Fatigue Fracture of Turbine Blades: Case Studies

2013 ◽  
Vol 592-593 ◽  
pp. 712-715
Author(s):  
Marta Kianicová ◽  
Jaroslav Pokluda
Keyword(s):  
Case Studies ◽  
Fatigue Fracture ◽  
Fatigue Cracks ◽  
Turbine Blades ◽  
Rotor Blades ◽  
Casting Defects ◽  
Aircraft Engines ◽  
Testing Procedures ◽  
Fracture Surfaces ◽  
Initiation And Propagation

Fracture surfaces of two sets of rotor blades failed after strong testing procedures of aircraft engines in the test-stand are investigated by means of SEM. While the process of fatigue fracture in the first set of blades did not reveal any defect features, both the initiation and propagation of fatigue cracks was strongly influenced by casting defects.

Degradation of Protective Al - Si Coatings during Exploitation of Gas Turbine Blades

2007 ◽  
Vol 567-568 ◽  
pp. 309-312 ◽  
Author(s):  
Marta Kianicová ◽  
Jaroslav Pokluda
Keyword(s):  
Turbine Blades ◽  
High Temperature Corrosion ◽  
Rotor Blades ◽  
Aircraft Engines ◽  
Relative Thickness ◽  
Surface Layers ◽  
Gas Turbine Blades ◽  
Oxide Phases ◽  
Exploitation Parameter ◽  
Sudden Decrease

Diffusion Al-Si coatings are often used to protect rotor blades of aircraft engines against high-temperature corrosion in environments containing sulfur compounds. Besides other microstructural changes, the degradation of AlSi layers can be indicated by an increasing amount of surface oxide phases and changes in parameters of the layer geometry. In practice, the timetemperature area beyond a critical temperature of the outgoing gas is used as an empirical exploitation parameter D indicating a degradation level. The efficiency of such approach was investigated by analyzing degradation features in the surface layers of rotor blades after exploitations corresponding to different values of D. Determined simple relationships between the relative thickness of degraded layer and the parameter D verify the methodology and yield its clear geometrical interpretation. However, this method fails to provide reasonable information in case when the gas is burning outside the combustion chamber due to a sudden decrease of turbine revolutions.

Analyses of P-S-N Curve and Fracture Morphology of Die-Casting Magnesium Alloy AZ91D Containing Mischmetal

2013 ◽  
Vol 467 ◽  
pp. 103-107
Author(s):  
Yu Lei Xu ◽  
Kui Zhang ◽  
Li Han ◽  
Ming Feng Li
Keyword(s):  
Magnesium Alloy ◽  
Fracture Surface ◽  
Fatigue Fracture ◽  
Fatigue Cracks ◽  
Die Casting ◽  
Fracture Morphology ◽  
Shrinkage Porosity ◽  
Lower Stress ◽  
Fracture Surfaces ◽  
Alloy Az91d

The p-S-N curve (p = 50%) of die casting magnesium alloy AZ91D with 1% mischmetal was determined and the fatigue strength corresponding to 3.8 × 105 cycles with 50% probability was 70 MPa. The fatigue fracture surfaces were observed using scanning electron microscopy. The fatigue factures varied with the applied stress and their own defects. The fracture surfaces of some samples loaded lower stress exhibited rubbing mark. The fatigue fracture surface of samples with minor defect possessed the mixed characteristics of quasi-cleavage, tearing ridge, dimple and fatigue striation. Fatigue cracks initiated at gas pores and shrinkage porosity clusters. It were found there was an minor defect size as the site of damage incubation on fracture surface of die casting testing bars which fatigue life was near to the upper bound of fatigue lives.

THE IMPACT OF STRESS CONCENTRATORS ON THE STRUCTURAL STRENGTH OF CAST TURBINE BLADES OF AIRCRAFT ENGINES

2019 ◽  
Vol 85 (5) ◽  
pp. 52-66
Author(s):  
A. N. Petukhov ◽  
F. D. Kiselev
Keyword(s):  
Turbine Blades ◽  
Quality Parameters ◽  
Casting Defects ◽  
Aircraft Engines ◽  
Manufacturing Defects ◽  
Stress Concentrators ◽  
Technological Stage ◽  
Design And Manufacture ◽  
The Impact

Assessing of the quality parameters of the blade manufacture, which can affect their operational performance, is an important step in determining the causes of turbine blade destruction. Manufacturing defects, despite their great diversity, tend to be stress concentrators. Apart from the defects listed in the specifications to be avoided upon blade manufacturing, we mean also various kinds of defects identified as concentrators that contribute to the destruction of the blades in operation. Assessment of the blade quality suggests identification and analysis of the defects, as well as determination of the technological stage at which they have been formed. For cooled turbine blades this is the foundry stage of their manufacture. Studies of the blades damaged in operation, revealed that despite the control and rejection of blades in the manufacture, the materials of the turbine blades installed on aircraft engines, contain casting defects. The revealed casting defects are shown to affect the strength characteristics and durability of turbine blades and contribute to their destruction through fatigue fracture in operation. The special features of the quality characteristics of the single-crystal turbine blades, affecting their performance, and defects that contribute to their destruction in operation are highlighted. The necessity of improving the valuation, standardization and quality control both at the stages of design and manufacture of blades is shown.

