The Numerical And Experimental Analysis Of T-joints Used In The Lightweight Technologies Of Car Body

In order to cope with energy crisis, the automotive industry needs to use the new energy strategy and lightweight technology. With the gradual improvement in automotive lightweight technology and the extensive application of new lightweight-highstrength materials, the traditional connection technology encounters bottleneck, however, the adhesion technology which can connect different materials and has good fatigue durability now has been widely concerned as one of the most important key technologies in the automotive lightweight area.This paper is mainly based on the slender beam model which considers the plastic response of the materials and combines the mixed-mode cohesive zone model to describe the mechanical response of the T-joints, then the numerical implementation of the model is given to support the finite element analysis. The orthogonal experimental method and the control variate mehod were used to design a series of experimental tests to study factors affecting the strength of T-joints. And the contrast between the experimental results and numerical results was used to verify the correctness of the theory. Meanwhile, the stiffness ratio R was proposed to be a parameter which can measure the mismatch level of a T-joint. Also, the effcet on the strength of a T-joint caused by the stiffness, the ratio R and the adhesive length was investigated.In order to explore an aspect of the service ability of a T-joint, i.e., the fatigue durability to the changes of temperature, a series of tests were conducted. During the tests T-joints were put into a certain enviroment with cycle temperature and then the tensile test was conducted to verify the changes to the strength of these T-joints compare with those which were not exposed to the certan enviroment. This paper proposed a theory-the degradation of mixed-mode cohesive zone model-to explain the changes observed in these test and the degradation parameter D was used to descreibe the phenomenon. Meanwhile, the contrast between the experimental results and the theoretical results was used to verify the correctness of the theory. 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.