Abstract
This paper is focused on the influence of the rough contact interfaces on the dynamics of a coupled mechanical system. For this purpose, a two‐degree‐of‐freedom model of a coupled seismic‐vibrator‐rough‐ground system is proposed with which the nonlinear vibration properties are analyzed. In this model, the force‐deflection characteristic of the contact interfaces is determined by finite element analysis. By analyzing the undamped free vibration, it was found that the variation of the second‐order natural frequency with amplitude increases with rougher contact interfaces; however, the amplitude has little influence on the first‐order natural frequency of the system. For the harmonic excited analysis, the jump frequencies and hysteretic region both decrease with rougher contact interfaces. Moreover, it is inferred from the bifurcation diagrams that, increasing the excitation force, the system can bring about chaotic motions on rough contact interfaces.
Highlights
Contact interfaces exist in a wide range of mechanical systems and play an important role in the overall static and dynamic characteristics of such systems. e rough surface topography of the contact interfaces affects the wear, friction, and normal contact stiffness of the contact mechanics, which has a great influence on the dynamic properties, vibration noise, and energy transfer of the whole mechanical system [1,2,3]
Berry and Lewis [6] formed the initial basis for a fractal surface roughness description using the Weierstrass– Mandelbrot fractal function. en, Majumdar and Bushan [7] developed the first-contact models for the rough surface using the Weierstrass–Mandelbrot function
A modi ed two-variable Weiestrass– Mandelbrot fractal function is used to construct the ground surface topographies, and the force-de ection characteristic of the vibrator in contact with the rough ground is determined by nite element contact analysis. e power-law function determined by the force-de ection relationship is used to describe the nonlinear contact sti ness between the vibrator and ground
Summary
Contact interfaces exist in a wide range of mechanical systems and play an important role in the overall static and dynamic characteristics of such systems. e rough surface topography of the contact interfaces affects the wear, friction, and normal contact stiffness of the contact mechanics, which has a great influence on the dynamic properties, vibration noise, and energy transfer of the whole mechanical system [1,2,3]. Several researchers studied the vibration characteristics of sphere-plane contact [17,18,19,20], but such contacts cannot reflect the actual topography of a rough surface. E aim of the present investigation is to study the nonlinear dynamic behavior of a TDOF vibration system that accounts for the in uence of rough contact interfaces. A modi ed two-variable Weiestrass– Mandelbrot fractal function is used to construct the ground surface topographies, and the force-de ection characteristic of the vibrator in contact with the rough ground is determined by nite element contact analysis. A nondimensional kinetic equation of the TDOF system is developed to study the e ect of the rough contact interfaces on the vibration response, and a eld experiment is carried out to verify the dynamic model. − k1 z1 − z2 F sin(ωt), where m1 is the mass of the reaction mass, m2 is the mass of the baseplate, z1 and z2 are the vibration displacements, k1 is the hydraulic sti ness, d1 and d2 are the linear damping coe cients of the hydraulic oil and the ground, respectively, Ft is the static load, including the hold-down load and the weight of the vibrator, zs is the static displacement due to the static load, and F sin(ωt) is the excitation force
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