Solid State Phenomena Vol. 236

Abstract: In this paper an analysis of the stress state of the hull of the ship Kormoran II loaded by non-contact mine explosion were performed. An empirical description of the pressure wave from the non-contact TNT explosion loads reported by authors such as RH Cole T. L. Geers and K.S. Hunter was used. The way of modeling the pressure wave using the acoustic medium implemented CAE programs was shown. The paper presents the results of pressure distribution on the hull of the ship Kormoran II at selected time points from TNT explosion under the keel of the ship. The paper presents detailed results of the stress state in the selected nodes, for example on the frame of main motor construction.

Abstract: Broadly understood technological progress, growth of the world's population and striving of individual countries for economic growth cause increased demand for energy. That energy is mainly obtained conventionally, from mineral fuels [16]. Limited fuel resources and high demand for fuels, which accompanies the increased demand for energy, result in continuous growth of fuel prices and, what it involves, the price of energy [6,16]. Another effect of the increased production of energy results is also the increased emission of combustion products which are harmful for the natural environment, mainly CO₂ and NO_x [6,9,10,]. Because of the above-mentioned factors, the importance of the assessment of energy efficiency, at the stage of energy production, distribution and end use as well as the problem of environmental protection gain more and more importance [4,5,15]. The idea of energy efficiency lies not only in energy conservation but also in finding ways for the present activities of producers and consumers to require reduced demand for primary energy expressed in tonnes of oil equivalent [3,7,13,14,17,19,21]. Energy companies must therefore respect a number of legal regulations concerning energy efficiency and environmental protection [3,4,5,15]. An energy company such as a cogeneration plant may achieve an improvement of energy efficiency mainly as a result of energy cogeneration itself but also as a result of improving the efficiency of internal processes (energy transformations) in the producing unit (in this case heating unit). Ensuring the maximum possible energy efficiency of the internal processes within the heating unit requires performing constant assessment of the entire unit and its components [7,11,12,13]. Even though energy cogeneration has been in use for a long time now [7,12,21], the problem of conducting a running energy efficiency assessment of the components of the heating unit still remains open [12].

Abstract: Paper presents the method for obtaining maximum contact pressure of Novikov gears. Described surface strength calculation method is based on Hertz theory of two bodies being in point contact. What’s more the influence of gear position errors on maximum contact stresses has been presented. Also the comparison of Hertz stresses for Novikov and involute gears has been made.

Abstract: The paper presents the dynamic behavior of gain for higher quality steel (armor) for the numerical simulation of fast processes, implemented in programs CAE, determined on the basis of results obtained from tensile tests of round samples conducted on the MTS testing machine type and rotary hammer, in terms of strain rate from 0,0001 to 500 s^-1 in tabular and equation JC. Posted simulation results armor penetration high quality steel bullet caliber 12,7 mm compared with experimental results.

Abstract: The main goal of this paper is, that if we want to correctly identify dynamic model of drive shaft made of carbon-epoxy composite, we must take into account the influence of deformation velocity on elasticity characteristic. In the paper, Authors showed the effect of passing shaft resonance (1st critical speed). It was shown in the conditions of acceleration and braking with different increases of rotational speed. When examining the results obtained with empirical and model research, it has been shown that in the structural design of carbon fiber drive shafts, the main factor affecting the right development of the structure should be dynamic criterion, since the only use of static criteria leads to big errors.

Abstract: The paper presents the results of investigations on mechanical properties and electrochemical potential distribution within arc welded (TIG) and friction stir welded (FSW) joints subjected to slow strain rate tests. The materials investigated were high-strength 7xxx series (7020 and its modification 7020M) aluminum alloys intended for shipbuilding. The objectives were joint quality assessment and comparison of the advantages of new FSW method with the traditional TIG methods commonly utilized in shipbuilding industry. Joint quality was evaluated based on mechanical investigations, hardness distribution tests and simultaneous electrochemical corrosion potential measurements at various locations within the welded joints.Initiation of corrosion processes on TIG and FSW joints was identified as a radical decrease in corrosion potential related to load followed by oxide layer cracking. Arc welded (TIG) joints of 7xxx series alloys undergo corrosion at lower values of tensile load applied as compared to the FSW joints. Superior mechanical properties and higher corrosion resistance of the FSW joints make this technology well-suited for joining high-strength 7xxx series alloys.

Abstract: The paper presents simulation studies, performed using Simulink, the impact of nonlinear flexural stiffness of shafts for critical speed range and amplitude of vibration. The tests were performed on the selected model of a rotating machine, consisting of a drive, two torsional vibration dampers, shaft with mounted on it two rigid rotors (discs), supported on a three self-aligning roller bearings and mechanical power receiver (brake). The machine startup and braking with crossing the critical states was simulated using specialized Simulink library, which was developed by authors for analysis of transient states in rotating machines and flexural-torsional couplings. In accordance with the concept of modeling adopted by the authors, rotating system is divided into inertial rigid elements (rotors, bearings, clutches, etc..) and compliance elements (parts of the shaft). The main component of the currently developed library is block modeling rigid rotor with 6 degrees of freedom and with the static and dynamic unbalance. By assumption the library is a modular, expandable and allows modeling the systems of any configuration. The goal of the simulation was to verify how nonlinear flexural stiffness of shaft influences the values of critical speeds and the level of flexural and torsional vibrations.

Abstract: This paper addresses a study undertaken to develop spatial numerical models of a piston, a piston pin and a connecting rod with reference to real components of a combustion engine crank system. The numerical studies conducted comprised an analysis of how the mechanical strength of piston pins was influenced depending on the change in their inner shape. For the purposes of calculations, various scenarios of shape modification were proposed for piston pins currently in use, enabling their weight to be reduced.

Abstract: The problem of damping of torsional vibrations of the crankshaft in a multi-cylinder engine is very important from the point of view of durability and reliability of the drive unit of the vessel or ship. Mostly dependent on the technical state of the torsional vibration damper that is located at the free end of the crankshaft. The paper presents selected results of the research that led to the acceptance criterion for assessing the technical condition of the viscous torsion damper.