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Emilien Azéma - One of the best experts on this subject based on the ideXlab platform.
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Combined effects of contact friction and particle shape on strength properties and microstructure of sheared granular media
Physical Review E, 2020Co-Authors: Theechalit Binaree, Emilien Azéma, Nicolas Estrada, Mathieu Renouf, Itthichai PreechawuttipongAbstract:We present a systematic numerical investigation concerning the combined effects of sliding friction and particle shape (i.e., Angularity) parameters on the shear strength and microstructure of granular packings. Sliding friction at contacts varied from 0 (frictionless particles) to 0.7, and the particles were irregular polygons with an increasing number of sides, ranging from triangles to disks. We find that the effect of local friction on shear strength follows the same trend for all shapes. Strength first increases with local friction and then saturates at a shape-dependent value. In contrast, the effect of Angularity varies, depending on the level of sliding friction. For low friction values (i.e., under 0.3), the strength first increases with Angularity and then declines for the most angular shapes. For high friction values, strength systematically increases with Angularity. At the microscale, we focus on the connectivity and texture of the contact and force networks. In general terms, increasing local friction causes these networks to be less connected and more anisotropic. In contrast, increasing particle Angularity may change the network topology in different directions, directly affecting the macroscopic shear strength. These analyses and data constitute a first step toward understanding the joint effect of local variables such as friction and grain shape on the macroscopic rheology of granular systems.
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Texture Properties of a-2D Granular Mixture of an Angular Particle under Bi-axial Compression Texture Properties of a-2D Granular Mixture of an Angular Particle under Bi-axial Compression
IOP Conference Series: Materials Science and Engineering, 2020Co-Authors: Theechalit Binaree, Itthichai Preechawuttipong, Emilien AzémaAbstract:Utilizing Discrete Element Modeling (DEM), we investigate the shear strength properties and microstructure of 2D granular mixture composed of various regular polygonal particles (from triangle to icosagon and disk) under biaxial compression. Three cases were considered: 1) increase of proportion and Angularity started from disk (S1); 2) increase of proportion by decreasing the Angularity started from triangle (S2); 3) increase of proportion by random Angularity started from disk (S3) and polygons (S4). The results show that the shear strength changes with the mean Angularity. On the other hand, the packing fraction slightly varies with the mean Angularity. At the microscopic scale, the granular texture in term of the force, the contacts transmitted the force higher than the average force (strong force) are oriented in the direction of externally applied loading but they represent only 40% of the total number of contacts. Besides, the tangential contact forces direction tend to be consistent with the maximum shear strength direction.
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Effects of particle shape mixture on strength and structure of sheared granular materials
Physical Review E, 2019Co-Authors: Theechalit Binaree, Itthichai Preechawuttipong, Emilien AzémaAbstract:Using bi-dimensional discrete element simulations, the shear strength and microstructure of granular mixtures composed of particles of different shapes are systematically analyzed as a function of the proportion of grains of a given number of sides and the combination of different shapes (species) in one sample. We varied the Angularity of the particles by varying the number of sides of the polygons from 3 (triangles) up to 20 (icosagons) and disks. The samples analyzed were built keeping in mind the following cases: (1) increase of Angularity and species starting from disks; (2) decrease of Angularity and increase of species starting from triangles; (3) random Angularity and increase of species starting from disks and from polygons. The results show that the shear strength vary monotonically with increasing numbers of species (it may increase or decrease), even in the random mixtures (case 3). At the micro-scale, the variation in shear strength as a function of the number of species is due to different mechanisms depending on the cases analyzed. It may result from the increase of both the geometrical and force anisotropies, from only a decrease of frictional anisotropy, or from compensation mechanisms involving geometrical and force anisotropies.
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packings of irregular polyhedral particles strength structure and effects of Angularity
Physical Review E, 2013Co-Authors: Emilien Azéma, Farhang Radjai, Frederic DuboisAbstract:We present a systematic numerical investigation of the shear strength and structure of granular packings composed of irregular polyhedral particles. The Angularity of the particles is varied by increasing the number of faces from 8 (octahedronlike shape) to 596. We find that the shear strength increases with Angularity up to a maximum value and saturates as the particles become more angular (below 46 faces). At the same time, the packing fraction increases to a peak value but declines for more angular particles. We analyze the connectivity and anisotropy of the microstructure by considering both the contacts and branch vectors joining particle centers. The increase of the shear strength with Angularity is shown to be due to a net increase of the fabric and force anisotropies but at higher particle Angularity a rapid falloff of the fabric anisotropy is compensated by an increase of force anisotropy, leading thus to the saturation of shear strength.
