Rotary actuator control based on tensile force elements made of shape memory Cu-Al-Ni crystals when operated in a cyclic modeA.I. Priadko, S.A. Pulnev, O.O. Kovalev & I.A. Ilin
An actuator design and a function scheme are developed. A control algorithm of a cyclic actuator is considered. We provide experimental results on the control algorithm and the actuator. The actuator operating range is 60°. The actuator sped is ~ 1 degree/second. The actuator operating is stable in any rotation angle in operating range.
Processes of heating and destruction of the breast fat tissue under the action of focused high-intensity ultrasound generated by a 128-element transducer are considered. The simulation of a thermal problem is carried out by anumerical solution of the heat transfer equation. The acoustic pressure field in the tissue is calculated using the Rayleigh integral. A system of dimensionless scaling parameters is proposed to describe the non-stationary process of heat propagation. The influenceof the space localization...
Non-destructive testing of the strength of structural materials is currently based on the correlation between the results of laboratory tests of the strength of standard macro samples and the strength characteristics of the material in a real object. The heterogeneity of the strength properties of different zones of the material makes this correlation ambiguous, introducing uncertainty in the test results. The solution of the problem relates to the necessity of transition to the micro- and...
Axial misfit stress relaxation in core-shell nanowires with hexagonal core via nucleation of rectangular prismatic dislocation loopsS.A. Krasnitckii, A.M. Smirnov, K.D. Mynbaev, L.V. Zhigilei & M.Yu. Gutkin
A theoretical model of axial misfit stress relaxation in core-shell nanowires with hexagonal cross section of the core through the nucleation of prismatic dislocation loops is suggested. Different nucleation sites of the loops in core-shell nanowires are considered. The energy change caused by the loop nucleation is calculated. The critical condition for the onset of the loops is given and analyzed in detail. The most favorable sites in nanowires and the optimal loop shape are...
An asymptotic representation is obtained at large times for the thermal wavefront propagating in a one-dimensional harmonic crystal. The propagation of thermal waves from a localized thermal perturbation and the transition zone between regions with different temperatures is considered. An explicit solution is given for a number of the simplest forms of the initial temperature distribution. It is shown that during the wave evolution, the wavefront smoothes, e.g., for a power-law dependence its degree increases...
Surface growth of solids includes a wide variety of processes starting from additive manufacturing technologies and ending with plenty of biological problems. Model of surface growth based on the expression of the configurational force, derived from fundamental laws and entropy inequality, is offered in the present paper. A new expression for the configurational force called surface growth force, which controls growth and resorption, is used. Analysis of the applicability of the developed model was carried...
Investigation and modeling the austenitization kinetics of steels with complex microstructure under continuous heatingA.A. Vasilyev, D.F. Sokolov, S.F. Sokolov & A.I. Rudskoy
An experimental investigation of the austenitization under continuous heating of various microstructures of 8 industrial steel grades with wide range of chemical compositions was carried out. A quantitative mathematical model describing the austenitization kinetics of the steels with complex microstructure and predicting austenite grain size in dependence on the chemical composition, volume fractions of structural components (ferrite, pearlite, bainite, martensite), ferrite grain size and heating rate, was developed. Values of the model empirical parameters were...
Employment of Eulerian, Lagrangian, and arbitrary Lagrangian-Eulerian description for crack opening problemE.A. Ivanova, D.V. Matyas & M.D. Stepanov
Numerical study of crack opening in the solid material of rock formation is presentedin this article. Initially introduced straight-line crack is widened by increasing internal pressure. The crack shape evolution resembles hydraulic fracturing and is considered as a transient process. Commercial code LS-DYNA was employed to obtain solutions by three types of descriptions, they are compared to the solution obtained in Eulerian description by a program based on the finite-volume method and written in Python...
Combined effect of boron alloying and ausforming on austenite transformation in low carbon steels under continuous coolingA.A. Vasilyev, D.F. Sokolov, S.F. Sokolov, A.A. Zisman & N.G. Kolbasnikov
The combined effect of boron addition and ausforming on the structure of low carbon low alloyed steel after the transformation of austenite has been investigated in a wide range of cooling rates. It is shown that boron hinders formation of polygonal ferrite in continuous cooling regardless of austenite predeformation and suppresses appearance of acicular ferrite. A qualitative explanation of this effect is proposed in terms of the deformation induced boron segregation on boundaries of austenite...
This paper deals with the issue of fatigue failure of materials. The process of generation of fatigue properties for the steel 08PS is described and obtained in the laboratory. The technique of conducting virtual tests for cyclic durability for vehicles is proposed. Virtual tests for cyclic durability by using the finite element method on the example of an off-road car body are performed.
Peter the Great St. Petersburg Polytechnic University10
Institute of Problems of Mechanical Engineering4
University of Virginia1
Saint Petersburg Mining University1
Saint Petersburg State University1
The Turner Scientific Research Institute for Children's Orthopedics1