Numerical and experimental analysis of the bi-stable state for frictional continuous system

Abstract

Unstable friction-induced vibrations are considered an annoying problem in several fields of engineering. Although several theoretical analyses have suggested that friction-excited dynamical systems may experience sub-critical bifurcations, and show multiple coexisting stable solutions, these phenomena need to be proved experimentally and on continuous systems. The present work aims to partially fill this gap. The dynamical response of a continuous system subjected to frictional excitation is investigated. The frictional system is constituted of a 3D printed oscillator, obtained by additive manufacturing that slides against a disc rotating at a prescribed velocity. Both a finite element model and an experimental setup has been developed. It is shown both numerically and experimentally that in a certain range of the imposed sliding velocity the oscillator has two stable states, i.e. steady sliding and stick–slip oscillations. Furthermore, it is possible to jump from one state to the other by introducing an external perturbation. A parametric analysis is also presented, with respect to the main parameters influencing the nonlinear dynamic response, to determine the interval of sliding velocity where the oscillator presents the two stable solutions, i.e. steady sliding and stick–slip limit cycle.

High-Precision Tribometer for Studies of Adhesive Contacts

“…Furthermore, although functional modification of the device for certain types of experiment is possible, more advanced studies or experiments under unique conditions require a special type of tribometer. As notable examples of such tribometers, we can refer to a millitribometer designed to study small friction units and small loads [ 50 ], a six-axis force/torque sensor for slow friction measurements under ultra-high vacuum and other conditions [ 51 ] and a setup for the study of friction-induced vibrations [ 52 ] and haptics [ 53 ].…”

Investigation of the Material Elasto-Plastic Response under Contact Indentation: The Effect of Indenter Material

“…Nevertheless, when using finite element models for investigating contact issues [34][35][36], material laws obtained by classical stress-strain experiments on bulk samples (volumetric samples) are often introduced as material properties [37]. In fact, available mechanical properties are generally obtained from tensile or compression tests; hence, they represent the strain and stress response within the bulk of the sample.…”

Dynamic response of multi-degree-of-freedom systems with a Coulomb friction contact under harmonic excitation

“…Further details on the semi-analytical and numerical approaches used in the last decades for the investigation of friction damped systems can be found in reviews [4,6,16]. More recently, fundamental research has focused on the numerical and experimental investigation of the stability of SDOF and MDOF frictional oscillators, showing that multiple stable vibration states may exist in both self-excited and externally excited systems [39][40][41][42].…”