Innovatives Zangenwalzwerkzeug*/An innovative pincer rolling tool

2016 ◽  
Vol 106 (07-08) ◽  
pp. 571-575
Author(s):  
B. Prof. Denkena ◽  
T. Grove ◽  
V. Prasanthan ◽  
K. Röttger ◽  
Z. Heni ◽  
...  
Keyword(s):  
Residual Stress ◽  
Turbine Blades ◽  
Aerospace Industry ◽  
Present Knowledge ◽  
Crack Initiation And Propagation ◽  
Compressive Stresses ◽  
Enhanced Resistance ◽  
Initiation And Propagation ◽  
Stress Profiles ◽  
Strength And Durability

In der Luft- und Raumfahrt werden höchste Anforderungen an die Belastbarkeit sowie Lebensdauer einzelner Komponenten gestellt. Bisherige Untersuchungen zeigen, dass insbesondere eingebrachte Druckeigenspannungen in der Werkstückrandzone aufgrund des erhöhten Widerstands gegen Rissbildung und -ausbreitung zu einer Lebensdauererhöhung von Turbinenschaufeln führen können. Mit dem Einsatz eines aerosolgelagerten Zangenwalzwerkzeug kann gezielt ein belastungsangepasstes Eigenspannungsprofil eingebracht werden.   In aerospace industry highest demands are placed on the strength and durability of individual components. The present knowledge shows that especially compressive stresses in the subsurface lead to an increased lifetime of turbine blades, due to the enhanced resistance to crack initiation and propagation. An innovative aerosol mounted pincer rolling tool has been developed for the induction of individual residual stress profiles into such components.

Fatigue crack paths and properties in A356-T6 aluminum alloy microstructurally modified by friction stir processing under different conditions

2015 ◽  
Author(s):  
A. Tajiri ◽  
Y. Uematsu ◽  
T. Kakiuchi ◽  
Y. Suzuki
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Crack Initiation ◽  
Friction Stir Processing ◽  
Casting Defects ◽  
Processing Conditions ◽  
Tool Rotational Speed ◽  
Crack Initiation And Propagation ◽  
Friction Stir ◽  
Initiation And Propagation

A356-T6 cast aluminum alloy is a light weight structural material, but fatigue crack initiates and propagates from a casting defect leading to final fracture. Thus it is important to eliminate casting defects. In this study, friction stir processing (FSP) was applied to A356-T6, in which rotating tool with probe and shoulder was plunged into the material and travels along the longitudinal direction to induce severe plastic deformation, resulting in the modification of microstructure. Two different processing conditions with low and high tool rotational speeds were tried and subsequently fully reversed fatigue tests were performed to investigate the effect of processing conditions on the crack initiation and propagation behavior. The fatigue strengths were successfully improved by both conditions due to the elimination of casting defects. But the lower tool rotational speed could further improve fatigue strength than the higher speed. EBSD analyses revealed that the higher tool rotational speed resulted in the severer texture having detrimental effects on fatigue crack initiation and propagation resistances.

scholarly journals A Robot-Assisted Large-Scale Inspection of Wind Turbine Blades in Manufacturing Using an Autonomous Mobile Manipulator

2021 ◽  
Vol 11 (19) ◽  
pp. 9271
Author(s):  
Heiko Engemann ◽  
Patrick Cönen ◽  
Harshal Dawar ◽  
Shengzhi Du ◽  
Stephan Kallweit
Keyword(s):  
Wind Turbine ◽  
Rotor Blade ◽  
Large Scale ◽  
Turbine Blades ◽  
Rotor Blades ◽  
Mobile Manipulator ◽  
Wind Turbine Blades ◽  
Left Hand ◽  
Planning Strategy ◽  
Execution Strategy

Wind energy represents the dominant share of renewable energies. The rotor blades of a wind turbine are typically made from composite material, which withstands high forces during rotation. The huge dimensions of the rotor blades complicate the inspection processes in manufacturing. The automation of inspection processes has a great potential to increase the overall productivity and to create a consistent reliable database for each individual rotor blade. The focus of this paper is set on the process of rotor blade inspection automation by utilizing an autonomous mobile manipulator. The main innovations include a novel path planning strategy for zone-based navigation, which enables an intuitive right-hand or left-hand driving behavior in a shared human–robot workspace. In addition, we introduce a new method for surface orthogonal motion planning in connection with large-scale structures. An overall execution strategy controls the navigation and manipulation processes of the long-running inspection task. The implemented concepts are evaluated in simulation and applied in a real-use case including the tip of a rotor blade form.

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