Mechanics and Control
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ISSN 2083-6759
e-ISSN: 2300-7079
Issue Date
2012
Volume
Vol. 31
Number
No. 2
Description
Journal Volume
Mechanics and Control
Vol. 31 (2012)
Projects
Pages
Articles
Vibrations of steel pipes and flexible hoses induced by periodically variable fluid flow
(2012) Czerwiński, Andrzej; Łuczko, Jan
This paper is concerned with the analysis of a model describing the vibrations of simply supported straight pipes conveying periodically pulsating fluid. The vibrations of the hydraulic system are described by a fourth-order partial differential equation, with the inclusion of geometrical non-linearities. Through the application of the Galerkin method, the non-linear problem is reduced to the solution of four ordinary differential equations. The influence of several significant parameters of the model on the rms value of velocity is investigated. The possibility of exciting sub-harmonic and chaotic excitations at certain intervals of excitation frequency and flow velocity is presented.
A study on the design of auxetic structure of seat skeleton
(2012) Jasińska, Dorota; Janus-Michalska, Małgorzata Beata; Smardzewski, Jerzy
This paper presents numerical study of deformation and stresses in seat skeleton elements subject to static and dynamic pressure loads. Elastic skeleton made of polyamide or elastomer is taken as an example of a seat material. Auxetic type of seat structure ensures the reduction of real contact stresses between human body and seat, making it more comfortable than typical. FEM analysis is performed using ABAQUS system. Numerical calculations are carried out to determine the nonlinear stiffness characteristics of seat springs. The study makes possible the selection of material and structural topology fulfilling design constraints and additional recommendations concerning structural flexibility, stability and optimal reduction of contact stresses. This paper presents an application of the theoretical prediction to solve the practical problem.
An interval finite difference method for the bioheat transfer problem described by the Pennes equation with uncertain parameters
(2012) Jankowska, Małgorzata Aleksandra; Sypniewska-Kamińska, Grażyna
In this paper the transient bioheat transfer problem given by the one-dimensional Pennes equation with mixed boundary conditions is considered. The model assumes the heat transfer between the skin and its surroundings in the case of a natural and forced convection. For computations the interval finite difference method of Crank-Nicolson type together with the floating-point interval arithmetic is used. In this way, uncertain geometric and thermophysical parameters can be represented in the form of intervals as well as the resultant temperature distribution over time.
Facility for investigating the vibration of the plate with magnetorheological fluid
(2012) Snamina, Jacek
This study briefly outlines the structure of the test facility for investigating the behaviour of a sandwich plate filled with magnetorheological (MR) fluid. The plate has two outer layers made of aluminium and the space between them is filled with MR fluid. The test facility is engineered within the framework of the research project focused on vibration reduction in beams and plates using MR fluids. The paper outlines the design of the test facility and the measurement equipment. Measurement data are summarised, including the free and forced vibration of the plate.
Methodology for experimental investigations of metal foams and their mechanical properties
(2012) Stręk, Anna M.
This paper presents a comprehensive, systematic approach on experimental investigations of structure and mechanical properties of metal foams. Based on a thorough state of the art study, the existing solutions have been synthesised with recent developments in the discussed field to become a proposition of a possibly complete methodology for observation and testing of cellular metals. Material properties acquired in the described manners can constitute reliable reference result base e.g. for identification and verification of failure criteria. This paper describes sample preparation procedures and next discusses techniques which enable one to characterise foam structure. There are also presented procedures for determining strength limits in different load cases: uniaxial tension or compression, shear and torsion as well as multiaxial states. The tests are discussed in terms of their specific application to study cellular metallic materials.