Reza Attarnejad

Bio: Reza Attarnejad is an academic researcher from University of Tehran. The author has contributed to research in topics: Finite element method & Beam (structure). The author has an hindex of 17, co-authored 67 publications receiving 1040 citations. Previous affiliations of Reza Attarnejad include University College of Engineering & University of Kashan.

New shape functions for non-uniform curved Timoshenko beams with arbitrarily varying curvature using basic displacement functions

Abstract: Basic Displacement Functions (BDFs) are introduced and derived using the basic principles of structural mechanics. BDFs are then utilized to obtain new shape functions for arbitrarily curved non-uniform beams, including the effects of shear deformation and extensibility of neutral axis. The main virtue of the proposed shape functions is their susceptibility to the variations in cross-sectional area, moment of inertia, and curvature along the axis of the beam element. Competence of the present method in static and free vibration analyses, as well as its applicability to the special case of straight Timoshenko beam has been verified through several numerical examples.

Free Vibration Analysis of Centrifugally Stiffened Tapered Functionally Graded Beams

Abstract: Free vibration of rotating tapered beams made of functionally graded (FG) materials is studied through a finite element approach. A new element is introduced that takes advantage of the exact shape functions for nonrotating tapered FG beam elements. Developing a new type of unit-dummy-load method, special functions, namely, basic displacement functions (BDFs) are derived from which the exact shape functions are obtained. The element is employed in free vibration analysis where the effects of taper ratio, rotational speed, and hub radius are investigated. The present results could be efficiently used for future research works in this field.

Basic Displacement Functions in Analysis of Centrifugally Stiffened Tapered Beams

Abstract: Introducing the concept of basic displacement functions (BDFs), a new beam element is presented for the analysis of rotating tapered beams. BDFs are obtained using the energy method; i.e., the unit-load method. Following the basic principles of structural mechanics, it is shown that the shape functions and consequently the structural matrices can be derived in terms of BDFs. The method is a combination of flexibility and stiffness methods and is considered as the logical extension of the conventional finite element method. The method is employed for both static and free vibration analyses of different types of tapered beams, and the results compare well with those in the literature. Finally, the effects of the taper ratio, hub radius and rotating speed parameter on the natural frequencies and static deflection are investigated. The results obtained are satisfactory even for only a few elements.

Analytical investigation of the behavior of a new smart recentering shear damper under cyclic loading

Abstract: Shear recentering polyurethane friction damper is a type of passive control device, including the shape memory alloy plates, polyurethane springs, and friction devices. This damper can be employed ...

Water Hammer Analysis by Characteristic Method

Abstract: Rapid changes in the velocity of fluid in closed conduits generate large pressure, which are transmitted through the system with the speed of sound. When the fluid medium is a liquid the pressure surges and related phenomena are described as water hammer. Water hammer is caused by normal operation of the system, such as valve opening or closure, pump starts and stoppages and by abnormal condition, such as power failure. Problem statement: Water hammer causes the additional pressure in water networks. This pressure maybe defects on pipes and connections. The likely effects of water hammer must be taken into account in the structural design of pipelines and in the design of operating procedures for pumps, valves, etc. Approach: The physical phenomena of water hammer and the mathematical model which provides the basis for design computations are described. Most water hammer analysis involves computer solution by the method of characteristics. In this study water hammer is modelled with this method and effect of valve opening and closure will be surveyed with a program that is used for this purpose and with a numerical example. Results: The more rapid the closure of the valve, the more rapid is the change in momentum and hence, greater is the additional pressure developed. Conclusions/Recommendations: For preventing of water hammer defects, is recommended that valves should be open or closed slowly. Also with using the method of characteristics, we can modelled all pipe networks, and see the affects of water hammer.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Introduction to the Finite Element Method

Abstract: This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Seismic Design Of Reinforced Concrete And Masonry Buildings

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