Research On Fatigue Behavior Of Single-lap Joint Under Vibration Loads

In order to sparing energy sources and protecting environment, automotive lightweight technology is get the favour of automotive makers, lightweight technologies require using more lightweight materials to replace the traditional metal materials and the adhesion technique provide a broad development platform for joining dissimilar materials. Compared with the traditional mechanical connection, adhesion technique had some advantages just like simple process, stress distribution uniformity, good sealing and good fatigue durability.Like other structures, adhesively bonded structure also inevitably affected by the static load and fatigue load. So when designing adhesively bonded structure, it is necessary to predict the static strength and study the fatigue characteristics under vibration loads. This article studied the CFRP-to-steel single lap joint(SLJ) by means of numerical, experiment and simulation. Based on Mindlin theory, the author constructed the numerical model of composite material and a numerical model of mixed-mode EPZ model was constructed on the basis of pure EPZ model. Using the numerical model of composite material and the numerical model of mixed-mode EPZ model, the author constructed the numerical model of adhesively bonded joint which made of composite. This numerical model was described the mechanical response of the adhesively bonded joints, then it was given to support for the finite element analysis.In addition, fatigue characteristics of SLJ made of steel and CFRP under vibration loading were primarily investigated by experiments. The aim of this work is to analyze the changes in the peak load and the model properties of the SLJ. Through the analysis of SEM on fracture surface of SLJ, the microscopic manifestation of the adhesive layer is analyzed to express the experimental results. Finally, the author constructed EPZ model to investigated the static strength of SLJ and a finite element model was used to analysis modal performance of SLJ. A damage factor was introduced into EPZ law and a finite element damage model is developed to evaluate the degradation process in the adhesive layer. A good correlation is achieved when comparing the simulation results to the experimental data, which verifies the feasibility of the proposed model. The research methods and results proposed in this paper can provide a basis guidance and help to the research, design and application of other adhesive structures.