Influence of particle morphology simplification on the simulation of granular material behavior

Considered is a sample of cohesionless granular material, in which the individual granules are regarded rigid, and which is subjected to overall macroscopic average stresses. On the basis of the principle of virtual work, and by an examination of the manner by which adjacent granules transmit forces through their contacts, a general representation is established for the macroscopic stresses in terms of the volume average of the (tensorial) product of the contact forces and the vectors which connect the centroids of adjacent contacting granules. Then the corresponding kinematics is examined and the overall macroscopic deformation rate and spin tensors are developed in terms of the volume average of relevant microscopic kinematical variables. As an illustration of the application of the general expressions developed, two explicit macroscopic results are deduced: (1) a dilatancy equation which both qualitatively and quantitatively seems to be in accord with experimental observation, and (2) a noncoaxiality equation which seems to support the vertex plasticity model. Since the development is based on a microstructural consideration, all material coefficients entering the results have well-defined physical interpretations.

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European Research into Granular Material for Pavement Bases and Subbases

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1721-11 ◽

2000 ◽

Vol 1721 (1) ◽

pp. 91-99 ◽

Cited By ~ 6

Author(s):

Andrew R. Dawson ◽

Michael J. Mundy ◽

Matti Huhtala

Keyword(s):

Granular Material ◽

State Of The Art ◽

The State ◽

Material Behavior ◽

European Research ◽

Repeated Load Triaxial Test ◽

In Situ Conditions ◽

Repeated Load ◽

Repeated Load Triaxial

Two transnational European research projects in the area of granular materials for road pavements are described. The results are used to illustrate the state of practice as compared to the state of the art and are placed within the setting of a broad picture of national research within Europe. Discussed are the direction of European research, its implementation, those areas that will continue to be problematic, and the findings and strategies that suggest better-practice for non-European users. The use of the repeated-load triaxial test is shown to be an important aspect. Although the test is shown to have limitations for practical purposes, it illustrates the nature of material behavior that may be expected in situ. It is shown that a fundamental engineering understanding has been applied to granular material pavement layer technology but that there remain issues of in situ assessment, analytical methods, and variability of in situ conditions that hinder full application of current understanding.

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Micro–macro analysis of granular material behavior along proportional strain paths

Continuum Mechanics and Thermodynamics ◽

10.1007/s00161-014-0347-8 ◽

2014 ◽

Vol 27 (1-2) ◽

pp. 173-193 ◽

Cited By ~ 9

Author(s):

François Nicot ◽

Luc Sibille ◽

Pierre-Yves Hicher

Keyword(s):

Granular Material ◽

Material Behavior ◽

Strain Paths

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Granular Material Radial Deformation Measurements with a Circumferential Extensometer in Repeated Load Triaxial Testing

Transportation Research Record Journal of the Transportation Research Board ◽

10.3141/1614-08 ◽

1998 ◽

Vol 1614 (1) ◽

pp. 61-69 ◽

Cited By ~ 2

Author(s):

Erol Tutumluer ◽

Navneet Garg ◽

Marshall R. Thompson

Keyword(s):

Granular Material ◽

Material Behavior ◽

Measuring System ◽

Triaxial Testing ◽

Radial Deformation ◽

Nonlinear Stress ◽

Wheel Loading ◽

Repeated Load ◽

Stress Dependent ◽

Repeated Load Triaxial

Determination of both axial and radial specimen strains in a repeated load triaxial test is essential for properly characterizing the directional dependency of resilient granular material behavior. Radial deformation measurement is not yet included in the standard AASHTO test procedure. The method of measuring radial strains adopted in this study emphasizes the use of a contact-type specimen instrumentation technique with a circumferential chain extensometer. The circumferential extensometer was successfully used in repeated load triaxial testing to measure radial strains of three aggregate samples with different material types and properties. The accuracy of the measuring system was within 10−5 (in strains) when the smallest strains recorded were on the order of 10−4. Nonlinear stress-dependent models for properly characterizing the anisotropic granular material stiffnesses were developed from measured axial and radial strains. The vertical/horizontal stiffness ratios in the triaxial sample consistently increased with increasing principal stress ratios, which often occurs in pavements under wheel loading. In general, the repeatability in radial strain measurements was deemed to be satisfactory and more reliable strains were measured at low confining pressures.

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Ultra-Rapid Freezing of Isolated Skeletal Muscle Fibers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100080316 ◽

1977 ◽

Vol 35 ◽

pp. 576-577

Author(s):

Joachim R. Sommer ◽

Nancy R. Wallace

Keyword(s):

Skeletal Muscle ◽

Sarcoplasmic Reticulum ◽

Granular Material ◽

Nuclear Envelope ◽

Intracellular Calcium ◽

Ruthenium Red ◽

Threshold Concentration ◽

Rapid Freezing ◽

Frog Skeletal Muscle ◽

Electrical Isolation

After Howell (1) had shown that ruthenium red treatment of fixed frog skeletal muscle caused collapse of the intermediate cisternae of the sarcoplasmic reticulum (SR), forming a pentalaminate structure by obi iterating the SR lumen, we demonstrated that the phenomenon involves the entire SR including the nuclear envelope and that it also occurs after treatment with other cations, including calcium (2,3,4).From these observations we have formulated a hypothesis which states that intracellular calcium taken up by the SR at the end of contraction causes the M rete to collapse at a certain threshold concentration as the first step in a subsequent centrifugal zippering of the free SR toward the junctional SR (JSR). This would cause a) bulk transport of SR contents, such as calcium and granular material (4) into the JSR and, b) electrical isolation of the free SR from the JSR.

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Effect of Some Metabolic Inhibitors on Vinblastine-Induced Ribosomal-Granular Material Complexes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066796 ◽

1971 ◽

Vol 29 ◽

pp. 548-549

Author(s):

Awtar Krishan ◽

Dora Hsu

Keyword(s):

Granular Material ◽

Rna Synthesis ◽

Culture Medium ◽

Actinomycin D ◽

Metabolic Inhibitors ◽

Protein And Rna Synthesis ◽

Apparent Reduction ◽

Plant Alkaloids ◽

In Cells

Cells exposed to antitumor plant alkaloids, vinblastine and vincristine sulfate have large proteinacious crystals and complexes of ribosomes, helical polyribosomes and electron-dense granular material (ribosomal complexes) in their cytoplasm, Binding of H3-colchicine by the in vivo crystals shows that they contain microtubular proteins. Association of ribosomal complexes with the crystals suggests that these structures may be interrelated.In the present study cultured human leukemic lymphoblasts (CCRF-CEM), were incubated with protein and RNA-synthesis inhibitors, p. fluorophenylalanine, puromycin, cycloheximide or actinomycin-D before the addition of crystal-inducing doses of vinblastine to the culture medium. None of these compounds could completely prevent the formation of the ribosomal complexes or the crystals. However, in cells pre-incubated with puromycin, cycloheximide, or actinomycin-D, a reduction in the number and size of the ribosomal complexes was seen. Large helical polyribosomes were absent in the ribosomal complexes of cells treated with puromycin, while in cells exposed to cycloheximide, there was an apparent reduction in the number of ribosomes associated with the ribosomal complexes (Fig. 2).

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