Mechanics and Control
Loading...
ISSN 2083-6759
e-ISSN: 2300-7079
Issue Date
2010
Volume
Vol. 29
Number
No. 2
Description
Journal Volume
Mechanics and Control
Vol. 29 (2010)
Projects
Pages
Articles
Applications of the Burzyński hypothesis of material effort for isotropic solids
(2010) Frąś, Teresa; Pęcherski, Ryszard B.
The paper contains a short presentation of main idea of energy-based hypothesis of material effort proposed by Burzyński with discussion of the resulting failure criteria. Some examples illustrating applications of these criteria are discussed and visualizations of limit surfaces in the space of principal stresses are presented.
Possibilities of optimum selection of value of parameters of scraper pipe conveyor
(2010) Furmanik, Kazimierz; Kasza, Piotr
Still growing requirements connected with environmental protection, work safety, but also many advantages of scraper pipe conveyors caused that they find more and more wide applications in transport of fine grained, bulk, dusty materials and pulp in chemical, ceramic, aluminium industry, cement mills, electric plants and steelworks. Those conveyors have: simple construction and maintenance, small dimensions in crosswise section, easy configuration of routes, transport materials at high temperatures (even at 700 degrees of Celsius). Those conveyors have also disadvantages, their great resistances of movement (friction) causing significant friction wear of parts, which is essential problem in exploitation. Parameters connected with conveyor construction, route configuration and transported materials properties have essential influence on those resistances. In the paper had been indicated possibilities of selection of such scraper pipe conveyor basic parameters like internal pipe diameter, distance between scrapers and speed, at which resistances of movement or needed drive power are minimal. It has essential meaning for rational designing and exploitation of scraper pipe conveyors.
Assessment of the material strength of anisotropic materials with asymmetry of the elastic range
(2010) Kordzikowski, Piotr; Pęcherski, Ryszard B.
The aim of the paper is to apply the energy-based criterion of limit elastic states for the assessment of the material effort of anisotropic materials. The linear elastic anisotropic materials in the plane state of stress are considered. The theory of elastic eigen states determined by the symmetry of the Hooke elastic tensors (stiffness and compliance tensors) and the energy-based criterion of elastic limit states for anisotropic materials is used according to the theory proposed by Jan Rychlewski. Experimental data for paperboard and the results of atomic calculations were applied. The common feature of the aforementioned materials is the strength differential effect related to the asymmetry of the elastic range. Often, to determine the degree of this asymmetry one uses the ratio of the experimentally measured limit of elasticity (yield) in compression to the limit of elasticity in tension. Also, the failure criterion of P. S. Theocaris is mentioned within the discussion of the possibility of the extension of the criterion proposed by Rychlewski for anisotropic materials revealing asymmetry of elastic range and the related strength differential effect.
Significance of rivet flexibility for load transfer in lap joints
(2010) Skorupa, Małgorzata; Machniewicz, Tomasz; Korbel, Adam; Skorupa, Andrzej
Presented in this paper are results of an experimental investigation on the rivet flexibility and load transmission in a riveted lap joint representative for the aircraft fuselage. The test specimens consisted of two aluminium alloy Alclad sheets joined with three rows of rivets. Rivet flexibility measurements have been performed under constant amplitude fatigue loading using several methods including two novel optical techniques developed by the present authors. The axial forces in the sheets required to determine the rivet flexibility have been derived from strain gauge measurements. In order to eliminate the effect of sheet bending the strain gauges have been bonded at the same locations on the outside and faying surface of the sheet. Variations of the rivet flexibility during the fatigue loading as well as the dependence of the rivet flexibility and load transmission on the rivet squeeze force have been studied. The experiments enabled to evaluate the usefulness of various techniques to determine the rivet flexibility. It was observed that although the measured flexibility was identical for both outer rivet rows, the load transfer through either of these rows was different. Previous experimental results of the authors suggest that the non-symmetrical load transfer distribution through the joint is associated with large differences between the rivet hole expansion in the sheet adjacent to the driven rivet head and the sheet under the manufactured head. It has been concluded that commonly used computation procedures according to which the load transfer is only related to the rivet flexibility may lead to erroneous results.
Phase trajectory run as a useful tool in axial-piston pump wear detection
(2010) Stojek, Jerzy
In this paper the possibility of phase trajectory use in detecting of axial piston pump damage was presented. The wear of main part of pump elements such as: rotor and swash plate have been studied. The phase trajectories were estimated from vibration signal measured on pumps body in third directions. In order to get quantitative specification of analyzed trajectory At/pi parameter was introduced. At the and the relation between At/pi parameter and the wear of the pumps parts have been set.