Surface Failure

2020 ◽  
pp. 317-342
Author(s):  
Ansel C. Ugural ◽  
Youngjin Chung ◽  
Errol A. Ugural
Keyword(s):  
1980 ◽  
Vol 41 (C9) ◽  
pp. C9-95-C9-100 ◽  
Author(s):  
R. W. MacPherson ◽  
J. C. Anctil
Keyword(s):  

Author(s):  
Joseph G. Monir ◽  
William K. Powers ◽  
Joseph J. King ◽  
Thomas W. Wright ◽  
Bradley S. Schoch

Author(s):  
Girish M. Shejale ◽  
David Ross

The 1st stage buckets in Frame 3002, 10 MW industrial gas turbine experienced premature failures. The buckets failed unexpectedly much earlier than the designed bucket life. Bucket material is Inconel 738, with platinum-aluminized coating on the surface. Failure investigation of the buckets was performed to know the root cause of the failure. The failure investigation primarily comprised of metallurgical investigation. The results of the metallurgical investigation were co-related with the unit operational history. This paper provides an overview of 1st stage buckets investigation. The metallurgical investigation performed concluded prime failure mechanism due to high carbon content of bucket material and improper heat treatment. The bucket coating was initially damaged during the first loading and fracture occurred due to grain boundary embrittlement in short span of service. The metallurgical tests performed included Visual inspection, Scanning Electron Microscopy (SEM), Energy Dispersive Analysis of X-ray (EDS), Chemical analysis, Tensile test and Hardness survey. The test results, discussions and conclusions are presented in this paper.


2018 ◽  
Vol 883 ◽  
pp. 53-62 ◽  
Author(s):  
Shin Yuh Chern ◽  
Jeng Haur Horng ◽  
Cheng Han Tsai ◽  
Hung Jung Tsai

The surface micro-temperature of sliding, rough bodies is an important factor affecting contact properties, such as chemical reactions of automatic injectors for medicine and chemical processes and surface failure of micro-and macro-devices. In this work, the Finite Element Method is used to analyze the micro-temperature of the peaks and valleys of multiplying asperity sliding contact surfaces. The affecting parameters include pressure, roughness, sliding speed, Peclet number, and thermal conductivity of rough surfaces. Analysis results showed that the effects of the studied parameters are different to those of peak and valley temperatures. While pressure increased, the increasing rate of the temperature rise parameter of valleys was larger than those of peaks. The temperature rise of peaks increased as roughness increased. On the contrary, the temperature rise of valleys decreased as roughness increased. Sliding speed and thermal conductivity played the most important roles in affecting the maximum micro-temperature rise. The temperature rise difference between peaks and valleys was almost proportional to thermal conductivity, and was inversely proportional to sliding speed for all cases. This transient thermal analysis enables precision control of interface micro-temperature for micro-moving devices.


2020 ◽  
Vol 124 (1277) ◽  
pp. 1016-1054
Author(s):  
R. Norouzi ◽  
A. Kosari ◽  
M. Hossein Sabour

ABSTRACTExtensive research in recent years has focused on improving the current loss-of-control prevention systems and developing new strategies for safe path planning of the impaired aircraft. Success in developing such systems requires a comprehensive perception of the influence of damage on the aircraft’s dynamic behaviour and performance, and the effect of various failure degrees on the flight envelope confinement and the remaining safe maneuvers. This paper comprehensively describes the effects of lateral control surface failure on the NASA Generic Transport Model (GTM) flight envelope, defined by a set of attainable steady-state maneuvers herein referred to as trim points. The study utilises a large database of high-fidelity maneuvering flight envelopes computed for the unimpaired case and wide ranges of the aileron and rudder failure cases at different flight conditions. Flight envelope boundary is rigorously investigated, and the key parameters confining the trim points at different boundary sections are identified. Trend analyses of the impaired flight envelopes and the corresponding limiting factors demonstrate the effect of various failure degrees on the remaining feasible trim points. Results can be employed in emergency path planning with potential uses in the development of aircraft resilient control and upset recovery systems.


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