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• Pure Bending of Homogenous Isotropic Elastic Curved Beam

  67-75

  István Ecsedi

  Attila Baksa

  Marwen Habbachi

  Views:

  49

  In this paper a detailed analysis is given for the pure bending problem of curved beams. The material of the curved beam is homogenous isotropic linearly elastic. The mantle of the curved beam is stress free and there is no body force on the curved beam. The plane of the curvature of the beam is the plane of symmetry for the whole beam. Paper gives the expressions of circumferential and radial normal stresses. A strength of material approach is used to derive the governing equations. A numerical example illustrates the application of the presented solutions. 

• Full-Scale Tests of Pipeline Girth Welds Under Complex Cyclic Internal Pressure and Static Bending Loading Conditions

  76-82

  Ahmad Yasser Dakhel

  János Lukács

  Views:

  95

  The critical elements of high-pressure hydrocarbon transporting pipelines are often the girth welds, which are subjected to complex loads. The aims of our research and this paper are to introduce our full-scale pipeline fatigue and burst tests applying cyclic internal pressure and superimposed external bending stress on girth welds, furthermore, attracting the importance and the applicability of the investigation results. A unique testing system was built to study the behaviour of pipeline girth welds under simultaneous loads. The tests were evaluated using video camera recordings, internal pressure vs. burst time functions and failure pressure values.

• Properties of Cellulose Sheets Modified with Potassium-Humate and Copper (II)-Sulfate

  276-285

  Annamária Tóth

  Katalin Halász

  Views:

  98

  Throughout our research we have made potassium-humate from brown coal of Dudar. With potassiumhumate and copper(II)-sulfate we made test sheets of linter cellulose fibers. The surface energy, surface wettability, CIE Lab color-coordinates changing, bending resistance and tensile strength of the produced test sheets has been examined. There was no big difference in the different samples during surface energy and wettability testing. Examination of mechanical properties suggests that potassium-humate content increases bending resistance of the test sheets. The bending resistance of samples increased by 32%, 100% and 336% compared to the control test sheets while adding potassium-humate.

• Study on Nonlinear Behavior of Variable Thickness Plates

  72-80

  Lan Hoang That Ton

  Views:

  37

  The analysis of variable-thickness plates is much more complicated than that of uniform-thickness plates because variable coefficients occur in the equations. In reality, this analysis is of great interest in various engineering disciplines, such as civil engineering, aerospace engineering, machine design, and so on. Although there is extensive literature on analyses of plates with constant thickness, a rather limited amount of technical literature is available on the solutions to problems dealing with plates with nonuniform thickness. The reason is that the analytical solutions meet insurmountable difficulties. Besides, the nonlinear analysis process also faces more difficulties than the linear analysis of structures. For these reasons, the nonlinear behavior of variable-thickness plates based on a finite element procedure is presented in this study. Although the topic is not special, it will help the engineer have a specific view of the nonlinear bending of the plate with variable thickness. This survey will be based on the change in geometrical parameters. Numerical solutions are then presented to verify the simplicity of this proposed procedure.

• Investigation of the Eigenfrequency of the Bending Vibration of the Beam Clamped at Both Ends Around the Principle Directions of Inertia Based on a Single-Degree Freedom Model and a Finite Element Method Analysis

  69-79

  Zsolt Vadai

  Sándor Hajdu

  Imre Kovács

  Views:

  175

  In this study, we have dealt with the calculation methods of the eigenfrequencies associated with the bending vibrations of rectangular-shaped beams clamped at both ends. Said eigenfrequencies were determined analytically in the single-degree of freedom model of the beam and the case of the three-dimensional solid and three-dimensional rod models by finite element modal vibration analysis. We presented the calculation method of the characteristics of the analytical model and then calculated the eigenfrequency for a concrete example. We have described the concept of modal characteristics, and in the following, we have determined its natural frequency based on the solid-beam and rod models of the former beam. We calculated and compared the solutions belonging to the models recorded in different ways in 11 additional cases of the presented methods.

• Comparison of the Euler-Bernoulli- and Solid Models of Three-Point Bending Test Specimens

  53-68

  Zsolt Vadai

  Views:

  125

  For hand calculations, the Euler-Bernoulli beam model has become widespread in engineering practice due to its simplicity and accuracy. In the present study, I compare the state variables calculated based on the Euler-Bernoulli model of a crack-free concrete beam and a crack-free concrete beam reinforced with FRP bars with the result of the three-dimensional solid body model.

• Building’s Constructions and Structures. Part II. Changes of Structures in Supporting Structures of Buildings

  79-99

  Géza Lámer

  Views:

  118

  In the Part II. we deal with the changes of structures in supporting structures of buildings. The changes of the structure we will connected with new materials or new approach. We deal with two problems. First is the formations and change of the vault. The second is the change of the supporting structure of buildings in case of using new materials with bending or only stretching resistance.