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Open access

M. Drusa and J. Vlcek

Abstract

In the case of realized geotechnical monitoring (GTM) of reinforced retaining wall in difficult geological conditions is demonstrated the important role at realisation of transport infrastructures, which are often realized in insufficient quality due to inappropriate geotechnical parameters from survey works or not fitted well design of structure at certain conditions. This can result in large deformations of structure, or losing stability or structure life-time is very limited and remediation work is complicated and expensive. There was built on the modernized railway line Bratislava – Trenčín, closed to Zlatovce, overpass and connected road embankments on the route of first class I/61. Structure was designed as a bridge over the railway track before the northern portal of the railway tunnel Turecký vrch was open. A part of the embankment and overpass was a retaining wall reinforced by geosynthetics. The results of the geotechnical monitoring of this wall were afterwards simulated using finite element method (FEM) and results of this comparison are the scope of this article.

Open access

Piotr Szewczyk and Maciej Szumigała

Abstract

The paper presents exemplary static equilibrium paths of an element strengthened while under load. A steel-concrete composite beam was analyzed. The study discusses the effect of strengthening method, initial load values, welding stress, concrete shrinkage and introduction of additional control of distortion state on the course of static equilibrium path. Results calculated in numerical FEM simulation were verified with experimental data and were found to be consistent.

Open access

Martin Magura

Abstract

Gas pipelines pass through different topographies. Their stress level is influenced not only by gas pressure, but also by the adjacent soil, the thickness of any covering layers, and soil movements (sinking, landslides). The stress level may be unevenly spread over a pipe due to these causes. When evaluating experimental measurements, errors may occur. The value of the resistance reserve of steel can be adjusted by a detailed analysis of any loading. This reserve can be used in the assessment of a pipeline’s actual state or in reconstructions. A detailed analysis of such loading and its comparison with the simple theory of elasticity is shown in this article.

Open access

P. Chyła, Z. Pater, J. Tomczak and P. Chyła

Abstract

This paper presents the research results of the balls rolling process according to the conventional and modified methods of rolling. Theoretical analysis was carried out by using numerical methods based on the Finite Element Method. The Simufact package version 10.0 were used for calculation. Simulations of balls rolling were carried out under conditions of 3D state of strain, taking into account the effect of thermal conditions occurring during forming. The study of the achieved results showed that the best rolling process parameters were obtained for the modified method, in which the feed material is heated up to 1150 °C. In this case, the rolling parameters such as: rolling force and torque as well as tool wear reached the smallest values.

Open access

Bartłomiej Żyliński

Finite element local analysis of wave slamming on offshore structure

Offshore platforms are exposed to waves slamming event. Waves hitting the columns with a high velocity are in many cases the design criteria for column structure. This paper focuses on the analysis of wave slamming on floating platform column. Significant for wave slamming pressure is load history, which is usually based on model test. Wave slamming loads were defined on all four walls of column to assess the worst place. For south wall of column three positions exposed to slamming loads between elevation 21.000 (SWL) and elevation 35.500 were checked. Dynamic analysis has been performed with nonlinear FEM program ABAQUS/explicit. The steel was modeled as an elastic-plastic material with isotropic hardening.

Open access

M. Repka, J. Sládek, V. Sládek and M. Wünsche

Abstract

The finite element method (FEM) is developed for coupled thermoelastic crack problems if material properties are continuously varying. The weak form is utilized to derive the FEM equations. In conventional fracture theories the state of stress and strain at the crack tip vicinity is characterized by a single fracture parameter, namely the stress intensity factor or its equivalent, J-integral. In the present paper it is considered also the second fracture parameter called as the T-stress. For evaluation of both fracture parameters the quarter-point crack tip element is developed. Simple formulas for both fracture parameters are derived comparing the variation of displacements in the quarter-point element with asymptotic expression of displacement at the crack tip vicinity. The leading terms of the asymptotic expansions of fields in the crack-tip vicinity in a functionally graded material (FGM) are the same as in a homogeneous one with material coefficients taken at the crack tip.

Open access

Pavel Kraus, Juraj Úradníček, Miloš Musil and Michal Bachratý

Abstract

The evaluation of disk brake squeal is nowadays performed using Finite Element Model. In this standard procedure the thermal effects are omitted. The omission is done because of long computing time of fully coupled brake system thermo-structural transient analysis. This paper is presenting an effective uncoupled thermo-structural FEM procedure. This method is applied on a pin-on-disc system and its time effectiveness is compared to standard full coupled transient analysis.

Open access

A. Tofil, J. Tomczak and Z. Pater

Abstract

The paper describes cross wedge rolling with upsetting, a process in which axially symmetric parts with steps whose diameters are larger than billet diameters can be formed. Taking advantage of numerical modeling, the effect of such basic geometric parameters of the rolling process as the spreading angle, forming angle, reduction ratio, and rolling length on upsetting (defined by the diameter increase ratio) was determined. The paper also presents the results of experimental tests performed to roll a stepped shaft whose one step had a diameter half as large as that of the billet.

Open access

N. Nikolov, T. Avdjieva and I. Altaparmakov

Abstract

Some specially designed metallic alloys crystallize during process of rapid quenching which aims their amorphization. Nevertheless, change in their mechanical properties could be seen compared to these obtained during conventional technological regimes of cooling. That attracts the attention in this elaboration. Full 3-D numerical simulations of nanoindentation process of two material models are performed. The models reflect equivalent elastic and different plastic material properties. The plastic behaviour of the first one is subjected to yield criterion of Dracker-Prager and this of the second one to yield criterion of Mises. The reported numerical results depending on the nanoindentation scale length of 1000 nanometers, suggest different adequacy of the two yield criteria to the data obtained experimentally with a Zr-Al-Cu-Ni-Mo alloy. It could be speculated that the different effects developed depending on the indenter travel of 1000 nanometers and taken into account in the two yield criteria stand behind this fact and determinate three structural levels of plastic deformation.

Open access

Milan Sokol, Petra Velísková, Ľuboš Rehák and Martin Žabka

Abstract

The aim of the work is oriented towards the simulation or modeling of the lumbar and thoracic human spine as a load-bearing 3D system in a computer program (ANSYS). The human spine model includes a determination of the geometry based on X-ray pictures of frontal and lateral projections. For this reason, another computer code, BMPCOORDINATES, was developed as an aid to obtain the most precise and realistic model of the spine. Various positions, deformations, scoliosis, rotation and torsion can be modelled. Once the geometry is done, external loading on different spinal segments is entered; consequently, the response could be analysed. This can contribute a lot to medical practice as a tool for diagnoses, and developing implants or other artificial instruments for fixing the spine.