A design methodology based on full dynamic model for magnetorheological energy absorber equipped with disc springs

The spring of magnetorheological energy absorber (MREA) is an indispensable component that provides a restoring force for the piston back to the initial position. To reduce impact force, the stroke of a typical MREA is usually sacrificed (i.e., extended stroke and prolonged buffer time). In some situations, however, a fast return of piston is required and the impact load is huge. It is difficult for conventional coil/gas springs to qualify due to the limitations in obtaining high stiffness. In this study, we employ the disc spring as a rebound element for MREA because of its feature in providing large force within narrow deformation. Optimal designs are significant for improving the MREA performance, but most of them have been developed based on the quasi-static model that ignores inertia effect. However, the inertia effect becomes an important role in dynamic behavior under high-speed impacts. Most recently, we proposed a full dynamic model considering inertia effect by using the non-averaged acceleration. As a further step, this study presents a design methodology based on this full dynamic model for an MREA with disc spring. The design objective is to identify the geometric dimensions of disc spring and MR valve to return the piston back to its initial position as fast as possible after a fast impact loading. The design flowcharts for disc spring and MR valve are presented. The load-deflection relationship of disc spring is obtained based on Almen-Laszlo theory. The magnetic field intensity in the MR gap is analyzed by using Kirchhoff's law and the magnetic flux conversation rule. Two identical MREAs are fabricated and tested via a high-speed drop tower system. The effectiveness of the design methodology is validated by a comparison of MREA behaviors between the tests and full dynamic modeling.