Contents of Journal of Mechanical Engineering 57, 5 (2006) 




ŠTIGLER, J.: Tee junction as a pipeline net element. Part 1. 
A new mathematical model                                                249

ŠTIGLER, J.: Tee junction as a pipeline net element. Part 2. 
Coefficients determination                                              263

SINGH, S., MAHESHWARI, S., DEY, A.: Electrical Discharge 
Machining (EDM) of aluminium metal matrix composites using 
powder-suspended dielectric fluid                                       271

KADRY, S.: Generalization of probabilistic transformation 
method for solving random differential equations                        291

MOCHNACKI, B., PAWLAK, E.: Micro/macro models of crystallization 
process - comparison of the results of numerical simulations            300

Abstracts



Tee junction as a pipeline net element. Part 1. A new mathematical model

JAROSLAV ŠTIGLER

The problem of mathematical model of the tee junction is divided into two parts. The first part is theoretical. It is focused on the derivation of a new mathematical model of the tee junction as a pipeline net element. New loss coefficients, which describe fluid flow in the tee junction, are introduced. The mathematical model is derived for the unsteady incompressible fluid flow.

Tee junction as a pipeline net element. Part 2. Coefficients determination

JAROSLAV ŠTIGLER

A new mathematical model of the tee junction has been established in Part 1. In Part 2, the attention is focused on the numerical experiment of turbulent fluid flow in the tee junction. Domain size and loss coefficients of the tee junction are determined on the basis of numerical experiment.

Electrical Discharge Machining (EDM) of aluminium metal matrix composites using powder-suspended dielectric fluid

SHANKAR SINGH, SACHIN MAHESHWARI, ALOKE DEY

Aluminium Metal Matrix Composites (AMMCs), owing to their better multiple functional characteristics, find a vast range of applications in the aerospace, automobiles, defence, sports and tools industries. These materials pose a greater challenge to manufacturing engineers due to the constraints in traditional machining to form complex shapes and achieve fine surface finish because of their abrasive reinforcements, high hardness and brittleness.

This paper reports experimental investigations of the effect of process parameters on the performance measures, namely Material Removal Rate (MRR) and surface roughness, via a hybrid manufacturing process Abrasive Electrical Discharge Machining (AEDM) involving the interaction of mechanical abrasion and thermal process, on stir-casted 6061Al/Al2O3p/20p work specimens with copper electrode and SiC abrasive powder-suspended dielectric fluid. A mixed orthogonal array L18 (21´ 37) experimental design was chosen to identify the effect of seven control factors viz. pulse current (Ip), pulse ON time (T ON), duty cycle (t), gap voltage (Vg), tool electrode lift time (TL), Abrasive Powder Concentration (APC) and Abrasive Particle Size (APS) with three levels each, and a noise factor, aspect ratio having two levels.

An attempt has been made to develop models for optimizing AEDM characteristics, and the significance of the models was checked using the Analysis of Variance (ANOVA) technique and F-tests. The experimental results have shown that MRR and the surface roughness increased with an increase in the addition of abrasives into the dielectric fluid.

Generalization of probabilistic transformation method for solving random differential equations

SEIFEDINE KADRY

The probabilistic transformation method with the finite element analysis is a new technique to solve random differential equations. The advantage of this technique is finding the expression in an "exact" form of the probability density function of the solution when the probability density function of the input is known. The disadvantage is that it is limited to some special cases and it depends on the characteristics (geometry and materials) of the analysed structure, which is included in the random differential equation. In this paper, a developed formula is used to generalize this technique by obtaining the "exact" joint probability density function of the solution in any situation. Also, a technique for the non-linear case is proposed.

Micro/macro models of crystallization process - comparison of the results of numerical simulations

BOHDAN MOCHNACKI, EDYTA PAWLAK

The micro/macro models of crystallization (the second generation ones) based on the assumption that the kinetics of nucleation and nuclei growth is proportional to the undercooling below the solidification point are discussed. In particular, the linear model described among others in scientific works, the exponential one and its modification are considered. The aim of our research is to estimate the influence of the assumed mathematical description on the results of numerical simulation of solidification process. On the stage of computations the control volume method has been used.