Case study on the integrity and nondestructive inspection of flux-cored arc welded joints of Francis turbine runners

2018 ◽  
Vol 98 (5-8) ◽  
pp. 2201-2211 ◽  
Author(s):  
Hamid Habibzadeh Boukani ◽  
Martin Viens ◽  
Souheil-Antoine Tahan ◽  
Martin Gagnon
Keyword(s):  
Welded Joints ◽  
Nondestructive Inspection ◽  
Francis Turbine

Decomposition-Based Assembly Synthesis Based on Structural Stiffness Considerations

2002 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Genetic Algorithm ◽  
Welded Joints ◽  
Joint Stiffness ◽  
Structural Stiffness ◽  
Passenger Car ◽  
Front Door ◽  
Design Variables ◽  
Door Panel ◽  
Minimum Distortion

This paper presents a method for systematically decomposes product geometry into a set of components considering the structural stiffness of the end product. A structure is represented a graph of its topology, and the optimal decomposition is obtained by combining FEM analyses with a Genetic Algorithm. As a case study, the side frame of a passenger car is decomposed for the minimum distortion of the front door panel geometry, where spot-welded joints are modeled as torsional springs. First, the rates of the torsional springs are treated as constant values obtained in the literature. Second, they are treated as design variables within realistic bounds. By allowing the change in the joint rates, it is demonstrated that the optimal decomposition can achieve the smaller distortion with less amount of joint stiffness (hence less welding spots), than the optimal decomposition with the typical joint rates available in the literature.

scholarly journals Cracking of welded joints made of steel X10CrMoVNb9-1 (T91) - case study

2013 ◽  
Vol 50 (04) ◽  
pp. 285-294 ◽  
Author(s):  
M. LOMOZIK ◽  
M. ZEMAN ◽  
R. JACHYM
Keyword(s):  
Welded Joints

Sediment erosion in guide vanes of Francis turbine: A case study of Kaligandaki Hydropower Plant, Nepal

Wear ◽  
2016 ◽  
Vol 362-363 ◽  
pp. 53-60 ◽  
Author(s):  
Ravi Koirala ◽  
Bhola Thapa ◽  
Hari Prasad Neopane ◽  
Baoshan Zhu ◽  
Balendra Chhetry
Keyword(s):  
Hydropower Plant ◽  
Francis Turbine ◽  
Sediment Erosion ◽  
Guide Vanes

scholarly journals Analysis of the Root Causes of Damage to the Edges of Tank Manholes on the Main Deck of Handy-Size Bulk Carriers

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 632
Author(s):  
Leszek Chybowski ◽  
Katarzyna Gawdzińska
Keyword(s):  
Welded Joints ◽  
Poor Quality ◽  
Test Results ◽  
Quality Steel ◽  
Wear Life ◽  
Bulk Carriers ◽  
Deck Cracks ◽  
Scanning Electron Microscope Fractography ◽  
Metallic Impurities

This study analyzes the root causes of cracks in the deck plating around tank manholes. Four handy-size bulk carriers built in one shipyard were analyzed. In all cases, deck cracks were found near manholes, and the average time from the commencement of operation until the occurrence of cracks was 1356 days. Due to this short wear-life of the vessel’s structural material, the authors believed that it was unlikely to be caused by corrosion fatigue. The authors hypothesized that main decks cracked around manholes because of very poor-quality welded joints and poor-quality steel (large amounts of non-metallic impurities) used to make the manholes. In order to verify this hypothesis, on each of the vessels, material samples were collected from near the cracks and then examined thoroughly. Each sample was subjected to the macroscopic examination of the natural surfaces of cracks and their vicinity, microscopic examination of the material, mechanical property tests, and scanning electron microscope fractography for samples obtained after impact tests. The examination and test results were used to draw detailed conclusions for each case study. The general conclusions based on examination of the whole damage population validated the authors’ hypothesis that main decks cracked around manholes because of very poor-quality welded joints and poor-quality steel used to make the manholes.

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