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Your search keyword '"Teodorescu-Draghicescu, Horatiu"' showing total 18 results
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18 results on '"Teodorescu-Draghicescu, Horatiu"'

5. Finite-Element-Analysis-Based Study of a Failure Phenomenon in HDPE Pipes.

Author

Teodorescu Draghicescu, Horatiu, Scutaru, Maria Luminita, and Vlase, Sorin

Subjects
*FINITE element method, *WATER supply, *WATER use
Abstract

In pipes made of HDPE used in city water supply networks, a specific type of failure is commonly noted, called the parrot's beak failure. It requires expensive intervention. The prediction and study of the development of this defect, therefore, requires thorough research. In this work, the finite element method is used to study the mechanism of the occurrence and development of this defect. Two examples of the calculation for the concrete case of some tubes used in a water supply network are presented. This study is important for the designers of such networks, to predict and prevent the occurrence of this defect that can lead to unwanted network downtime and high repair costs. [ABSTRACT FROM AUTHOR]

Published
2023
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9. A Review over Electromagnetic Shielding Effectiveness of Composite Materials.

Author

Afilipoaei, Cezar and Teodorescu-Draghicescu, Horatiu

Subjects
ELECTROMAGNETIC shielding, COMPOSITE materials, ABSORPTION, OPTICAL reflection, INDUSTRIAL applications
Abstract

The aim of this paper is to review and compare the response to the electromagnetic radiation of different structural or non-structural composites on absorption, reflections and re-reflection grades. The area of interest has been reduced to the carbon allotropy and conducting non-magnetic/magnetic fillers (inclusions, metallic powders, granular ferrites) in dielectric hosts characterized by existing mixing rules. The results could be grouped in distinctive ranges, SE ≤ 10 dB corresponding to a poor shielding, 10-30 dB describing an acceptable effectiveness and SE ≥ 30 dB exceeding the acceptable range for industrial and commercial applications of 20 dB. [ABSTRACT FROM AUTHOR]

Published
2020
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10. NEW COMPOSITE SANDWICH WITH ALUMINUM CORE.

Author

TEODORESCU-DRAGHICESCU, Horatiu, STANCIU, Mariana Domnica, and TEODORESCU-DRAGHICESCU, Florin

Subjects
*ALUMINUM, *SANDWICH construction (Materials), *MECHANICAL behavior of materials, *EPOXY resins, *DEFLECTION (Mechanics)
Abstract

This paper presents a new developed ultra-lightweight composite sandwich with very good mechanical properties suitable for aerospace and defense applications. The 13.8 mm thick structure has a 3003 aluminum honeycomb core with 5.2 mm cell size and two opposite skins made of woven glass fabric reinforced epoxy resin laminates. Very good stiffness and mechanical work have been obtained during three-point bend tests. Samples have been subjected to load at break and up to 50 mm deflection. More compact values of mechanical properties have been obtained at break than at 50 mm deflection. [ABSTRACT FROM AUTHOR]

Published
2017
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12. Damping Analysis of a New Sandwich Structure.

Author

Teodorescu-Draghicescu, Horatiu, Vlase, Sorin, Rosu, Dorin, Purcarea, Ramona, and Munteanu, Violeta

Subjects
*DAMPING (Mechanics), *FIBROUS composites, *COMPOSITE materials, *POLYSTYRENE, *VISCOELASTICITY
Abstract

The aim of the paper is to determine the most important features of damping in the case of an advanced sandwich composite structure starting from the dampings, dynamic Young moduli and Poisson ratio for every lamina. The structure features two carbon/epoxy skins reinforced with twill weave fabric and an expanded polystyrene (EPS) core. At the damping analysis of fibre reinforced composite materials, a so called concept of complex moduli will be used in which the elastic constants will be replaced through their viscoelastic correspondences. The mechanical modeling is based on the correspondence principle of linear viscoelastic theory. Testing scheme allows specimens to be put in one side fixed connection and subjected at bending oscillations in normal conditions: 23°C, 50% relative air humidity. Dampings, rigidities and compliances of the composite structure are computed. [ABSTRACT FROM AUTHOR]

Published
2009

13. Bending Behaviour of the Composite Materials Made by Recycling of the CDs and DVDs.

Author

CERBU, Camelia and TEODORESCU-DRAGHICESCU, Horatiu

Subjects
*WASTE recycling, *COMPOSITE materials, *COMPACT discs, *DVD media, *MECHANICS (Physics)
Abstract

The paper describes the aspects concerning a methodology of recycling of CDs (compact disks), DVDs to develop a new composite material made of a polyester resin reinforced with chopped material of CDs, DVDs. It is known that polycarbonates are mainly used to manufacture of CDs, DVDs while a very thin aluminium layer is additionally used to record information. The first of all, the hand lay-up technology is used to prepare a board made of the composite material involved. Then, the composite specimens were cut from the board and subjected to the flexural test (three points method). Herein, the mechanical characteristics of the specimens were analysed. Moreover, the photos acquired by using a metallographic microscope are presented to discuss about the homogeneity of the composite structure. Finally, some applications of the new composite material are proposed by taking into account the experimental results shown and above all, the recycling necessity of the large quantity of CDs / DVDs wastes. [ABSTRACT FROM AUTHOR]

