The Two-Parameter- Fracture-Criterion (TPFC) was validated using an elastic-plastic two-dimensional (2D) finite-element code, ZIP2D, with the plane-strain- core concept. Fracture simulations were performed on three crack configurations: (1) middle-crack-tension, M(T), (2) single-edge- crack-tension, SE(T), and (3) single-edge crack-bend, SE(B), specimens. They were made of 2014-T6 (TL) aluminum alloy. Fracture test data from Thomas Orange work (NASA) were only available on M(T) specimens (one-half width, w = 1.5 to 6 in.) and they were all tested at cryogenic (-320 o F) temperature. All crack configurations were analysed over a very wide range of widths (w = 0.75 to 24 in.) and crack-length- to-width ratios ranged from 0.2 to 0.8. The TPFC was shown to fit the simulated fracture data fairly well (within 6.5%) for all crack configurations for net-section stresses less than the material proportional limit. For M(T) specimens, a simple approximation was shown to work well for net-section stresses greater than the proportional limit. Further study is needed for net-section stresses greater than the proportional limit for the SE(T) and SE(B) specimens.
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A system of boundary integral equations is presented which governs the crack-opening displacements for two-crack configurations. The integral equations are highly singular and they cannot be solved directly by numerical methods. By the approach of this paper the higher order singularities are, however, reduced to integrable singularities, and the integral equations are subsequently discretized and solved numerically. For several configurations numerical results have been obtained for scattered fields and for elastodynamic stress intensity factors. The scattered-field results are interpreted to apply for a partially closed crack as well as for two separate but neighboring cracks. The stress-intensity factors are intended to apply only to the case of separate cracks. The scattered-field results have relevance to the problem of detection and characterization of cracks in the field of quantitative nondestructive evaluation.
Adjust truss rod, file nut slots, set bridge height & saddle radius, balance & adjust tremolo, set pickup heights & balance, intonate, tighten tuners & hardware, clean & oil fretboard and polish frets, restring, detail & clean. (Instruments that are exceptionally dirty or have rusty/seized hardware will incur an additional expense). All setups are guaranteed from within 14 days of pickup.
with today's update, the trivia crack app has restored its accessibility in the bottom dock, where chats, friends, ranking, menu, etc ... is located.I'll also update with olympic cards machine, the proper thread here on AppleVis.
Methods: 80 extracted premolar teeth with intact buccal enamel were divided into five groups. In each group, enamel cracks were evaluated by stereomicroscope before and after debonding. All teeth were bonded with metal brackets by self-cure adhesive (3M, USA) and then debonded by bracket debonding plier, fixed on the UTM machine, through five methods based on location of plier on brackets: OGwing (occlusogingival), MDwing (mesiodistal), Oblique, OGbase (occlusogingival) and Cusp-base.
Results: Based on non-parametric distribution of data, there was no significant difference between groups in ARI and enamel cracks length change. The highest shear bond strength for debonding presented in OG base method (25.25 8.4) and the difference was statistically significant (P-value = 0.029). There was no linear relationship between shear bond strength and cracks length change and also between ARI and cracks length change.
Conclusion: Despite the lower cracks length change in Cusp-base method than other groups, there wasn't significant difference between debonding methods. Also the amount of debonding forces and ARI do not affect the changes of cracks length.
Hundreds, perhaps thousands of articles have been written about the vulnerability of WEP (W ired E quivalent P rivacy), but how many people can actually break WEP encryption? Beginners to WEP cracking have often been frustrated by the many wireless cards available and their distribution-specific commands. And things are further complicated when the beginner is not familiar with Linux.
This first article will help you set up your wireless lab and guide you through the scanning portion of WEP cracking. After all, you will need to find and document the wireless networks before you can crack them. The second article will describe the stimulation of the target WLAN to generate traffic and the actual process of capturing data and cracking the WEP key. After reading these two articles, you should be able to break WEP keys in a matter of minutes. A third article will turn things around and describe how to defend against multiple skill levels of wireless intruders
Note that using an active attack vs. passively capturing traffic increases your chances of detection. But it can significantly speed a WEP key crack by forcing the generation of more packets than you would normally capture in a short time from a lightly-used WLAN.
