| With the new light metal materials and composite materials are widely used in automobile manufacturing, the traditional connection technologies such as welding, riveting and so on are too limited on the link heterogeneous materials and guaranteeing surface smooth. However, the adhesive technology can make full use of its advantage to connect the materials which are difficult to welding, and heterogeneous materials, etc. In fact, the adhesive on connecting structure parts are rarely used. The reason is not only the many factors influencing the fracture strength of adhesive, but also that it is the key to establish an accurately method to predict bonding structure fatigue service life on the current research of adhesive technology.This paper combines with two kinds of adhesive such as Sikaflex265 and ISR7008 which are provided by an enterprise to study the weatherability of the two kinds of adhesive. The final purpose is to seek a method to evaluate the service life of the two kinds of adhesive, and then discuss the method to guide the engineering application. First, the weatherability experiment method of the adhesive is proposed. Then the weatherability of two kinds of adhesive is studied by analyzing the experiment data under without load and with load, and the relationship between the fracture strength of two kinds of adhesive and the cycle number or the load are analyzed respectively. Finally the empirical formulas are attained.The main contents of this paper as follows:(1)The weatherability experiment method of the adhesive is proposed. Consult the standard ‘GB/T7124-2008 adhesive tensile shear strength test method’, the weatherability experiment method of the adhesive is designed in this paper.First, the three kinds of adhesive joint forms included 0 ° lap specimens, 90 ° and 45 ° docking specimens are designed, representing the three loaded modes of the pure shear stress, tensile stress and shear ratio of 1:1 respectively. Then a set of perfect bonding processes are formulated. Thus, the experiment error interference is eliminated, beside, the accuracy of experimental results are attained.(2)The weatherability of the two kinds of adhesive is studied under no-load. First of all, the artificial accelerated weatherability experiment conditions of the two adhesive are determined according to DIN50015 standard. Then the weatherability experiments and the adhesive tensile experiments are done, and each adhesive section damage form and the fracture strength of the specimens are recorded. The adhesive joints’ section damage forms of weatherability experiment cycles are analyzed. And each experimental data of adhesive specimens are dealt with reliably by used the sample mean and standard deviation. Beside, according to the curves trend and choose two kinds of function, the two adhesive’s fracture strength along with the change of weather resistance cycles’ relationship curves are attained by used the least squares fitting respectively. At last, the curves and the experience formulas of two kinds of adhesive are modified. The influence law of weatherability of two kinds of adhesive is Summarized.(3)The effect of load on the weatherability of two adhesive is studied. The influence of load on the weatherability of the two adhesive is further discussed in the paper based on the study of climate conditions which have influenced on the damage section forms and fracture strength of adhesive. Therefore, the loading method of a weatherability experiment is proposed and the experimental loading device is designed. The two kinds of adhesive section damage forms are analyzed varying with the size of the load. The phenomenon was found that the fracture strength of the two kinds of adhesive has gradually reduced with the increase of load by using the least squares fitting experimental data. It is concluded that there is a great influence of load on destruction forms and fracture strength of two kinds of adhesive which have been done the weatherability experiment. At last, the fitting curves of the two kinds of adhesive are modified as well as the experience formulas. Thus, the engineering personnel are fully guided to take into account the weather and load effects on bonding structures during the vehicles running better when choosing two kinds of adhesive so that the safety and reliability of the bonding structures are guaranteed during the vehicle running. The basis is provided to establish the correlation model between the artificial accelerated weatherability experiment and natural weatherability experiment of the two kinds of adhesive in the future. |
PDF Full Text Request