Stress-strain state of a half-space in the neighborhood of a stiff sphere subjected to a normal load

Institute of Mechanics, Academy of Sciences of the Ukrainian SSR, Kiev. Institute of Ultrahard Materials, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Prikladnaya Mekhanika, Vol. 24, No. 4, pp. 19–25, April, 1988.     

Thermomechanical dynamic behavior of a disk subject to an impulsive thermal load at the center

The dynamic coupled thermoelastic problem formulation and the thermodynamically consistent theory of inelastic behavior of materials are used to solve an axisymmetric problem for a steel disk subject to a heat pulse at the center. The temperature dependence of the physical and mechanical properties of the disk is taken into account. The problem is solved by the FEM. The evolution in time and features of the strain-stress and thermal states of the disk and the dynamic effects accompanying the processes of heating and gradual cooling are studied __________ Translated from Prikladnaya Mekhanika, Vol. 44, No. 5, pp. 45–57, May 2008.     

The Complex-Moduli Solution of an Axisymmetric Dynamic Problem of Coupled Thermoviscoplasticity Under Harmonic Loading

An approximate formulation is given to the axisymmetric dynamic thermoviscoplastic problem with coupled mechanical and thermal fields. The formulation employs an approximate cyclic thermoviscoplastic model based on the concept of complex moduli. The distribution of the field quantities and the temperature— and amplitude—frequency resonant characteristics of a circular disk under forced flexural vibrations are studied. The capabilities of the approximate model in solving this class of problems are also studied     

Concentration of stresses and strains in a notched cyclinder of a viscoplastic material under harmonic loading

Certain aspects of the correct definitions of stress and strain concentration factors for elastic-viscoplastic solids under cyclic loading are discussed. Problems concerning the harmonic kinematic excitation of cylindrical specimens with a lateral V-notch are examined. The behavior of the material of a cylinder is modeled using generalized flow theory. An approximate model based on the concept of complex moduli is used for comparison. Invariant characteristics such as stress and strain intensities and maximum principal stress and strain are chosen as constitutive quantities for concentration-factor definitions. The behavior of time-varying factors is investigated. Concentration factors calculated in terms of the amplitudes of the constitutive quantities are used as representative characteristics over the cycle of vibration. The dependences of the concentration factors on the loads are also studied. The accuracy of Nueber's and Birger's formulas is evaluated. The solution of the problem in the approximate formulation agrees with its solution in the exact formulation. The possibilities of the approximate model for estimating low-cycle fatigue are evaluated. S. P. Timoshenko Institute of Mechanics, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Prikladnaya Mekhanika, Vol. 35, No. 2, pp. 15–22, February, 1999.