Magnetorheological fluid

About: Magnetorheological fluid is a research topic. Over the lifetime, 8538 publications have been published within this topic receiving 131502 citations. The topic is also known as: MRF & MR fluid.

Performance evaluation and comparison of magnetorheological elastomer absorbers working in shear and squeeze modes

Abstract: The adaptive tuned vibration absorbers based on magnetorheological elastomers are mainly developed in shear and squeeze working modes. The distinctions between the two kinds of magnetorheological e...

Principle and validation of modified hysteretic models for magnetorheological dampers

Abstract: Magnetorheological (MR) dampers, semi-active actuators for vibration and shock control systems, have attracted increasing attention during the past two decades. However, it is difficult to establish a precise mathematical model for the MR dampers and their control systems due to their intrinsic strong nonlinear hysteretic behavior. A phenomenological model based on the Bouc–Wen model can be used to effectively describe the nonlinear hysteretic behavior of the MR dampers, but the structure of the phenomenological model is complex and the Bouc–Wen model is functionally redundant. In this paper, based on the phenomenological model, (1) a normalized phenomenological model is derived through incorporating a 'normalization' concept, and (2) a restructured model, also incorporating the 'normalization' concept, is proposed and realized. In order to demonstrate this, a multi-islands genetic algorithm (GA) is employed to identify the parameters of the restructured model, the normalized phenomenological model, and the phenomenological model. The performance of the three models for describing and predicting the damping force characteristics of the MR dampers are compared and analyzed using the identified parameters. The research results indicate that, as compared with the phenomenological model and the normalized phenomenological model, (1) the restructured model can not only effectively decrease the number of the model parameters and reduce the complexity of the model, but can also describe the nonlinear hysteretic behavior of MR dampers more accurately, and (2) the meanings of several model parameters of the restructured model are clearer and the initial ranges of the model parameters are more explicit, which is of significance for parameter identification.

A phenomenological dynamic model of a magnetorheological damper using a neuro-fuzzy system

Abstract: A magnetorheological (MR) damper is a promising appliance for semi-active suspension systems, due to its capability of damping undesired movement using an adequate control strategy. This research has been carried out a phenomenological dynamic model of two MR dampers using an adaptive-network-based fuzzy inference system (ANFIS) approach. Two kinds of Lord Corporation MR damper (a long stroke damper and a short stroke damper) were used in experiments, and then modeled using the experimental results. In addition, an investigation of the influence of the membership function selection on predicting the behavior of the MR damper and obtaining a mathematical model was conducted to realize the relationship between input current, displacement, and velocity as the inputs and force as output. The results demonstrate that the proposed models for both short stroke and long stroke MR dampers have successfully predicted the behavior of the MR damper with adequate accuracy, and an equation is presented to precisely describe the behavior of each MR damper.

Closure lockdown assemblies and methods utilizing active materials

Abstract: In combination with a vehicle and a closure, one or more lockdown regions disposed between the closure and the vehicle body, the one or more lockdown includes a device including an active material disposed in operative communication with the closure and the vehicle body, wherein the active material includes a shape memory alloy, a magnetic shape memory material, a shape memory polymer, a magnetorheological fluid, an electroactive polymer, a magnetorheological elastomer, an electrorheological fluid, a piezoelectric material, or combinations comprising at least one of the foregoing active materials; and an activation device coupled to the active material, the activation device being operable to selectively provide an activation signal to the active material and effectuate a change in a dimension, a shape, and/or a flexural modulus property of the active material, wherein the change in the dimension, a shape, and/or flexural modulus of the active material locks down or releases the closure from the vehicle. Such active materials include shape memory alloys, magnetic shape memory alloys, electroactive polymers, shape memory polymers, magnetorheological fluids, magnetorheological elastomers, electrorheological fluids, and piezoelectric materials. Also provided herein are methods for selectively stiffening a closure hingeably attached to a vehicle body.