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为研究胶粘剂的黏弹性本构关系和粘贴CFRP加固钢梁各设计参数变化对CFRP-钢界面应力的影响,以改进的Maxwell模型表征胶粘剂的黏弹性本构关系。针对加固梁胶层以剪切变形为主的情况,对胶粘剂黏弹性本构进行简化分析,利用拉普拉斯变换和逆变换的数学方法,给出了改进的Maxwell模型各变量的求解方法,利用有限元软件ABAQUS对典型的粘贴CFRP加固简支钢梁进行有限元分析。分析了界面应力随加载时间的变化规律,详细地讨论CFRP弹性模量变化、CFRP厚度变化、胶层厚度变化和CFRP端部到支座的距离变化对CFRP-钢界面应力的影响。依据敏感性分析的基本原理,从定量分析的角度研究界面应力对各参数的敏感程度。结果表明:胶粘剂黏弹性会导致黏结界面发生应力重分布,界面峰值剪应力和峰值正应力随时间增加而减小;胶层越厚,CFRP越薄,CFRP弹模越小;CFRP离支座越近,黏结界面应力越小;对CFRP端部界面剪应力影响最大的参数为CFRP端部到支座的距离,其敏感度因子为1.359;对CFRP端部界面正应力影响最大的参数为CFRP厚度,其敏感度因子为0.956。
In order to study the viscoelastic constitutive relation of the adhesive and the influence of the design parameters of the CFRP-strengthened steel beams on the stress of the CFRP-steel interface, the viscoelastic constitutive relation of the adhesive was characterized by the improved Maxwell model. Aiming at the situation that the shear stress is the main factor of the reinforced beam, the viscoelastic constitutive model of the adhesive is simplified. By using the Laplace transform and the inverse transform, the method of solving the variable of the Maxwell model is given. Finite element analysis of a typical simply supported CFRP-strengthened steel beam is performed using the finite element software ABAQUS. The variation of interfacial stress with loading time was analyzed. The influence of the change of CFRP elastic modulus, CFRP thickness, adhesive layer thickness and distance between CFRP end and bearing on CFRP-steel interfacial stress was discussed in detail. According to the basic principle of sensitivity analysis, the sensitivity of interface stress to each parameter is studied from the perspective of quantitative analysis. The results show that the viscoelasticity of the adhesive will lead to the stress redistribution at the bonded interface, and the peak shear stress and the peak positive stress at the interface decrease with time. The thicker the adhesive layer, the thinner the CFRP, the smaller the CFRP elastic modulus. The smaller the stress is, the smaller the stress is, the smaller the stress is. The parameter that has the most influence on the shear stress of CFRP is the distance from the end of CFRP to the support, the sensitivity factor is 1.359. The most influential parameter of CFRP end- , The sensitivity factor is 0.956.