Papers by Keyword: Shielding Effect

Abstract: The aim of the present work is to analyze the influence of residual stresses in the particulate ceramic composite on the crack propagation. The crack propagation direction was estimated using Sih’s criterion based on the strain energy density factor. A two-dimensional finite element model was developed for determination of crack path. The residual stresses resulting from the mismatch of coefficients of thermal expansion during the fabrication process of the composite were implemented to the computational model. The effect of the particles shape on the crack propagation was investigated. Conclusions of this paper can contribute to a better understanding of the propagation of micro-cracks in particulate composites in the field of residual stresses.

Abstract: The induced voltage generated by AC submarine cables would effect the normal operation of communication cables nearby. The paper calculated the induced voltage generated by AC submarine cable according to formula and procedures related to magnetic induction. The maximum parallel length between submarine cable and communications table was calculated under horizontal arrangement, and shielding effect was taken into account to the impact of the results. The causes of various induced voltage on communication cable were analysed under normal operation and various fault conditions. The results show that the induced voltage on communication cable is proportional to the parallel length and inversely proportional to parallel spacing. When the parallel length does not exceed a certain value, the induced voltage is in the allowable range and will not affect the normal operation of the communication cable.

Abstract: With the wide application of electronic technology, electromagnetic interference has become one of the main factors to weaken electronic system performance. In communication technology and equipment, it is the development of light-duty design, low cost, high quality electronic components and electronic system that is the main object of this study. Radio frequency MEMS devices are low energy consumption, good stability. Therefore it has a strong competitiveness in the communications electronics. But EMI electromagnetic interference problem has increasingly become prominent, and based on this, this paper makes a further study on the main electromagnetic interference electromagnetic radiation of MEMS devices. In addition, this paper also establishes the mathematical model of electromagnetic radiation. Finally this paper makes an analysis and study on the shielding effect of MEMS antenna under certain magnetic materials. Through the simulation research, it is obtained that the electromagnetic effect of electronic system MEMS is good and its highest performance is more than 60 db. Whats more, shielding materials are within the range of 15 to 20 GHZ, whose shielding effects reach the maximum. The largest is close to 80 db.

Abstract: In this paper a particulate composites with polypropylene matrix and rigid mineral fillers are studied. The polymer particulate composites are frequently used in many engineering applications. Due to the physical and chemical interaction between matrix and particles a third phase (generally called interphase) is formed. The composite is modeled as a three-phase continuum. The properties of particles and interphase have a significant effect on the global behavior of the composite. On the basis of fracture mechanics methodology the interaction of micro-crack propagation in the matrix filled by rigid particles covered by the very soft interphase is analyzed. The effect of the composite structure on their mechanical properties is studied here from the theoretical point of view. The properties of particles and matrix were determined experimentally. Conclusions of this paper can contribute to a better understanding of the behavior of micro-crack in polymer particulate composites with respect to interphase.

Abstract: This paper mainly studies the distribution characteristics of surface wind pressure on low-rise buildings. Based on the theory of fluid dynamics, this study uses CFD software Fluent 6.3.26 to conduct numerical simulation of the models in wind tunnel tests by Yong Chul Kim involving four working conditions of different spacing or area density in regular arrangement. Compared with data of wind tunnel tests, the results show that different spacing or area density has significant influence on surface wind pressure of low-rise buildings and surrounding buildings have shielding effect over target buildings.

Abstract: In this paper, in order to study the wind interference effect,with change of height of the upstream building, the numerical simulation of the downstream construction disturbance of wind pressure distribution has been done. With architecture of upstream, wind pressure coefficient values of windward and leeward faces of downstream building basically reduces,and interference effect shows shielding effect.

Abstract: Particulate composites with polymer matrix and solid fillers are one of important types of materials. Generally, these materials are usually used as construction materials, high-performance engineering materials or protective organic coatings. The main aim of a present paper is an estimation of the micro-crack behavior in the particulate composite with non-linear polymer matrix. The polymer matrix filled by magnesia-based mineral filler is investigated by means of the finite element method. A non-linear material behavior of the matrix was obtained from experiment as well as properties of mineral filler. Numerical model on the base of representative plane element (RPE) was developed. The results show that the presence of interphase between particle and matrix can improve fracture toughness of polymer particle composite through debonding process. The conclusions of this paper can contribute to a better understanding of the behavior of micro-crack in particulate composites with respect to interphase.

Abstract: Particulate composite with soft polymer matrix and rigid mineral fillers are one of most frequently used construction and engineering materials. The main focus of a present paper is an estimation of the load influence on behavior of micro-crack placed in close proximity to the particle with interphase in soft matrix. The particulate composite with polymer matrix filled by magnesium-based mineral fillers is investigated by means of the finite element method. A non-linear material behavior of the matrix was considered. Numerical model on the base of representative plane element (RPE) was developed. The conclusions of this paper can contribute to a better understanding of the behavior of micro-crack in particulate composites with soft polymer matrix.

Abstract: The presented paper is focused on the numerical study of fracture behavior of polymer particulate composites. The polymer particulate composite is modeled as a three-phase continuum. Together with particles and matrix is considered an interphase. The interphase is created on particle-matrix interface. Non-linear matrix material properties were experimentally determined and used in calculations. The main aim is to estimate micro-crack propagation direction for the variety of matrix and interphase material properties. The results are obtained using the finite element commercial code ANSYS.

Abstract: This paper presented a numerical evaluation of the lightning electromagnetic environment inside a typical telecommunication building when a lightning strikes at its lightning protection system (LPS). A model based on ‘circuit approach’ was constructed to simulate the building reinforced steel structure. Through numerical simulation, the magnetic field inside the building for two different types of LPS and for two typical lightning stroke positions was evaluated and compared. From the analysis result, some advices were proposed to protect electronic equipment against the impact of the magnetic field.