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ABSTRACT:Curing kinetics models used in numerical simulations describe the exothermic chemical reaction of thermosetting materials. The mathematical formula known as Kamal's model is discussed in the following paper. Traditionally, the coefficients of Kamal's equations are estimated based on differential scanning calorimetry (DSC) measurements and results from an experimental verification of such created curing kinetics model are presented. Furthermore, an inverse analysis is proposed for additional adjustment of the model. The new coefficients thus found provide better accuracy in the computer simulations. The methodology of development of the curing kinetics model is proposed as an alternative solution to the standard DSC measurements. Particularly, it could be useful for materials with a complex structure, such as composites. C

A design optimization of a staggered pin fin heat sink made of a thermally conductive polymer is presented. The influence of several design parameters like the pin fin height, the diameter, or the number of pins on thermal efficiency of the natural convection heat sink is studied. A limited number of representative heat sink designs were selected by application of the design of experiments (DOE) methodology and their thermal efficiency was evaluated by application of the antecedently validated and verified numerical model. The obtained results were utilized for the development of a response surface and a typical polynomial model was replaced with a neural network approximation. The particle swarm optimization (PSO) algorithm was applied for the neural network training providing very accurate characterization of the heat sink type under consideration. The quasi-complete search of defined solution domain was then performed and the different heat sink designs were compared by means of thermal performance metrics, i.e., array, space claim and mass based heat transfer coefficients. The computational fluid dynamics (CFD) calculations were repeated for the most effective heat sink designs.

The paper presents an attempt of temperature distribution simulation of a polymer bearing. In order to create model, tribological tests were performed and thermal behavior of the bearing was observed until temperature constant values were achieved. Thermal simulations were done with commercial software package ANSYS Fluent for 3D geometrical model that included polymer bearing, its housing, shaft and some volume of the surrounding air. The heat generation caused by friction forces was implemented by volumetric heat source. The heat transfer and dissipation was through conduction, radiation and convection. The numerical model included all three mechanisms and in case of convection the heat transfer coefficient was not estimated by directly solved basing on the air flow around the bearing and adjacent parts.

ABSTRACT:Reactive molding technologies, especially the automated pressure gelation (APG) method, are commonly used in the production of a wide range of medium and high voltage electrical equipment, including switch gears, voltage and current transformers, sensors, and bushings. In such products, not only very good electrical insulation properties but also high mechanical and thermal performance are required. In order to achieve these, a suitable manufacturing process has to be established. Therefore, the use of optimal process parameters, such as mold temperature, filling time, filling velocity, initial temperature of internal parts, gelation time, as well as appropriate product design is key factors for better quality components derived from minimized shrinkage and crack avoidance. The simulation approach for analyzing the filling and curing stages of reactive molding manufacturing processes has been successfully utilized for some time, providing useful information about thermal conditions during the production. In this paper, the principles of a newly developed structural analysis are rationalized and described. A novel simulation procedure for stress and shrinkage calculations, as well as the simulation results,