Internal Friction Coefficient Research Articles

Engineering Properties of Foxtail Millet Seeds for Development of Planter for Millet Crop

Millets are sown by broadcasting and drilling by traditional implements. By using these tools, seeds were not distributed uniformly, which led to an excess of plants and irregular spacing. Furthermore, if seed is sown in a line rather than a spread pattern, harvesting and threshing activities become more efficient. In keeping the views of above facts, planter for millet seeds was developed. A study was carried out to measure the engineering properties of foxtail millet seeds for development of planter for millet crop. Engineering properties helps in design of machine parameters like type of seed metering mechanism, size of cell and hopper capacity etc. The engineering properties such as mean linear dimensions viz., length, width and thickness are 2.20 mm, 1.23 mm and 1.11 mm respectively. The physical properties like geometrical mean diameter, bulk density and true density of are 1.43 mm, 670.33 kg m-3, 1156.2 kg m-3 respectively. The frictional properties such as angle of repose, co-efficient of internal and external friction are 24.30 degrees, 1.23 and 0.45 degrees respectively. In developing the millet planter, these measured engineering parameters were taken into account.

A Euler-lagrange Model of dynamic internal friction

A Euler-Lagrange model of dynamic internal friction is proposed and is shown to match the frequency and decay of oscillations in both simple extension (pull) and cantilever beam experiments. The proposed dynamic internal frictional stress, τij, is proportional to the rate of change of the engineering stress, σ˙ij. i.e.τij=μmσ˙ij,with μm the dynamic internal friction coefficient. A single value of the dynamic internal friction coefficient is shown to match the results of the experiments for a number of different geometries of the silicon rubber, Dragon SkinTM. Dragon SkinTM is used in skin effects for movies and in prosthetics and cushioning applications. It is chosen here because of its ease of preparation and relatively simple non-linear stress-strain response. Because of these characteristics, it provides a simple starting place for simulating more complicated synthetic rubber and biological materials, which are used in a myriad of commercial applications.

Sensitivity analysis of slope stability based on eXtreme gradient boosting and SHapley Additive exPlanations: An exploratory study

Slope instability through can cause catastrophic consequences, so slope stability analysis has been a key topic in the field of geotechnical engineering. Traditional analysis methods have shortcomings such as high operational difficulty and time-consuming, for this reason many researchers have carried out slope stability analysis based on AI. However, the current relevant studies only judged the importance of each factor and did not specifically quantify the correlation between factors and slope stability. For this purpose, this paper carried out a sensitivity analysis based on the XGBoost and SHAP. The sensitivity analysis results of SHAP were also validated using GeoStudio software. The selected influence factors included slope height (H), slope angle (β), unit weight (γ), cohesion (c), angle of internal friction (φ) and pore water pressure coefficient (ru). The results showed that c and γ were the most and least important influential parameters, respectively. GeoStudio simulation results showed a negative correlation between γ, β, H, ru and slope stability, while a positive correlation between c, φ and slope stability. However, for real data, SHAP misjudged the correlation between γ and slope stability. Because current AI lacked common sense knowledge and, leading SHAP unable to effectively explain the real mechanism of slope instability. For this reason, this paper overcame this challenge based on the priori data-driven approach. The method provided more reliable and accurate interpretation of the results than a real sample, especially with limited or low-quality data. In addition, the results of this method showed that the critical values of c, φ, β, H, and ru in slope destabilization are 18 Kpa, 28°, 32°, 30 m, and 0.28, respectively. These results were closer to GeoStudio simulations than real samples.

