Analysis of tearing test results for joining tips of metal-composite joints

Background: Designing highly loaded joints of metal-composite ends of aerospace engineering units meets the problem of assessing their bearing capacity, checking the adequacy of created mathematical calculation models to real testing results, and studying the dependence of the production technology of such joints on their final load-bearing capacity. Objective: The study of the dependence of the load-bearing capacity of "metal-composite" joints on the technology of their creation and the evaluation of the quality control process of combined joints with cylindrical transversal microelements and the adhesive bond between connecting parts was chosen as the goal of the research. Methods: The joint of a flat metal tip with a carbon fiber part using transverse cylindrical pins and adhesive is considered as an object of research. Transversal pins of different diameters are inserted into the composite package. Various technological processes of preparing the surface of the metal part and pins for subsequent adhesive joining are considered in order to maximize the adhesion between the polymer binder and the metal elements of the joint. Also, for a more rational distribution of stiffness and corresponding stresses in the parts, the metal tip has a variable stepped thickness along the length of the joint. Results. As the results of the study, the theoretical failure load of the joints was evaluated and compared with the results of experimental tests. Also the technological process of preparing the surface of the metal part and the pins for further joining with the composite part is recommended, which ensures maximum adhesion between the joining parts. A conclusion was made regarding the diameter of the pins and the shape of the profiled metal part, which ensure the maximum load-bearing capacity of the connection. The types of joint failure were analyzed and conclusions were drawn regarding changes in the technology of surface preparation, the layout of the pins and the choice of their diameter. Conclusions: As conclusions, recommendations were formulated regarding a certain technology for surface treatment of a metal part, which guarantees maximum adhesion between the metal part, pins and composite, and actual processes of quality control of "metal-composite" joints with transversal microelements were selected.