scholarly journals A Brief Review on Dynamics of a Cracked Rotor

2009 ◽  
Vol 2009 ◽  
pp. 1-6 ◽  
Author(s):  
Chandan Kumar ◽  
Vikas Rastogi
Keyword(s):  
Fatigue Crack ◽  
Lagrangian Formulation ◽  
Catastrophic Failure ◽  
Time Study ◽  
Cracked Rotor ◽  
Main Emphasis ◽  
Cracked Shafts

Fatigue crack is an important rotor fault, which can lead to catastrophic failure if undetected properly and in time. Study and Investigation of dynamics of cracked shafts are continuing since last four decades. Some review papers were also published during this period. The aim of this paper is to present a review on recent studies and investigations done on cracked rotor. It is not the intention of the authors to provide all literatures related with the cracked rotor. However, the main emphasis is to provide all the methodologies adopted by various researchers to investigate a cracked rotor. The paper incorporates a candid commentary on various methodologies. The paper further deals an extended Lagrangian formulation to investigate dynamics of cracked rotor.

Comparison Between API 579-1/ASME FFS-1 and ASME VIII Division 3 Stress Intensity Factor Solutions Used for Fracture Mechanics and Fatigue Analysis of Thick Walled Cylinders

2008 ◽  
Author(s):  
Jan G. M. Keltjens
Keyword(s):  
Stress Intensity Factor ◽  
Fatigue Crack ◽  
Stress Intensity ◽  
Intensity Factor ◽  
Life Time ◽  
Time Study ◽  
Worked Example ◽  
Failure Assessment ◽  
Section Viii ◽  
Burst Analysis

The paper discusses the differences between API 579-1/ASME FFS-1-1/ASME FFS-1 [1] and ASME Section VIII Division 3 [2] stress intensity factor solutions. In addition to this, the use of the Failure Assessment Diagram (FAD) in leak before burst analysis is compared to the present Division 3 approach. The paper contains the background of both approaches and a worked example demonstrating the effect of both methods. Finally, a simplified fatigue crack growth based life time study is presented.

An Experimental Study of Breathing Mechanism for the Transversely Cracked Shafts

2011 ◽  
Vol 338 ◽  
pp. 547-552
Author(s):  
He Len Wu ◽  
Zhong Yi Cai ◽  
Ke Qin Xiao
Keyword(s):  
Fatigue Crack ◽  
Diagnostic Techniques ◽  
Transverse Cracks ◽  
On Line ◽  
Stiffness Variation ◽  
Heavy Loads ◽  
Opening And Closing ◽  
Cracked Shafts ◽  
Breathing Mechanism ◽  
Line Crack

Shaft fatigue crack is one of the most common defects in rotating equipment, due to its extensive operation with continuous heavy loads. Finding an efficient way to evaluate the true stiffness variation due to the crack rotation is the key step to develop both on-line and off-line crack diagnostic techniques. This study analyzed time-variant bending stiffness of elastic shafts with experimentally-induced fatigue, welding and wire cut transverse cracks. It was found that crack gap has a significant effect on the opening and closing behaviour of the transverse crack. As in the case of a cut crack, large crack gap could completely prevent the crack from closing during rotation. A fatigue crack without a clear gap shows a typical opening and closing behavior. Further, it remains fully closed within a small angular range and most of time it is partially closed. It was also observed that both switch and harmonic models cannot describe periodic stiffness variation well enough to represent the actual breathing function of the fatigue crack.

Experimental Analysis of Cracked Rotor

2004 ◽  
Vol 127 (3) ◽  
pp. 313-320 ◽  
Author(s):  
Tong Zhou ◽  
Zhengce Sun ◽  
Jianxue Xu ◽  
Weihua Han
Keyword(s):  
Fatigue Crack ◽  
Theoretical Analysis ◽  
Dynamic Behavior ◽  
Experimental Analysis ◽  
Nonlinear Dynamic ◽  
Experimental Confirmation ◽  
Experimental Result ◽  
Cracked Rotor ◽  
Narrow Slot ◽  
Theoretical Results

The dynamic behavior of a cracked rotor has been theoretically analyzed by many researchers. In this paper, an experimental confirmation of the theoretical results is sought, especially for the nonlinear dynamic behavior of the cracked rotor. The crack in the rotor was simulated by a real fatigue crack, instead of a narrow slot. It can be seen from the orbit and spectrum of the rotor’s center that the effect of the crack becomes obvious only if the crack is deep enough. The experimental result conforms to theoretical analysis very well.

Impact Induced Internal Fatigue Cracks

1999 ◽  
Author(s):  
Gábor Stépán ◽  
Zsolt Szabó
Keyword(s):  
Fatigue Crack ◽  
Numerical Calculation ◽  
Fatigue Cracks ◽  
Travelling Waves ◽  
Design Stage ◽  
Catastrophic Failure ◽  
Tensile Stresses ◽  
Machine Element ◽  
Service Operation ◽  
Precise Prediction

Abstract When cracks appear on the surface of a machine element, they can often be treated and the service operation of the machine can be prolonged. When cracks appear inside the material of the corresponding machine element, the internal fatigue crack grows during operation, and when it reaches the surface, the catastrophic failure is already unavoidable. One way to handle this problem is the precise prediction of the repeated tensile stresses in the material, and the results of this method are to be used already at the design stage. The paper deals with the explanation and numerical calculation of tensile stresses related to travelling waves induced by impacts in tups during forging.

Discussion on “Time study and ratefixing charts” at the Luton, Bedford and Disctrict Section of the Institution

1932 ◽  
Vol 11 (9) ◽  
pp. 412
Author(s):  
R.W. Bedford ◽  
Roland ◽  
Bedford ◽  
Horridge ◽  
Wright ◽  
...  
Keyword(s):  
Time Study
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