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EXPERIMENTAL INVESTIGATIONS ON STABLE CRACK-GROWTH IN 3-POINT BEND SPECIMENS UNDER MODE-I AND MIXED-MODE (I AND II) LOADING

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Title EXPERIMENTAL INVESTIGATIONS ON STABLE CRACK-GROWTH IN 3-POINT BEND SPECIMENS UNDER MODE-I AND MIXED-MODE (I AND II) LOADING
 
Creator MAHANTY, DK
SAVANT, GY
 
Subject fracture-mechanics
ductile fracture
tip deformation
finite-element
initiation
 
Description In many ductile materials, there is evidence of stable crack growth prior to instability. The instability occurs at a load level higher than the crack initiation load. A design based on the initiation load may lead to an under utilisation of the material. In order to exploit the full potential of the material, it is necessary to characterise the stable crack growth. Experiments were conducted in an aircraft grade aluminium alloy (D16AT) to investigate crack initiation, stable crack growth and instability under quasi-static loadings. The three-point bend (TPB) specimen was chosen for the investigations. The ratio between initial crack length (a0) to width (w) of the TPB specimen (a0/w) was taken as 0.5. Different loading angles (beta) of 45-degrees, 60-degrees, 75-degrees and 90-degrees were tested, where beta = 90-degrees corresponds to the mode I case. Crack opening displacement at the crack mouth (CMOD) was measured by a clip gauge for crack initiation and stable crack growth investigations. Data pertaining to load-displacement diagrams, crack initiation angle, crack initiation load (P(i)) and crack mouth opening displacement (CMOD) at different stages of crack growth, maximum fracture load (P(max)), crack front geometry etc. for different beta were obtained. The CMOD at the initiation point remained almost constant within a range for the whole span of beta. Initially the crack extends along a straight line for mixed mode cases, and is inclined at an angle with the initial crack. A substantial amount of tunnelling (i.e. crack front curving) is observed in all the experiments at all stages of stable crack growth. At the maximum load P(max), the tunnelling is between 5.5 and 9.0 mm for different beta. The ratio between P(max) and P(i) ranges from 1.195 to 1.40. From these studies, it can be concluded that CMOD can be used as a characterising parameter to study stable crack growth in mode I and mixed mode (I and II) loading.
 
Publisher PERGAMON-ELSEVIER SCIENCE LTD
 
Date 2011-08-24T08:56:19Z
2011-12-26T12:56:49Z
2011-12-27T05:46:07Z
2011-08-24T08:56:19Z
2011-12-26T12:56:49Z
2011-12-27T05:46:07Z
1992
 
Type Article
 
Identifier ENGINEERING FRACTURE MECHANICS, 43(1), 41-&
0013-7944
http://dx.doi.org/10.1016/0013-7944(92)90311-2
http://dspace.library.iitb.ac.in/xmlui/handle/10054/10828
http://hdl.handle.net/10054/10828
 
Language en