rotating bending
Circular bending is the loading of a component - usually rod-shaped, in particular metallic - component perpendicular to the longitudinal axis thereof by a bending force, the active direction of which circumscribes the component radially, so that it undergoes a circumferential elastic deformation. In practice, the kinematic behavior is usually reversed: the component, for example a shaft with a circular or circular ring-shaped cross section, rotates about its longitudinal axis, while the bending force remains unchanged from the viewpoint of an external observer. The result, namely a circumferential elastic deformation of the shaft, is, of course, the same in both variants.
In a first construction, the bending force can act on the free end of a rotating shaft which is mounted on one side and cantilever-like. According to the second, in practice much more frequent construction, the rotating shaft will be supported at two points at a suitable axial distance and be flexed between the two bearing locations. Edit sample source text
A wheel axle which is rigidly connected at its two ends with two towing wheels bends around elastically under the carriage load carried by it (via a bearing) between the wheels
The circumferential bending is therefore an alternating stress on the shaft material. In this case, the risk of fracture depends both on the magnitude of the bending force and on the number of bending stresses (load play) of the shaft which are continuously successive as a result of the shaft revolutions. The higher the bending force and / or the more load-bearing play takes place, the greater the probability of premature breaking of the shaft.
The dependence of the fracture behavior on the bending stress (and the voltage generated in the material) on the one hand and the load index (wave revolutions) on the other can be graphically represented and illustrated by a Wöhler curve. In this case, the higher the voltage produced by the bending force in the shaft material, the smaller the first load (left) curve load (the so-called time strength). With a decreasing load (voltage), the winding curve finally passes approximately tangentially into a second curve branch, which adjoins the right, and has a rectilinear horizontal path. This rectilinear horizontal curve branch is termed a fatigue strength. In this comparatively low stress or stress range, load numbers (wave revolutions) of many millions are possible before breaking the shaft.
Circular bending can cause the occurrence of vibration cracking corrosion when the bending load and the high bending frequency (corrugation speed) are correspondingly high in conjunction with a corrosion medium. This leads to (further) reductions in the breaking stress and the breaking load. Edit source text Edit source text
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