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The fatigue behavior of several steels, AISI 4130, E52100, and 304 ELC stainless, as well as that of a nonferrous alloy, 5456-H311, was investigated in rotating bending fatigue after these materials were subjected to a prestress for different cyclic histories. The data obtained corroborated the hypothesis proposed by the authors that lines representing the S - log N relation of a material prestressed in varying amounts will intersect the S - log N line of the original material near a common point. A correlation was found between the stress at this intersection point and the ultimate tensile strength. Thus, the only requirements for establishing the fatigue behavior of a prestressed material in the range of stresses where the S -log N line is inclined are the S - log N line of the original material and the ultimate tensile strength. The importance of determining the new endurance limit of a material after prestressing was shown analytically.

RESULTS of an investigation to measure the operating temperatures in a disc of a typical gas turbine engine are presented here. These temperature data were used to determine operating stresses and their implications on disc bursting, rim cracking, and inner-region cooling. In turbine blades the major unknowns are reported to be temperatures and vibrational stresses during operation. Results are shown of investigations to measure temperature distributions and vibrational stresses in a typical gas-turbine engine. The temperatures and centrifugal stresses were such as to allow little vibratory stress. Measurements showed that appreciable vibration was present, however, excited mainly by the nozzle vanes and the combustion chambers.