文档介绍：外文翻译
FACTORS AFFECTING THE ENDURANCE STRENGTH
Published data for endurance strength are determined by special fatigue testing devices,which typically use a polished specimen subjected to a reversed bending load,similar that sketched in the actual operating conditions of a part in a machine are they usually are,the faigue strength must be reduced from the reported of the factors that decrease the endurance strength are discussed next.
This discussion relates to the endurance strength for materials subjected only to tensile normal stresses,that is,tensile stresses resulting from bending actions or axial involving fluctuating torsional shear stresses are discussed failures are most likely to occur in regions of high tensile stress rather pressive stress.
Size of the section
The test specimen is usually inch ( mm)in section sizes exhibit lower strengths,have a less favorable stress distribution,and have less uniformity of properties,particularly with heat-treated 1 includes a suggested method of determing the size factor for rotating shafts up to inches(250 mm)in diameter. We will use that method here also because we are basing our analysis on the reversed bending shows the suggested relationships for determing a size factor,to be applied to the endurance strength to account for the size of the cross section .Figure shows plots of the equations from Table,with some blending of the curves,Reading from the curves should provide acceptable accuracy.
When ponent being designed is not circular like a shaft,judgment is required to determine the characteristic dimension to use in the flat,rolled shapes,the thickness should be that the use of these equations is approximate.
Surface Finish
Any deviation from a polished surface reduces endurance shows rough estimates for the endurance pared with the ultim