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Journal of Theoretical
and Applied Mechanics
6, 1, pp. 3-31, Warsaw 1968
and Applied Mechanics
6, 1, pp. 3-31, Warsaw 1968
Wpływ historii obciążenia na powierzchnię plastyczności (część druga)
Przejście ciała ze stanu sprężystego w plastyczny w przypadku obciążenia go złożonym stanem naprężenia można opisać pewnym związkiem pomiędzy naprężeniami, nazywanym warunkiem plastyczności. W rozdziale pierwszym omówione zostały dwa najbardziej rozpowszechnione warunki plastyczności, tj. warunek stałego największego naprężenia stycznego i warunek stałej intensywności naprężeń stycznych. Z przytoczonego przeglądu prac doświadczalnych wynika, że tylko nieliczne eksperymenty potwierdzają koncepcję izotropowego rozszerzania się powierzchni plastyczności pod wpływem wstępnych odkształceń plastycznych.
ON THE EFFECT OF THE PRESTRAINING HISTORY ON THE YIELD SURFACE. PART II
Experimental results for tubular specimens of a M 63 brass, subjected to combined biaxial tension are presented in the study of the effect of the prestraining history on the shape of the yield surface. Each of the two groups of specimens has been prestrained in a different manner. In the first group all the specimens were prestrained by the axial tensile force until certain constant stress beyond the initial yield locus. Then after unloading, they were loaded by internal pressure until certain stress, different for each of three subgroups. Specimens belonging to the second group were loaded only by the internal pressure until the same stress levels as the specimens of the first group. For each particular case of prestraining history, yield surfaces for various definitions of the yield locus corresponding to different values of plastic deformations have been found. Comparing the respective yield surfaces obtained for both prestraining paths, the effect of the “memory” of the material has been analysed. The experimental results show that if the prestraining by internal pressure is sufficiently large, the material does not “remember” the initial prestraining by axial force, and its behavior is the same as the behaviour of the material prestrained by internal pressure only. Presented is also a review of the experimental papers concerning the investigation of the yield surfaces.
ON THE EFFECT OF THE PRESTRAINING HISTORY ON THE YIELD SURFACE. PART II
Experimental results for tubular specimens of a M 63 brass, subjected to combined biaxial tension are presented in the study of the effect of the prestraining history on the shape of the yield surface. Each of the two groups of specimens has been prestrained in a different manner. In the first group all the specimens were prestrained by the axial tensile force until certain constant stress beyond the initial yield locus. Then after unloading, they were loaded by internal pressure until certain stress, different for each of three subgroups. Specimens belonging to the second group were loaded only by the internal pressure until the same stress levels as the specimens of the first group. For each particular case of prestraining history, yield surfaces for various definitions of the yield locus corresponding to different values of plastic deformations have been found. Comparing the respective yield surfaces obtained for both prestraining paths, the effect of the “memory” of the material has been analysed. The experimental results show that if the prestraining by internal pressure is sufficiently large, the material does not “remember” the initial prestraining by axial force, and its behavior is the same as the behaviour of the material prestrained by internal pressure only. Presented is also a review of the experimental papers concerning the investigation of the yield surfaces.