超音波減衰による鋼材の疲れ機構の研究

概要

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Ultrasonic attenuation in steel bars was measured after various numbers of repeated tensile loading. The result was that the attenuation decreased rapidly at first, then increased gradually, until finally dropped abruptly before failure. As the cause of the attenuation, a model was considered to represent the energy loss of the wave motion due to Coulomb friction between particles of different elastic modulus. Assuming a proper distribution of the element of Coulomb friction within the material, the attenuation is found to behave in the same manner as the one due to viscous friction for a set frequency. The change of attenuation with the number of repetition of loading is attributed to the disorientation of the crystals at an early stage and the increase of the number of microcracks later. The investigation suggests the possibi1ity of detecting the degree of fatigue in materials by measuring the change of ultrasonic attenuation with the load repetition.
社団法人日本機械学会の論文
1958-03-25