Volumen 8 (2014): Heft 1 (March 2014)

The present paper describes modern methodology of the bevel gear design with a particular focus on issues concerning the theoretical basis and the preparation of the numerical simulation of the machining. The assumptions used in developing the mathematical model of cutting teeth are given and an example of the teeth flank surfaces of a gear and a pinion resulting from the virtual processing is shown. The correctness of the mathematical model of cutting teeth was verified by comparing the resulting based on the model grid points, the side of the tooth surface, resulting from the simulation cutting teeth in CAD. A high convergence of the two surface geometry was demonstrated, which allows for the use of the analysis for each of the models independently.

According to lots of books, the pressure in offset printing affects the optical density and the quality of printouts. One of the quality parameters is a tone value increase. An advantage of our research method is obtaining printing effects for different pressures on one printout, thus meaning for identical printing conditions. We obtained the same printing conditions through using different amounts of underlay sheets fixed to the blanket cylinder, under a blanket. The pressure was increased from optimal settings - in accordance with the machine manufacturer’s recommendation. The test printouts were printed using Adast Dominant 515, on a coated and an uncoated paper. The optical density value was measured on the tone value scale from 10% to 100% stepping regularly by 10%. For this scale the tone value increase was computed. The research shows that for both types of paper the optical density and the tone value increase changes not very much above the optimal pressure recommended by the machine manufacturer. A difference in the optical density and in the tone value increase is bigger for coated paper than for uncoated paper. Changes in these two parameters are negligible in places where used form 0 to 4 underlay sheets and are quite significant in the place where 5 underlay sheets were.

The paper presents the strategy for identifying the shape of defects in the domain defined in the boundary value problem modelled by the nonlinear differential equation. To solve the nonlinear problem in the iterative process the PIES method and its advantages were used: the efficient way of the boundary and the domain modelling and global integration. The identification was performed using the genetic algorithm, where in connection with the efficiency of PIES we identify the small number of data required to the defect’s definition. The strategy has been tested for different shapes of defects.

In this contribution an influence of random contrast patterns creation on the quality of the obtained results of experimental modal analysis performed by high-speed digital image correlation is described. Three common forms of random pattern creation were investigated. While the first form was presented by the black speckles printed on white matt vinyl foil and bonded on the sample surface, in the second and the third case, respectively, the black speckles were sprayed on white sprayed sample surface or on paint white one. For the purposes of modal parameters estimation in the form of natural frequencies, mode shapes and damping ratios the program called Modan3D, developed in the authors department, was used. The results obtained by Modan3D were compared with the results achieved by system Pulse specialized for vibration analysis.

The submitted article deals with the evaluation of the somatotype of persons and determination of a suitable somatotype for selected sports. In the introduction the method for determining and evaluating a somatotype according to Carter and Heath is characterised. The processes used for calculating the individual components - endomorphy, mesomorphy, ectomorphy - are presented as well as a description of these elements. The calculated components are subsequently put into a somatograph. The evaluation of a somatotype is of great benefit and offers a guideline with the selection of sporting activities; it subsequently helps assign athletes into a suitable position where they will be able to best develop their talents in view of their bodily construction. In this work two types of sports are evaluated - basketball and bodybuilding. With each sport the measurements which give the prerequisites for the given sport are presented. The selection of the presented sports was made with regard to the different requirements and demands in the scope of bodily constitution. The aim of the presented paper is to assess physical parameters of subjects groups in relation to selected sports (basketball and bodybuilding). Based on the body constitution to determine the conditions for developing the physical condition and success in the appointed sports. Another objective is to compare the rating form and equation methods for somatotype determination. The sample consist 32 subjects with age between 22-28 years of both sexes, who are dedicated to basketball, or bodybuilding at amateur level.

The three-dimensional problem of elasticity concerning inhomogeneous half-space under normal and tangential loading applied in circular region was considered. The half-space is composed of the homogeneous body and double-layer coating which includes a homogeneous top coat and a gradient interlayer. The solution method is based on the two-dimensional integral Fourier transform. The influence of mechanical properties of coatings component and coefficient of friction on the first principal stress distribution was considered.

In this paper, a mathematical model of electromechanical transduction of Ionic Polymer-Metal Composites is presented. The aim of the research was to create a physics-based, geometrically scalable model to use in control systems. The relation between actuating voltage and the tip displacement was described with a transfer function. The model is derived from the basic physical properties of researched materials. To calculate the final transfer function, two impedance models are considered - with and without neglecting the resistance of the metal electrodes. In this paper, the model with non-zero electrode resistance is calculated. Later, the model is simplified (taking the physical properties into account) and the numerical values based on the parameters of the samples are calculated. The simplifications allow the model to predict the response to low-frequency sine wave actuation. The frequency-domain characteristics of the samples were created experimentally and compared to the model. The results have proven the accuracy of the model.

The increasing application of composite materials in the construction of machines causes strong need for modelling and evaluating their strength. There are many well known hypotheses used for homogeneous materials subjected to monotone and cyclic loading conditions, which have been verified experimentally by various authors. These hypotheses should be verified also for composite materials. This paper provides experimental and theoretical results of such verifications for bimaterial structures with interfacial cracks. Three well known fracture hypotheses of: Griffith, McClintock and Novozhilov were chosen. The theoretical critical load values arising from each hypotheses were compared with the experimental data including uni and multi-axial loading conditions. All tests were carried out with using specially prepared specimens of steel and PMMA.

Intermetallic-based alloys (so called intermetallics) of the Fe-Al binary system are modern construction materials, which in recent decades have found application in many branches of the power, chemical and automotive industries. High resistance of FeAl based alloys to cavitational erosion results first of all from their high hardness in the as-cast state, large compressive stresses in the material, as well as homogeneous structure. In the present paper, the effect of aluminum content on the microstructure, texture and strain implemented upon cavitation wear of FeAl intermetallic alloys, have been analyzed by field emission gun scanning electron microscopy (FEG SEM) and electron backscatter diffraction (EBSD) analysis. Obtained results of structural characterization indicates that with increasing aluminium content effects of orientation randomization (weakening of <100>//ND casting texture), grain refinement and rising of mechanical strenght (and so cavitational resistance) take place.

The paper presents the issue of a knife proof ballistic package. This issue was emphasized since most of modern vests are designed to match the threat posed to them only by firearms. There was observed negligence of protection against melee attacks. There is, thus, a need to develop a research methodology in this matter, because it is a valid and necessary problem in a modern developed society. The aim of this study was to perform a numerical model which simulated the phenomenon of penetration of a ballistic package by an engineering blade. Specification of an engineering blade was taken from standard NIJ Standard-0115.00. Commercial software LSDYNA was used to carry out the analysis.