At this point, you know the basic approach to WEP cracking, have a target WLAN configured and have both sniffing and attack computers configured and working. You also have gained a basic familiarity with Auditor and used Kismet to find in-range wireless LANs.
In Part 2, we will use the second notebook to stimulate the target LAN to generate wireless traffic that we will capture and perform the actual WEP key crack. Until then, you can familiarize yourself with Kismet, go WLAN hunting and explore some of the other tools on the Auditor CD.
Therefore, this study investigated a double-layered structure of patterns exhibiting different crack configurations under tensile deformation, as a possible solution. The crack due to deformation results in a change in the resistance of the pattern. The crack size and density differ considerably depending on the materials, structures, and the fabrication process of the patterns. Patterns with different crack configurations show different electrical characteristics. A previous study [21] classified the crack configurations into two types: single and multiple crack growths. Single crack growth is often observed in patterns using metal foils with thicknesses of several micrometers or more on stretchable substrates, such as polydimethylsiloxane and polyurethane [22,23,24]. In many cases, the metal foil is patterned to a meandering shape, and a single large crack occurs at the apex of the meander. Multiple crack growth is often observed in patterns using very thin metal films (thickness of several tens of nanometers) [25,26,27] or stretchable conductive inks [28] on stretchable substrates. Many microcracks occur in the whole of the pattern, regardless of the shape of the pattern. Comparing these patterns, the patterns with the single crack growth exhibit lower initial resistance because of their lower material resistivity and thicker pattern thickness. In addition, they exhibit a lower resistance change rate against deformation. In contrast, patterns with multiple crack growth maintain their conductivity even under deformations where electrical failure occurs in patterns with singe crack growth. The reason is that the growth rate of multiple cracks against deformation is much slower. We considered that a double-layered structure could combine these electrical characteristics, and that the combined characteristics should maintain a low resistance even under deformation. That is, we considered that the layer with single crack growth should contribute to the low initial resistance and resistance change rate. Moreover, the layer with multiple crack growth should contribute to maintaining the conductivity even under deformation where electrical failure occurs in the layer with single crack growth.
Fabrication processes and dimensions for (a) meandering copper (single crack growth); (b) silver ink (multiple crack growth); and (c) double-layered patterns (a combination of single and multiple crack growths).
Finite element analysis has been employed to evaluate the mode I geometric factor solutions of asymmetric cracks, as well as symmetric cracks in a cylindrical fracture specimen in tension, as a function of wire aspect ratio and relative crack depth. Our study establishes the defining role of wire aspect ratio on the geometric factor solutions. The influence of on wire aspect ratio is explained in terms of the contributions of tension and bending ahead of an asymmetric crack due to the boundary conditions that result out of the axial constraints of a tension test. Experimental validation of the geometric factor solutions is carried out on - Poly(methylmethacrylate). The applicability of these solutions to fracture toughness measurements at the micro and nanoscale, especially in ceramic fibres and metallic wires is discussed.
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Structural failures resulting from prolonged low-amplitude loading are particularly problematic. Over the past century a succession of mechanisms have been hypothesized, as experimental validation has remained out of reach. Here we show by atomistic modeling that sustained fatigue crack growth in vacuum requires emitted dislocations to change slip planes prior to their reabsorption into the crack on the opposite side of the loading cycle. By harnessing a new implementation of a concurrent multiscale method we (1) assess the validity of long-hypothesized material separation mechanisms thought to control near-threshold fatigue crack growth in vacuum, and (2) reconcile reports of crack growth in atomistic simulations at loading amplitudes below experimental crack growth thresholds. Our results provide a mechanistic foundation to relate fatigue crack growth tendency to fundamental material properties, e.g. stacking fault energies and elastic moduli, opening the door for improved prognosis and the design of novel fatigue resistance alloys. 2ff7e9595c
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