Published
2009

14. A Homogenization Method for Pre-Impregnated Composite Materials.

Author

Teodorescu-Draghicescu, Horatiu, Vlase, Sorin, Chiru, Anghel, Scutaru, Maria Luminita, and Motoc, Dana Luca

Subjects
*COMPOSITE materials, *ELASTICITY, *CHEMICAL molding equipment, *ESTIMATION theory, *MATHEMATICAL models
Abstract

The paper presents an original homogenization method to predict the elastic properties of multiphase pre-impregnated composite materials like Sheet- and Bulk Molding Compounds. The upper and lower limits of the homogenized coefficients for a 27% fibres volume fraction SMC are computed. It is presented a comparison between the upper and lower limits of the homogenized elastic coefficients of a SMC material and the experimental data. The estimation model used as a homogenization method of these heterogeneous composite materials, gave emphasis to a good agreement between this theoretical approach and experimental data. [ABSTRACT FROM AUTHOR]

Published
2009

15. Thermomechanical Response of a Thin Sandwich Composite Structure.

Author

Teodorescu-Draghicescu, Horatiu, Vlase, Sorin, Motoc, Dana Luca, and Chiru, Anghel

Subjects
*POLYESTERS, *REINFORCED plastics, *STRENGTH of materials, *GLASS fibers, *THERMAL expansion
Abstract

The paper presents a stiffness evaluation as well as thermal response of a sandwich structure with thin nonwoven polyester mat as core. The structure presents dissimilar skins from which one is a glass fabric reinforced polyester. Tensile and three-point bend tests have been carried out to determine the most important features of this structure. The thermal expansions have been measured using a DIL 420 PC dilatometer from NETZSCH, on both glass fabric reinforced polyester skin and for the whole structure. The coefficients of thermal expansion have been determined only for the structure's upper skin. For each sample, two successive heating stages in order to size the influence of the thermal cycling, and temperature interval from 20°C to 250°C, at a heating rate of 1 K/min have been used. To eliminate the system errors, the dilatometer has been calibrated by measuring a standard SiO2 specimen under identical conditions. The experimental researches accomplished on specimens show a twelve times increase of the flexural rigidity against the upper skin one. [ABSTRACT FROM AUTHOR]

Published
2010

17. EXPERIMENTAL APPROAC HES ON A FIBRE-REINFORCED COMPOSITE LAMINATE FOR PRESSURE TANKS APPLICATIONS.

Author

TEODORESCU - DRAGHICESCU, Horatiu, STANCIU, Anca, VLASE, Sorin, ROSU, Dorin, SCUTARU, Luminita Maria, and TEODORESCU, Florin

Subjects
*BENDING (Metalwork), *STRUCTURAL shells, *PRESSURE vessels, *HIGH pressure (Science), *STEAM generators, *TANKS, *GLASS fibers, *SILICATE fibers, *ELASTICITY, *MATHEMATICAL physics
Abstract

The paper presents some experimental results like tensile and three-point bend tests accomplished on a glass fibre-reinforced composite laminate with eight layers (two 450 g/m² chopped glass mats, four 800 g/m² glass fabrics and two 600 g/m² chopped glass mats). The laminate has been used to manufacture a 10 m³ pressure tank in hand lay-up process. Tensile tests show medium values of Young moduli and stiffness while three-point bend tests show scatter values of Young moduli of bending but good flexural rigidities. [ABSTRACT FROM AUTHOR]

Published
2009

18. COMPARATIVELY ANALYSIS OF THE EFFECTS OF WATER/ SEAWATER ON THE COMPOSITES MADE OF E-GLASS WOVEN FABRICS AND CHOPPED FIBRES.

Author

CERBU, Camelia, CIOFOAIA, Vasile, TEODORESCU - DRAGHICESCU, Horatiu, and ROSCA, Ioan Calin

Subjects
*SEAWATER, *GLASS fibers, *COMPOSITE materials, *SALINE waters, *SILICATE fibers, *SURFACE chemistry, *SURFACE tension, *POLYESTER fibers, *POLYESTERS
Abstract

The paper describes aspects concerning the effects of the water / seawater absorption on some mechanical characteristics of some composite materials reinforced with E- glass woven fabrics. The specimens were manufactured by reinforcing a polyester resin Copoly 7233 with woven fabric EWR300 made of E-glass fibres The first of all, some specimens were immersed in water while the others were immersed in seawater for a long time (approximately 7 months). The data regarding the moisture content were periodically recorded. Then, the wet composite specimens were subjected to the tensile test. Finally, the experimental results obtained in case of the immersed specimens were comparatively analysed with the results recorded in case of the dried specimens subjected to the tensile test too. [ABSTRACT FROM AUTHOR]

Published
2009

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