A. Milenin

Identification of material model of TiN using numerical simulation of nanoindentation test

The development of the model of the multistep nanoindentation test with Berkovich indenter, accounting for the residual stress distribution, is one of the aims of the present paper. The specimen is unloaded in the intervals between the deformation steps. Substrate, which is composed of a ferritic steel and biocompatible pulsed laser deposition TiN coating, is considered. The selection of the TiN was inspired by its perspective application as the coating for a constructional element of the heart prosthesis (blood chamber and aortic valves). Sensitivity analysis of the model predictions with respect to its parameters is presented in the present paper. The theory of elastic-plastic deformations is used in the finite element model, which simulates both loading and unloading phases, accounting for the real geometry of the indent. The main goal of the present paper was to inversely analyse the tests for coating/substrate system. Square root error between measured and predicted forces is the objective function in the analysis. Results of the inverse calculations, which are presented in the present paper, may be helpful in simulations of the behaviour of TiN deposited on substrate in various applications as bionanomaterials.

A mathematical model of the formation of the plastic deformation zone in the rolling of rheologically complex metals and alloys

A new mathematical model of the plastic deformation zones in the rolling of rheologically complex metals and alloys has been developed on the basis of the finite-element method. The rheological curves are considered through hydrodynamic approximations. The model can be used for the calculation of the formation of knurling during cogging. The appearance of the knurl and the means of its prevention are modelled. The results of the model are in good agreement with experimental findings.

The Multi-Scale FEM Simulation of Wire Fracture during Drawing of Perlitic Steel

The fracture development during wire drawing operation is an important phenomenon governing the productivity as well as the mechanical properties of the drawn wire. The wire drawing processes was investigated in present paper in two separate levels - using the 2-dimensional rigid-plastic finite element method (macro-level) and modelling the microstructure changes (micro-level) by the Representative Volume Elements (RVEs). To predict fracture initiation the phenomenological theory of fracture is used. The influence of initial cementite lamellas orientation on triaxity factor and localization of deformation in micro-level is investigated. Obtained results are helpful for a fundamental understanding of pearlitic deformation during development of high strength steel wires for tire cord applications.

The FEM Simulation Of Cementite Lamellas Deformation In Pearlitic Colony During Drawing Of High Carbon Steel

In paper the wire drawing processes was investigated in two levels — steady‐state solve using the 2‐dimensional rigid‐plastic finite element method (macro‐level) and modeling of a microstructure change (micro‐level). In macro level the joint deformation‐temperature problem was considered. In micro‐level the process of deformation of representative volume element — RVE was considered. The pearlitic colony deformation and orientation of cementite lamellas change in RVE was modeled with help of a FEM. The micro‐level model to rigid‐plastic finite element code was implemented. The experimental data of microstructure and orientation of cementite lamellas change was compared with results of a simulations. The influence of multi‐pass drawing parameters (as friction, drawing schedule) on orientation of cementite lamellas was investigated.

3D Numerical modeling of thermomechanical processes during continuous casting for shape rolling

Paper deals with problems of crystallization, uprising and development of thermal stresses as well as bending and unbending of workpiece in continues casting machine. To obtain numeric solution the finite element method is used. The problem is solved in three‐dimensional formulation. Constructive features of continues casting machine is taken into account, namely location and parameters of rolls, spray nozzles and crystallization. It is shown an example of casting process for 300×400 mm workpiece of LH15SG steel. The results of dilatometric and plastometric tests as well as results of temperature, strain and stresses modeling during casting process are presented in the paper.

Plastic deformation of metal particles in gas-dynamic spraying

The main stage of the gas-dynamic spraying process is the deformation and heating of particles upon impact with the substrate. A solution of the impact deformation problem by use of the finite element method is given. The model developed enables determination of the extent of particle deformation and the time and temperature of impact as functions of the material and particle properties and the initial velocity and temperature of particles.