Stabilizing a strongly nonlinear structure through shaker dynamics in fixed frequency voltage control tests. (1st May 2023)

• Record Type: Journal Article
• Authors: Robbins, E.; Kuether, R.J.; Pacini, B.R.; Moreu, F.
• Is Part Of: Mechanical systems and signal processing. Volume 190(2023)
• Publication Date: 2023-05-01
• Subjects: Nonlinear stability -- Nonlinear structures -- Force drop-out phenomenon -- Shaker-structure dynamics -- Stepped sine testing; Structural dynamics -- Periodicals; Vibration -- Periodicals; Constructions -- Dynamique -- Périodiques; Vibration -- Périodiques; Structural dynamics; Vibration; Periodicals; 621
• DOI: 10.1016/j.ymssp.2023.110118
• Languages: English
• ISSNs: 0888-3270

Abstract

Graphical abstract: Highlights: Passive voltage control method stabilizes nonlinear systems through shaker dynamics. Electromechanical shaker parameters influence stability of nonlinear structure. Excitation drive points on nonlinear structures influence stabilizing behaviors. Unstable branch was experimentally measured on strongly nonlinear structure. Abstract: Bifurcations are commonly encountered during force controlled swept and stepped sine testing of nonlinear structures, which generally leads to the so-called jump-down or jump-up phenomena between stable solutions. There are various experimental closed-loop control algorithms, such as control-based continuation and phase-locked loop, to stabilize dynamical systems through these bifurcations, but they generally rely on specialized control algorithms that are not readily available with many commercial data acquisition software packages. A recent method was developed to experimentally apply sequential continuation using the shaker voltage that can be readily deployed using commercially available software. By utilizing the stabilizing effects of electrodynamic shakers and the force dropout phenomena in fixed frequency voltage control sine tests, this approach has been demonstrated to stabilize the unstable branch of a nonlinear system with three branches, allowing for three multivalued solutions to be identified within a specific frequency bandwidth near resonance. Recent testing on a strongly nonlinear system with vibro-impact nonlinearity has revealed jumping behavior when performing sequential continuation along the voltage parameter, like the jump phenomena seen during more traditional force controlled swept and stepped sine testing. This paper investigates the stabilizing effects of an electrodynamic shaker on strongly nonlinear structures in fixed frequency voltage control tests using both numerical and experimental methods. The harmonic balance method is applied to the coupled shaker-structure system with an electromechanical model to simulate the fixed voltage control tests and predict the stabilization for different parameters of the model. The simulated results are leveraged to inform the design of a set of experiments to demonstrate the stabilization characteristics on a fixture-pylon assembly with a vibro-impact nonlinearity. Through numerical simulation and experimental testing on two different strongly nonlinear systems, the various parameters that influence the stability of the coupled shaker-structure are revealed to better understand the performance of fixed frequency voltage control tests.