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Abstract <p>The process of cyclic elastoplastic loading is noted to be characterized by a deformation diagram in stress–strain coordinates. The appearance of this diagram generally depends on the level of acting stresses and strains, the loading mode and conditions, and the type of structural material. One of the fundamental problems in deformation and fracture mechanics, the solution of which makes it possible to formulate basic equations describing the conditions for reaching limit states based on damage accumulation criteria, is the establishment of patterns in the kinetics of deformations during cyclic elastoplastic deformation, which directly form the basic parameters of the deformation criteria for low-cycle fracture. Based on the results of the experimental studies, it has been shown that, in the presence of exposure cycles at load extremes and the imposition of variable stresses on these exposures, in comparison with regular cyclic loading with equal stress amplitudes, additional deformations occur due to the development of creep processes. These deformations largely determine the increase in the range of cyclic plastic deformation in each loading cycle and also stimulate an increase in the range of elastoplastic deformation from active cyclic deformation. Furthermore, the presence of exposures at stress extremes without the imposition of additional alternating stresses has the greatest impact on the increase in plastic strain amplitudes during cycles. The imposition of additional alternating stresses during exposures also increases creep strain values, but this is more pronounced under lower-frequency loads than under dynamic application. The increase in cyclic plastic deformation during cycles with exposure periods and the imposition of additional alternating stresses during their course causes a reduction in low-cycle fatigue life compared to regular loading without exposure periods, with equal stress amplitudes, and, to a greater extent, the higher the strain values from static and dynamic creep. The increase in the range of cyclic plastic deformation due to the progression of additional plastic creep deformation during the exposure time according to the strain-kinetic criterion increases the damageability of the material during cyclic elastoplastic deformation, which causes a decrease in cyclic durability.</p>

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Evolution of Strains and Damages at Cyclic Elastoplastic Deformation with Exposures and Imposition of Additional Load Pulsations on Them

  • 期刊论文

  • 发表日期：

    2025年1月1日

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  • M. M. Gadenin

摘要

Abstract

The process of cyclic elastoplastic loading is noted to be characterized by a deformation diagram in stress–strain coordinates. The appearance of this diagram generally depends on the level of acting stresses and strains, the loading mode and conditions, and the type of structural material. One of the fundamental problems in deformation and fracture mechanics, the solution of which makes it possible to formulate basic equations describing the conditions for reaching limit states based on damage accumulation criteria, is the establishment of patterns in the kinetics of deformations during cyclic elastoplastic deformation, which directly form the basic parameters of the deformation criteria for low-cycle fracture. Based on the results of the experimental studies, it has been shown that, in the presence of exposure cycles at load extremes and the imposition of variable stresses on these exposures, in comparison with regular cyclic loading with equal stress amplitudes, additional deformations occur due to the development of creep processes. These deformations largely determine the increase in the range of cyclic plastic deformation in each loading cycle and also stimulate an increase in the range of elastoplastic deformation from active cyclic deformation. Furthermore, the presence of exposures at stress extremes without the imposition of additional alternating stresses has the greatest impact on the increase in plastic strain amplitudes during cycles. The imposition of additional alternating stresses during exposures also increases creep strain values, but this is more pronounced under lower-frequency loads than under dynamic application. The increase in cyclic plastic deformation during cycles with exposure periods and the imposition of additional alternating stresses during their course causes a reduction in low-cycle fatigue life compared to regular loading without exposure periods, with equal stress amplitudes, and, to a greater extent, the higher the strain values from static and dynamic creep. The increase in the range of cyclic plastic deformation due to the progression of additional plastic creep deformation during the exposure time according to the strain-kinetic criterion increases the damageability of the material during cyclic elastoplastic deformation, which causes a decrease in cyclic durability.