THE ELECTRORHEOLOGICAL LONG-STROKE DAMPER: A NEW MODELLING TECHNIQUE WITH EXPERIMENTAL VALIDATION

Semi-active damping devices offer improved performance over passive devices, without the power requirements or instability problems of fully active devices. Smart fluids (electrorheological and magnetorheological) are well suited to use in semi-active dampers—their flow properties can be rapidly altered, with a low-power requirement. However, the force/velocity response is highly non-linear, and this is without doubt hindering the development of effective control strategies. In this paper, the authors develop a new model of an electrorheological damper. The key advantage of this model is that its algebraic form is suitable for use in control system design, whilst it is able to predict and explain observed behaviour. The model consists of a spring, mass, and damper connected in series. The spring stiffness term is based upon the fluid bulk modulus, and the mass is determined from the fluid density. The damping characteristic utilizes a modified non-dimensional Bingham Plastic function. The model predictions are compared with experimental results at a range of operating frequencies. Excellent agreement was achieved by updating the stiffness and viscosity parameters using experimental data.