A Novel Technosol Formulation for Sustainable Landfill Top Covers Using Non-Hazardous Wastes

This study explores the potential of non-hazardous wastes for crafting an engineered soil-like material (Technosol) suitable for landfill capping applications. Three distinct materials—waste foundry sand (WFS), washing aggregate sludge (WAS), and composted biosolids (CBS)—were strategically combined to develop this innovative Technosol. The formulation process involved a comprehensive analysis of their physical–chemical properties, mineral composition, leachate quality, and a series of geotechnical assessments to ensure compliance with landfill top cover construction standards. The blend 90WFS/10WAS showed optimal geotechnical properties for constructing a protective layer, including maximum dry density (1.77 g cm−3), void ratio (0.4), CBR index (23.2), cohesive strength (40 kPa), internal friction (ϕ = 30°), and permeability coefficient (k = 1.48 × 10−6 cm s−1). Further enhancement was achieved by adding 10% CBS, resulting in the development of a functional organo-mineral topsoil horizon (81WFS/9WAS/10CBS). Importantly, leachate analysis confirmed the negligible environmental footprint of this Technosol. Moreover, a pot-based experiment with Brassica juncea planting validated its capacity to support plant growth and establish a vegetative cover on the landfill surface.

A metamaterial with enhanced effective stiffness and negative Poisson's ratio for frictional energy dissipation

Unlike traditional energy dissipation structures that dissipate energy through irreversible plastic deformation or collapse, metamaterials based on friction energy dissipation have attracted attention due to their reusability. This article proposed a novel energy dissipation metamaterial by integrating friction energy dissipation mechanism into negative Poisson's ratio (NPR) structures. The integration of friction energy dissipation mechanism can simultaneously enhance the effective stiffness and NPR effect. The mechanical properties of the proposed structure were investigated using theoretical analysis, experiments, and finite element (FE) simulations. The influence of variables such as internal concave angle, friction coefficient, and number of reinforcing ribs was discussed. The results indicate that both unit cell and honeycomb structure can repeatedly dissipate energy within the elastic range. Compared with the traditional concave hexagonal structure, the effective stiffness and NPR effect were enhanced. This work provides a novel idea for the design of NPR energy dissipation structures.

Objective texture evaluation of cosmetic sericite powders mixed with oil using constant-volume shear cell tester

Although sensory evaluation is often used to evaluate cosmetic powder textures, such evaluations are problematic because they are subjective and depend on human senses. Consequently, an objective evaluation is highly desired. We therefore report herein the use of a constant-volume shear tester to objectively evaluate the physical properties of a cosmetic powder. The goal of the study is to detect the differences in the physical properties of powders, which is done by applying a constant-volume shear test to oil-wet powders of differing textures mixed with dimethicone or squalane. Differences between dimethicone and squalane mixtures appear in the stress relaxation ratio (softness), the shear cohesion (moist feeling), the internal friction coefficient for friction (for normal stress of <10 kPa) between powder beds (smoothness), and the dynamic friction coefficient for friction between powder beds. Although the oils presented a similar degree of the powder yield locus, the shape of the powder yield locus indicates the state of the powder beds. The results of the study show that constant-volume shear testing can be used to objectively evaluate oil-wet powder textures.

Viscous effects in sheared unsaturated wet granular materials

We report on experiments and discrete element simulations of homogeneous, simple, normal stress-controlled, shear flows of model unsaturated granular materials: assemblies of frictional spherical particles bonded by a small quantity of a wetting liquid. The rheology of such unsaturated granular materials in the dense flow regime was characterized in recent publications of our group, in terms of internal friction coefficient μ∗ and solid fraction Φ, depending on the reduced pressure P∗ comparing capillary forces to controlled normal stress, and on inertial number I. The present study extends this description to the influence of the liquid viscosity on material rheology in the low saturation regime. The quantitative agreement of simulations with experiments is confirmed for the quasistatic limit, and our numerical results, despite some quantitative differences, capture the correct trends in the regime dominated by viscous forces. Rheological properties are then determined, to a large extent, by the same viscous numberIv as used to formulate constitutive laws in saturated, dense suspensions. More precisely, a visco-inertial numberJ, combining Iv with inertial number I as J=Iv+2I2, appears apt to describe the rheological laws, as expressed by the internal friction coefficient and the solid fraction, measured in the laboratory or in the simulations, as well as the numerically investigated internal state of the flowing material. Simulations provide insight into the role of viscous forces: predominantly tensile, they contribute to the increase with shear rate of the macroscopic friction coefficient μ∗ through a direct positive contribution to shear stress, a negative contribution to normal stresses (enhancing the strength of the contact network), and microstructural changes affecting the network of contacts and liquid bridges.

