有限要素法によるばねの疲労き裂発生開始点の推定

抄録

Due to the need of increasing fuel efficiency, the weight of springs and many other components in automobiles need to decrease their weight. The weight reduction can be achieved by increasing the strength of material, however, it may cause the problems of reduced workability, toughness and durability. Even increasing the material strength, enhancing their fatigue properties will expand the service life of them, i.e., delaying the initiation of cracks. A crack initiation is caused by the accumulation of dislocations, which is resulted by yielding on the surface due to repeated loading. Finite element analysis was recently available to apply the stress distribution analysis of a complicated shape, e.g., a helical coil spring subjected to compression loading. In this research an attempt was made to presume the point of the fatigue fracture initiation in coil springs according to the distribution of Mises stress, that is the crucial index of yielding phenomenon. The point inside and surface of a coil spring wire at which the Mises stress has its maximum value is the same place as a crack nucleation during fatigue progress according to referring experimental papers.