Douglas E. Ivers

Improving vehicle performance and operator ergonomics: Commercial application of smart materials and systems

This article will discuss how controllable material technology, such as the use of active magnetorheological dampers, improves primary and secondary suspensions of vehicle. Although relatively new to the marketplace, semiactive suspensions in commercial automobiles and off-highway vehicles have been proven through the use of active magnetorheological dampers since 1998. In fact, magnetorheological suspension dampers are found today on the commercial vehicles of an increasing number of automotive original equipment manufacturers and leading off-highway original equipment manufacturers. Magnetorheological fluid dampers are simple in design and have the advantage of no moving parts. The resistive force from a magnetorheological damper is generated as iron particles, suspended in the magnetorheological fluid, pass through a magnetic field controlled by the electrical current passing through an electric coil contained within a moving piston surrounded by the fluid. By adjusting the current to the damper coil in response to feedback from vehicle sensors and a controller, the damping response of the suspension can be optimized and controlled in real time to provide optimal operator comfort. The magnetorheological damper system has a full-scale step response of less than 10 ms. Sophisticated control algorithms adapt to large changes in payload, enabling the vehicle to meet ride metrics without pneumatic load leveling. Other benefits of the magnetorheological damping system include higher speed in North Atlantic Treaty Organization double-lane change tests, reduced risk of rollover, improved accuracy of mounted weapons, and improved vehicle durability and readiness.

Whirling-Beam Self-Tuning Vibration Absorber

A classic tuned vibration absorber (TVA) is a device that, when attached to a structure, will greatly reduce the motion of the attachment at a specific excitation frequency. When a fixed frequency input is present, a TVA can be manufactured for the specific frequency input. When the input frequency changes during the course of operation, then an active adaptive TVA can be used where sensors, signal conditioning, and power are provided so that the tuned frequency can be varied over some range. A self-tuning vibration absorber (STVA) is a device that uses energy from the vibrating structure to produce some physical motion that changes the tuned frequency of the device. Through proper design, the tuned frequency will change in the appropriate direction and then stop changing when the tuned frequency matches the input frequency. This paper addresses the physics of one realization of a STVA and shows both analytical and experimental results.

Improving Vehicle Performance and Operator Ergonomics: Commercial Application of Smart Materials and Systems

This paper will discuss how controllable material technology, such as the use of active magneto-rheological (MR) dampers, improves vehicle primary and secondary suspensions. Although relatively new to the marketplace, semi-active suspensions in commercial automobiles and off-highway vehicles have been proven through the use of active MR dampers since 1998. In fact, MR suspension dampers are found today on the commercial vehicles of an increasing number of automotive OEMs and leading off-highway OEMs. MR fluid dampers are simple in design and have the advantage of no moving parts. The resistive force from an MR damper is generated as iron particles, suspended in the magneto-rheological fluid (MR fluid); pass through a magnetic field controlled by the electrical current passing through an electric coil contained within a moving piston surrounded by fluid. By adjusting the current to the damper coil in response to feedback from vehicle sensors and a controller, the damping response of the suspension can be optimized and controlled in real time to provide optimal operator comfort. The MR Damper System has a full-scale step response of less than 10 milliseconds. Sophisticated control algorithms adapt to large changes in payload, enabling the vehicle to meet ride metrics without pneumatic load leveling. Other benefits of the MR damping system include higher speed in NATO double-lane change tests, reduced risk of roll-over, improved accuracy of mounted weapons, and improved vehicle durability and readiness.Copyright