Comparison of the reliability of strength limit calculation methods for prismatic samples with different spreading of normal contact stresses in their wedge failure shape

This article explores methods for calculating the strength limits of solid objects subjected to compression. Traditionally, two stress distribution patterns are used: the exponential pattern by E.P. Unksov and the linear pattern by L. Prandtl. The authors introduce an enhanced stress distribution method. They compare the accuracy of these methods in calculating strength limits and constructing “normal stress - longitudinal strain” diagrams for wedge-shaped failures in rock samples. Four properties are considered: shear strength, coefficients of internal and external friction, and elasticity modulus. The results show that, with an external friction coefficient up to 0.3, all methods yield similar accuracy in strength limit calculations and ultimate stress-strain curves. Some curves exhibit stress drops, explained by a transition from convex to concave slip lines during failure. Additionally, there are hardening curves in the ultimate curves without theoretical justification. The comparison of calculated strength limits with experimental data confirms the method’s accuracy: 13.7% error for the exponential method, 11.4% for the linear method, and 8.1% for the enhanced distribution, especially for low contact friction values (up to f c=0.3).

A Study on Moisture Dependent Properties of Barnyard Millet (Echinochloa frumentacea) Grains

A vital component in the design of threshers, dehuskers, shellers, and winnowers is the combination of geometrical, frictional, gravimetric, and aerodynamic characteristics. Consequently, to assess these qualities of barnyard millet grain, experiments were conducted. samples within a suitable moisture content range of 6.21 to 22.57% (db). were used in the experiments. Based on the moisture content appropriate for the majority of post-harvest operations, a range of 6 to 24% was selected. The geometrical mean diameter, equivalent mean diameter, arithmetic mean diameter, and square mean diameter increased from 2.05 to 2.24 mm, 2.63 to 2.87 mm, 2.18 to 2.38 mm, and 3.67 to 4.00 mm, respectively, with an increase in moisture content. Similarly, the coefficient of static friction with mild steel, GI sheets, plywood, and glass increased linearly from 0.369 to 0.533, 0.342 to 0.492, 0.288 to 0.301, and 0.314 to 0.363, respectively. Comparing the other three surfaces, it was found that mild steel had the highest coefficient of static friction while plywood had the lowest. Porosity, bulk density, and true density decreased from 0.572 to 0.429, 682.92 to 563.72 kg m-3, and 1318.95 to 1196.81 kg m-3 within the moisture content range, while angle of repose, aspect ratio, sphericity, surface area, volume, 1000 grain weight, coefficient of internal friction, and terminal velocity increased from 23.62° to 40.82°, 65.53 to 66.77, 0.6492 to 0.6569, 13.20 to 15.76 mm2, 4.35 to 6.22 mm3, 3.97 to 5.07 g, 0.556 to 0.863, and 4.42 to 5.23 ms-1.

Effects of Proline on Internal Friction in Simulated Folding Dynamics of Several Alanine-Based α-Helical Peptides.

