Research On Mechanical Properties Of Single-lap Joint Under Salt Spray Environment

With the development of automotive lightweight, the applications of adhesively bonded joints are becoming more and more widely. Compared with the traditional connection type including welding, riveting and bolting, adhesively bonded joints have many advantages: bonding dissimilar materials more uniform stress distribution, good sealing property, higher corrosion resistance and so on. The environmental durability of single-lap joint (SLJ) has always been the research emphasis of many scholars. The aim of this paper was to develop an experimental-simulated approach to investigate the effect of salt spray environment on single-lap joints.Firstly, salt spray experiment and quasi-static tensile testing were conducted on Araldite(?)2015 bulk adhesive and single-lap joints. According to Fickian model, the moisture diffusion model of 2015 adhesive was developed, and the moisture content in different ageing time and the moisture diffusion coefficient were obtained by a gravimetric method. The results of quasi-static tensile testing showed the strength of bulk adhesive and SLJ significantly decreased with the ageing time increasing. The above experimental results on bulk adhesives and SLJs were used to determine the CZM parameters of adhesive in the finite element modeling (FEM) and compare with the results of FEM, respectively.Secondly, the three-dimension finite element model was set up in the FEM package Abaqus(?) to simulate the damage propagation of the adhesive joints layer using a bilinear traction-separation cohesive zone model (CZM). The environment degradation model (EDM) was developed to predict the degradation in joint strength. The degraded CZM parameters, determined from environmental degradation factor Deg and static tests on bulk adhesive, were imported into the cohesive zone model using an approximate moisture concentration gradient (AMCG) approach. Finally, the reduction in residual strength of SLJ under salt spray environment was successfully predicted through comparing the experimental and numerical results.