Rotation Of Grains Research Articles

A New Model of Local Elastic Deflections in Grinding

Mathematical models describing the deflection behavior of the wheel-work contact presented so far are based on the assumption that contact deflections are a direct function of the normal force on the wheel or the grains during grinding. This paper presents experimental results showing the evidence of a new mechanism of contact deflections due to the rotation of grain as a result of the tangential force component. In this perspective, a new model which considers the deflections due to both the normal and the tangential force is proposed and developed with the assumption of elasto-plastic deformation of the workpiece material around the grain during cutting. The model is shown to be consistent with experimental deflections obtained from single grain cutting on mild steel and EN25 steel specimens.

Experiments on the production of transverse grain alignment in a sheared dispersion

ABSTRACT A series of experiments was designed to investigate grain orientation in flows with concentrations of granular solids in the range from 0.5 to 15%. Fourteen experiments were carried out in which sand‐sized material was dispersed in liquid plaster of paris and the dispersion allowed to flow down a slope until it came to rest. The preferred orientation of the grains was then estimated by measuring the anisotropy of magnetic susceptibility of specimens cut from the solidified flows.Five of the experiments showed signs of deformation, both in the gross characteristics of the flow and in the grain alignment. The remaining nine had grain alignment dependent on grain concentration. At concentrations of 1.2% and less and 11.1% and more, by volume, alignment of long axes was parallel to flow. These observations were consistent with the existing theories for low concentrations, in which preferred alignment is shown to result from the varying rate of rotation of grains in a shearing flow, and for high concentrations, in which preferred alignment results from the transfer of angular momentum between colliding grains.At some intermediate concentrations transverse alignment was observed. A theoretical explanation combining the theories of the extreme cases is suggested. The observation of transverse alignment is compared with a similar observation in some turbidites.

Experimental folding of rocks under confining pressure, Part VIII—Forced folding of unconsolidated sand and of lubricated layers of limestone and sandstone

Research Article| May 01, 1980 Experimental folding of rocks under confining pressure, Part VIII—Forced folding of unconsolidated sand and of lubricated layers of limestone and sandstone M. FRIEDMAN; M. FRIEDMAN 1Center for Tectonophysics, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar R.H.H. HUGMAN, III; R.H.H. HUGMAN, III 1Center for Tectonophysics, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar J. HANDIN J. HANDIN 1Center for Tectonophysics, Texas A&M University, College Station, Texas 77843 Search for other works by this author on: GSW Google Scholar Author and Article Information M. FRIEDMAN 1Center for Tectonophysics, Texas A&M University, College Station, Texas 77843 R.H.H. HUGMAN, III 1Center for Tectonophysics, Texas A&M University, College Station, Texas 77843 J. HANDIN 1Center for Tectonophysics, Texas A&M University, College Station, Texas 77843 Publisher: Geological Society of America First Online: 01 Jun 2017 Online ISSN: 1943-2674 Print ISSN: 0016-7606 Geological Society of America GSA Bulletin (1980) 91 (5): 307–312. https://doi.org/10.1130/0016-7606(1980)91<307:EFORUC>2.0.CO;2 Article history First Online: 01 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation M. FRIEDMAN, R.H.H. HUGMAN, J. HANDIN; Experimental folding of rocks under confining pressure, Part VIII—Forced folding of unconsolidated sand and of lubricated layers of limestone and sandstone. GSA Bulletin 1980;; 91 (5): 307–312. doi: https://doi.org/10.1130/0016-7606(1980)91<307:EFORUC>2.0.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract Field and laboratory data suggest that variations in structural style are associated with differences in lithologic composition, stratigraphic sequence, and the mechanical behavior of the layers that are drape (forced) folded by differential vertical movements of underlying essentially rigid blocks. This hypothesis is tested by study of experimental, faulted, drape folds in veneers of loose, dry, unconsolidated sand and in multilithologic layered sequences with lubricated interfaces produced under confining pressures to 200 MPa (2 kb) at 25 °C. Deformation of the sand veneer provides a classic example of cataclastic flow. Forced folds develop as a result of microfracturing, rigid-body rotation of grains and fragments, and faulting and gouge development. The sand veneer is thinned drastically in the zone of faulting. The multilithologic, layered veneers with lubricated interfaces exhibit the same magnitudes of “bedding-plane” slip and somewhat more variability in the senses of slip than do specimens not lubricated. With lubrication, however, there is less deformation of the leading edge of the forcing block, less extensile faulting in the upthrown block, and more folding without faulting in the veneer. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Characteristics of drying remanent magnetization in sediments

