Fatigue Tests on Small-Sized Springs : Development of Small-Sized Spring Fatigue Testing Machine and Some Experiments of Electrical Apparatus Springs

Abstract

In presenting this article, it is our desire to describe the development of a fatigue testing machine for bent wire springs and shaped flat springs in sizes ranging from 0.1 mm to 1 mm diameter or thickness, and some consideration on the repeated bending fatigue strength of corrosion resistant spring materials ; nickel silver, phosphor bronze, and 18-8 stainless steel. The results indicate that when a cantilever spring is vibrated by applying force to it at the point 74.5% of the whole length from the fixed end, the effect of circular frequency of excitation in the fatigue tests is the smallest. The fatigue strength of an 18-8 stainless steel spring is notably increased as the section size of the spring is decreased, but in the case of nickel silver, the size effect on the fatigue strength is small.