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Nonlinear effects of particle shape Angularity in sheared granular media
Physical Review E : Statistical Nonlinear and Soft Matter Physics, 2012Co-Authors: Emilien Azéma, Nicolas Estrada, Farhang RadjaiAbstract:We analyze the effects of particle shape Angularity on the macroscopic shear behavior and texture of granular packings simulated by means of the contact dynamics method. The particles are regular polygons with an increasing number of sides ranging from 3 (triangles) to 60. The packings are analyzed in the steady shear state in terms of their shear strength, packing fraction, connectivity, and fabric and force anisotropies, as functions of the Angularity. An interesting finding is that the shear strength increases with Angularity up to a maximum value and saturates as the particles become more angular (below six sides). In contrast, the packing fraction declines towards a constant value, so that the packings of more angular particles are looser but have higher shear strength. We show that the increase of the shear strength at low Angularity is due to an increase of both contact and force anisotropies, and the saturation of the shear strength for higher angularities is a consequence of a rapid fall-off of the contact and normal force anisotropies compensated by an increase of the tangential force anisotropy. This transition reflects clearly the rather special geometrical properties of these highly angular shapes, implying that the stability of the packing relies strongly on the side-side contacts and the mobilization of friction forces.
Massimiliano Procura - One of the best experts on this subject based on the ideXlab platform.
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one loop Angularity distributions with recoil using soft collinear effective theory
Journal of High Energy Physics, 2019Co-Authors: Ankita Budhraja, Ambar Jain, Massimiliano ProcuraAbstract:Angularities are event shapes whose sensitivity to the splitting angle of a collinear emission is controlled by a continuous parameter b, with −1 < b < ∞. When measured with respect to the thrust axis, this class of QCD observables includes thrust (b = 1) and jet broadening (b = 0), the former being insensitive to the recoil of soft against collinear radiation, while the latter being maximally sensitive to it. Presently available analytic results for Angularity distributions with b ≠ 0 can be applied only close to the thrust limit since recoil effects have so far been neglected. As a first step to establish a comprehensive theoretical framework based on Soft-Collinear Effective Theory valid for all recoil-sensitive angularities, we compute for the first time Angularity distributions at one-loop order in αs for all values of b taking into account recoil effects. In the differential cross section, these amount to novel sub-leading singular contributions and/or power corrections, where the former are characterized by fractional powers of the Angularity and contribute appreciably close to the peak region, also for b ≳ 0.5. Our calculations are checked against various limits known in the literature and agree with the numerical output of the Event2 generator.
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one loop Angularity distributions with recoil using soft collinear effective theory
arXiv: High Energy Physics - Phenomenology, 2019Co-Authors: Ankita Budhraja, Ambar Jain, Massimiliano ProcuraAbstract:Angularities are event shapes whose sensitivity to the splitting angle of a collinear emission is controlled by a continuous parameter $b$, with $ -1 < b < \infty$. When measured with respect to the thrust axis, this class of QCD observables includes thrust ($b=1$) and jet broadening ($b=0$), the former being insensitive to the recoil of soft against collinear radiation, while the latter being maximally sensitive to it. Presently available analytic results for Angularity distributions with $b \neq 0$ can be applied only close to the thrust limit since recoil effects have so far been neglected. As a first step to establish a comprehensive theoretical framework based on Soft-Collinear Effective Theory valid for all recoil-sensitive angularities, we compute for the first time Angularity distributions at one-loop order in $\alpha_s$ for all values of $b$ taking into account recoil effects. In the differential cross section, these amount to novel sub-leading singular contributions and/or power corrections, where the former are characterized by fractional powers of the Angularity and contribute appreciably close to the peak region, also for $b \gtrsim 0.5$. Our calculations are checked against various limits known in the literature and agree with the numerical output of the Event2 generator.
Gunnar Wiedenbauer - One of the best experts on this subject based on the ideXlab platform.
