Micro-strain distribution around a crack tip by electron beam moiré methods

KSME Journal ◽  
1995 ◽  
Vol 9 (3) ◽  
pp. 298-311 ◽  
Author(s):  
Ouk Sub Lee ◽  
David T. Read
Keyword(s):  
Electron Beam ◽  
Strain Distribution ◽  
Crack Tip ◽  
Electron Beam Moiré

Plastic Strain Distribution at the Tips of Propagating Fatigue Cracks

1976 ◽  
Vol 98 (1) ◽  
pp. 24-29 ◽  
Author(s):  
D. L. Davidson ◽  
J. Lankford
Keyword(s):  
Aluminum Alloy ◽  
Fatigue Crack ◽  
Plastic Strain ◽  
Plastic Zone ◽  
Strain Distribution ◽  
Dimensionless Parameter ◽  
Fatigue Cracks ◽  
Crack Tip ◽  
Cyclic Plastic Zone ◽  
Plastic Zones

The techniques of selected area electron channeling and positive replica examination have been used to study the plastic zones attending fatigue crack propagation in 304 SS, 6061-T6 aluminum alloy, and Fe-3Si steel. These observations allowed the strain distribution at the crack tip to be determined. The results indicate that the concepts of a monotonic and a cyclic plastic zone are essentially correct, with the strains at demarcation between these two zones being 3 to 6 percent. Strain distribution varies as r−1/2 in the cyclic zone and as ln r in the monotonic plastic zone. The strain distributions for all materials studied may be made approximately coincident by using a dimensionless parameter related to distance from the crack tip.

Measurement of electron beam moire fringes with pulsed-dilation framing camera using different lasers

Optik ◽  
2019 ◽  
Vol 195 ◽  
pp. 163149
Author(s):  
Yanli Bai ◽  
Rongbin Yao ◽  
Haiying Gao ◽  
Xun Wang ◽  
Dajian Liu
Keyword(s):  
Electron Beam ◽  
Moiré Fringes ◽  
Framing Camera ◽  
Electron Beam Moiré

Analysis of an extraordinary electron beam moiré phenomena in a pulse-dilation framing camera

Optik ◽  
2019 ◽  
Vol 199 ◽  
pp. 163516
Author(s):  
Yanli Bai ◽  
Rongbin Yao ◽  
Haiying Gao ◽  
Xun Wang ◽  
Dajian Liu
Keyword(s):  
Electron Beam ◽  
Framing Camera ◽  
Electron Beam Moiré

Hybrid Measurement of CT and Strain Distribution of Internal Crack Using Synchrotron High-Energy Monochromatic X-Rays

2010 ◽  
Vol 652 ◽  
pp. 202-209
Author(s):  
Keisuke Tanaka ◽  
Takahisa Shobu ◽  
Hiroshi Kimachi
Keyword(s):  
Strain Distribution ◽  
Crack Opening ◽  
Three Dimensional ◽  
Crack Tip ◽  
High Energy ◽  
Internal Crack ◽  
X Rays ◽  
Crack Face ◽  
Dimensional Shape ◽  
Three Dimensional Shape

Using high-energy monochromatic X-rays of energy 66.4keV from the synchrotron radiation source, SPring-8, we have developed a system to perform a hybrid measurement of imaging of cracks and strain distribution around cracks. This system was applied to a fatigue crack made in a round bar made of carbon steel with a diameter of 4 mm. Computed tomography of the specimen gave the three-dimensional shape of a thumb-nail crack. High tensile strain ahead of the crack was measured at the applied maximum stress, while the strain on the crack face was low because of stress relief due to crack opening. The full width at half maximum (FWHM) increased near the crack tip under loading, and then decreased after unloading. The recoverable part of FWHM by unloading was caused by the steep distribution of the applied stress in the vicinity of the crack tip. The FWHM increased by plastic deformation does not change when unloaded. The measured distributions of the lattice strain and FWHM agreed well with those of the elastic and plastic strains calculated by the finite element method, respectively.

Electron beam moiré

1993 ◽  
Vol 33 (4) ◽  
pp. 270-277 ◽  
Author(s):  
J. W. Dally ◽  
D. T. Read
Keyword(s):  
Electron Beam ◽  
Electron Beam Moiré

Experimental Determination of Fatigue Crack Growth Behavior and Surface Strain Distribution of ‘Faint-Waist Pure Shear’ Specimens with Different Crack Tip Radii

2006 ◽  
Vol 79 (4) ◽  
pp. 712-733 ◽  
Author(s):  
Christian Feichter ◽  
Zoltan Major ◽  
Reinhold W. Lang
Keyword(s):  
Crack Growth ◽  
Strain Gradient ◽  
Strain Distribution ◽  
Strain Analysis ◽  
Crack Tip ◽  
Growth Behavior ◽  
Crack Growth Behavior ◽  
Analysis Method ◽  
Growth Initiation ◽  
Tip Radius

Abstract The influence of the initial crack-tip radius on the fatigue behavior and the strain distribution in the vicinity of the blunted crack tip was determined experimentally using a servo-hydraulic testing machine and an optical full-field strain analysis method. Two different elastomer grades (SBR, EPDM) were selected for the experimental work. The strain analysis method used, based on the image correlation technique, was found to be an effective tool to determine strains, strain distributions and gradients near the crack tip for elastomeric materials. Different material behavior was observed in the two rubber types investigated. While the crack tip was regularly blunted (half circle shape) for EPDM and the strain gradient was low (less steep), the crack tip was sharp (less blunted) with a higher strain gradient for SBR. Furthermore the crack tip radius was found to be an important influencing factor on the initiation of crack growth, but not on the crack growth behavior after initiation. Based on the experimental results a phenomenological, first-order, crack-growth initiation law was proposed, dependent on the crack tip radius, the tearing energy at crack growth initiation for a sharp crack and a parameter representing the influence of the crack tip radius.

Sign in / Sign up

Export Citation Format

Share Document