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Shear Mode (shear + mode)
Selected AbstractsNumerical simulation of the fracture process in cutting heterogeneous brittle materialINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 13 2002H. Y. Liu Abstract The process of cutting homogeneous soft material has been investigated extensively. However, there are not so many studies on cutting heterogeneous brittle material. In this paper, R-T2D (Rock and Tool interaction), based on the rock failure process analysis model, is developed to simulate the fracture process in cutting heterogeneous brittle material. The simulated results reproduce the process involved in the fragmentation of rock or rock-like material under mechanical tools: the build-up of the stress field, the formation of the crushed zone, surface chipping, and the formation of the crater and subsurface cracks. Due to the inclusion of heterogeneity in the model, some new features in cutting brittle material are revealed. Firstly, macroscopic cracks sprout at the two edges of the cutter in a tensile mode. Then with the tensile cracks releasing the confining pressure, the rock in the initially high confining pressure zone is compressed into failure and the crushed zone gradually comes into being. The cracked zone near the crushed zone is always available, which makes the boundary of the crushed zone vague. Some cracks propagate to form chipping cracks and some dip into the rock to form subsurface cracks. The chipping cracks are mainly driven to propagate in a tensile mode or a mixed tensile and shear mode, following curvilinear paths, and finally intersect with the free surface to form chips. According to the simulated results, some qualitative and quantitative analyses are performed. It is found that the back rake angle of the cutter has an important effect on the cutting efficiency. Although the quantitative analysis needs more research work, it is not difficult to see the promise that the numerical method holds. It can be utilized to improve our understanding of tool,rock interaction and rock failure mechanisms under the action of mechanical tools, which, in turn, will be useful in assisting the design of fragmentation equipment and fragmentation operations. Copyright © 2002 John Wiley & Sons, Ltd. [source] Hypersingular integral equation method for three-dimensional crack problem in shear modeINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2004Y. Z. ChenArticle first published online: 19 APR 200 Abstract This paper presents the use of the hypersingular integral equation method for solving the flat crack problem in shear mode. In the method, the crack opening displacement (COD) functions are assumed to be polynomials with several undetermined coefficients. The involved hypersingular integral can be reduced into a repeat integral in a particular polar co-ordinate, and further integrated by a known quadrature rule. This technique considerably reduces the effort of derivation and computation to obtain the final solution. The undetermined coefficients in the COD functions are obtained from an algebraic equation. The stress intensity factors (SIF) along the boundary of the flat crack can then be easily calculated. Numerical examples are given to demonstrate the efficiency of the proposed method. Copyright 2004 John Wiley & Sons, Ltd. [source] IgG binding kinetics to oligo B protein A domains on lipid layers immobilized on a 27,MHz quartz-crystal microbalanceJOURNAL OF MOLECULAR RECOGNITION, Issue 2 2007Hideyuki Mitomo Abstract Although molecular recognitions between membrane receptors and their soluble ligands have been analyzed using their soluble proteins in bulk solutions, molecular recognitions of membrane receptors should be studied on lipid membranes considering their orientation and dynamics on membrane surfaces. We employed Staphylococcal Protein A (SpA) oligo B domains with long trialkyl-tags from E. coli (LppBx, x,=,1, 2, and 5) and immobilized LppBx on lipid layers using hydrophobic interactions from the trialkyl-tag, while maintaining the orientation of B domain-chains on a 27,MHz quartz-crystal microbalance (QCM; AT-cut shear mode). The binding of IgG Fc regions to LppBx on lipid layers was detected by frequency decreases (mass increases) on the QCM. The maximum amount bound (,mmax), association constants (Ka), association and dissociation rate constants (k1 and k,1, respectively) were obtained. Binding kinetics of IgG to LppB2 and LppB5 were quite similar, showing a simple 1:1 binding of the IgG Fc region to the B domain, when the surface coverage of LppB2 and LppB5 on the lipid surface is low (1.4%). When LppB5 was immobilized at the high surface coverage of 3.5%, the complex bindings of IgG such as one IgG bound to one or two LppB5 on the membrane could be observed. IgG-LppB1 binding was largely restricted because of steric hindrance on lipid surfaces. This gives a suggestion why Protein A has five IgG binding domains. Copyright © 2006 John Wiley & Sons, Ltd. [source] PREDICTING TEXTURE ATTRIBUTES FROM MICROSTRUCTURAL, RHEOLOGICAL AND THERMAL PROPERTIES OF HAZELNUT SPREADSJOURNAL OF TEXTURE STUDIES, Issue 5 2008ROSSELLA DI MONACO ABSTRACT Eight trained assessors evaluated one visual, eight texture and four gustative attributes of 15 commercial spreads. In addition, 100 consumers evaluated the acceptability of the spreads. Rheological behavior of the samples was evaluated in transient (stress,relaxation test) and dynamic (strain and frequency sweep test) shear mode. Thermal measurements were also performed. Finally, the microstructure of the samples was analyzed by scanning electron microscopy. Partial least squares regression was used to predict acceptability from sensory attributes and texture from instrumental data. Scanning electron micrographs indicated that spreads differed in morphology, size and distribution of hazelnut particles. Overall liking of the spreads was found to be related to hazelnut flavor and texture attributes. Prediction of the most important texture properties from instrumental measurements was quite successful, especially for spreadability which was found negatively related to the consistency and flow indices and, secondly, for meltability which was found to be strongly dependent on measured thermal parameters. PRACTICAL APPLICATIONS This study contributes to knowledge development in the research area of acceptability, sensory and instrumental correlation for semi-solid foods. The results confirm that texture properties of spreadable foods play a most important role in consumer acceptability. The research also allows better understanding as to why no single measurement is able to predict all texture attributes adequately and why more appropriate tests need to be developed for an accurate prediction of some sensory attributes as perceived by the human senses. [source] A survey of the 2001 to 2005 quartz crystal microbalance biosensor literature: applications of acoustic physics to the analysis of biomolecular interactionsJOURNAL OF MOLECULAR RECOGNITION, Issue 3 2007Matthew A. Cooper Abstract The widespread exploitation of biosensors in the analysis of molecular recognition has its origins in the mid-1990s following the release of commercial systems based on surface plasmon resonance (SPR). More recently, platforms based on piezoelectric acoustic sensors (principally ,bulk acoustic wave' (BAW), ,thickness shear mode' (TSM) sensors or ,quartz crystal microbalances' (QCM)), have been released that are driving the publication of a large number of papers analysing binding specificities, affinities, kinetics and conformational changes associated with a molecular recognition event. This article highlights salient theoretical and practical aspects of the technologies that underpin acoustic analysis, then reviews exemplary papers in key application areas involving small molecular weight ligands, carbohydrates, proteins, nucleic acids, viruses, bacteria, cells and lipidic and polymeric interfaces. Key differentiators between optical and acoustic sensing modalities are also reviewed. Copyright © 2007 John Wiley & Sons, Ltd. [source] | |||||||||||||