A ply scale non-local fibre rupture criterion for CFRP woven ply laminated structures

2007 ◽  
Vol 80 (3) ◽  
pp. 321-326 ◽  
Author(s):  
Christian Hochard ◽  
Noël Lahellec ◽  
Cyril Bordreuil
Keyword(s):  
Non Local ◽  
Laminated Structures ◽  
Rupture Criterion

Prediction of Delamination Crack Growth in Carbon/Fiber Epoxy Composite Laminates Using a Non-Local Cohesive Zone Modeling

2012 ◽  
Vol 570 ◽  
pp. 25-36 ◽  
Author(s):  
Hassan Ijaz ◽  
L. Gornet ◽  
M.A. Khan ◽  
W. Saleem ◽  
K. Nisar ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Crack Growth ◽  
Composite Laminates ◽  
Damage Mechanics ◽  
Epoxy Composite ◽  
Cohesive Zone Modeling ◽  
Delamination Crack ◽  
Non Local ◽  
Laminated Structures ◽  
Carbon Fiber Epoxy

The global behavior of composite materials is strongly influenced by the quality of adhesion between different components. A component can be single phase, like fibers or particles used as reinforcement in a homogenous matrix, or a multiphase material like a layer in long-fiber laminate. In the latter case the degradation of adhesion implies the separation of the layers, known as delamination. Among all different failure mechanisms, Delamination is considered to be the most prominent mode of failure in fiber-reinforced laminates as a result of their relatively weak inter-laminar strength. When laminated structures are subjected to static, dynamic or cyclic loadings, the inter-laminar adhesion strength between individual plies tends to deteriorate significantly and act as the origin of the final failure. Therefore, an efficient and reliable design tool capable of predicting delamination could improve the durability for composite laminates. There exist damage mechanics based formulations capable of simulating the delamination crack growth in carbon/glass fiber epoxy based composite laminates. The present study is focused on taking a step forward in this respect. At first, already existed local interface models effectiveness is tested and results are successfully compared with available experimental data for UD IMS/924 Carbon/fiber epoxy composite laminate. Next, a non-local integral-type regularization scheme is introduced to overcome the spurious localization problem associated to the existing local model. Basic concepts and mathematical modeling of Non-Local damage evolution law are comprehensively studied and presented in this study. Finite Element simulation results based on proposed model are discussed in detail and are compared with experimental results.

Toward High-Resolution Low-Voltage SEM

1988 ◽  
Vol 46 ◽  
pp. 218-219
Author(s):  
Zhifeng Shao
Keyword(s):  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Limiting Factor ◽  
Operating Voltage ◽  
Probe Radius ◽  
Non Local ◽  
Electron Microscopes ◽  
Image Position ◽  
Scanning Electron Microscopes

Recently, low voltage (≤5kV) scanning electron microscopes have become popular because of their unprecedented advantages, such as minimized charging effects and smaller specimen damage, etc. Perhaps the most important advantage of LVSEM is that they may be able to provide ultrahigh resolution since the interaction volume decreases when electron energy is reduced. It is obvious that no matter how low the operating voltage is, the resolution is always poorer than the probe radius. To achieve 10Å resolution at 5kV (including non-local effects), we would require a probe radius of 5∽6 Å. At low voltages, we can no longer ignore the effects of chromatic aberration because of the increased ratio δV/V. The 3rd order spherical aberration is another major limiting factor. The optimized aperture should be calculated as

Chromatic aberration and low-voltage SEM

1987 ◽  
Vol 45 ◽  
pp. 546-547
Author(s):  
Zhifeng Shao ◽  
A.V. Crewe
Keyword(s):  
Electron Energy ◽  
Low Voltage ◽  
Spherical Aberration ◽  
Chromatic Aberration ◽  
Primary Electron ◽  
Probe Size ◽  
Non Local ◽  
Optical Treatment ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

For scanning electron microscopes, it is plausible that by lowering the primary electron energy, one can decrease the volume of interaction and improve resolution. As shown by Crewe /1/, at V0 =5kV a 10Å resolution (including non-local effects) is possible. To achieve this, we would need a probe size about 5Å. However, at low voltages, the chromatic aberration becomes the major concern even for field emission sources. In this case, δV/V = 0.1 V/5kV = 2x10-5. As a rough estimate, it has been shown that /2/ the chromatic aberration δC should be less than ⅓ of δ0 the probe size determined by diffraction and spherical aberration in order to neglect its effect. But this did not take into account the distribution of electron energy. We will show that by using a wave optical treatment, the tolerance on the chromatic aberration is much larger than we expected.

Imperfections in non-local elasticity

1998 ◽  
Vol 08 (PR8) ◽  
pp. Pr8-309-Pr8-316 ◽  
Author(s):  
Y. Z. Povstenko
Keyword(s):  
Non Local

On velocity selection for needle-crystals in a fully non-local model of solidification

1987 ◽  
Vol 48 (4) ◽  
pp. 547-552 ◽  
Author(s):  
B. Caroli ◽  
C. Caroli ◽  
C. Misbah ◽  
B. Roulet
Keyword(s):  
Local Model ◽  
Non Local ◽  
Selection For ◽  
Velocity Selection

NON-LOCAL ELECTROMAGNETIC EFFECTS AT METAL SURFACES

1983 ◽  
Vol 44 (C10) ◽  
pp. C10-305-C10-314
Author(s):  
S. Lundqvist ◽  
P. Apell
Keyword(s):  
Metal Surfaces ◽  
Electromagnetic Effects ◽  
Non Local
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