ENGINEERING TRANSACTIONS
ROZPRAWY INŻYNIERSKIE
A QUARTERLY JOURNAL
- M.R. Khoshravan, A. Rahmani:
Numerical analysis of the effect of torispherical head on the buckling of pressure vessel
- K. Jastrzębski, Z. Kotulski:
On improved image encryption scheme based on chaotic map lattices
- B. Reggiani, F. Cosmi:
Multi-goal optimization of a carry-mould
- Z.L. Kowalewski, T. Szymczak:
Variation of mechanical parameters of engineering materials under tension due to cyclic deformation by torsion
- M.R. Khoshravan, A. Rahmani:
Numerical analysis of the effect of torispherical head on the buckling of pressure vessel
- The shape of end heads of a pressure vessel is usually torispherical. Buckling of this head is
one of the most important points for designing of pressure vessels. This subject has been studied
extensively since last years. In this field, the experimental methods are expensive and need a lot
of time. In addition, because of lack of accuracy in the producing procedure, sometimes two
models with identical geometry show different buckling behavior. Hence the use of finite element
method in analyzing of buckling behavior of heads has a lot of benefits. In this dissertation,
the finite element method has been used. Firstly with nonlinear buckling analysis, the effects
of geometrical parameters such as thickness, knuckle radius and diameter of cylindrical part,
on the buckling of heads have been studied, then the buckling behavior of different kinds of
heads with identical geometry have been analyzed. For the nonlinear analysis we used the Arc
Length method which can control the load level, the length of the displacement increment and
the maximum displacement. The most important characteristic of this method is its ability to
converge, even when the behavior is highly nonlinear. From the verification performed with
the European Convention for Constructional Steelwork (ECCS) code, it has been confirmed
that the nonlinear buckling analysis could assure accurate results for the buckling strength.
In the case of internal pressure, it has been shown that initial imperfection had no effect
on the pre-buckling behavior and buckling pressure of head; it just affects the post-buckling
behavior.
Contents
- K. Jastrzębski, Z. Kotulski:
On improved image encryption scheme based on chaotic map lattices
- In this paper we examine one of the recently proposed chaotic image encryption algorithms,
based on chaotic map lattices (CML). We show certain problems with the chaotic map, as well
as errors in the designed algorithm. Then we propose a way to improve it and present a new
version of algorithm and its implementation. At the end, we show the results of a security
analysis and a comparison of both schemes. These results were obtained in the MSc Thesis [25].
Contents
- B. Reggiani, F. Cosmi:
Multi-goal optimization of a carry-mould
- A common engineering task is the optimization of components that are part of multibody
assemblies, in which it is difficult to extrapolate and define the boundary conditions
to be applied for the component optimization. This work presents a procedure for multi-goal
optimization of components that are integrated in multipart engineering systems. The efficiency
of the procedure is illustrated by means of a test case, a carry-mould that is part of a multicomponent
blowing machinery. Target goals of the optimization process are the minimization
of moment of inertia and of global mass and the maximum allowable displacement in a number
of control points.
Contents
- Z.L. Kowalewski, T. Szymczak:
Variation of mechanical parameters of engineering materials under tension due to cyclic deformation by torsion
- The paper presents experimental results of investigations carried out under complex stress
state on the 2024 aluminium alloy (used by aircraft industry) and P91 steel (used at power
plants). Second-order effects associated with cyclic loadings enforced by the trapezoidal signals
in the two mutually perpendicular directions are identified. It is shown, how the cyclic loading
and its parameters (strain amplitude and frequency) influence the simultaneous monotonic
loading in the direction perpendicular with respect to the cyclic one. Moreover, the paper
presents an analysis of the selected mechanical properties variations on the basis of an initial
yield locus evolution.
Contents
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