Drying remanent magnetization is shown to be a physical phenomenon which is dependent on water content and magnetic grain shape. Anhysteretic remanent magnetization (ARM) acquisition studies show that no significant chemical changes occur on drying. There is a critical water content below which grain motion ceases. In a clay matrix, this water content is about 75% for single-domain needles and below 70% for single-domain euhedral grains. The rotation of grains during drying causes the magnetic moment to rotate toward the plane perpendicular to drying compression, and toward the external magnetic field. The rotation for euhedral grains is not restricted by shape anisotropy, while that for acicular grains is. Drying remanence cannot be completely removed once a sample has dried below its critical water content; however, most natural samples may be near or below their critical water content when cored.

Grain rearrangements during superplastic deformation

Current models for obtaining large superplastic flow without change of grain size are two-dimensional; they therefore involve rearrangement of grains without increasing the surface area of the specimen as it deforms. A new model is proposed in which grainboundary sliding (GBS) in a group of grains is accommodated by a grain emerging from the next layer of grains, giving the correct increase in surface area. This also produces curved grain boundaries and there is some rotation of grains involving plastic flow in a zone along grain boundaries (the “mantle”) of predictable width. Grains do not have to be uniform and regular for the process. Characteristic configurations of marker lines are produced by the deformation. All these features are shown to have been observed in the literature. The model does not predict a threshold stress. It can be linked with a previous constitutive equation based on the climb and glide of dislocations in the grain mantles.

Permanganate oxidation of humic acids extracted from a gray wooded soil under different cropping systems and fertilizer treatments

Long-term effects of two cropping systems and of manure, fertilizer and lime treatments on products resulting from the permanganate oxidation of humic acids extracted from a gray wooded soil were investigated. The major oxidation products were benzenecarboxylic and phenolic acids. Humic acids extracted from soils under a 5-year rotation of grains and legumes yielded, per unit weight, more benzenecarboxylic acids than did those originating from soils under a wheat-fallow sequence. By contrast, the type of cropping system did not seem to affect the yields of phenolic acids. The application of lime and manure tended to reduce the yields of benzenecarboxylic and phenolic acids, suggesting that these treatments degraded the “cores” or more resistant chemical structures of humic acids. Other useful indexes of the relative molecular complexities of the humic acids were the total yields of oxidation products. These, regardless of rotation, were highest for the check plots and lowest for the plots treated with lime. Between 75 and 90% of the oxidation products were identified. The data show that the type of rotation, and especially the application of lime and manure, have significant effects on the synthesis and degradation of humic acid “nuclei”. These effects may be brought about by increased microbial activity and/or by chemical means. Permanganate oxidation may thus serve as a guide for assessing the degree of humification of soil humic acids.

NITROGEN FRACTIONS IN A GRAY WOODED SOIL AS INFLUENCED BY LONG-TERM CROPPING SYSTEMS AND FERTILIZERS

A study was undertaken to determine long-term effects of two cropping systems and various fertilizer treatments on the distribution of N in a Gray Wooded soil of Alberta. The relative amount (expressed as percent of total soil N) of total acid hydrolyzable N in soils from plots in the five-year rotation of grains and legumes was significantly greater than in the wheat-fallow sequence. A similar effect was also noted from the proportion of soil N present in the form of amino sugar N, amino acid N, hydroxyamino acid N and unidentified N in the acid hydrolyzates. The relative amounts of ammonium N in the acid hydrolyzate, the non-hydrolyzable N and the non-exchangeable ammonium N in soil were greater in the wheat-fallow plot soils than in the rotation. The relative amount of total hydrolyzable N was significantly lower in the manure, NPKS, NS, lime or P treated soils than in the control. The proportion of amino sugar N increased following the manure treatment. Long-term application of mineral fertilizers had no significant effect upon the percentage distribution of the different forms of hydrolyzable soil N and the non-exchangeable ammonium N in the soil. The relative distribution of amino acids was not affected by the two cropping systems or various fertilizer treatments, but differences were noted in the absolute amounts.

