Experimental characterization of veering crossing and lock-in in simple mechanical systems

• Published in: Mechanical systems and signal processing 2016-05, Vol.72-73, p.846-864
• Main Authors: Giannini, O., Sestieri, A.
• Format: Article
• Language: English
• Subjects: Brake squeal; Crossing; Effect of damping; Eigenvalues; Experimental investigation; Gyroscopic systems; Joining; Lock-in; Mathematical analysis; Mechanical systems; Resonant frequency; Signal processing; Veering
• ISSN: 0888-3270; 1096-1216
• DOI: 10.1016/j.ymssp.2015.11.012

In this paper, mode veering, crossing and lock-in phenomena are experimentally analyzed and characterized. Their occurrence is generally found, under different conditions, when there is a parameter variation in the system that produces a change in its behaviour. It often happens that, when the natural frequencies of two modes approach each other, they can cross, veer and eventually present a lock-in state. The problem is analytically investigated for general weakly-coupled two-degrees of freedom systems and experiments, appropriately designed to highlight these phenomena, are presented. In particular, experimental evidence of the damping-dependent transition from veering to crossing is investigated for a two beam system, and experimental lock-in is recalled to show how the gyroscopic systems become unstable when two coupled mechanical parts have the same eigenvalue. •Crossing, veering and lock-in, are fully characterized in a simple 2-dof system.•. Parameters influencing the behavioral are found in closed form•The experiments proved that highlighted phenomena occur in real environment.•Experiments confirm the influence of the damping in determining the overall behaviour.•Systems with non uniform damping distribution may exhibit unusual dynamics.