Features of modeling of stress in vinicity of crack tip at vibrations of turbomashine blading

Authors

Keywords:

blades, damages, singular finite elements, vibrations characteristics, modes of vibrations, stress localization, finite element method

Abstract

On the base of 3D finite elements models of compressor blade with damages his vibration state is investigated. The modeling of objects was spent on the basis of the three-dimensional approach of a finite elements method with the use of the special singular finite elements that account for the stress localization affect in the crack apex. Using 3D finite-element models allowed for in-depth analysis of the vibration strength of elements of blading with damages.Various crack lengths were created using a three-dimensional finite element model with the 3D prismatic quarter-point isoparametric elements and 20-node isoparametric elements to calculate the natural frequencies and mode shapes of the rotor blades.The natural frequencies obtained using the 3D, prismatic, quarter-point, isoparametric element model were lower. But the main difference was seen in the modal stresses of the crack region.A higher stress gradient in the crack region was observed when singularity, quarter-point elements were used. Maximal stress was noted in the crack front, from where the crack spread. Using a singularity, quarter-point element mesh in the crack region reduced the total number of degrees of freedom in the model.

Author Biography

А. М. Чугай, A.N. Podgorny Institute for Mechanical Engineering Problems of the National Academy of Sciences of Ukraine

PhD

References

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Published

2014-11-28

Issue

Vol. 17 No. 3 (2014)

Section

Dynamics and Strength of Machines

License

Copyright (c) 2015 А. М. Чугай

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