Nonmonotonic Elastoplastic Deformation Under Simple Loading

The phenomenon of nonmonotonic deformation and change in the deformation sign of individual material fibers under simple loading has been established. It is shown that if the deviator and layer components of the deformation of material fiber are close in absolute value and have different signs, then the deformation of these fibers is nonmonotonic. Using the example of tension of solid specimens of steel, anisotropic aluminum alloy, and gray cast iron and compression of solid gray cast iron specimens, nonmonotonic deformation beyond the plastic limit of material fibers oriented at different angles to the specimen axis is demonstrated. The tensile experiment has been carried out on solid cylindrical Kh18N10T steel specimens. Comparison of the experimental result with the calculation based on the transverse and longitudinal strain data shows their good agreement. The studies have demonstrated the possibility of using the effects of sign change and nonmonotonic deformation of individual material fibers to monitor the state of plasticity in the body element. Using the proposed method of monitoring the state of plasticity of material allows to record this state only by changing the deformation sign of individual material fibers or the sign of its increase.