变化不大;多孔ZnO/HA复合材料的孔隙率>40%,孔径在50～500 μm之间,抗压强度>148 MPa,弹性模量为6.5 GPa左右,能够满足骨修复材料的要求;模拟人工体液中矿化和降解实验表明,多孔ZnO/HA复合材料浸泡7天后表面开始形成大量类骨磷灰石层,且随着ZnO含量增加,磷灰石形成能力明显增强而降解速率加快。      

编织角和承载方向对三维四向编织复合材料动态压缩性能的影响

利用分离式霍普金森压杆（SHPB）装置对三维四向编织碳纤维增强树脂基复合材料的动态压缩性能进行了研究。通过对编织角为20°、30°和45°的试验件分别进行沿纵向、横向和厚度方向的动态压缩试验,得到材料在800~2 000/s应变率范围内的应力-应变曲线,并与准静态压缩试验结果进行对比,研究了应变率、压缩方向及编织角对材料极限强度和弹性模量的影响。结合高速摄影记录的动态压缩过程,进一步分析了不同情况下材料的破坏模式与破坏过程。结果表明：应变率越高,材料的极限强度和弹性模量越大,材料在受压的三个方向上均具有一定的应变率强化效应,且高应变率下表现出比准静态压缩时更明显的脆性;编织角的改变对材料在三个方向上的动态压缩性能均有影响,其中对纵向的影响最为明显;不同方向受压时材料的失效形式不同,且准静态和高应变率下的失效形式也有区别。     

碳纤维/TiO2改性树脂复合材料的制备及力学性能

针对环氧树脂脆性大、与碳纤维形成的界面性能较差等问题,本文选用纳米TiO₂对5284环氧树脂进行改性,并以角联锁机织物为增强体制备了碳纤维/环氧树脂复合材料。使用FT-IR、旋转流变仪、表面张力仪等设备对TiO₂/环氧树脂进行表征,并研究了树脂改性对复合材料压缩与层间剪切性能的影响。研究表明：TiO₂的羟基与环氧树脂的环氧基和羟基发生了反应;经1wt.%TiO₂改性的树脂复数黏度为0.066 Pa·s,纤维与树脂间接触角为28.85°,浸润效果较好;相较于未改性复合材料,树脂改性的复合材料纵向压缩强度与模量分别提高了7.46%和11.03%,横向压缩强度与模量分别提高了6.99%和4.96%,纵向、横向的剪切强度分别提高了6.88%和4.65%。TiO₂改性环氧树脂提高了复合材料的承载能力,改善了界面结合强度。     

短切芳纶纤维/聚硅氧烷-甲基丙烯酸锌复合材料的结构与性能

为提高聚硅氧烷-甲基丙烯酸锌(ZDMA)树脂材料的性能,采用短切通用型芳纶纤维与聚甲基乙烯基硅氧烷-ZDMA复合并在高温下交联固化,得到短切芳纶纤维/聚硅氧烷-ZDMA复合材料.采用SEM、FTIR、拉伸和压缩试验方法、霍普金斯压杆试验方法,表征了短切芳纶纤维/聚硅氧烷-ZDMA复合材料的结构和静态力学性能,研究了芳纶...     

Preparation and characterization of glass-like carbon/silica composites from rice hull and phenolic resin

Glass-like carbon/silica composites were prepared from rice hull and phenolic resin. Monolithic composites were prepared by carbonizing green bodies made from phenolic resin and rice hull in nitrogen atmosphere at temperatures raging from 1173 K to 1773 K. The resultant composites consisted of approximately 70 mass% of glass-like carbon and 30 mass% of silica, the latter being originated from rice hull. The highest compressive strength, bending strength, and fracture toughness were 227 MPa, 50 MPa, and 0.80 MPam^1/2, respectively. The composites did not show any detectable hygroscopic expansion upon immersing in water. The mechanical properties were not deteriorated up to 1573 K, as long as the silica maintained its amorphousness.     

