TANCSICS, F.,GERGYE, T.,HALBRITTER, E.: Using up-to-date software in technological improvement and optimization of multiple-cavity forging 191 ZHU, L., JEN, T.-C., YIN, C.-L., KONG, X.-L., YEN, Y.-H.: Experimental verification of the feasibility and effectiveness of heat pipe cooling in drilling applications 205 AREFI, M., RAHIMI, G. H.: General formulation for the thermoelastic analysis of an arbitrary structure made of functionally graded piezoelectric materials, based on the energy method 221 ARAFAT A. BHUIYAN, SADRUL ISLAM, A. K. M.: CFD analysis of different fin-and-tube heat exchangers 237
F. TANCSICS, T. GERGYE, E. HALBRITTER
Forging is a technology frequently used in production of vehicle parts. Shape and
dimensions of the blank and occasionally of the finished work piece are provided, and
mechanical properties of the starting material are improved by forging. In production of
vehicle parts competitiveness is getting more and more important. Frequently,
competitiveness can only be increased by making the product to strict deadlines by
improving the quality and by reducing the production costs.
These complex requirements can only be met by quicker, more exact and more reliable production planning. Our work is aimed at setting an example for improvement as well as at elaborating an optimization method, at presenting the results gained in order to increase potential to enter the markets. In improvement of mechanical properties, the good grain flow free of folds is very important. A case of folds in grain and its elimination will be presented through an industrial task. In multiple-cavity forging process the blank has significant influence on how much force and work are required in forming. A blank which requires less work in forming is considered more favourable. In making comparisons it is required that various blanks have the same volume. Various blanks were designed with Pro/Engineer software and the same volumes were provided by optimization restricted within the design software. By taking the blank areas into account, in restricted optimization we tried to find a solution how to realize gradual forming beside constant volume of various blanks. The optimization method we have elaborated will also be presented through an industrial task.
L. ZHU, T.-C. JEN, C.-L. YIN, X.-L. KONG, Y.-H. YEN
M. AREFI, G. H. RAHIMI
This study deals with the thermoelastic analysis of an arbitrary structure using the energy method. The structure is loaded under the temperature gradient. This structure can be subjected to other external loads such as rotational load and also inner and outer pressures. In this issue, energy method is used for the general thermoelastic analysis of the piezoelectric structures. Energy equation with considering the classical terms cannot predict the thermal behavior of a piezoelectric structure as true as previous methods. The present study proposes a novel term that is introduced as additional energy. This term is necessary energy for increasing the temperature for those sections of structure expanded due to external loads. Final derived equation includes the equilibrium and Maxwell's equations. This procedure indicates that the Maxwell's equation can be derived independently from the energy equation. As an applied problem in the context of the piezoelectric structures, thermoelastic analysis of a FGP rotating pressure vessel is analyzed using the energy method.
ARAFAT A. BHUIYAN, A. K. M. SADRUL ISLAM
The objective of this numerical investigation is to examine the effect of heat transfer and pressure drop characteristics inside a three-dimensional, four-row fin-and-tube heat exchanger allowing for staggered and in-lined tube array of plain and wavy fin for laminar (400 £ ReH £ 1200) and turbulent (1300 £ ReH £ 2000) flow range using the commercial Computational Fluid Dynamics (CFD) code ANSYS CFX-11. For transitional flow, the k-w turbulence model has been used. Results are presented in the form of streamline patterns, velocity vectors, and temperature and pressure distributions. Code validation is carried out by comparing the simulated case friction factor (f) and Colburn factor (j) to experimental results from the literature. This study reveals that the flow distinction between plain and wavy fin has an intense influence on the heat transfer and pressure drop performance. Wavy fin shows greater heat transfer and pressure drop performance compared to plain fin arrangements. On the other hand, for a particular Reynolds number (ReH), the efficiency is higher in in-line arrangement than in the staggered case.