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distance cognition in virtual environmental space further investigations to clarify the route Angularity effect
Psychological Research-psychologische Forschung, 2006Co-Authors: Petra Jansenosmann, Gunnar WiedenbauerAbstract:Two experiments with 72 participants in total investigated the route-Angularity effect. This effect is shown when a greater number of turns along a route increase the estimated length of this route. In this study it was shown that the route-Angularity effect is likely to be a memory-based effect depending on task difficulty. The important factor seems to be how heavily memory is loaded during learning. The route-Angularity effect even appears in intentional learning, when memory is loaded heavily. Under this learning condition participants know beforehand that they have to estimate distances. All experiments were conducted in a controlled virtual environment, which allows a reliable investigation of distance estimations in environmental space.
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the influence of turns on distance cognition new experimental approaches to clarify the route Angularity effect
Environment and Behavior, 2004Co-Authors: Petra Jansenosmann, Gunnar WiedenbauerAbstract:Three experiments investigated the route-Angularity effect, which is demonstrated when a greater number of turns along a route increases the estimated length. So far, a route-Angularity effect has ...
Itthichai Preechawuttipong - One of the best experts on this subject based on the ideXlab platform.
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Combined effects of contact friction and particle shape on strength properties and microstructure of sheared granular media
Physical Review E, 2020Co-Authors: Theechalit Binaree, Emilien Azéma, Nicolas Estrada, Mathieu Renouf, Itthichai PreechawuttipongAbstract:We present a systematic numerical investigation concerning the combined effects of sliding friction and particle shape (i.e., Angularity) parameters on the shear strength and microstructure of granular packings. Sliding friction at contacts varied from 0 (frictionless particles) to 0.7, and the particles were irregular polygons with an increasing number of sides, ranging from triangles to disks. We find that the effect of local friction on shear strength follows the same trend for all shapes. Strength first increases with local friction and then saturates at a shape-dependent value. In contrast, the effect of Angularity varies, depending on the level of sliding friction. For low friction values (i.e., under 0.3), the strength first increases with Angularity and then declines for the most angular shapes. For high friction values, strength systematically increases with Angularity. At the microscale, we focus on the connectivity and texture of the contact and force networks. In general terms, increasing local friction causes these networks to be less connected and more anisotropic. In contrast, increasing particle Angularity may change the network topology in different directions, directly affecting the macroscopic shear strength. These analyses and data constitute a first step toward understanding the joint effect of local variables such as friction and grain shape on the macroscopic rheology of granular systems.
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Texture Properties of a-2D Granular Mixture of an Angular Particle under Bi-axial Compression Texture Properties of a-2D Granular Mixture of an Angular Particle under Bi-axial Compression
IOP Conference Series: Materials Science and Engineering, 2020Co-Authors: Theechalit Binaree, Itthichai Preechawuttipong, Emilien AzémaAbstract:Utilizing Discrete Element Modeling (DEM), we investigate the shear strength properties and microstructure of 2D granular mixture composed of various regular polygonal particles (from triangle to icosagon and disk) under biaxial compression. Three cases were considered: 1) increase of proportion and Angularity started from disk (S1); 2) increase of proportion by decreasing the Angularity started from triangle (S2); 3) increase of proportion by random Angularity started from disk (S3) and polygons (S4). The results show that the shear strength changes with the mean Angularity. On the other hand, the packing fraction slightly varies with the mean Angularity. At the microscopic scale, the granular texture in term of the force, the contacts transmitted the force higher than the average force (strong force) are oriented in the direction of externally applied loading but they represent only 40% of the total number of contacts. Besides, the tangential contact forces direction tend to be consistent with the maximum shear strength direction.
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Effects of particle shape mixture on strength and structure of sheared granular materials
Physical Review E, 2019Co-Authors: Theechalit Binaree, Itthichai Preechawuttipong, Emilien AzémaAbstract:Using bi-dimensional discrete element simulations, the shear strength and microstructure of granular mixtures composed of particles of different shapes are systematically analyzed as a function of the proportion of grains of a given number of sides and the combination of different shapes (species) in one sample. We varied the Angularity of the particles by varying the number of sides of the polygons from 3 (triangles) up to 20 (icosagons) and disks. The samples analyzed were built keeping in mind the following cases: (1) increase of Angularity and species starting from disks; (2) decrease of Angularity and increase of species starting from triangles; (3) random Angularity and increase of species starting from disks and from polygons. The results show that the shear strength vary monotonically with increasing numbers of species (it may increase or decrease), even in the random mixtures (case 3). At the micro-scale, the variation in shear strength as a function of the number of species is due to different mechanisms depending on the cases analyzed. It may result from the increase of both the geometrical and force anisotropies, from only a decrease of frictional anisotropy, or from compensation mechanisms involving geometrical and force anisotropies.