针状纳米ZnO制备EP/ZnO复合材料及其力学性能的研究

研究了用热镀锌渣作原料制得的针状纳米ZnO对EP/ZnO复合材料力学性能的影响.结果表明:使用具有空间结构的针状纳米ZnO所制备的环氧树脂复合材料,与普通ZnO所制备的环氧树脂复合材料相比力学性能得到了较大的提高和改善.当纳米ZnO的含量为4％(质量分数)时,材料的力学性能得到了明显改善,其冲击强度提高46.9％,抗拉...     

A novel antibacterial resin composite for improved dental restoratives

A novel furanone-containing antibacterial resin composite has been prepared and evaluated. compressive strength (CS) and Streptococcus mutans viability were used to evaluate the mechanical strength and antibacterial activity of the composites. The modified resin composites showed a significant antibacterial activity without substantially decreasing the mechanical strengths. With 5-30 % addition of the furanone derivative, the composite kept its original CS unchanged but showed a significant antibacterial activity with a 16-68 % reduction in the S. mutans viability. Further, the antibacterial function of the new composite was not affected by human saliva. The aging study indicates that the composite may have a long-lasting antibacterial function. Within the limitations of this study, it appears that the experimental antibacterial resin composite may potentially be developed into a clinically attractive dental restorative due to its high mechanical strength and antibacterial function.     

UV光固化玻璃纤维布/EP-PBMA树脂复合材料的力学性能

设计了光热共引发环氧树脂-聚甲基丙烯酸丁酯(EP-PBMA)树脂,并制备了UV光固化玻璃纤维布增强EP-PBMA树脂基复合材料,研究了不同EP与PBMA质量比的玻璃纤维布/EP-PBMA复合材料在不同加载速率下的拉伸力学性能。结果表明: 玻璃纤维布/EP-PBMA复合材料具有明显的应变率效应;随着加载速率增大,复合材料的拉伸强度和弹性模量呈增大趋势;EP-PBMA树脂基体的组成对应变率效应有明显的影响;玻璃纤维布/EP-PBMA复合材料与纯EP基复合材料相比,在较低的加载速率下具有更高的拉伸强度,但当加载速率达到50 mm/min时拉伸强度较低。     

The durability of controlled matrix shrinkage composites

Controlled matrix shrinkage composites have resin matrices in which the cure shrinkage is controlled by adding expanding monomers to epoxy (and other) resins. The shrinkage stresses can be reduced to about one third of their normal values, accompanied by a 50% increase in impact resistance of the composites, with no corresponding loss of shear strength. Tensile and compressive properties of the composites are slightly reduced, although the resin matrices themselves have slightly improved properties as a result of the addition of the expanding monomer. In contrast to this, the addition to the resin matrix of a compatible solvent, dimethyl formamide, had very little effect on the shrinkage stress or composite impact strength but caused losses of resin properties which were manifested in a decrease in composite shear strength.     

构型参数及方式对Al2O3p/高锰钢球形网络复合材料压缩性能的影响

传统的耐磨金属基复合材料普遍存在塑韧性低的问题。对氧化铝颗粒(Al₂O₃p)增强高锰钢复合材料进行球形网络构型设计,研究了构型方式、参数及热处理对复合材料压缩性能的影响。制备了3种构型参数(球径?分别为6 mm、7 mm、8 mm)结合两种构型方式(平行、错落)的Al₂O₃p/高锰钢球形网络复合材料、均匀复合材料和基体材料。结果表明：同构型方式下,随着构型参数(复合区体积分数)的增加,材料的压缩性能降低,其中?6材料的屈服强度、抗压强度和(抗压强度下)应变最佳,相比于均匀复合材料分别提升203.8%、236.1%和134.8%,屈服强度相比于基体材料提升107.5%;同构型参数下,错落排布比平行排布的屈服强度、抗压强度和应变分别提升10.9%、28.5%和16.3%;水韧处理后,错落排布材料的屈服强度降低35.2%,抗压强度提升11.0%,应变提升163.1%。裂纹易在基体区与复合区界面处萌生并进行扩展,基体能够阻碍裂纹的扩展;错落排布增大了复合区的最小间距,提升了塑性。     

