|
This paper studies the optimization of the orifice's flow in shock absorber using shape memory alloys (SMA) wire. The motivation for this optimization is to ensure that the damping properties of shock absorber remained intact over the longer period of operating time and hence to maintain the overall energy dissipating performance of the damping system. The temperature of hydraulic fluid in a shock absorber increases every time when high-energy impacts have to be absorbed by the system. This in turn will lead to drop of viscosity of the fluid. Thus at the fixed size of orifice's opening, the fluid's flow rate through the orifice is significantly higher compare to the rate at lower temperature. The high flow rate through the orifice will impose in the end a negative impact to the energy dissipating capability of the shock absorber. In other words, the high flow rate through the orifice will induce the degeneration of damping constant and hence shorten the lifetime of the shock absorber. The paper discussed the possibility of varying the size of orifice's opening in order to reduce the volume flow rate through the orifice. For the purpose of varying the size of orifice's opening a piece of SMA wire was placed in the proximity of the orifice. The SMA wire was in such a way configured that at low temperature it will let the fluid flow through the orifice without hindrance and at high temperature it closes part of orifice's opening, so that the fluid flows through the orifice with significant amount of resistance. Although, the viscosity of fluid decreases, consequently the cross sectional area of orifice also decreases and the damping constant will improve. The application of this device has been experimentally and analytically studied. The study included component testing over a range of temperature, modeling of the orifice flow of absorber's fluid, analytical prediction of response and development of simplified analysis procedures. Experimental results demonstrate a significant improvement of damping constant due to the reduction of volume flow rate through the orifice at high temperature.
|
