SMA丝表面纳米SiO_2改性对SMA/环氧树脂复合材料界面粘结强度的影响

为了研究形状记忆合金(SMA)丝增强环氧树脂复合材料的界面粘结行为,首先通过单纤维拔出试验测定了SMA/环氧树脂界面的粘结强度,重点考察了埋入深度对界面极限粘结强度及其拔出行为的影响。然后,结合ABAQUS有限元分析方法,利用基于表面内聚力行为的单元对SMA丝拔出过程中应力分布随拔出时间的变化关系进行了模拟。最后,针对SMA/环氧树脂复合材料界面粘结强度较弱的缺陷,提出了利用纳米SiO2改性SMA丝表面提升材料界面粘结强度的方法,并通过拔出试验进行了验证。结果表明:随着埋入深度从1.0cm增加到1.5cm和2.0cm,最大拔出载荷显著增加,平均界面粘结强度却逐渐下降。当纤维埋入深度为2.0cm时,在0.300s时临界脱粘出现。利用在SMA表面涂覆纳米SiO2颗粒的方法可以增加纤维的表面粗糙度,进而有效提高SMA丝增强环氧树脂复合材料的临界拔出强度。研究结论为SMA丝在实际工程领域中的应用提供了理论指导。

Effects of SMA filament surface nano SiO2 modification on interface bonding strength of SMA/epoxy composites

In order to investigate the interface bonding behavior of shape memory alloy (SMA) filament reinforced epoxy composites, the interfacial bonding strength of SMA filament/epoxy was tested through single fiber pull-out test firstly. The effects of embedding depth on ultimate interfacial bonding strength and the debonding behavior were analyzed emphatically. Then, using ABAQUS finite element analyses method, the changing relationship of stress distribution versus time during the SMA filament pull-out process was simulated by the element based on surface cohesive behavior. Finally, for the defect of low interfacial bonding strength of SMA/epoxy composites, the method in which nano SiO₂ were used to modify the surfaces of SMA filaments was proposed to improve the interfacial bonding strength of materials, and was verified by debonding test. The results reveal that with the embedding depth increasing from 1.0 cm to 1.5 cm and 2.0 cm, the ultimate debonding load increases observably, while the average interfacial bonding strength decreases gradually. When the embedding depth of fiber is 2.0 cm, ultimate debonding appears at 0.300 s. By using the method of coating nano SiO₂ particles on SMA surfaces, the surface roughness of fibers can be enhanced, and then improves the ultimate debonding strength of SMA filaments reinforced epoxy composites effectively. The conclusions provide theoretic guidances for the application of SMA filaments in real engineering fields.