缝合复合材料可用性--环境条件下层合板的冲击后压缩性能

为了解决缝合复合材料在航空航天结构中的应用问题,对国内生产的缝合/树脂膜渗透成型工艺复合材料层合板在三种不同环境条件下的低速冲击后压缩性能进行试验研究.结果表明,缝合改变了含冲击损伤层合板的压缩破坏机理,可以大幅度提高层合板在干态常温下的冲击后剩余压缩强度,但是对湿态高温下层合板的冲击后剩余压缩强度影响不大;缝合方向对冲击损伤面积和剩余压缩强度的影响较小,其中以0°缝合较为有利.     

Compressive behaviour of unidirectional flax fibre reinforced composites

The compressive strength of unidirectional flax fibre epoxy composites was studied. The compressive strength is influenced negatively by the presence of kink bands in the flax fibres. Improvement of the adhesion between the fibres and the epoxy resin can be achieved easily by removing the thin wax layer which covers the surface of the flax fibres. However, improving the adhesion between fibres and matrix only improves the compressive strength to a very limited extent. Stabilisation of the kink bands present in the fibres and improvement of the compressive properties of the fibres can be achieved by impregnating the fibres with melamine formaldehyde (MF) resin. This results in a large increase in the compressive strength of the resulting composite. The increase in compressive strength is proportional to the amount of MF resin present in the composite. However, the presence of the resin in the fibres lowers their tensile strength, and subsequently the tensile strength of the resulting composite.     

聚乙烯纤维增强高延性碱矿渣复合材料的拉压性能及裂缝分布

在碱激发作用下,以矿粉为主要原材料,粉煤灰为辅助材料,共同制备聚乙烯(PE)纤维增强高延性碱矿渣复合材料。通过轴向拉、压实验,研究不同养护龄期(1天、3天、7天、28天、56天、120天)下材料的拉压性能,并借助数字图像技术(DIC)对裂缝进行了表征。结果表明:高延性碱矿渣表现出较好的延性,具有早强特征。7天强度值可达极限强度的84%以上(极限拉压强度分别为5.05 MPa、91.24 MPa),拉伸应变可达5.74%,多缝开裂基本饱和;28天后拉压性能趋于稳定(拉压强度、拉伸应变分别保持在6 MPa、100 MPa、6%);DIC数字分析云图直观地描述了裂缝的形成及发展过程,可从一定程度上对开裂破坏方向及位置进行可靠预判。      

UHMWPE交织双轴向纬编复合材料高应变率压缩性能研究

利用SHPB装置对UHMWPE交织双轴向纬编针织物/乙烯基酯树脂复合材料进行了高应变率压缩实验,研究了该材料的应变率效应和能量吸收.结果表明:等离子体处理后,复合材料的高应变率压缩性能有了较大的提高,放电功率100W是一个较为合适的处理条件.UHMWPE交织双轴向纬编复合材料呈现出一定的应变率敏感性:随着应变率的增加,最大应力、压缩模量、断裂应变能密度相应增大.由于交织双轴向纬编结构中的针织线圈及经纬纱交织作用,其具有较好的抗冲击性能.     

三维四向编织碳纤维/环氧树脂复合材料在热环境中的拉压力学性能实验

针对不同编织角度的三维四向编织碳纤维/环氧树脂复合材料,进行了热环境下的轴向拉伸和压缩力学性能实验研究,讨论了温度对三维四向编织复合材料的轴向拉伸和压缩力学性能的影响,并根据宏观断裂形貌和SEM图像分析了材料的破坏和断裂机制。结果表明,随着测试温度的升高,三维四向编织碳纤维/环氧树脂复合材料的纵向拉伸强度有小幅提高,而纵向压缩强度显著降低。在室温条件下,编织角对材料的纵向拉伸破坏特征没有影响,而对材料的纵向压缩破坏特征有较大影响。随着测试温度的升高,不同编织角度复合材料的纵向拉伸和压缩的损伤破坏形态均与室温条件下明显不同。      

