Effect of one- And two-stage shear cutting on the fatigue strength of truck frame parts

The longitudinal and transverse beams of trucks are manufactured with a large number of holes to fasten brackets for springs, fuel tanks, batteries etc. The quality of the holes, which is particularly influenced by the manufacturing process, has a major influence on the fatigue strength of the beams and thus the service lifetime of the vehicle. In most cases, the holes are produced using the highly economical shear cutting process. Previous investigations have shown that the fatigue strength of thin sheets can be increased by adjusting the shearing parameters and using a two-stage shear cutting process. This paper discusses the difference between one- and two-stage shear cutting on the hole quality of components made of S500MC (1.0984, thickness 8mm) and its resulting fatigue strength. The hole quality is characterized by the geometry of the shear cut surface, its roughness, microstructure, and microhardness. It was shown that the two-stage shear cutting process allows producing holes of better quality than the ones manufactured by a one-stage shear cutting process. Furthermore, this resulted in an improved fatigue behavior.