Roumen Iankov

Finite element simulation of profile rolling of wire

Abstract The profile rolling or wire is investigated by means of a finite element model. Three-dimensional simulation of wire rolling process with a round cross-section of wire by two cylindrical rolls is considered. The same example is simulated by a 2D generalised plane strain finite element model. The results for lateral spread from those two models are compared with the experimental one. The results for more complicated shape of rolls for three passes rolling are shown.

Sharp Bounds for Strains and Stresses in Uncertain Mechanical Models

Many mechanical systems, involving interval uncertainties and modelled by finite element method, can be described by parameter dependent systems of linear interval equations and response quantities depending on the system solution. A newly developed hybrid interval approach for solving parametric interval linear systems is applied to a 2D engineering model with interval parameters and the results are compared to other interval methods. A new technique providing very sharp bounds for the response quantities, such as element strains and stresses, is developed. The sources for overestimation when dealing with interval computations are demonstrated on a numerical plain strain example.

Finite Element Simulation of Nanoindentation Process

Recently, nanoindentation technique is gaining importance in determination of the mechanical parameters of thin films and coatings. Most commonly, the instrumented indentation data are used to obtain two material characteristics of bulk materials: indentation modulus and indentation hardness. In this paper the authors discuss the possibility by means of numerical simulations of nanoindentation tests to obtained the force-displacement curve employing various constitutive models for both the substrate and the coating. Examples are given to demonstrate the influence of some features of the numerical model and the model assumptions on the quality of the simulation results. The main steps in creation of the numerical model and performing the numerical simulation of nanoindentation testing process are systematically studied and explained and the conclusions are drawn.

Finite Element Simulation of Residual Stresses in Thermo-coupled Wire Drawing Process

The objective of this paper is to calculate residual stress in drawn wire taking into account induced temperature due to plastic dissipation energy. Finite element analysis (FEA) for the simulation of wire drawing is applied. The general purpose FEA code MARC, is used to analyse thermo-coupled wire drawing processes. The necessary condition for determination of range of steady state flow was proposed.