Applied Mechanics and Materials Vols. 725-726

Abstract: Up to the present solutions for geometrically nonlinear rods were obtained only by the Kirchhoff’s theory. This theory disregards flexibility of the rod on tension and shear. For rods in modern software suites the Cosserat-Timoshenko rod theory is generally used. As opposed to Kirchhoff’s theory it takes into account tensile and shear stiffness. This paper presents solutions obtained by Cosserat-Timoshenko rod theory. These results can be used as benchmark problem for verification of software suites.

Abstract: This paper deals with the effect of weathering and biological exposure on the tensile properties of needle-punched PP nonwoven fabric. In the experiment, samples of the geotextile were exposed to the above factors for different time, and then their tensile strength was determined. The obtained results showed the significant drop in the tensile strength after the exposure to UV radiation and slight drop after soil burial test.

Abstract: Nowadays, new types of concrete reinforcement are finding increasing use in civil engineering applications. The use of fibrous materials as reinforcement for building structures gives opportunity for the manufacturing of concrete elements with reduced thickness, high strength, and high corrosion resistance. This paper includes development and determination of mechanical behavior of concrete reinforced with glass fiber, roving and composite reinforcement.

Abstract: A stress state of the partially damaged underground steel pipeline after reconstruction by means of the fiberglass composite material is considered. The strength properties of the composite are determined experimentally. The effective elastic moduli of the composite are determined by means of the finite element homogenization. Tsai-Wu failure criterion is used for the composite part of the pipeline. The influence of geometrical parameters and loading conditions on the safety factor of the pipeline is analyzed and discussed.

Abstract: Fatigue crack growth rate at the plane stress is predicted by Paris equation, associating it with the stress intensity factor (SIF), generalized parameter of the elastic stress field near the crack tip. The finite element method allows modelling of the incremental crack growth in the plates, where the finite element grid should be re-meshed on each crack growth step fitting the first principal stress planes. However, the linear fracture mechanics format (LEFM) based evaluation of the two-dimensional fatigue cracks does not provide always the correct crack front assessment and appropriate life-predictions. It is shown that approach using the damage accumulation simulation and strain-life criterion may be promising in analysis of the two-dimensional cracks. Application of the approach is illustrated. The simulation results are in good agreement with the experimental data.

Abstract: The masonry model, representing an elastic mortar and elastic bricks, is analyzed with aim to evaluate effective elastic moduli and strength properties. By means of the direct finite element simulation and homogenization procedure the analysis of variation influence in the heterogeneous material microstructure characteristics (influence of brick aspect ratio and orientation angle) on the local stress-strain state and mechanical properties of the representative volume element of considered composite has been fulfilled.

Abstract: In this work, there are presented overviews of theoretical and numerical models for defining the stress-strain state in the cross section of moderately thick and thick composite plates in case of bending. Layered composite plates are constructed by combination of layers of various materials and geometrical characteristics, wherein each of them has got a bearing capacity in previously defined directions. By applying Equivalent Single-layer Laminate Theory (or ESL theory) these layers' problems cannot be solved successfully. That is the reason to apply contemporary theories of plates, in literature known as Layerwise theories. At the end of this work, there are given numeric examples of applying Partial Layerwise Theory.

Abstract: The classical approach to a posteriori error control considered in this paper bears on the counter variational principles of Lagrange and Castigliano. Its efficient implementation for problems of mechanics of solids assumes obtaining equilibrated stresses/resultants which, at the same time, are sufficiently close to the exact values. Besides, it is important that computation of the error bound with the use of such stresses/resultants would be cheap in respect to the arithmetic work. Following these guide lines, we expand the preceding results for elliptic partial differential equations and theory elasticity equations upon the problem of thin plate bending. We obtain guaranteed a posteriori error bounds of simple forms for solutions by the finite element method and discuss the algorithms of linear complexity for their computation. The approach of the paper also allows to improve some known general a posteriori estimates by means of arbitrary not equilibrated stress fields.

Abstract: Masonry is a complex multicomponent composite consisting of dissimilar materials (brick / stone and mortar). Masonry deformation process under loading depends on the mechanical characteristics of the basic composite materials, as well as of the parameters of the elements defining binding between brick and mortar being the interface elements. Traditional methods of masonry modeling are based on the use of generalized ("effective") mechanical properties of the composite as a continuant homogeneous continuant medium. This paper presents an overview and analysis of continuant masonry models adequately reflecting the process of elastic, and in some cases elastic-plastic masonry deformation within the composition of stone structural elements. The paper provides analysis of the experimental research results of masonry behaviour in a biaxial stress state at primary stresses of opposite signs; identifies masonry destruction mechanisms complying with the conditions of stress state. The work demonstrates the key role played by interface elements in the formation of masonry destruction processes. Based on destruction mechanisms deduced from experiments, there was developed a discrete model of masonry. A system of masonry strength criteria was proposed corresponding to the biaxial stress state conditions at primary stresses of opposite signs. For purposes of studying the elastic-plastic deformation and destruction of masonry, there was developed a technology of numerical experiment performance using calculation technologies with a stepwise tracking of stress-and-strain state, at step-by-step loading. The scope of this paper includes verification of modeling method and technology of numerical experiment at various parameters of interface elements defining binding between bricks and mortar.

Abstract: Cold formed steel members with edge stiffened holes are a new generation of cold formed members recently developed by the building industry. Very little research has been performed on such sections to determine their local and distortional buckling capacity. This article provides the numerical results of elastic local buckling analysis of cold-formed lipped channels with edge stiffened holes. For flexural elements values of critical buckling moments are calculated and the influence of hole spacing and diameter on elastic buckling capacity is determined.