This paper presents an experimental study on a base-excited piecewise linear oscillator with symmetrical flexible constrains of high stiffness ratio (above 20). The details of the adopted design of the oscillator, the experimental setup, and calibration procedure are briefly discussed. The regions of chaotic motion predicted theoretically were confirmed by the experimental results arranged into bifurcation diagrams. Clearance, stiffness ratio, amplitude, and frequency of the external force were used as branching parameters. The discussion of the system dynamics is based on bifurcation diagrams and Lissajous curves. The investigated system tends to be periodic for large clearances and chaotic for small ones. This picture is reversed for the amplitude of the forcing changes, where periodic motion occurred for small values and chaos dominated for larger forcing. The same behavior is observed for increasing frequency ratio where, for values below the natural frequency, the most interesting dynamics occurs. For the investigated parameter values, the stiffness ratio variation produces only periodic motion.

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A simple piecewise linear system with symmetrical flexible constraints was designed and manufactured to carry out a wide range of experimental dynamic analysis and ultimately to validate piecewise models. The design choice was based on the following criteria: accuracy in representing the mathematical model, manufacturing simplicity, flexibility in terms of parameter changes and cost effectiveness. The system consists of a block mass attached to two leaf springs, the stiffness of which can easily be varied by changing their length. The secondary stiffness in the form of cantilever beams can be widely varied in the same way. The clearance between the mass and secondary springs can also be varied by adjusting the screws at the ends of the beams. A variable pneumatic damper is mounted on the upper surface of the mass and provides a means of changing the viscous damping coefficient. The experimental set-up, calibration procedures and typical results are discussed.

A Coulomb oscillator with a variable normal force has been designed and manufactured to carry out a wide range of experimental dynamic analysis, especially the study of the non-reversibility of dry friction characteristics. The design choice was based on the criteria of accuracy of the mathematical model and flexibility in terms of parameter changes such as the natural frequency of the system, coefficient of friction and normal force. The system consists of a block mass attached to two coil springs and a dry frictional damper in which the friction force is varied by a pneumatic actuator. This allows a constant pressure between sliding surfaces to be maintained. The experimental set-up, the calibration procedure for the clamping device and typical results are presented. Experimental non-reversible dry friction characteristics are discussed.

The paper gives a short account on the experimental and numerical study of a piecewise based excited symmetrical linear oscillator undergoing non-linear vibrations. The details of the adopted design and the state-of-the-art experimental setup are explained in a great detail. The regions of chaotic motion predicted theoretically were confirmed by the experimental results arranged into bifurcation diagrams, which were obtained by numerical and experimental means. Clearance and amplitude of the external force were used as branching parameters. The discussion of the system’s dynamics is based on bifurcation diagrams, Lissajous curves and power spectrums. The investigated system tended to be periodic for large clearances and chaotic small ones. This is picture is reversed for the amplitude of the forcing, where periodic motion occurred for its small values and chaos dominated for larger forcing.