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Open access

Miroslav Pástor, Peter Frankovský, Martin Hagara and Pavol Lengvarský

Abstract

Anchoring parts of technical systems are often damaged due to the heavy forces acting on these systems during their operation. For that reason, various modifications are suggested and created on the anchoring screws, which should help to reduce the mechanical stress values in a place of the first load-bearing thread of a female screw. For the determination of stress fields on the surface of a plane model of a threaded joint, two non-contact optical methods were used – conventional transmission photoelasticimetry and modern digital image correlation.

Open access

Stefan Segla

Abstract

The paper deals with static balancing of various kinds of mechanisms and manipulation devices using spring balancing mechanisms. In case of parallelogram robots and manipulation mechanisms a spring balancing mechanism exerting a constant force is used. Problems of static balancing of variable payloads are also presented and investigated in the paper. Static balancing is formulated as an optimization problem with the objective function expressing minimization of the forces acting in the driving joints. As design variables geometrical variables and spring stiffnesses and their unloaded lengths are used. Optimization Toolbox for Use with Matlab and GOOD (Generator Of Optimal Designs) are used to solve the static balancing problems. The optimized mechanisms are evaluated by using multibody dynamics programs taking into account friction effects in mechanism joints. The results of static balancing optimization show essential reduction of the gravity load in drive joints and consequently driving forces with important energy savings.

Open access

Ivan Virgala, Tomáš Lipták and Ľubica Miková

Abstract

In the paper the locomotion of snake robot is introduced considering locomotion in straight and curved pipe. For the straight pipe locomotion was designed traveling wave locomotion pattern with sine-like wave which expands from rear of the robot to its front. For the locomotion in curved pipe was designed approach which is based on inverse kinematic model including besides primary task also secondary tasks, namely kinematic singularities avoidance task, obstacle avoidance task and joint limit avoidance task. For final inverse kinematic model was used approach of weight matrices by which can be stated the priorities of particular tasks. Both case studies were tested by experimental snake robot in order to verify introduced methodology for locomotion in the straight and curved pipe.

Open access

Michal Kelemen, Alexander Gmiterko and Darina Hroncová

Abstract

The paper deals with bristled in-pipe machine simulation. Simulation model is developed and experimentally identified properties are added into the model to achieve high coincidence of the model with real machine. Simulation gives the answers to some selected problems.

Open access

Pavel Élesztős, Roland Jančo and Vladimír Voštiar

Abstract

Welding is a complex technological process in which local heating takes place up to the melting point of the connecting and the additional material. Phase and crystallization processes are a strong non-linear function of the cooling rate. This non-linear function multiplies the complexity of the numerical simulation and optimization of the welding process. Lately, optimization with genetic algorithm has become the trend to optimize systems that behave in a non-linear manner and contain a number of local extremes. Genetic algorithm is therefore a method by which we seek an absolute extreme. It is a method which seeks a solution to near absolute extreme. In this paper the use of the genetic algorithm for welding process optimization is described.

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

Justín Murín, Mehdi Aminbaghai, Vladimír Goga, Vladimír Kutiš, Juraj Paulech and Juraj Hrabovský

Abstract

In this paper, results of numerical simulations and measurements are presented concerning the non-uniform torsion and bending of an angled members of hollow cross-section. In numerical simulation, our linear-elastic 3D Timoshenko warping beam finite element is used, which allows consideration of non-uniform torsion. The finite element is suitable for analysis of spatial structures consisting of beams with constant open and closed cross-sections. The effect of the secondary torsional moment and of the shear forces on the deformation is included in the local finite beam element stiffness matrix. The warping part of the first derivative of the twist angle due to bimoment is considered as an additional degree of freedom at the nodes of the finite elements. Standard beam, shell and solid finite elements are also used in the comparative stress and deformation simulations. Results of the numerical experiments are discussed, compared, and evaluated. Measurements are performed for confirmation of the calculated results.

Open access

Milan Žmindák

Abstract

In this paper the concept of generalized form of proportional damping is proposed. Classical modal analysis of non-conservative continua is extended to multi DOF linear dynamic systems with asymmetric matrices. Mode orthogonality relationships have been generalized to non-conservative systems. Several discretization methods of continua are presented. Finally, an expression for derivatives of eigenvalues and eigenvectors of non-conservative system is presented. Examples are provided to illustrate the proposed methods.

Open access

Peter Frankovský, Oskar Ostertag and Ingrid Delyová

Abstract

In the article we show the possibility of distorting the results of the experiment by photoelasticity path, in case the isochromatic fringe patterns are recorded by the camera. The recording of the color spectrum may be distorted by inappropriate selection of the recording medium, which is reflected by different types of aberrations. Transferring a record to a computer allows you to automate the experiment process, thus saving time to work with isochromatic fringes. As an example, we present the experimental determination of the stresses of the rotor with a symmetrical arm. The analysis was performed using software developed by the authors. This software enables full automation of the experiment process. The rotor is investigated by the method of reflection photoelasticity. The experimental solution is realized as a case of periodically repeating dynamic effects, in which a stroboscopic source of white light is needed. The results of the experiment are compared with the numerical solution and their dependence is represented by diagram.

Open access

Jozef Bocko, Roland Jančo and Branislav Hučko

Abstract

The article deals with the contribution of Dr.h.c. mult. prof. Ing. František Trebuňa, CSc to the field of engineering. Born in 1947, he studied and subsequently remained at the Faculty of Mechanical Engineering, Technical University of Košice since 1965. Under his leadership 25 dissertation theses were defended in the study programs Applied mechanics, Mechatronics and Forensic engineering. He is author to 14 monographs, 16 textbooks, 5 other books, 12 university textbooks and more than 350 original scientific papers published in domestic and foreign journals and conference proceedings. Professor Trebuňa is currently the dean at the faculty and is known as a gifted educator.