Humic acid fraction of a gray wooded soil as influenced by cropping systems and fertilizers

A study was made to determine the long-term effect of two cropping systems and various fertilizer treatments on the humic acid fraction of Breton plot soils. The humic acid content in soils under a five-year rotation of grains and legumes was significantly greater than those from wheat-fallow system. The values for humic acid-C fulvic-C , E 4/ E 6, neutralisation capacity and carboxyl contents of humic acid isolated from soils under the wheat-fallow system were greater than in the rotation. Continued use of manure on Breton soils resulted in a significant increase of humic acid content. Application of N P K S (Nitrogen, Phosphorus, Potassium, Sulphur) and NS widened the humic acid-C fulvic-C ratio. The neutralization capacity of humic acid from lime treated soils was significantly greater than from manure, N P K S and NS plots. Application of N P K S resulted in a significant increase of total acidity and carbonyl contents over the check whereas carboxyl content was not effected by either treatment. It was postulated that humic acid isolated from Breton plot soils under the wheat-fallow sequence was more humified than that from a 5-year rotation of grains and legumes.

SOME CARBOHYDRATE FRACTIONS OF A GRAY WOODED SOIL AS INFLUENCED BY CROPPING SYSTEMS AND FERTILIZERS

A study was made to determine the long-term effect of two cropping systems and various fertilizer treatments on organic carbon, nitrogen and some of the carbohydrate constituents in Breton plot soils.Organic carbon, nitrogen, hexose, pentose, uronic acid, hexosamine and hexosamine-N contents were significantly greater in soils from plots in a five-year rotation of grains and legumes than in a wheat–fallow sequence. The proportion of organic carbon in the form of hexose did not differ significantly in either of the cropping systems, but the values for pentose, uronic acid and hexosamine were markedly greater in the five-year rotation plot soils.The contents of organic carbon, nitrogen and carbohydrate materials in soils increased considerably following the manure and fertilizer applications, whereas lime had no effect. Manure and fertilizer treatments also appeared to increase markedly the proportion of organic carbon present as hexose and hexosamine.

EFFECT OF CROPPING SYSTEMS AND FERTILIZERS ON MEAN WEIGHT-DIAMETER OF AGGREGATES OF BRETON PLOT SOILS

Aggregate analyses of Breton plot soils using a wet sieving technique revealed marked differences resulting from cropping practices but few, if any, due to fertilizers. The mean weight-diameter of soils from plots in a 5-year rotation of grains and legumes was almost double the diameter of soils from plots in a wheat-fallow sequence. With respect to fertilizers, however, mean weight-diameter of soils from high yielding plots in either cropping system were in general similar to those on low-yielding plots of the system in question. Incidentally polysaccharide content of the soil showed a definite relationship to mean weight-diameter.

Plastic Deformation of the Face-Centred Cubic Polycrystalline Metals in Consideration of the Deformation and Rotation of Grains (Part 1)

As Calnan and Clews pointed out, the grains in the aggregate do not deform on simple slip system but on multiple slip systems, because deformation of the grains on simple system would create the gaps at the grain boundary, and this is known not to happen. Therefore, the constraints due to the surrounding grains produce the local stress, which must be such as to produce multiple slips and simultaneous rotation of crystallographical orientations of the grain. The deformation textures, deformation hysteresis, skin effect and Heyn stress can be explained from rotation and deformation of the grains. In Part I the behavior of each grain in the aggregate is explained.

Plastic Deformation of the Face-Centred Cubic Polycrystalline Metals in Consideration of the Deformation and Rotation of Grains (Part II)

The face-centred cubic metals deform plastically by means of slip along the direction <110> on the plane {111}. From this fact, we obtained theoretically the deformation textures of these metals, and the results are in good agreement with experimental results.

An X-Ray Study of the Changes That Occur in Aluminum During the Process of Fatiguing

Carefully prepared test bars of 17S-T aluminum alloy have been fatigued; x-ray diffraction patterns of each specimen were taken at intervals as fatiguing progressed. Approximately thirty different test bars have been studied. Seven series of diffraction patterns, corresponding to seven different specimens, are reproduced and discussed in this paper. This study shows that (1) fatigue failure of 17S-T aluminum is always preceded by fatigue damage which is detectable by the use of x-ray diffraction patterns; (2) nearly all of the detectable changes occur in the last stages of fatiguing and consist of rotation of grains, introduction of strains in some of the crystallites, and fragmentation of some of the crystallites; (3) these changes do not occur when the specimen is fatigued below its endurance limit, but always occur prior to failure when it is fatigued above the endurance limit; (4) failure is probably intercrystalline rather than intracrystalline in character.