Theechalit Binaree - One of the best experts on this subject based on the ideXlab platform.
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Combined effects of contact friction and particle shape on strength properties and microstructure of sheared granular media
Physical Review E, 2020Co-Authors: Theechalit Binaree, Emilien Azéma, Nicolas Estrada, Mathieu Renouf, Itthichai PreechawuttipongAbstract:We present a systematic numerical investigation concerning the combined effects of sliding friction and particle shape (i.e., Angularity) parameters on the shear strength and microstructure of granular packings. Sliding friction at contacts varied from 0 (frictionless particles) to 0.7, and the particles were irregular polygons with an increasing number of sides, ranging from triangles to disks. We find that the effect of local friction on shear strength follows the same trend for all shapes. Strength first increases with local friction and then saturates at a shape-dependent value. In contrast, the effect of Angularity varies, depending on the level of sliding friction. For low friction values (i.e., under 0.3), the strength first increases with Angularity and then declines for the most angular shapes. For high friction values, strength systematically increases with Angularity. At the microscale, we focus on the connectivity and texture of the contact and force networks. In general terms, increasing local friction causes these networks to be less connected and more anisotropic. In contrast, increasing particle Angularity may change the network topology in different directions, directly affecting the macroscopic shear strength. These analyses and data constitute a first step toward understanding the joint effect of local variables such as friction and grain shape on the macroscopic rheology of granular systems.
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Texture Properties of a-2D Granular Mixture of an Angular Particle under Bi-axial Compression Texture Properties of a-2D Granular Mixture of an Angular Particle under Bi-axial Compression
IOP Conference Series: Materials Science and Engineering, 2020Co-Authors: Theechalit Binaree, Itthichai Preechawuttipong, Emilien AzémaAbstract:Utilizing Discrete Element Modeling (DEM), we investigate the shear strength properties and microstructure of 2D granular mixture composed of various regular polygonal particles (from triangle to icosagon and disk) under biaxial compression. Three cases were considered: 1) increase of proportion and Angularity started from disk (S1); 2) increase of proportion by decreasing the Angularity started from triangle (S2); 3) increase of proportion by random Angularity started from disk (S3) and polygons (S4). The results show that the shear strength changes with the mean Angularity. On the other hand, the packing fraction slightly varies with the mean Angularity. At the microscopic scale, the granular texture in term of the force, the contacts transmitted the force higher than the average force (strong force) are oriented in the direction of externally applied loading but they represent only 40% of the total number of contacts. Besides, the tangential contact forces direction tend to be consistent with the maximum shear strength direction.
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Effects of particle shape mixture on strength and structure of sheared granular materials
Physical Review E, 2019Co-Authors: Theechalit Binaree, Itthichai Preechawuttipong, Emilien AzémaAbstract:Using bi-dimensional discrete element simulations, the shear strength and microstructure of granular mixtures composed of particles of different shapes are systematically analyzed as a function of the proportion of grains of a given number of sides and the combination of different shapes (species) in one sample. We varied the Angularity of the particles by varying the number of sides of the polygons from 3 (triangles) up to 20 (icosagons) and disks. The samples analyzed were built keeping in mind the following cases: (1) increase of Angularity and species starting from disks; (2) decrease of Angularity and increase of species starting from triangles; (3) random Angularity and increase of species starting from disks and from polygons. The results show that the shear strength vary monotonically with increasing numbers of species (it may increase or decrease), even in the random mixtures (case 3). At the micro-scale, the variation in shear strength as a function of the number of species is due to different mechanisms depending on the cases analyzed. It may result from the increase of both the geometrical and force anisotropies, from only a decrease of frictional anisotropy, or from compensation mechanisms involving geometrical and force anisotropies.