The present paper describes a new method for tooth contact analysis in plunge cut shaving process. A computer simulation program has been developed to reduce trial-and-error pro-cesses that are required to improve of a shaved gear tooth forms. In the simulation, stock removals of shaved gear tooth flanks are evaluated from depth of cut of cutting edge. The depths of cut are calculated at all of referred points on the cal-culating tooth flanks. In order to shorten a calculation time, the depth of cut was calculated only for positions near geo-metrical contact area. As a result, the calculation time is remarkably reduced.

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In the present study, a computer simulation program for hot forging process of gears has been developed using the finite element method. For this purpose, a constitutive equation and a finite element model must be contrived. The present paper describes a constitutive equa-tion which enables visco-plasticity to be considered. The constitutive equation can reproduce a stress-strain relationship in torsion of a bar.

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The interactions of hydronium and water with nafion(R) membrane are relevant in proton transfer process in nafion(R), a fuel cell electrolyte membrane. To investigate such crucial actions, molecular dynamic simulations were studied in this work using a model consisting of nafion(R) side chains cluster with water molecules and hydronium ions comparing with dry system. After simulations, the trajectories were analyzed in term of intermolecular distances, potential energy, and radial distribution function. In addition, quantum calculations were investigated to clarify the role of hydronium ions and water in proton transfer manner.

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Considerable effort is spent in the design and testing of disk brakes of modern passenger cars. This effort can be reduced if refined mathematical-mechanical models are used for studying the dynamics of these brakes before prototypes are available. Brake squeal is a self-excited vibration resulting from the transfer of rotational energy to vibrating energy of brake components. Dynamic instability arising from the friction force is agreed to be the reason behind brake squeal. Intensive researches on low frequency squeal (noise between 1-5 kHz) have been carried out by the authors and the present paper is devoted to the modeling of the floating caliper disk brake and the suppression of brake squeal using active control. The model includes the brake disk, housing, piston, yoke and brake pads. The floating nature of the caliper has also been taken into account. In a test rig built in TU Darmstadt, the model of the floating caliper disk brake is validated. In addition, the set-up also permits active control by introducing "smart pads". Those brake pads, which include piezoceramic actuators, are successfully used for the suppression of squeal. The authors believe that the "smart pads" can be used as a powerful tool with a high potential for the rapid prototyping of quiet brakes.

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