T-ZnO晶须增强环氧树脂复合材料的力学行为

研究了以四脚状氧化锌（T-ZnO）晶须为增强剂，环氧树脂复合材料的力学行为。结果表明，由具有三维空间结构的T-ZnO晶须为增强剂所制备的环氧树脂复合材料具有各向同性的力学性能，T-ZnO晶须填加质量分数为6%时，就可使材料的力学性能改善；拉伸强度提高到169%，拉伸功几乎提高了100%，冲击强度提高到300%，抗弯的断裂功提高到158%，而压缩强度略有下降。     

The dynamic properties of SiCp/Al composites fabricated by spark plasma sintering with powders prepared by mechanical alloying process

The dynamic compressive properties of SiC particle reinforced pure Al matrix composites, fabricated by spark plasma sintering technique with mixture powders prepared by mechanical alloying process, were tested in this paper. Two different average SiC particle sizes of 12 μm and 45 μm were adopted, and the compressive tests of these composites at strain rates ranging from 800/s to 5200/s were conducted by split Hopkinson pressure bar. The damage mechanism of the SiC_p/Al composites was analyzed through the microstructural observations and high-precision density measurements. Results show that the dynamic properties and damage accumulation of these composites are significantly affected by the particle distribution, size, particle cracking, particle/matrix interface debonding and adiabatic heat softening. The composites containing smaller SiC particles exhibit higher flow stress, lower strain rate sensitivity, and less damage at high strain rate deformation.     

Improvement of the Compressive Strength of Carbon Fiber/Epoxy Composites via Microwave Curing

Microwave processing was used to cure the carbon fiber/epoxy composites and designed for improving the compressive strength of the materials. By controlling the power of microwave heating, vacuum bagged laminates were fabricated under one atmosphere pressure without arcing. The physical and mechanical properties of composites produced through vacuum bagging using microwave and thermal curing were compared and the multistep(2-step or 3-step) microwave curing process for improved compressive properties was established. The results indicated that microwave cured samples had somewhat differentiated molecular structure and showed slightly higher glass transition temperature. The 2-step process was found to be more conducive to the enhancement of the compressive strength than the 3-step process. A 39% cure cycle time reduction and a 22% compressive strength increment were achieved for the composites manufactured with microwave radiation. The improvement in specific compressive strength was attributed to better interfacial bonding between resin matrix and the fibers, which was also demonstrated via scanning electron microscopy analysis.     

Thermoplastic matrix continuous filament composites of Kevlar® aramid or graphite fiber

Key static mechanical properties and laminating processes of thermoplastic matrix continuous filament composites reinforced with Kevlar® aramid or graphite fibers are presented and discussed. A tow of Kevlar or graphite impregnated with a thermoplastic matrix from a proprietary melt-coating process involving injection of a melted thermoplastic polymer can be consolidated into a sound, void-free composite laminate by compression molding. The unidirectional composites of Kevlar 49 or graphite from the melt-coated tows possess mechanical properties superior to those of similar composites prepared by other processes such as yarn cowinding and film laminating. The unidirectional composites of Kevlar 49 with thermoplastic matrices prepared from the melt-coated tows are equivalent or superior to those using Epon® epoxies or polyvinylester in flexural, shear and compressive strengths. Using J-polymer, a polyamide copolymer and a proprietary Du Pont resin candidate as a thermoplastic matrix model, a static mechanical test data base has been developed for graphite/thermoplastic matrix composites showing significant advantages in damage tolerance, compression after impact, and interlaminar fracture toughness. Although the unidirectional compressive strength of graphite/epoxy composites has been shown to correlate with matrix modulus, the thermoplastic matrix composites show no such correlation.