The techniques of modeling of continual fracture process for spatial bodies under long-term static force loading condition in non-homogenous temperature field are presented. The scalar damage parameter is used to describe the material continual fracture process. A stress-strain problem solution made with semianalytic finite element method SFEMSFEM. Results of lifetime determination of responsible parts are presented.

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Finite Element Analysis of Influence of Non-homogenous Temperature Field on Designed Lifetime of Spatial Structural Elements under Creep Conditions

High-rate Deformation and Spall Fracture of Some Metals

A mathematical model describing the unsteady creep of metals under complex loading is proposed. The results of numerical simulation of creep of St.304 steel in complex regimes of block multiaxial cyclic deformation are given. The numerical calculation results obtained are compared with the data of full-scale experiments. Creep is simulated in complex deformation processes accompanied by the rotation of main regions of stress, strain, and creep strain tensors.

State Equations of Unsteady Creep under Complex Loading

Numerical modeling of elastic-plastic compression along the normal of two symmetric fragments of a package of woven steel grid is carried out. The dynamic loading mode was carried out in the ANSYS LS-DYNA computer system. A porous grid stack is formed by overlapping layers while maintaining wire directions. The packet has a quasi-periodic structure and a symmetric fragment can be distinguished. One grid layer and two grid layers were simulated, when the second layer is shifted by half the periodicity cell. Compression was carried out by a pair of absolutely rigid plates moving symmetrically towards each other. The calculations used a plasticity model with isotropic hardening. In the calculation, two diagrams of material deformation were used: dynamic and static, obtained by increasing the yield stress. With an increase in the yield point of the material, the deformation curves of the fragment change qualitatively, as in the experiments. The final duration of the loading pulse and the friction between the wires for this type of grid do not have a significant effect. The material in the dynamic mode has time to irreversibly deform during the action of the loading pulse. A comparison of the results obtained with the experimental curve obtained under dynamic compression is shown.

Numerical study of elastoplastic dynamic compression of metal braided grid

A Study of the Deformation of a Low-Density Aluminum–Lithium Alloy under Impact Compression and Localized Shear

A mathematical model is developed within the framework of equations of damaged medium mechanics to describe the processes of viscoplastic straining and damage accumulation in structural steels with allowance for fatigue and creep of the material. A model of damage summation due to interaction of low-cycle fatigue and creep of the material is proposed. Material parameters and scalar functions of equations of mechanics of damaged media are determined. Viscoplastic straining and fatigue-induced damage accumulation in 08Kh18N10T and 12Kh18N9 are studied numerically, and the data obtained are compared with available results of physical experiments.

Assessment of the service life of structural steels by using degradation models with allowance for fatigue and creep of the material

Results of an experimental study of the behavior of St.3, 20Kh13, and 08Kh18N10T steels under static and dynamic loading are reported. The influence of the strain rate and temperature on characteristics of strength and plasticity is studied. Based on the data obtained, the parameters of the Johnson–Cook model are determined. This model is used in commercial software to describe the yield surface radius as a function of loading parameters. The adequacy of the identified model is verified in a series of special test experiments.

F. M. Mitenkov

Papers

Assessment of the service life of structural steels by using degradation models with allowance for fatigue and creep of the material

Experimental study and mathematical modeling of the behavior of St.3, 20Kh13, and 08Kh18N10T steels in wide ranges of strain rates and temperatures