Crack Closure Behavior of Surface Cracks Under Pure Bending

2009 ◽  
pp. 260-260-10 ◽  
Author(s):  
R Foroughi ◽  
JC Radon
Keyword(s):  
Crack Closure ◽  
Surface Cracks ◽  
Pure Bending

Closure Effect on Interaction of Two Surface Cracks Under Cyclic Bending

2010 ◽  
Author(s):  
Masanori Kikuchi ◽  
Yoshitaka Wada ◽  
Maigefeireti Maitireyimu ◽  
Hirotaka Sano
Keyword(s):  
Crack Growth ◽  
Crack Closure ◽  
Crack Front ◽  
Surface Crack ◽  
Specimen Surface ◽  
Surface Cracks ◽  
Paris Law ◽  
C Value ◽  
Closure Effect ◽  
Surface Crack Growth

Crack closure effect on interaction of two surface crack growth processes by fatigue is studied. At first, change of C value in Paris’ law along crack front of single surface crack is measured experimentally. It is shown that C value decreases near specimen surface. Crack closure effect is studied numerically for a surface crack by elastic-plastic cyclic analyses. It is found that closure effect appears more strongly near specimen surface than the maximum-depth point. By determining effective stress intensity factor including closure effect, it is shown that change of C value is equal to the change of closure effect along crack front. Using new C value considering closure effect, fatigue crack growth is predicted using S-FEM. It is shown that fatigue life and crack configuration agree well with experimental ones. Finally, interaction of two surface cracks is evaluated numerically, and it is shown that crack closure plays important role on the interaction of two cracks.

Limit Load Solutions for Surface Cracks in Plates Under Different Loading Types

2002 ◽  
Author(s):  
Peter Dillstro¨m ◽  
Iradj Sattari-Far
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Crack Length ◽  
Crack Depth ◽  
Limit Load ◽  
Surface Cracks ◽  
Pure Bending ◽  
Element Analysis ◽  
Linear Finite Element ◽  
Cracked Plates

Limit load solutions of plates containing surface cracks are determined using non-linear finite element analysis. The study covers both shallow and deep cracks with different crack length/crack depth ratios under different loading types. The crack configurations consist of semi-elliptical surface cracks with a/t = 0.20, 0.40, 0.60, 0.80 and l/a = 2, 5, 10. Also studied are plates containing infinite surface cracks with a/t = 0.00, 0.20, 0.40, 0.60, 0.80. The cracked plates are subjected to pure tension, pure bending and combined tension and bending. The finite element results obtained from this study are compared with some published limit load solutions in the literature. It is shown that the exiting solutions are in general overly conservative.

J estimation for shallow semi-elliptical surface cracks in wide plates under pure bending

1999 ◽  
Vol 22 (5) ◽  
pp. 399-408 ◽  
Author(s):  
D. P. Boothman ◽  
M. M. K. Lee ◽  
A. R. Luxmoore ◽  
J. D. Sumpter
Keyword(s):  
Surface Cracks ◽  
Pure Bending ◽  
J Estimation

Thermally-induced Crack Healing in Poly(Methyl Methacrylate)

2002 ◽  
Vol 17 (6) ◽  
pp. 1335-1340 ◽  
Author(s):  
Jane-Sang Shen ◽  
Julie P. Harmon ◽  
Sanboh Lee
Keyword(s):  
Activation Energy ◽  
Methyl Methacrylate ◽  
Crack Closure ◽  
Healing Process ◽  
Fourth Power ◽  
Surface Cracks ◽  
Crack Healing ◽  
Closure Rate ◽  
Thermally Induced ◽  
Poly Methyl Methacrylate

A microscopic theory of thermally induced crack healing in poly(methyl methacrylate) is presented. Both laser-induced cylindrical cracks and knife-induced surface cracks were analyzed. For a given temperature, the crack closure rate was constant for both types of cracks. However, the crack closure rate was lower for samples with cylindrical cracks than for those with surface cracks. The former exhibited higher activation energy for crack closure than the latter, because the knife-induced cracks had sharper crack tips. Fracture stress was proportional to surface crack healing time to the one-fourth power for thermal healing at a given temperature. Based on the reptation model of polymer chains, the activation energy of chain diffusion was calculated. The healing process was monitored via fractography and crack closure was confirmed. The results were compared with solvent healing and thermal healing in the literature.

On Microwave Dual Frequency Technique for Evaluation of Surface Cracks

2004 ◽  
Vol 261-263 ◽  
pp. 955-962 ◽  
Author(s):  
Masumi Saka ◽  
Yang Ju ◽  
Y. Uchimura ◽  
Toru Miyadu
Keyword(s):  
Carbon Steel ◽  
Crack Closure ◽  
Crack Surface ◽  
Crack Depth ◽  
Surface Cracks ◽  
Dual Frequency ◽  
Closed Crack ◽  
Closure Stress

A method to estimate crack closure stress on the crack surface was introduced. The crack closure stress was estimated based on the compliance technique, while crack depth was measured by means of the microwave dual frequency technique. The effect of crack closure stress on detection and evaluation of a closed crack in a carbon steel by using the microwave dual frequency technique was discussed in details.

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