ALDAJAH, S.: Thermal residual stress development in a laser glazed carbon steel 121 ÉCSI, L., ÉLESZTÖS, P.: One of the possible variational formulations of fully coupled thermal-structural analysis 135 KOTAIAH, K. R., SRINIVAS, J., BABU, K. J.: Prediction of optimal stability states in inward-turning operation using genetic algorithms 145 FIALOVÁ, S., POCHYLÝ, F., FEDOR, P.: Gels as construction materials 161 KOTAIAH, K. R., SRINIVAS, J., BABU, K. J.: Force feed effects on stability in turning 169

SAUD ALDAJAH

Laser glazing is a relatively new surface modification technique in which a high-power laser beam is used to melt the top layer of the surface, followed by rapid cooling and resolidification. This results in a new surface layer microstructure with enhanced hardness properties. Due to the melting and rapid solidification of laser glazing process, thermal stresses are developed within the substrate. These stresses are high enough to cause microcracks to develop in the glazed region. This paper introduces an analytical model to determine thermal stresses developed in a laser glazed 1080 steel rectangular sample.

LADISLAV ÉCSI, PAVEL ÉLESZTÖS

In this paper, a possible variational formulation of fully coupled thermal structural analysis is presented. The aim of the formulation is to solve a specific thermal-structural problem with heat convection using the finite element method. In this particular case the applied heat equation may be extended with the conservation of mechanical energy, which results in the complete first principle of thermodynamics to be included in the variational formulation of the problem. Such a constrained formulation automatically ensures the two-way coupling in weak solution of the governing equations, which, if additionally supplemented with thermal dissipation, will result in a more complete formulation of solid body deformation thermodynamics outside the equilibrium. The constraint equation is of great importance as it ensures the two-way coupling normally realised via the Neumann type boundary condition of the Euler-Cauchy equation of motion. In this paper some results in the early stage of the mathematical model development are presented using a cross-shaped specimen in biaxial tension.

KALLURI RAMA KOTAIAH, JONNALAGADDA SRINIVAS, K. J. BABU

This paper proposes a neural network-based optimisation scheme for predicting localized stable cutting states in inward turning operation. A set of cutting experiments is performed in inward orthogonal turning operation. The cutting forces and critical chatter locations are predicted as a function of operating variables including tool-overhanging length. A neural network model is employed to develop the generalized relations. The optimum cutting parameters are predicted from the model with the help of binary-coded Genetic Algorithms. Results are illustrated with the data of four different work materials.

SIMONA FIALOVÁ, FRANTIEK POCHYLÝ, PAVOL FEDOR

The convolute equation of the gel structure as a rheology material is
presented in the paper.

The convolute equation is expressed in the memory dependence as a
linear model in the first case. This model is compound of reversible and
irreversible parts that characterize the stress tensor. The dependence is
formulated by the convolution integral.

Next model considers the nonlinearity between certain characteristic
stress and the strain rate.

Another part of the paper is the methodology concept of the gel
memory determination and the volumetric compressibility modulus
definition.

The gels usage is assumed as well in the biomedical engineering as in
the engineering industry, for example for the noise and shocks elimination
and the special sleeve bearings design.

KALLURI RAMA KOTAIAH, JONNALAGADDA SRINIVAS, K. J. BABU

This paper presents an analytical stability analysis of turning using a non-linear force-feed model in two dimensions. Most of the existing analytical models ignored the effect of static feed term on the regeneration phenomenon. In practice there is a marked effect of feed on stability due to force variation. The modified analytical equations for cutting insert using three-dimensional tool geometry are obtained by considering relative motion of tool with respect to a two-dimensional elastic model of the work-piece. The critical stability limits obtained as a function of feed are confirmed by time domain analysis. Experiments are conducted on a flexible work-piece at varying feed conditions. The measured cutting forces show a marked effect of feed on stability. Neural network models were developed to obtain the critical depth of cut at various values of operating speed and feed.