Local Delaminations Induced by Interaction Between Intralaminar Cracking and Specimen Edge in Quasi-Isotropic CF/EP NCF Composites in Fatigue Loadings

2020 ◽  
Vol 56 (3) ◽  
pp. 291-302
Author(s):  
H. B. Kahla ◽  
Z. Ayadi ◽  
J. Varna
Keyword(s):  
Intralaminar Cracking ◽  
Specimen Edge

Electrolytic Isolation of Twin-Type Shock Deformation Structures

1967 ◽  
Vol 25 ◽  
pp. 318-319
Author(s):  
F. I. Grace ◽  
L. E. Murr
Keyword(s):  
Grain Boundaries ◽  
Thin Foil ◽  
Electrolyte Composition ◽  
Experimental Conditions ◽  
Average Current Density ◽  
Electron Transmission ◽  
Deformation Structures ◽  
The Matrix ◽  
Average Current ◽  
Specimen Edge

During the course of electron transmission investigations of the deformation structures associated with shock-loaded thin foil specimens of 70/30 brass, it was observed that in a number of instances preferential etching occurred along grain boundaries; and that the degree of etching appeared to depend upon the various experimental conditions prevailing during electropolishing. These included the electrolyte composition, the average current density, and the temperature in the vicinity of the specimen. In the specific case of 70/30 brass shock-loaded at pressures in the range 200-400 kilobars, the predominant mode of deformation was observed to be twin-type faults which in several cases exhibited preferential etching similar to that observed along grain boundaries. A novel feature of this particular phenomenon was that in certain cases, especially for twins located in the vicinity of the specimen edge, the etching or preferential electropolishing literally isolated these structures from the matrix.

Evaluation of Microscopic Deformation in CFRP Laminates with Delamination by Micro-Grid Methods

1998 ◽  
Vol 32 (1) ◽  
pp. 83-100 ◽  
Author(s):  
Nobuo Takeda ◽  
Shinji Ogihara ◽  
Satoshi Suzuki ◽  
Akira Kobayashi
Keyword(s):  
Crack Opening ◽  
Displacement Fields ◽  
Transverse Cracks ◽  
Opening Displacement ◽  
Cfrp Laminates ◽  
Edge Surface ◽  
Micro Grid ◽  
Microscopic Deformation ◽  
Micro Grids ◽  
Specimen Edge

Micro-grid methods were applied to measure displacements in 90° ply in CFRP cross-ply laminates with only transverse cracks or with both transverse cracks and delaminations. The COD (crack opening displacement) of the transverse cracks were also measured. Micro-grids were printed on the specimen edge surfaces by using the photo-lithography technique. The displacement fields of the specimen edge surface obtained from the experiment were compared with McCartney's [1] and Lee et al.'s [2] analyses which predicted the displacement field of a cross-ply laminate with only transverse cracks. Furthermore these analyses were modified to consider the existence of delamination.

Magnetic Deflecting Microscopy: A Novel Visualizing Method of Magnetic Stray Fields for Thick or Non-Transparent Magnetic TEM Samples

1998 ◽  
Vol 4 (S2) ◽  
pp. 404-405
Author(s):  
V.V. Volkov ◽  
Y. Zhu
Keyword(s):  
Imaging Techniques ◽  
Sample Thickness ◽  
Magnetic Domains ◽  
Lorentz Microscopy ◽  
New Class ◽  
Magnetic Imaging ◽  
Hard Magnets ◽  
Tem Method ◽  
Fringing Fields ◽  
Specimen Edge

For microstructure analysis of magnetic materials, in particular, for a new class of Nd-Fe-B hard magnets, a number of magnetic imaging techniques can be applied to gain different microstructure information. For instance, SEM magnetic imaging can be successfully used for very thick samples from a bulk ones down to a sample thickness of 10-20 μ. Below this limit the resolution of SEM magnetic images generally is too low to visualize fine details of magnetic structure. For very thin samples (less then 0.5 μm) magnetic Lorentz microscopy methods in conventional TEM are very useful tools to reveal magnetic domains and their structure. Therefore, it seems that relatively thick films of 0.5-20 μm in thickness are left out of the experimental limits of the methods discussed.We report on a novel, indirect TEM method that allows us to extend the limits of magnetic imaging for TEM non-transparent magnetic samples by viewing the surface stray fields and fringing fields generated by magnetic domains at specimen edge.

Microdamage in Composite Laminates: Experiments and Observation

2014 ◽  
Vol 518 ◽  
pp. 84-89
Author(s):  
Janis Varna ◽  
Leif Asp
Keyword(s):  
Composite Laminates ◽  
Speckle Interferometry ◽  
Damage State ◽  
Axis Orientation ◽  
Fiber Reinforced Composite ◽  
X Ray ◽  
Reinforced Composite ◽  
Loading Direction ◽  
Intralaminar Cracking

The first mode of damage in fiber reinforced composite laminates is usually intralaminar cracking in layers with off-axis orientation regarding the main loading direction. This papers analyzes the most typical methods used for the characterization of the damage state: edge replicas, optical microscopy, x-ray images, acoustic emission, speckle interferometry and Raman spectroscopy

scholarly journals Observation of intralaminar cracking in the edge crack torsion specimen

2014 ◽  
Vol 120 ◽  
pp. 1-14 ◽  
Author(s):  
M.W. Czabaj ◽  
J.G. Ratcliffe ◽  
B.D. Davidson
Keyword(s):  
Edge Crack ◽  
Intralaminar Cracking
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