Location of Initial Debonding and Stress Singularity at Interface End

2008 ◽  
Vol 33-37 ◽  
pp. 315-320
Author(s):  
Ying Dai ◽  
Li Lang Zhou ◽  
Li Juan Fu ◽  
Xing Ji
Keyword(s):  
Stress Distribution ◽  
Characteristic Length ◽  
Stress Singularity ◽  
Interfacial Stress ◽  
Length Scale ◽  
Test Results ◽  
Characteristic Length Scale ◽  
Concentrated Force ◽  
Size Scale ◽  
Large Size

Interfacial stress distribution of bonded quarter-planes subjected to a concentrated force was re-investigated based on Bogy’s solution[1]. The characteristic length of the singular interface end, δ, was defined, and found varying in a very large size scale with the index of stress singularity from millimeter to nanometer or even smaller scale. The influences the characteristic length scale on the initial debonding of the interface end is a new question worth to pay attention. Photoelasticity experiment was employed to verify whether the initial debonding is always located at interface end with stress singularity. The test results show that the initial debonding does not start from singular interface end if the index of stress singularity is small enough.

Effect of Stress Singularity on Stress Distribution and Initial Debonding of Interface End

2007 ◽  
Vol 334-335 ◽  
pp. 641-644
Author(s):  
Ying Dai ◽  
Xing Ji ◽  
Guo Dong Jiang
Keyword(s):  
Stress Distribution ◽  
Characteristic Length ◽  
Stress Singularity ◽  
Interfacial Stress ◽  
Unique Characteristic ◽  
Concentrated Force

Interfacial stress distribution of bonded quarter planes subjected a concentrated force was re-investigated based on Bogy’s solution [1]. It’s found that the characteristic length of the singularity of interface end (δ), varies with the index of stress singularity at interface end from millimeter to nanometer. This is a unique characteristic of stress singularity at interface end. How the characteristic length of the singularity of interface end (δ) influences the initial de-bonding of the interface end is a new question worth to pay attention. It’s found in the photoelasticity experiments that usually the debonding initiated at the interface end with singularity, but as the index of stress singularity, as well as the characteristic length of singularity of interface end, decrease to some extent, the initial debonding moves to an inner point near the interface end. This phenomenon clearly shows the index of stress singularity has obvious influence on the debonding of interface end.

Identification of the characteristic length scale for fatigue cracking in fretting contacts

1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-159-Pr8-166 ◽  
Author(s):  
S. Fouvry ◽  
Ph. Kapsa ◽  
F. Sidoroff ◽  
L. Vincent
Keyword(s):  
Characteristic Length ◽  
Fatigue Cracking ◽  
Length Scale ◽  
Characteristic Length Scale

scholarly journals Lettau’s Contribution to the Obukhov Length Scale: A Scientific Historical Study

2021 ◽  
Author(s):  
Thomas Foken ◽  
Michael Börngen
Keyword(s):  
Characteristic Length ◽  
Stability Parameter ◽  
Historical Study ◽  
Length Scale ◽  
Characteristic Length Scale ◽  
Obukhov Length ◽  
The Future

AbstractIt has been repeatedly assumed that Heinz Lettau found the Obukhov length in 1949 independently of Obukhov in 1946. However, it was not the characteristic length scale, the Obukhov length L, but the ratio of height and the Obukhov length (z/L), the Obukhov stability parameter, that he analyzed. Whether Lettau described the parameter z/L independently of Obukhov is investigated herein. Regardless of speculation about this, the significant contributions made by Lettau in the application of z/L merit this term being called the Obukhov–Lettau stability parameter in the future.

Mesoscopic Disorder

MRS Bulletin ◽  
1994 ◽  
Vol 19 (5) ◽  
pp. 11-13 ◽  
Author(s):  
D.A. Weitz
Keyword(s):  
Molecular Level ◽  
Characteristic Length ◽  
Disordered Materials ◽  
Length Scale ◽  
Interconnected Network ◽  
Characteristic Length Scale ◽  
Fiber Network ◽  
Disordered Structure ◽  
Reading Glasses ◽  
Strong Scattering

Disorder characterizes most of the materials that surround us in nature. Despite their great technological importance, materials with ordered crystalline structures are relatively rare. Examples of disordered materials, however, abound, and their forms can be as varied as their number. The paper on which these words are printed has a disordered structure composed of a highly interconnected network of fibers. It has also been coated with particulate materials to improve its properties and the visibility of the ink. The reading glasses you may require to focus on these words are composed of a glass or polymer material that is disordered on a molecular level. Even the structure of your hand holding this magazine is disordered. These and virtually all other disordered materials are typically parameterized by a characteristic length scale. Above this length scale, the material is homogeneous and the effects of the disorder are not directly manifest; below this characteristic length the disorder of the structure dominates, directly affecting the properties.The range of characteristic length scales for the disordered materials around us is immense. For the glass or polymer of your reading glasses, it is microscopic; the disorder is apparent only at the molecular level, while above this level the material is homogeneous. For the paper on which this magazine is printed, the scale is larger; the paper is white partly because the disordered fiber network has within it structures that are comparable in size to the wavelength of light, resulting in strong scattering of the light.

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