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There are many difficulties in the rollover evaluation test of a vehicle because of the risks such as driver's accident and vehicle damage. Recent developpent of hardware and software of computers has made it possible to analyze the area of difficult tests. Among the dynamic stability of a vehicle, such including lateral stability and roll stability, the roll stability is mainly concerned with the rollover risk of a vehicle. This paper treats the roll stability evaluated by J-turn and bump simulation. The reliability of the model used for computer simulation is first verified by comparing the driving characteristics obtained by simulation with test results. Then, the roll stability of the vehicle with various position of the center of gravity is evaluated.

UNSM technology increases surface hardness, induces a large amount of compressive residual stress in the subsurface, refines the grain size into 50∼200 nm, and modifies the surface into micro dimple structure which reduces the friction coefficient about 50% simultaneously. In order to show the possibility of weight and friction reduction at Hub bearing application, hardness, roughness, residual stress, surface topology, friction coefficient and wear rate are compared before and after UNSM treatment of test specimens. Two type of rolling contact fatigue test and pin-on-disc test are carried out for test specimens. Finally dynamo test of hub bearing assembly is being carried out. Test results show that UNSM technology can reduce the weight and friction loss of hub bearing and is very effective technology for fuel consumption and CO2 emissions of vehicle.