Automotive & Transportation

Professor Jim Barber's research focuses mostly on those aspects of solid mechanics pertaining to the contact of deformable bodies and particularly to situations in which non-uniform temperatures result from frictional heat generation at the interface or from heat flow across it. In such cases, thermoelastic deformation of the contacting bodies modifies the contact pressure distribution and can lead to a rich variety of phenomena including localization and dynamic instabilities. These effects are of considerable technological importance, including, for example, non-uniform contact pressure, high local temperatures and vibrations in clutches and braking systems: a phenomenon known as frictionally-excited thermoelastic instability (TEI). The figure on the left shows a transmission clutch plate after a single engagement. The dark areas correspond to regions in which high local temperatures have been experienced. The complete disk in this case exhibits 12 equally spaced hot spots on each side and they are arranged antisymmetrically. In other words, the hot spots on the opposite side of the disk are located in the gaps between those shown in the figure. (James Barber)

Active safety of ground vehicles through advanced sensing, estimation and control techniques (Huei Peng)

Crashworthy and blast-protective structure designs are two of the most challenging tasks in vehicle development programs. The greatest challenge facing both of the automotive industry and US military is providing safer vehicles with high fuel efficiency at minimum cost. Among other new methodologies, a Magic Cube (MQ) approach has been developed at ARC for crashworthy and blast-protective structures designs with a focus on how to systematically and optimally design a structural and material system for improved safety against vehicular crash and explosive assault. The goal is to design an optimum structure in terms of all of topology, shape, and size, for both structural and material layouts. (Zheng-Dong Ma)

Direct-injection lean-burn engines use highly stratified fuel/air mixture and flow conditions at the time of spark ignition to increase efficiency and reduce pollutant formation. Reliable ignition then requires that energy transfer from the spark plasma channel to the fuel be guaranteed even under highly transient mixture and turbulence conditions. High-speed laser imaging diagnostics that was developed at UM enabled studies that revealed the physics and chemistry of unsuccessful engine cycles.

Multi-vehicle systems
Driver behavior has significant effects on emerging multi-vehicle patterns. Analyzing car-following models that incorporate driver reaction time, it can be shown that a single driver can bring vehicular traffic to a halt. When a driver brakes harder than a critical threshold predicted by the theory, he/she creates a ripple that gets amplified as it propagates backward on the chain of vehicles leading to a stop-and-go wave. This nonlinear string instability is responsible for a large fraction of traffic congestion occurring on highways. (Gabor Orosz)