Experiments on a beam-rigid body structure repetitively impacting a rod

Abstract

This paper investigates the experimental dynamics of a beam structure that supports an attached rigid body and that can impact a comparatively compliant base structure. The problem area is motivated by impact phenomena that are observed in certain structures internal to nuclear reactors. The assembly is subjected to base excitation at specified frequency and acceleration, and the resulting displacement and velocity time histories are recorded and used to obtain spectra, phase diagrams, and Poincaré sections. The measurements validate simulation results obtained by using a constraint and modal mapping method based on the two sets of modes when the structure is in-contact, and when it is not-in-contact. Generalized coordinates are mapped across the impact discontinuities in the modal representation. The forced response simulation predicts the test specimen's response over a range of excitation frequencies. The specimens are fabricated as single integral structures from acrylnitrile butadene styrene plastic through rapid prototyping technology in order to eliminate the undesirable dissipation and flexibility arising from joints and connections. The experimental system can exhibit complex response characteristics, and the influences on complexity of deadband clearance and of asymmetry in the point of impact are examined in the experiments.

Modeling and sticking motion analysis of a vibro-impact system in linear ultrasonic motors

“…The friction material adopted in the LUSMs is usually a material having both high hardness and wear resistance (the Al 2 O 3 ceramic, for example, is often chosen as the friction material in LUSM), the normal impacts between the stator and mover is considered as rigid impacts in this paper. The dynamics of the continuous systems such as beams, strings and robs subjected to impacts have been studied extensively [10][11][12][13][14][15]. The CoR method is an attractive and effective approach to simulate the impacts with rigid obstacle.…”

Nonsmooth Modeling of Vibro-Impacting Euler-Bernoulli Beam

“…The dynamics of continuous systems like beams, strings, and rods subjected to impacts caused by motion-limiting constraints have been studied extensively. A representative set of studies can be found in [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. The impact of these systems is modelled using two different methods.…”

Investigation of the near-grazing behavior in hard-impact oscillators using model-based TS fuzzy approach

“…Impacting systems are non-smooth dynamical systems in which components may experience impacts. Many experiments have been conducted on the dynamics of systems whose numerical models interchange between continuous and discrete states [12,15,21,33,42]. Strong nonlinear behavior, induced by rigid collisions, has been observed in most cases driving these systems into chaos [11].…”

“…Other attempts using explicit mapping to analyze mechanical impacting systems have also been published [7,31]. In all cases, however, disagreements have been observed between the theoretical analysis employing the above methods and various experimental studies [12,14,42,43]. More recently, numerical analysis of soft-impact oscillators employing the discontinuity-mapping approach has been proposed to study the onset of the grazing bifurcation [24,25] with results showing good agreement with experimental observations [15,25].…”