Acta Mechanica Slovaca, 2011 (vol. 15), issue 2

Impact Force Reconstruction for Structural Health Monitoring of Composite Beam

Vladislav Laš, Tomáš Kroupa, Jan Bartošek, Robert Zemčík

Acta Mechanica Slovaca 2011, 15(2):6-12 | DOI: 10.21496/ams.2011.012  

Reconstruction of the impact force history and identification of the impact location are important tasks in structural health monitoring (SHM) applications, namely in case of composite structures. These tasks are critical especially in cases, when it is not possible to measure the impact force directly and the knowledge of the intensity and position of loading force is necessary for the damage prediction of the structure. This paper tests two methods for the reconstruction of impact force and identification of impact location. The first method uses finite element analysis (FEA) for determination of a transfer matrix of a system. The second method uses...

Using of Program Mezvyna for Measurement of Residual Stresses to Solving Practical Problems

František Trebuňa, Patrik Šarga

Acta Mechanica Slovaca 2011, 15(2):14-20 | DOI: 10.21496/ams.2011.013  

The hole-drilling method has wide application in solving of various tasks resulting from practice. On the Department of Applied Mechanics and Mechatronics of Technical university of Košice were solved many problems on the basis of contracts on which we could verify our theoretical knowledge from the area of determination of residual stresses. The paper is devoted to using of program MEZVYNA (Šarga, 2005) to determination of residual stresses by the hole-drilling method. The program was developed on the above-mentioned department.

From Partial Factors Design to the SBRA Probabilistic Method

Plánička František, Šolc Martin, Marek Pavel

Acta Mechanica Slovaca 2011, 15(2):22-27 | DOI: 10.21496/ams.2011.014  

Two decades ago, a computer revolution made available personal computers to all designers of load carrying structures. Through proposing and gradual improving of the probabilistic method SBRA (Simulation Based Reliability Assessment), significant adjustment of the assessment of structural safety, serviceability and durability is assured. The probabilistic approach and simulation technique have introduced new definitions of loads, achieving a higher precision for their combinations and allowing to consider multicomponent problems. The very essence of the SBRA method consists in repeated calculations of relatively simple equations, where input variables...

Porous Sound Absorbers and Determination of their Acoustical Properties

Lumnitzer Ervin, Badida Miroslav, Bilová Monika

Acta Mechanica Slovaca 2011, 15(2):28-32 | DOI: 10.21496/ams.2011.015  

One of the most frequent problems faced by noise control engineers is how to design sound absorbers that provide the desirable sound absorption coefficient that minimizes the size and cost, does not introduce any environmental hazards, and stands up to hostile environments. The designers of sound absorbers must know how to choose the proper sound absorbing materials, its geometry and the protective facing. Porous sound-absorbing materials are utilized in almost all areas of noise control engineering. This paper deals with the acoustical parameters of porous materials and their measurement.

Fatigue Behaviour of Laser Machined Aluminium Alloy 2024-T3

Růžička Milan, Doubrava Karel, Vargas Miguel, Kramberger Janez

Acta Mechanica Slovaca 2011, 15(2):34-40 | DOI: 10.21496/ams.2011.016  

The advantages offered by the laser technology to cut materials are very attractive for the manufacturing industry. This is due to its versatility and to the fact that they can be faster and cleaner than conventional machining techniques, leaving edges with a high quality surface finish. Nevertheless, this technology cuts the material either melting it, vaporizing it away or blowing it away by a jet of gas. It causes changes on and around the cut off zone and therefore changes in the mechanical response for the whole part. Geometric microstructure of the cut surface content micronotches, where fatigue cracks can nucleate. Considering this, the study...

Desing of Dual Phase Steel Sheets for Auto Body

Evin Emil

Acta Mechanica Slovaca 2011, 15(2):42-48 | DOI: 10.21496/ams.2011.017  

This paper outlines the considerations of strength and energy absorbing car body by applying mechanical properties of steel sheets with higher strength properties. Good combination of strength and ductile properties of dual-phase steel helps reduce weight and improve crash safety body. High-strength dual-phase steels have better deep-drawing capacity and stretching capacity compared to microalloyed at the same strength. Dual phase steel sheet have comparable streching capacity but poorer deep drawing capacity than DC04. Measured values LDR and FLD0 have to serve engineers who haven't experience with application of high strength steel sheets for car body.

A FEM Analysis of Cross-Wedge Rolling of Toothed Shafts

Zbigniew Pater

Acta Mechanica Slovaca 2011, 15(2):50-58 | DOI: 10.21496/ams.2011.018  

This paper presents a new concept for forming toothed shafts based on the cross-wedge rolling process (CWR). This method consists in using special inserts in the shape of flat rack bars, which, acting on a billet, extrude material from tooth spaces to tooth points. These inserts are placed at the finish end of a wedge tool. Numerical calculations (based on FEM) and experimental rolling tests unequivocally demonstrate the effectiveness of the proposed method for forming spur (straight-cut), helical, curved and herringbone gear teeth.

The Model of Topological Relations-Relation Between Two Constructed Equipment

Kováč Jozef, Knežo Dušan, Ižaríková Gabriela

Acta Mechanica Slovaca 2011, 15(2):60-69 | DOI: 10.21496/ams.2011.019  

Application of topological models for automated planning of sub-assembled systems is a new trend in design process. The paper deals with mathematical models of topological relations between distributed constructed equipments of assembled systems.

Computer Simulations of the Static State of the Turbocharger Turbine

M. Mseddi, Z. Driss, M. Baccar, M. S. Abid

Acta Mechanica Slovaca 2011, 15(2):70-78 | DOI: 10.21496/ams.2011.020  

In the present work, a numerical study of a turbulent flow through a turbocharger turbine in a static state is presented. Solutions of the time averaged Navier-Stokes in conjunction with the standard k-f turbulence model were developed using a control volume discretization method. The resolution was found by the commercial code Fluent 5.6. Geometry and the meshing were built by the software Gambit 6.1. This study is expected to provide a finer knowledge of structures of the flow such as velocity, pressure, turbulent kinetic energy, dissipation rate of the turbulent kinetic energy and viscosity. The proposed model has been tested on a turbocharger turbine...

Identification of Structure of Hydro-Erosion Operation

Spišák Emil, Badida Miroslav, Kmec Ján, Sobotová Lýdia

Acta Mechanica Slovaca 2011, 15(2):80-86 | DOI: 10.21496/ams.2011.021  

The automation of hydro-erosion manufacturing processes comes to increase the demands on engineering works in the preparation of production, at shortening of deadlines for implementation of scientific knowledge into practice, at the design of production processes and at the economization in production processes. This process is associated with extensive utilisation of mathematical methods, using of computational procedures for specific tasks and at the utilisation of methodology of mathematics for methods of formulating solutions. During the solving of problem, there is mostly used: operational analysis, set theory, theory of structures, theory of...