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Open access

S. Sobieszczyk, W. Wojnicz and B. Nowak

FEM Approach to Estimate the Behaviour of Biocomposite Metal-Surface Coating Systems

A three dimensional (3D) model of biocomposite metal-surface coating system, which is influenced by known external forces, is proposed. This model consists of the metallic substrate (Ti6A14V) and the hydroxyapatite (HA) coating. Using FEM (finite element method), strain-stress maps of model were generated for investigating relations between the extreme stress of HA coating and the magnitude of external force and the thickness of the coating. The analysis of numerical simulations results confirms that the system with the greatest coating thickness (i.e. 10-3 m) has the least extreme stress in this surface coating.

Open access

Łukasz Gołuński and Bolesław Augustyniak

Modeling by finite element methods of impact of erosion on frequency of normal modes of l-0 blade

After some time of exploitation steam turbine rotors blades in energetic industry they are being eroded and also their frequency of normal modes is changed. Those changes can cause to unwanted shift of blades normal mode frequencies. It is necessary to find quick method of rating changes of frequency in connection of mass loss due erosion. The evaluation of this dependence was made by finite element modeling method using HyperWorks 8.0 software. Geometrical model of blade L-0 with mass of 22 kg and length of 74 cm was used. There were calculated frequencies of the first five modes in function of mass loss along the leading blade edge (up to mass loss of 1,2%). Small losses of weight (around 0,2%) cause similar changes in values (around 0,2%) for all modes but with different types of frequency change (decrease or increase). The frequency decreases for all modes except mode the 3rd. For bigger mass loss an monotonic decrease of frequency was observed in 1st, 2nd, 5th mode and maximum (around +1,5 %) for 3rd mode and minimum (- 0,5%) for 4th mode. For maximum mass loss (1,2%) maximal decrease of frequency was observed in 2nd mode around -2%. Results of this modeling can be used to estimate changes of frequencies caused by erosion in exploited blades when their mass loss is known.