纳米SiO2质量分数对胶粘碳纤维增强树脂复合材料板-钢搭接界面黏结性能的影响

胶黏剂力学性能对碳纤维增强树脂复合材料(CFRP)加固钢结构的界面黏结性能影响显著。基于研制的胶黏剂配比，分析了不同纳米SiO₂质量分数对胶黏剂常温固化后基本力学性能及微观结构的影响，制作了31个CFRP板-钢板双搭接试件，对其进行了常温固化后的承载能力、有效黏结长度、传力模式、黏结-滑移本构等试验研究，得出了纳米SiO₂质量分数对CFRP板-钢板搭接试件界面黏结性能的影响规律，并与常用商品胶黏剂进行了比较。研究结果表明:随纳米SiO₂质量分数的增加，胶黏剂应力-应变关系由线性转变为非线性，应变能、断裂伸长率及剪切强度分别最高提升了292.10%、202.88%和133.12%。微观结构分析表明纳米SiO₂的添加使断面粗糙度显著增加，形成了密集的塑性空穴，产生了更多的微裂纹，使胶黏剂的韧性大幅度提高。当纳米SiO₂质量分数从0增至1wt%，搭接试件破坏模式由界面破坏逐渐变为CFRP板层离破坏。掺入纳米SiO₂能显著增加搭接试件的极限承载力(提升256.96%)及界面有效黏结长度(提升3倍)，提高CFRP表面的应变及界面剪应力峰值。纳米SiO₂质量分数为0与0.5wt%的搭接试件的黏结-滑移曲线为双线性三角形模型，纳米SiO₂质量分数为1wt%的搭接试件的黏结-滑移曲线为三线性梯形模型，黏结界面韧性大幅提升。CFRP-钢界面承载能力受胶黏剂拉伸强度与断裂伸长率的双重影响，非线性高强度(即具有较高应变能)胶黏剂对应的CFRP-钢搭接接头具有更好的界面性能。 

Effect of nano-SiO2 mass fraction on the interface performance of glued carbon fiber reinforced polymer composite-steel specimen

The mechanical performance of adhesives has significant effects on the interfacial bond behavior of the carbon fiber reinforced polymer (CFRP)-reinforced steel structures. Based on the developed ratio of adhesives, the effects of different nano-SiO₂ on the basic mechanical properties and microstructure of the adhesives after curing at room temperature were analyzed. A total of 31 CFRP plate-steel double lap joint specimens were fabricated, and the experimental researches on bearing capacity, effective bonding length, force transmission mode, and bond-slip constitutive after curing at room temperature were carried out. The influence of the amount of nano-SiO₂ on the interfacial bonding properties of CFRP-steel lap joints was obtained and compared with commonly used adhesives. The results show that with the increase of nano-SiO₂, the stress-strain relationship of the adhesive changes from linear to nonlinear, the strain energy, elongation at break and shear strength are increased by 292.10%, 202.88% and 133.12%, respectively. Microstructural analysis shows that the addition of nano-SiO₂ significantly increases the section roughness forms dense plastic cavities, resulting in more microcracks, and greatly improves the toughness of the adhesive. When the amount of nano-SiO₂ is from 0 to 1wt%, the failure mode changes from interface failure to CFRP plate delamination. The incorporation of nano-SiO₂ can increase the ultimate bearing capacity of the lap test piece (increase by 256.96%) and the effective bond length of the interface (up to 3 times), and improve the strain and interfacial shear stress peak of CFRP surface. The bond-slip curves could be simplified into a bilinear model (triangle-shape) for CFRP-steel joints with 0 and 0.5wt% of the nano-SiO₂, the bond-slip curve could be simplified into a trilinear model (trapezoidal-shape) of CFRP-steel joints with 1wt% of nano-SiO₂, and the bonding interface toughness is greatly improved. The bearing capacity of CFRP-steel interface is affected by the tensile strength and elongation at break of the adhesive. The CFRP-steel lap joint based on nonlinear high-strength adhesive (i.e. adhesive with higher strain energy) has excellent interface performance.