Acta Mechanica Slovaca, 2011 (vol. 15), issue 1
Intelligent Design and Metrology for Higher Quality, Accuracy and Improving Production Efficiency
M. Numan Durakbasa, P. Herbert Osanna
Acta Mechanica Slovaca 2011, 15(1):6-11 | DOI: 10.21496/ams.2011.001 
Adequate knowledge in the areas of intelligent metrology and design are important presuppositions to achieve waste free production and low costs of manufacturing and accuracy at the same time within the sophisticated production systems. This is of extreme importance in present time of worldwide international competition in industry and production engineering and at the same time increasingly higher costs of energy and raw material. The prescription and consumption of material and energy to achieve the necessary and required workpiece accuracy in series manufacturing depends to a great extent from the (geometrical) workpiece tolerances of any kind (roughness,...
Evaluation of the Quality of the Renovation Layers Applied by Thermal Spraying Technology
Janette Brezinová, Anna Guzanová, Branislav Hadzima
Acta Mechanica Slovaca 2011, 15(1):12-21 | DOI: 10.21496/ams.2011.002
This contribution deals with research results focused on analysis of renovative layers applied by thermal spraying. There were two types of sprayed wires used - formerly used S-NiCro 80/20 and new cored wire marked DURMAT. Micro hardness of thermally sprayed coatings was measured by Vickers indenter, wear resistance of coatings was checked by erosion test, simulated by abrasive grit blasting. EDX analysis proved the presence of particular structural phases. Higher micro hardness values were found in DURMAT coating and this property led to higher wear resistance of this coating in comparison with previously used S-NiCro 80/20 coating. Test results showed...
Instantaneous Plastic Flow Properties of Thin Brass Sheets Under Uniaxial and Biaxial Testing
Feliks Stachowicz
Acta Mechanica Slovaca 2011, 15(1):22-27 | DOI: 10.21496/ams.2011.003
In the prediction of formability of sheet metals, it is necessary to determine material properties which are normally evaluated on the data obtained by performing simple tests. The most important parameters affecting the value of limit strains of a sheet metal are the strain hardening exponent (n) and plastic anisotropy ratio (r). It was established that especially the value of n-parameter of brass sheets strongly depend on the specimen elongation and stress/strain state. The effect of instantaneous (differential) nt - value and rt - value on the forming limit curve was computed theoretically.
Joining Car Body Steel Sheets Using the Clinching Method
Emil Spišák, Ľuboš Kaščák
Acta Mechanica Slovaca 2011, 15(1):28-35 | DOI: 10.21496/ams.2011.004
The paper deals with joining steel sheets for automotive industry using the clinching method. This method is a relatively new technique in joining car body sheets and it is beginning to find its place in the automotive industry as an alternative to resistance spot welding, especially in joining materials of different qualities or materials with different surface treatment. Combination of three hot-dip galvanized steel sheets: microalloyed steel sheet H220PD with the thickness of 0,8 mm, TRIP steel 40/70+Z100MBO with the thickness of 0,77 mm and drawing grade sheet DX51D+Z with the thickness of 0,9 mm were used for the experiments. The tensile test...
Wasteless Splitting of Metal Round Bars Basing on Cross-Wedge Rolling Process
Arkadiusz Tofil, Zbigniew Pater
Acta Mechanica Slovaca 2011, 15(1):36-43 | DOI: 10.21496/ams.2011.005
This paper presents research works on a new method of wasteless splitting of metal round bars. This method is connected with rolling on the bar circumference of a groove in the shape of letter V, and, later, on repeated rotary bending of the bar separate part, leading to the metal cracking. Special tools sets, in which a flat-wedged rolling mill LUW-2 used at the Lublin University of Technology was equipped with, were applied in the splitting process. A typical set includes: mounting, cutting knife and bending pad. Laboratory tests confirmed the effectiveness of the worked out splitting method. This process was also analyzed theoretically, basing on...
