Model predictive control of an air suspension system with damping multi-mode switching damper based on hybrid model

A high-frequency first-principle model of a shock absorber and servo-hydraulic tester

The aim of this paper was to study the dynamic response of a single-degree-of-freedom (SDOF) oscillator exited by a base acceleration and constrained by two unilateral constraints (bumpers). The coupled equations of motion are formulated in dimensional and dimensionless form for the case in which both SDOF oscillator and bumpers exhibit a nonlinear behavior. Two possible states characterize the system’s response: flight, when the mass of the oscillator is not in contact with the bumper, and contact, when the mass touches the bumper. When the system is in the flight state, the independent time evolution of the bumpers’ response is also considered in equations of motion. In the numerical investigations, a viscoelastic SDOF oscillator and viscoelastic perfectly plastic bumpers subjected to a harmonic base excitation are considered. First, the transient versus steady-state dynamic response is considered, and afterward the only steady-state dynamic response is studied by means of pseudo-resonance curves of maximum absolute acceleration and relative displacement excursion of the SDOF oscillator. Furthermore, the continuation technique is applied in some cases in order to highlight in the system’s dynamic response hysteresis ranges, jumps between multi-periodic orbits, and super-harmonics. The dynamic analysis with and without bumpers is compared to observe how unilateral constraints modify the dynamic response of the SDOF oscillator with respect to the absence of bumpers and when their presence may be beneficial with respect to response mitigation.

Nonlinear dynamic response of a base-excited SDOF oscillator with double-side unilateral constraints

The paper presents results of research on hydraulic automotive shock absorbers. The considerations provided in the paper indicate certain flaws and simplifications resulting from the fact that damping characteristics are assumed as the function of input velocity only, which is the case of simulation studies. An important aspect taken into account when determining parameters of damping performed by car shock absorbers at a testing station is the permissible range of characteristics of a shock absorber of the same type. The aim of this study was to determine the damping characteristics entailing the stroke value. The stroke and rotary velocities were selected in a manner enabling that, for different combinations, the same maximum linear velocity can be obtained. Thus the influence of excitation parameters, such as the stroke value, on force versus displacement and force versus velocity diagrams was determined. The 3D characteristics presented as the damping surface in the stoke and the linear velocity function were determined. An analysis of the results addressed in the paper highlights the impact of such factors on the profile of closed loop graphs of damping forces and point-type damping characteristics.

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Sun Nin

Papers

Measurement, simulation on dynamic characteristics of a wire gauze–fluid damping shock absorber