Interface load–displacement behaviour of sand grains coated with clayey powder: Experimental and analytical studies

Kasyap, Sathwik S.; Senetakis, Kostas

doi:10.1016/j.sandf.2019.07.010

Cited by 21 publications

(12 citation statements)

References 47 publications

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“…The results in Figure 20 and Table 2 show that the Hertz model applies reasonably well for both LBS and CDG contacts and their respective composite interfaces for a maximum load of 1.5 N. It is acknowledged, however, as previous studies have also reported on geological materials [ 70 , 102 ], that the application of Hertz fitting needs to consider the initial plastic displacements (soft behavior) so that the theoretical curves are shifted to slightly larger displacements prior to the implementation of the fitting process. In the abovementioned analysis, for LBS and LBS–rubber interfaces, fitting was applied without any shift of the theoretical curve (i.e., the Hertz model was applied from the regime of initial displacements); however, for CDG and CDG–rubber, a slight shift to larger displacements, of the order of a few microns, was applied to fit the analytical expression to the experimental data.…”

Section: Resultsmentioning

confidence: 52%

“…Thus, in the subsequent analysis and implementation of the Hertz model, local radii of the sand grains are used. These local radii are determined based on images taken from two microscope digital cameras placed orthogonally, which capture the local shape in the vicinity of the grain contacts (similar to previous studies by [ 79 , 81 , 102 ]) and the computation of the arithmetic mean of the local radius of the LBS and CDG grains (for both rigid and rigid–soft interfaces).…”

Section: Resultsmentioning

confidence: 99%

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Influence of Loading History and Soil Type on the Normal Contact Behavior of Natural Sand Grain-Elastomer Composite Interfaces

2021

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Recycled rubber in granulated form is a promising geosynthetic material to be used in geotechnical/geo-environmental engineering and infrastructure projects, and it is typically mixed with natural soils/aggregates. However, the complex interactions of grains between geological materials (considered as rigid bodies) and granulated rubber (considered as soft bodies) have not been investigated systematically. These interactions are expected to have a significant influence on the bulk strength, deformation characteristics, and stiffness of binary materials. In the present study, micromechanical-based experiments are performed applying cyclic loading tests investigating the normal contact behavior of rigid–soft interfaces. Three different geological materials were used as “rigid” grains, which have different origins and surface textures. Granulated rubber was used as a “soft” grain simulant; this material has viscoelastic behavior and consists of waste automobile tires. Ten cycles of loading–unloading were applied without and with preloading (i.e., applying a greater normal load in the first cycle compared with the consecutive cycles). The data analysis showed that the composite sand–rubber interfaces had significantly reduced plastic displacements, and their behavior was more homogenized compared with that of the pure sand grain contacts. For pure sand grain contacts, their behavior was heavily dependent on the surface roughness and the presence of natural coating, leading, especially for weathered grains, to very high plastic energy fractions and significant plastic displacements. The behavior of the rigid–soft interfaces was dominated by the rubber grain, and the results showed significant differences in terms of elastic and plastic fractions of displacement and dissipated energy compared with those of rigid interfaces. Additional analysis was performed quantifying the normal contact stiffness, and the Hertz model was implemented in some of the rigid and rigid–soft interfaces.

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Section: Resultsmentioning

confidence: 52%

Section: Resultsmentioning

confidence: 99%

Influence of Loading History and Soil Type on the Normal Contact Behavior of Natural Sand Grain-Elastomer Composite Interfaces

2021

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“…The summation of the radius of curvature at each data point on the boundary within the specified pixel range results in the local radius of curvature of a grain. A similar approach was also adopted by Kasyap and Senetakis [ 37 ] and Wang and Coop [ 21 ] in their micromechanical studies. The procedures of the manual and Matlab methods are further explained using a representative picture of a grain in Figure 3 .…”

Section: Resultsmentioning

confidence: 99%

“…As these experiments involve grain contacts, the Hertz model [ 36 ] was applied to estimate the contact area, which is necessary to be obtained to derive stresses from the measured forces. The application of Hertz modeling has been implemented in many previous studies examining the contact behavior of particles (e.g., [ 25 , 37 , 38 ]), however, this has been majorly directed in the analysis of the pre-failure behavior of granular systems, which was one of the major novel concepts in the present study, i.e., implementation of Hertz analysis in grain contact crushing experiments. An important new contribution from the present work was also the rigorous examination of the influence of the method of analysis of the data, particularly the way local radius (i.e., the radius of the grains in the vicinity of their contact) is estimated to apply Hertz modeling.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Failure Behavior of Sand Grain Contacts with Hertz Modeling, Image Processing, and Statistical Analysis

