Increasing Strain (increasing + strain)

Distribution by Scientific Domains

Selected Abstracts

A soluble fibre gel produced from rice bran and barley flour as a fat replacer in Asian foods

George E. Inglett
Summary A hydrocolloidal fibre composite made from rice bran and barley flour, called Ricetrim, was found to have similar rheological properties to coconut cream. Coconut cream displayed a very narrow region of linear viscoelastic behaviour, both above and below strain values of 0.1%, the oscillatory shear modulus dropped sharply with increasing strain, indicating non-linear viscoelastic behaviour. This region of linear viscoelastic behaviour extended to strains of 10%. When Ricetrim was substituted for coconut cream in Thai foods, it was found to produce acceptable products, but with lower saturated fat contents. Cookies, pumpkin pudding, layer cake, dip for pot crust, taro custard and sauté chicken curry were produced with fat contents reduced by 47.8, 94.3, 59.8, 75.3, 61.3 and 60.6%, respectively. Some differences in flavour and texture were observed at the higher levels of substitution, but these differences appeared to present only small changes in the overall score of general acceptability, or suitability, of the fibre gel foods. Scanning electron micrographs of the pumpkin pudding revealed only small changes in their surfaces with Ricetrim addition, even at higher levels of substitution. [source]

Deformation-enhanced metamorphic reactions and the rheology of high-pressure shear zones, Western Gneiss Region, Norway

Abstract Microstructural and petrological analysis of samples with increasing strain in high-pressure (HP) shear zones from the Haram garnet corona gabbro give insights into the deformation mechanisms of minerals, rheological properties of the shear zone and the role of deformation in enhancing metamorphic reactions. Scanning electron microscopy with electron backscattering diffraction (SEM,EBSD), compositional mapping and petrographic analysis were used to evaluate the nature of deformation in both reactants and products associated with eclogitization. Plagioclase with a shape-preferred orientation that occurs in the interior part of layers in the mylonitic sample deformed by intracrystalline glide on the (0 0 1)[1 0 0] slip system. In omphacite, crystallographic preferred orientations indicate slip on (1 0 0)[0 0 1] and (1 1 0)[0 0 1] during deformation. Fine-grained garnet deformed by diffusion creep and grain-boundary sliding. Ilmenite deformed by dislocation glide on the basal and, at higher strains, prism planes in the a direction. Relationships among the minerals present and petrological analysis indicate that deformation and metamorphism in the shear zones began at 500,650 °C and 0.5,1.4 GPa and continued during prograde metamorphism to ultra-high-pressure (UHP) conditions. Both products and reactants show evidence of syn- and post-kinematic growth indicating that prograde reactions continued after strain was partitioned away. The restriction of post-kinematic growth to narrow regions at the interface of garnet and plagioclase and preservation of earlier syn-kinematic microstructures in older parts layers that were involved in reactions during deformation show that diffusion distances were significantly shortened when strain was partitioned away, demonstrating that deformation played an important role in enhancing metamorphic reactions. Two important consequences of deformation observed in these shear zones are: (i) the homogenization of chemical composition gradients occurred by mixing and grain-boundary migration and (ii) composition changes in zoned metamorphic garnet by lengthening diffusion distances. The application of experimental flow laws to the main phases present in nearly monomineralic layers yield upper limits for stresses of 100,150 MPa and lower limits for strain rates of 10,12 to 10,13 s,1 as deformation conditions for the shear zones in the Haram gabbro that were produced during subduction of the Baltica craton and resulted in the production of HP and UHP metamorphic rocks. [source]


ABSTRACT A starch-glycerol gel was subjected to a two-bite compression test using two sample-instrument geometries, various speeds of compression and strain levels, both with lubrication or not. Results were interpreted using the primary characteristic terminology previously defined in Texture Profile Analysis. Compression speeds from 0.1 to 10 m/s showed a logarithmic relationship with hardness, cohesiveness, corrected cohesiveness and adhesiveness. Gels survived compression to strains of 0.90 without failing, strain levels from 0.25 to 0.90 resulted in an exponential rise in hardness with increasing strain and linear reduction in corrected cohesiveness. Lubrication had no significant influence on any of the measured parameters and an application of force with different sample-instrument geometry revealed that parallel plates and plungers only had an influence on gel hardness. Caution is urged when researchers modify the test protocol from 75% deformation with parallel plates. A minimum crosshead speed of 2 mm/s is recommended. PRACTICAL APPLICATIONS Texture Profile Analysis has been widely applied to test solid and semisolid foods; however, some researchers deviate from the original test protocol. This article attempts to show how modifying the parameters in the test protocol can influence the apparent properties of the sample. [source]

Effect of sparse long-chain branching on the step-strain behavior of a series of well-defined polyethylenes

Christopher D. McGrady
The effect of sparse long chain branching, LCB, on the shear step-strain relaxation modulus is analyzed using a series of eight high-density polyethylene (HDPE) resins. Strains of 1 to 1250% are imposed on materials with LCB content ranging from zero to 3.33 LCB per 10,000 carbon atoms. All materials are observed to obey time,strain separation beyond some characteristic time, ,k. The presence of LCB is observed to increase the value of ,k relative to the linear resin. The behavior of the relaxation modulus at times shorter than ,k is investigated by an analysis of the enhancement seen in the linear relaxation modulus, G0(t), as a function of strain and LCB content. This enhancement is seen to (1) increase with increasing strain in all resins, (2) be significantly larger in the sparsely branched HDPE resins relative to the linear HDPE resin, and (3) increase in magnitude with increasing LCB content. The shape and smoothness of the damping function is also investigated. The finite rise time to impose the desired strain is compared to the Rouse relaxation time of linear HDPE resins studied. Sparse LCB is found to increase the magnitude of the relaxation modulus at short times relative to the linear resin. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers [source]