When there is a parameter varying in a system, so that one natural frequency approaches another one, the phenomenon of veering is generally found and highly coupled modes are the emerging characteristic of this dynamic behavior. It is far more difficult to find systems that instead of a veering present crossing between modes, and the crossing phenomenon is almost unreported in the scientific literature, unless the case of uncoupled modes is considered.
In this paper, the two-modes interaction is presented. In particular, mode veering and mode crossing are introduced and investigated through a simple analytic 2-dof model that allows for closed-form solution. Then, an experimental setup, appropriately designed to study the two-modes veering and crossing is presented and experimental evidences of both phenomena are measured showing the main characteristics of such modal interaction..