Wyniki wyszukiwania - BazTech

1

Evaluation of geometrical influence on the hydrodynamic characteristics and power absorption of vertical axisymmetric Wave Energy Converters in irregular waves

Zhang Wanchao, Zhu Yang, Liu Shuxu, Wang Jianhua, Zhang Wentian

Polish Maritime Research

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2023

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nr 2

130--145

EN

To obtain the mechanical energy of waves from arbitrary directions, the vibration absorbers of wave energy converters (WEC) are usually vertically axisymmetric. In such case, the wave-body interaction hydrodynamics is an essential research topic to obtain high-efficiency wave energy. In this paper, a semi-analytical method of decomposing the complex axisymmetric boundary into several ring-shaped stepped surfaces based upon the boundary approximation method (BAM) is introduced and examined. The hydrodynamic loads and parameters, such as the wave excitation forces, added mass and radiation damping of the vertical axisymmetric oscillating buoys, can then be achieved by using the new boundary discretisation method. The calculations of the wave forces and hydrodynamic coefficients show good convergence with the number of discretisation increases. Comparison between the constringent results and the results of the conventional method also verifies the feasibility of the method. Then, simulations and comparisons of the hydrodynamic forces, motions and wave power conversions of the buoys with series draught and displacement ratios in regular and irregular waves are conducted. The calculation results show that the geometrical shape has a great effect on the hydrodynamic and wave power conversion performance of the absorber. In regular waves, though the concave buoy has the lowest wave conversion efficiency, it has the largest frequency bandwidth for a given draught ratio, while in irregular waves, for a given draught ratio, the truncated cylindrical buoy has the best wave power conversion, and for a given displacement of the buoy, the concave buoy shows the best wave power conversion ability.

2

Numerical thermo-mechanical strength analysis of an IC engine component

Ali M. A. N., Hussein R. A., Hussein H. A.

International Journal of Applied Mechanics and Engineering

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2021

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Vol. 26, no. 3

1--11

EN

This research investigates a thermo-mechanical strength of three geometrical shape designs of an internal combustion (IC) engine piston by a finite element analysis (FEA). FEA was performed using Solidworks software for modelling geometrical piston designs, and the models were imported into ANSYS software for thermo-mechanical fatigue simulation. The work focused on predicting high stress intensity and indicated the fatigue critical regions and life of the piston shape design. AL7075-T6 aluminium alloy was used as a piston material and thermo-mechanical fatigue simulation was conducted based on the experimental stress-number of cycles recorded data from literature. Analytical results showed the similarity of the critical failure positions to some real failures in the IC engine piston, and the shape design modification of the piston. Hence, this concept can be used to satisfy the IC engine design needs at low cost.

3

Podejmowanie decyzji o postaci geometrycznej podczas projektowania części maszyn

Kołodziej A., Dudziak M.

Mechanik

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2010

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R. 83, nr 1/S

94-101

PL

Wykazano potrzebę jednoznacznego oraz spójnego języka komunikacji pomiędzy konstruktorem a inżynierami: wytwarzania, pomiaru i eksploatacji podczas projektowania i opisu geometrycznych cech konstrukcji. Na przykładzie specyfikacji tolerancji okrągłości średnicy zewnętrznej sworzni wykazano potrzebę doskonalenia wymiarowania i tolerowania z uwzględnieniem wytycznych co do metody i strategii pomiaru oraz zdefiniowania poszczególnych jego czynności.

EN

There was analysed technical record in technical documentation of axialsymmetrical elements applied in aeronautical engineering. On the basis of construction of pins there was pointed out that measurement and verification of geometrical shape quality of elements, which are manufactured according to criterion of form deviation - roundness, have not a formal definition and documentation for applied measurement methodology. There was showed that during conducting some measuring procedures of roundness deviations there are taken subjective criteria for measurement and estimation of achieved results. On the basis of selected examples of measurement of geometrical form of diameter and roundness deviations there were given reasons of discrepant results obtaining, which were caused by variable parameters of measurement.

4

Numerical simulation of aluminium extrusion with a Lagrangian FEM code

Aukrust T.

International Journal of Applied Mechanics and Engineering

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2002

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Vol. 7, no 1

157-171

EN

The demands from the extrusion market are constantly evolving towards tighter geometrical tolerances. Simulation models that with sufficient accuracy describe the flow in the container and die, as well as the deflection after exit will therefore become important tools to understand how to avoid geometrical deflection and shape variations. From a simulation point of view the extrusion process is very challenging as it involves large reduction ratios, friction in the bearing channel region and complex deformations after the exit. While Eulerian codes are ideal for studies of flow and temperature evolution in the container and die, Lagrangian FEM codes are more suitable for simulation of friction in the bearing channel region and deformations after the outlet. In this work examples of simulations of extrusion in two and three dimensions with the Lagrangian FEM code Marc AutoForge are presented.