Characterizing collision of vibro-soft impact SDOF systems against unilateral and dissipative symmetrical bumpers via suitable impact parameters

This paper presents some of the results of an experimental laboratory campaign, where experimental tests were carried out to investigate the dynamic response of a base-isolated single-degree-of-freedom oscillator, excited by a harmonic base acceleration and symmetrically and unilaterally constrained by two deformable and dissipative bumpers. In this work the attention is focused (i) on some parameters characterizing the system, such as stiffness of bumpers and width of gap, and the input (peak acceleration of the shaking table), and (ii) on some characteristics of the dynamic response with impact, such as time and force of contact between body and bumpers, coefficient of restitution and bumpers? deformation. The experimental tests were carried out in two successive phases, in the absence and in the presence of the impact cells, in order to compare and verify the approximate estimates of the values assumed by the impact parameters, carried out using the analytical formulation. The results of the experimental tests were used to identify the parameters of stiffness and damping of a numerical model which was suitably formulated, and which is able to simulate the behavior of the system by using a dedicated computer code in MATLAB and allows to interpret and extend the experimental results. The results shown are not limited to characterizing the impact phenomenon through appropriate impact parameters, but also allow for the extraction of design-related indications.