Single-monolayer inkjetted oligothiophene organic TFTs exhibiting high performance and low leakage
ABSTRACT Through the use of a novel oligothiophene precursor, we have demonstrated organic TFTs exhibiting relatively high mobility while simultaneously retaining ultra-low leakage and excellent on-off ratios. The unique tendency of this material to self-assemble into a crystalline morphology allows non-uniform printed droplets to reorganize into high-quality monolayers. The resulting structure provides excellent electrostatic characteristics, ideal for low power analog applications.
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ABSTRACT: This paper presents a technique for the experimental measurement of stress intensity factors in cracked specimens under mixed-mode loading. This technique is based on full-field measurement using digital image correlation and an interaction integral. Such domain-independent integrals are often used in the finite element method to calculate stress intensity factors. The main advantage of this technique is that the errors made in the estimation of the measured displacement field near the cracks tip do not affect the measurement of the stress intensity factors. The capabilities of the method are illustrated through fracture measurements on compact tension specimens made of maraging steel. Another test under mixed-mode loading is presented.International Journal of Fracture 02/2005; 132(1):65-79. · 1.25 Impact Factor
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ABSTRACT: This paper presents the findings of work carried out to describe the micromechanisms of radial crack growth in wood. TR and TL cracks are both radial cracks but TR grows radially and TL longitudinally. TR cracks are known to show higher fracture toughness than TL cracks. The TR fracture surfaces also indicate a more tortuous crack path. Since the reason for this is unclear, details of the TR crack growth mechanisms in green Pinus sylvestris L were studied. This was done by in-situ optical microscopy as the crack was cutting through alternating layers of soft earlywood and stiff latewood. At the scale of individual cells, the crack tip advanced by separating cell walls at the middle lamella in a splitting or peeling mode. At the scale of growth rings, stick-slip type of crack growth was observed and new crack planes were often formed. The stress distribution in a material with alternating stiff and soft layers is causing this. This stress distribution also contributes to the tendency for inclined cracks to deviate in the radial direction. For interpretation of fracture mechanisms, the importance of scale interaction and the combined influences of microstructure and stress state are emphasized.Journal of Materials Science 11/2000; 35(24):6277-6283. · 2.16 Impact Factor
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ABSTRACT: The use of the path independent J' integral for dynamic crack propagation, which has the physical meaning of energy release rate is numerically studied by the finite element method. Other path independent integrals are also investigated along with the J' integral. Numerical results show that the combined use of the J' integral and the finite element method is a useful tool to obtain the fracture parameters such as the stress intensity factors and the energy release rates. The use of the several other types of path-independent integrals, despite their lack of a direct interpretation as energy release rates, is also demonstrated. This is so, because the alternate path-independent integrals have been explicitly expressed in terms of the time-dependent K-factors, or the energy release rate, in the present work.Engineering Fracture Mechanics. 01/1983;