Curved rotary module for modular construction of motion structures
Jozef Svetlík, Peter Demeč
Acta Mechanica Slovaca 2011, 15(1):44-49 | DOI: 10.21496/ams.2011.006
The article deals with the mechanics of modular machines and examines in detail the parameters of the principle of joining newly designed curved rotary modules into homogeneous serial kinematical chain with five degrees of freedom of movement. The result of analysis is generated workspace built on the basis of 60° curved rotary module with unlimited rotation for a serial kinematical structure with homogeneous 5DOF.
Assessment of Cutting Area Temperature to the Face Milling using Several Cooling Methods
Domnita Florina Fratila
Acta Mechanica Slovaca 2011, 15(1):50-55 | DOI: 10.21496/ams.2011.007
This paper analyzes the temperature variations in the cutting zone under flood cooling (FC), near dry machining (NDM) and dry cutting (DC) conditions. The research compares the dual effects of air-oil mixture in near-dry machining with the cooling effect to dry cutting and flood cooling in terms of the reduction of cutting temperature through the cooling effect, as well as the reduction of heat generation through the lubricating effect to face milling.
Determination of Forming - Limit Diagrams Considering Various Models for Steel Sheets
Ján Slota, Emil Spišák
Acta Mechanica Slovaca 2011, 15(1):56-62 | DOI: 10.21496/ams.2011.008
In this paper a comparative investigation of three mathematical models (Marciniak - Kuczynski model, Swift-Hill model and Sing-Rao model) as well as on an empirical model proposed by the North American Deep Drawing Research Group (NADDRG) has been carried out. The yield criterion proposed by Hill is used for the calculation of the limit strains in connection with the Swift's instability condition for diffuse necking and by using the Marciniak - Kuczynski analysis. The emphasis of this investigation is to consider these different approaches to predicting the FLD. Experimental results has been carried out for low carbon steel sheets of drawing quality...
Actuators Placement for Active Damping of Vibration on Two Dimensional Clamped Plate
Peter Šolek, Martin Horínek
Acta Mechanica Slovaca 2011, 15(1):64-69 | DOI: 10.21496/ams.2011.009
This article deals with the investigation of optimal actuator placement for two dimensional systems. In this article the two dimensional system is represented by a clamped plate. The intention of optimal actuator placement is to place actuators in minimal number of actuators to ensure controllability of the system. In this article is compared placement of force actuators and piezoelectric actuators. The approach proposed in this article is based on the evaluation of the H2 and H∞ norms. The optimal actuator placement satisfies the condition of controllability.
Increasing of Power Output of Racing Motorcycle Engine using of Exhaust System Optimisation
Peter Bigoš, Michal Puškár
Acta Mechanica Slovaca 2011, 15(1):70-77 | DOI: 10.21496/ams.2011.010
An exhaust gas system of a two-stroke piston combustion engine has a significant impact on its maximal power output and speed characteristics. In the first part of this paper there is described an impact of the exhaust gas pipeline system on the output speed characteristics. In the second part is analysed a relation between temperature of exhaust gases and speed characteristics, as well as there is determined an optimal temperature for achievement of the best output characteristics. Results presented in this paper enable to optimise curve of the speed characteristics for application in various kinds of single-track vehicles.
The Boundary States Investigation of the Proportional Loaded Materials Using the Multiaxial Strength Criteria
Jan Fuxa, František Fojtík
Acta Mechanica Slovaca 2011, 15(1):78-84 | DOI: 10.21496/ams.2011.011
The contribution describes the experimental results obtained from the combined loading of the specimens in the field of high-cycle fatigue. Those specimens were manufactured from common construction steel 11523.The following experiments were performed: The first set of the specimen was loaded by the alternating torque amplitude. The second set was loaded by the alternating amplitude of the bending moment. The next set was loading by alternating amplitude of the torque and bending moment. This experiment was performed for two loading levels applied in the same phase. The results were evaluated by the conjugated strength criterion and another generally...