Surface-Crack Shape Change in Bending Fatigue Using an Inexpensive Resonant Fatiguing Apparatus

1978 ◽  
Vol 6 (3) ◽  
pp. 183 ◽  
Author(s):  
RT Horstman ◽  
KC Lieb ◽  
RL Meltzer ◽  
IC Moore ◽  
WS Pierce ◽  
...  
Keyword(s):  
Surface Crack ◽  
Shape Change ◽  
Bending Fatigue ◽  
Crack Shape

In-Situ Estimation of Surface Crack Shape From Crack Opening Displacement by Use of NCOD Database System

2010 ◽  
Author(s):  
Jingxia Yue ◽  
Zheng He ◽  
Yukio Fujimoto ◽  
Weiguo Wu
Keyword(s):  
Crack Opening Displacement ◽  
Surface Crack ◽  
Fatigue Cracks ◽  
Crack Opening ◽  
Crack Depth ◽  
Database System ◽  
Shape Estimation ◽  
Opening Displacement ◽  
Crack Shape

This paper proposes an in-situ estimation of crack shape from crack opening displacement (COD) by using of a visualized database system consisting of numerical calculation data of normalized crack opening displacement (NCOD) for some kinds of crack types. The relation between crack depth and corresponding NCOD is discussed based on FE analysis results, from which a crack shape estimation principle is deduced. Visualized software named NCOD Database System was developed to facilitate convenient in-situ estimation of crack shape. Shapes of three kinds of surface crack, partial circle crack in plate, fatigue cracks in gusset weld joint and in large-scale member, are successfully estimated by this system. The paper is supported by the Programme of Introducing Talents of Discipline to Universities (B08031).

Probabilistic Critical Fatigue Safety State of the RD2 Type Axle of China Railway Freight Car

2008 ◽  
Vol 44-46 ◽  
pp. 751-758 ◽  
Author(s):  
Yong Xiang Zhao ◽  
Bing Yang ◽  
Ming Fei Feng ◽  
Y. Li ◽  
M.J. Liu ◽  
...  
Keyword(s):  
Crack Growth ◽  
Residual Life ◽  
Shape Change ◽  
Fatigue Cracks ◽  
Crack Size ◽  
Elliptical Crack ◽  
Dynamics Simulation ◽  
Crack Shape ◽  
Railway Freight ◽  
China Railway

Critical fatigue safety state is investigated on RD2 type axle of China railway freight cars. Attention is paid on the grooves near axle boxes, where more fatigue cracks were early appeared even result in at least six derailed accidents. Load history was obtained by vehicle dynamics simulation combining with on-line inspection. Braking loads and effects of maintenance and off-round of wheels are also incorporated. Semi-elliptical and external circumferential cracks are employed for crack growth simulation. Crack shape change and shear stressing of the semi-elliptical crack are taken into account. New crack growth rate modeling in which covers from cracking threshold to toughness related fracture state is applied for residual life evaluation. Critical fatigue safety state is defined as the crack size from which the axle can be safely operated to next overhaul inspection. Critical crack size is estimated step-by-step with the crack shape change. Results show that the external circumferential crack is more dangerous than the semi-elliptical crack. Application more than two years in production verifies that the present assessment is available and reliable.

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