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Trebuňa František, Bocko Jozef, Pástor Miroslav, Lengvarský Pavol and Prada Erik

Abstract

The paper deals with design and computation of precise positioning mechanism. The aim of mechanism is to transfer applied load without any change of position of parts in question. The stabilization of position is assured by elastic elements connected to reductor which is adjusted into correct position by an actuator. The functionality of mechanism and its stiffness and strength characteristics were checked by the finite element method. The computations were accomplished for prescribed displacement of reductor. On the base of this type of loading the behaviour of the structure was evaluated.

Open access

Vizi Máté Benjámin and Stépán Gábor

Abstract

Traditionally, the Furuta pendulum was used for testing advanced control strategies on a simple nonlinear and underactuated structure. In this paper, we investigate analytically and experimentally the dynamical description of the Furuta pendulum focusing on the effect of dry friction on a special bifurcation behaviour of the downward equilibrium position.

Open access

Cross-Coupled Heat and Moisture Transport Part 2/1: Applications in Mechanics

Electrical Analogy – Analytical Solution – Experiments

Szekeres Andras and Fekete Balazs

Abstract

Based on the theory laid down in the Part 1 [1] in this paper we are going to display applications in physics and especially in mechanics. After a short summary on coupled fields in mechanics, we generally analyze the analogies in mechanics. As the most important, the electrical analogy is discussed in details. By the electrical analogy based analytical solution we display the results of the coupled thermo-hygro problem with second sound. Finally, a few experiments are discussed, eg. experiments by electrical analogy, experiment on diffusivities, experiment on relaxation time, experiment on hydroglobe. This latter one leads to the engineering application of the problem.

Open access

Tůma Jiří, Šuránek Pavel and Žiaran Stanislav

Abstract

The problem of active vibration control of weakly damped mechanical structures is potentially unstable modes of vibrations due to the positive feedback for some vibration modes. The paper will discuss the change of positive feedback on the negative one using all-pass discrete-time filters. These filters can be arranged in a cascade to stabilize many potentially unstable modes. The piezoelectric actuator as a source of force is used to damp vibration.

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

Štefan Gužela and František Dzianik

Abstract

There are the various types of heat exchangers. The selection of the heat exchanger right type is the first basic assumption for its optimal operation. The heat exchanger calculation itself is another prerequisite for its optimal operation. This article deals with the variables which are usually used to describe the stationary operation of any recuperative heat exchanger with two incoming and two outgoing streams. The knowledge of these variables, including the facts resulting from them, is necessary not only from the point of view of the calculation but also from the point of view of the evaluation of the experimental data of any heat exchanger. The variables values needed for the calculation of heat exchangers, so-called key variables, must always fall within the values range determined on the basis of generally valid knowledge about heat exchangers. The article also deals with the determination of the limit values defining the values range of these key variables.

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

Saha Sabhasachi, Roy Koushik, Roy Souvik, Rahman Md. Asfakur and Hasan Md. Zahid

Abstract

In the present world, nuclear energy is a must need for various purposes. The main cause of nuclear energy is because of the increasing energy demand, which is not possible to provide by using convenient energy generation. Bangladesh is a lower income country and the energy sector is not so developed here though there is a very high demand for energy. Rooppur Nuclear Power Plant is the only one nuclear generation plant which can provide this kind of huge energy within a very short time. This paper mainly depicts the ins and outs of this plant and discusses it’s feasibility in Bangladesh. It also focuses on the worlds various power generation methods and comprises it with nuclear energy generation. A detailed technical brief is presented in this paper along with advantages, location selection, financial and environmental impacts. This will help researchers to do further researches about nuclear energy in Bangladesh.