Browsing by Subject "homogenization"

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Access status: Open Access ,
Analysis of effective properties of piezocomposites by the subregion BEM-Mori-Tanaka approach
(2011) Dziatkiewicz, Grzegorz
Recently, many approaches have been proposed to estimate the effective properties of composites. The most typical are: the self-consistent method and the Mori-Tanaka method. However, they are restricted to simple geometries of phases. Also for complex constitutive laws the analytical results are complicated. On the other hand, the combination of numerical methods and these approaches gives an efficient computational scheme for estimating effective properties of composite materials. In this paper the hybrid subregion boundary element method (BEM) and Mori-Tanaka approach is implemented to solve coupled field equations of linear piezocomposites in the unit cell approach and then to determine the effective properties. To obtain the BEM fundamental solutions, the Stroh formalism is used. The numerical examples demonstrate an effectiveness of the BEM-Mori-Tanaka approach.
Access status: Open Access ,
Development of strength and electrical properties of Al-Si-Mg casting aluminum alloys with an Mg content of 1 wt%
(2016) Knych, Tadeusz Antoni; Wiecheć, Justyna; Uliasz, Piotr
Silumins (i.e., alloys where the main alloy additive is silicon) are the largest casting aluminum alloy group. Materials of this kind are characterized by high strength properties, high corrosion resistance, and low density, which make it possible to use them for construction purposes. A new group of developed properties typical for casting silumins are electrical and thermal conductivity. Thermal and electrical conductivity can be optimized by the suitable selection of chemical composition of the alloy, in the process of precipitation hardening, or by means of a combination of both. The present paper includes test results of the strength and electrical properties of AlSiMg casting aluminum alloys. The alloys that were subject to testing were AlSi5Mg1, AlSi7Mg1, and AlSi11Mg1. Heat treatment included homogenization at a temperature of 535°C over a time period of 8 h, quenched, and artificial aging. The strength tests involved a Brinell hardness measurement as well as an electrical properties test involving electrical conductivity measurement tests.
Access status: Open Access ,
Direct electrospinning of short polymer fibers: factors affecting size and quality
(2024) Ura, Daniel Paweł; Stachewicz, Urszula
Wydział Inżynierii Metali i Informatyki Przemysłowej
The growing demand for lightweight and robust materials drives the development of polymer-based and fiber-reinforced composites. Here, using short fibers offers several advantages; however, currently employed methods for producing short fibers, such as homogenization, result in a wide dispersion of dimensions in the produced fibers, which is an undesirable effect in composite materials. In this study, electrospinning is used to produce polymer short fibers directly. This research highlights, for the first time, the differences in the electrospinning process dynamics between short and continuous fibers. By adjusting parameters: voltage and distance, we control dimensions of short fibers below 1 µm in diameter and around 4 µm in length to a few microns in diameter and approximately 14 µm in length. Direct electrospinning of short fibers offers significant advantages, including a narrow size distribution and reproducibility compared to chopped continuous fibers with homogenization.