Kasyap

Senetakis

2021

Sensors

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The crushing behavior of particles is encountered in a large number of natural and engineering systems, and it is important for it to be examined in problems related to hydraulic fracturing, where proppant–proppant and proppant–rock interactions are essential to be modeled as well as geotechnical engineering problems, where grains may crush because the transmitted stresses at their contacts exceed their tensile strength. Despite the interest in the study of the crushing behavior of natural particles, most previous experimental works have examined the single-grain or multiple-grain crushing configurations, and less attention has been given in the laboratory investigation of the interactions of two grains in contact up to their failure as well as on the assessment of the methodology adopted to analyze the data. In the present study, a quartz sand of 1.18–2.36 mm in size was examined, performing a total of 244 grain-to-grain crushing tests at two different speeds, 0.01 and 1 mm/min. In order to calculate stresses from the measured forces, Hertz modeling was implemented to calculate an approximate contact area between the particles based on their local radii (i.e., the radius of the grains in the vicinity of their contact). Based on the results, three different modes of failure were distinguished as conservative, fragmentary, and destructive, corresponding to micro-scale, meso-scale, and macro-scale breakage, respectively. From the data, four different classes of curves could be identified. Class-A and class-B corresponded to an initially Hertzian behavior followed by a brittle failure with a distinctive (single) peak point. The occurrence of hardening prior to the failure point distinguished class-B from class-A. Two additional classes (termed as class-C and class-D) were observed having two or multiple peaks, and much larger displacements were necessary to mobilize the failure point. Hertz fitting, Weibull statistics, and clustering were further implemented to estimate the influence of local radius and elastic modulus values. One of the important observations was that the method of analysis adopted to estimate the local radius of the grains, based on manual assessment (i.e., eyeball fitting) or robust Matlab-based image processing, was a key factor influencing the resultant strength distribution and m-modulus, which are grain crushing strength characteristics. The results from the study were further compared with previously reported data on single- and multiple-grain crushing tests.

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“…In repeated monotonic loading, each specimen was subjected to three cycles of normal loading and shearing, i.e., after the application of the nominal F N , the specimen was subjected to shearing for the required sliding path and consecutively, the pair of grains was set to their reference position and a second (and a third) cycle of normal loading and shearing was applied so that to maintain the same contact region among all the cycles. Based on the experimental protocol for the repeated loading tests, the influence of loading history could be examined, similar to previous studies on various types of geological materials [ 75 , 76 , 77 ]. As different MMS-1 specimens showed highly varied normal and tangential contact responses, monotonic shearing tests were performed on 12 specimens and three cycles of repeated loading tests were conducted on a representative set of two specimens.…”

Section: Material Equipment and Methodologymentioning

confidence: 99%

A Grain-Scale Study of Mojave Mars Simulant (MMS-1)

Kasyap

Senetakis

2021

Sensors

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Space exploration has attracted significant interest by government agencies and the scientific community in recent years in an attempt to explore possible scenarios of settling of facilities on the Moon and Mars surface. One of the important components in space exploration is related with the understanding of the geophysical and geotechnical characteristics of the surfaces of planets and their natural satellites and because of the limitation of available extra-terrestrial samples, many times researchers develop simulants, which mimic the properties and characteristics of the original materials. In the present study, characterization at the grain-scale was performed on the Mojave Mars Simulant (MMS-1) with emphasis on the frictional behavior of small size samples which follow the particle-to-particle configuration. Additional characterization was performed by means of surface composition and morphology analysis and the crushing behavior of individual grains. The results from the study present for the first time the micromechanical tribological response of Mars simulant, and attempts were also made to compare the behavior of this simulant with previously published results on other types of Earth and extra-terrestrial materials. Despite some similarities between Mars and Moon simulants, the unique characteristics of the MMS-1 samples resulted in significant differences and particularly in severe damage of the grain surfaces, which was also linked to the dilation behavior at the grain-scale.

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Interface load–displacement behaviour of sand grains coated with clayey powder: Experimental and analytical studies

Cited by 21 publications

References 47 publications

Influence of Loading History and Soil Type on the Normal Contact Behavior of Natural Sand Grain-Elastomer Composite Interfaces

Influence of Loading History and Soil Type on the Normal Contact Behavior of Natural Sand Grain-Elastomer Composite Interfaces

A Study on the Failure Behavior of Sand Grain Contacts with Hertz Modeling, Image Processing, and Statistical Analysis

A Grain-Scale Study of Mojave Mars Simulant (MMS-1)

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