The study of multicomponent loading effect on thin­walled structures with bolted connections

Features of influence of various factors on the stress-strain state of composite thin-walled structures with bolted connection of separate elements were studied on an example of the test problem. As an example of such structures, a metallic granary (a silo) consisting of panels connected with bolts was taken. The test structure contained two lapping narrow flat strips. A bolt is inserted in bolt holes bored in these strips and pre-tightened. Friction and slipping of the strips and the bolt, contact between the side surface of the bolt and the holes as well as mutual influence of bending and stretching were taken into consideration. Thus, the model has taken into consideration geometric, physical and structural nonlinearities. The system was subjected to a transverse load applied to one side of the strip. Staged loading of the systems was modeled. It was established that under load, the studied system acquires a deflection which unevenly increases with the load increase. This is determined by the fact that it is affected by both elastic deformation of the strips and mutual slip in the connection zone. When the gap between the bolt and the holes in the panels finally vanishes, mainly elastic deformation of the system takes place. Residual deflection was established in the system after the first unloading. It was also established that longitudinal forces act in the system. They can be much larger than transverse forces from the load. The system featured strong mutual influence of bending and stretching of the strip. As a result of the studies, factors determining stress-strain state of the studied system were determined: geometric nonlinearity, contact interaction, friction and slip, connection between deflection and stretching. Thus, the design model for such thin-walled structures will be inadequate without all these factors, the results of calculations with its application will have significant errors and recommendations will be unreliable. The conducted studies have made it possible to develop more adequate models for analysis of reaction of composite thin-walled structures to the effect of loading