Components that deform and change their shape substantially can fold and have different parts of the surface come into contact with each other. In such cases it can be difficult to predict at the outset of the analysis where such contact may occur and, therefore, it can be difficult to define two independent surfaces to make up a contact pair.
A jounce bumper, sometimes referred to as a “helper spring,” is a highly compressible component that is used as part of the shock isolation system in a vehicle. It is typically located above the coil spring that connects the wheels to the frame. Microcellular material is used because of its high compressibility and low Poisson's ratio value at all but fully compressed configurations.
The bumper initially sits against a fixed flat rigid surface on one end; on the other end, another flat rigid surface is used to model the compression of the bumper. The geometry of the bumper is such that it folds in three different locations. Separate surfaces are defined at the locations where self-contact is expected. This modeling technique produces an economical analysis because the scope of contact searches is limited.
Fuel cells constitute one of the most promising sources of environmental friendly energy for the future. These systems produce electrical energy by converting the chemical energy stored in a fuel, such as hydrogen or methanol, through oxidation-reduction reactions. A proton exchange membrane (PEM) fuel cell is a stack of electrochemical cell systems (Figure) placed in series. Since the electrons must transit from the anode of one cell to the cathode of the next cell, electrical conductivity through the plate is a main requirement. Another important requirement is the low permeability to the reacting gases or to ions. The bipolar plates should remain chemically inert for an extended period of time. The bipolar plates also should be lightweight and easily manufactured using mass-production technologies. Cost reduction is the most critical issue for automotive industry to achieve the practical use of proton exchange mem…