Evaluation of fatigue damage using laser speckle: relation between surface profile and diffraction pattern

2001 ◽  
Author(s):  
Akira Kato ◽  
Fumihiko Okuya
Keyword(s):  
Diffraction Pattern ◽  
Fatigue Damage ◽  
Surface Profile ◽  
Laser Speckle

Observations of Fatigue Damage in the Press-Fitted Shaft under Bending Loads

2006 ◽  
Vol 326-328 ◽  
pp. 1071-1074 ◽  
Author(s):  
Dong Hyung Lee ◽  
Seok Jin Kwon ◽  
Jae Boong Choi ◽  
Young Jin Kim
Keyword(s):  
Fatigue Damage ◽  
Fatigue Cracks ◽  
Surface Profile ◽  
Fretting Fatigue ◽  
Fatigue Tests ◽  
Fretting Wear ◽  
Multiple Cracks ◽  
Test Machine ◽  
Edge Region ◽  
Fretting Damage

In this paper, the characterization of fretting damage on press-fitted specimens is proposed by experimental methods. A series of fatigue tests and interrupted fatigue tests on pressfitted specimens were carried out by using a rotate bending fatigue test machine. Macroscopic and microscopic characteristics were observed to identify fretting damage mechanism with a scanning electron microscope (SEM) and profilometer. The mechanism of fretting fatigue damage on pressfitted structure is discussed from experimental results. It is found that small cracks of 30~40m in depth are initiated when the specimen reached about 10% of the total life, and thus almost 90% of the fretting fatigue life of press fits can be considered to be in the crack propagation phase. Most of fatigue cracks are initiated at 1050m inner side of contact edge, and multiple cracks are nucleated and interconnected in the fretted surface. The crack nucleation angle in the near contact edge region is larger than that in the inside of the contact edge region. The fretting wear increased with increasing fatigue cycle. Since the fretting wear is relevant to the evolution of surface profile, the fretting fatigue is observed to be closely related with the fretting wear.

Evaluation of Fatigue Damage in Steel Using Laser Speckle

2003 ◽  
Vol 243-244 ◽  
pp. 201-206
Author(s):  
Akira Kato ◽  
Fumihiko Okuya
Keyword(s):  
Fatigue Damage ◽  
Laser Speckle

Analysis of electron-diffraction intensity profiles using a photodiode-array detection system

1983 ◽  
Vol 41 ◽  
pp. 322-323
Author(s):  
J. B. Warren
Keyword(s):  
Electron Diffraction ◽  
Diffraction Pattern ◽  
Detection System ◽  
High Energy ◽  
Photographic Emulsion ◽  
Diffraction Intensity ◽  
Silicon Photodiode ◽  
Photodiode Array Detection ◽  
Analog To Digital ◽  
Photodiode Array

Electron diffraction intensity profiles have been used extensively in studies of polycrystalline and amorphous thin films. In previous work, diffraction intensity profiles were quantitized either by mechanically scanning the photographic emulsion with a densitometer or by using deflection coils to scan the diffraction pattern over a stationary detector. Such methods tend to be slow, and the intensities must still be converted from analog to digital form for quantitative analysis. The Instrumentation Division at Brookhaven has designed and constructed a electron diffractometer, based on a silicon photodiode array, that overcomes these disadvantages. The instrument is compact (Fig. 1), can be used with any unmodified electron microscope, and acquires the data in a form immediately accessible by microcomputer.Major components include a RETICON 1024 element photodiode array for the de tector, an Analog Devices MAS-1202 analog digital converter and a Digital Equipment LSI 11/2 microcomputer. The photodiode array cannot detect high energy electrons without damage so an f/1.4 lens is used to focus the phosphor screen image of the diffraction pattern on to the photodiode array.

Light Optical Diffraction Studies of Macromolecular Ultrastructure

1970 ◽  
Vol 28 ◽  
pp. 258-259
Author(s):  
Glen B. Haydon
Keyword(s):  
High Resolution ◽  
Diffraction Analysis ◽  
Diffraction Pattern ◽  
Electron Micrographs ◽  
Optical Diffraction ◽  
Electron Micrograph ◽  
Its Analysis ◽  
Resolution Electron ◽  
Diffraction Patterns

Analysis of light optical diffraction patterns produced by electron micrographs can easily lead to much nonsense. Such diffraction patterns are referred to as optical transforms and are compared with transforms produced by a variety of mathematical manipulations. In the use of light optical diffraction patterns to study periodicities in macromolecular ultrastructures, a number of potential pitfalls have been rediscovered. The limitations apply to the formation of the electron micrograph as well as its analysis.(1) The high resolution electron micrograph is itself a complex diffraction pattern resulting from the specimen, its stain, and its supporting substrate. Cowley and Moodie (Proc. Phys. Soc. B, LXX 497, 1957) demonstrated changing image patterns with changes in focus. Similar defocus images have been subjected to further light optical diffraction analysis.

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