We have studied in silico the effect of proline, a model cosolvent, on local and global friction coefficients in (un)folding of several typical alanine-based α-helical peptides. Local friction is related to dwell times of a single, ensemble-averaged hydrogen bond (HB) within each peptide. Global friction is related to energy dissipated in a series of configurational changes of each peptide experienced by increasing the number of HBs during folding. Both of these approaches are important in relation to future atomic force microscopic-based measurements of internal friction via force-clamp single-molecule force spectroscopy. Molecular dynamics (MD) simulations for six peptides, namely, ALA5, ALA8, ALA15, ALA21, (AAQAA)3, and H2N-GN(AAQAA)2G-COONH2, have been conducted at 2 and 5 M proline solutions in water. Using previously obtained MD data for these peptides in pure water as well as upgraded theoretical models, we obtained variations of local and global internal friction coefficients as a function of solution viscosity. The results showed the substantial role of proline in stabilizing the folded state and slowing the overall folding dynamics. Consequently, larger friction coefficients were obtained at larger viscosities. The local and global internal friction, i.e., respective, friction coefficients approximated to zero viscosity, was also obtained. The evolution of friction coefficients with viscosity was weakly dependent on the number of concurrent folding pathways but was rather dominated by a stabilizing effect of proline on the folded states. Obtained values of local and global internal friction showed qualitatively similar results and a clear dependency on the structure of the studied peptide.

Influence of the Chemical Composition of Kulantau Vermiculite on the Structure of Modified Bitumen Compositions

The article presents the chemical composition of vermiculite ores from the Kulantau deposits and the atomic structure of vermiculite during dehydration, in 1-, 2- and 3-layer hydrated states. It has been shown that vermiculites from deposits in the Turkestan region have significant differences in mineralogical composition. Rational ways of using Kulantau vermiculite as an innovative modifying additive in bitumen compositions are considered, which are intended to improve the asphalt concrete mixture during its preparation. A slight increase in structuring resins is a result of the elevated content of high-molecular-weight asphaltenes in the modified bitumen, as indicated by the analysis of the provided spectra. In turn, the systematization or structuring of bitumen leads to an increase in the mixture density, accompanied by a simultaneous rise in internal friction coefficients, and resistance to loads (shear and impact), as well as an enhancement in compressive strength. The influence of the chemical composition of Kulantau vermiculite on the structure of bitumen compositions is characterized by high adsorption capacity and effectively absorbs products resulting from the oxidation of hydrocarbons. Vermiculite is characterized by high efficiency in the activation phase, large pore volume, and selectivity. The alteration of the bitumen’s group composition due to the selective diffusion of oils, as well as resins in the material, occurs as a result of the interaction between bitumen and a material characterized by a fine-porous structure and high specific surface area. This process modifies the properties of bituminous layers on the surface of particles and leads to the formation of robust bitumen films appearing on the grain surfaces. Thus, enhancing the longevity of coatings, improving the quality of binding bitumen, and reducing asphalt concrete coverings necessitate the use of vermiculite in creating modified bituminous compositions.

Experimental investigation on rheological behavior of dry granular mixtures based on direct measurement of basal friction

Geophysical flows, characterized by diverse particle-size mixtures, pose challenges for hazard risk assessment due to their anomalous fluidity and rheological behavior. This study investigates the rheological behavior of dry granular mixture flow in a flume setup using particle image velocimetry and triaxial force measurement. Key findings include a power-law relationship between the inertia value and the internal friction coefficient, affirming the applicability of the monodisperse friction model in mixed particle-size scenarios. A strong positive correlation is identified between the effective basal friction coefficient and internal friction coefficient, suggesting an influence of internal frictional properties on basal friction for granular flows on a flat surface. Additionally, positive correlations are observed between normalized stress fluctuation and both internal friction coefficient and inertia number, linking basal stress fluctuations to variations in internal frictional characteristics. These insights enhance our understanding of granular material dynamics, holding potential implications for geological disaster risk assessment.

Asphalt Concrete Production Technology Using Oil Sludge from Zhaik Munay LLP

Oil sludge exhibits a compositional similarity to bitumen, a pivotal constituent in asphalt concrete mixtures. This similarity underscores the potential applicability of oil waste in the production of asphalt concrete, serving not only as an organic binder to fortify indigenous soils but also as a binding agent for the fabrication of organomineral mixtures. The incorporation of oil sludge in road construction endeavors holds promise for the conservation of natural resources, the amelioration of the environmental landscape, and a concurrent reduction in the cost of construction materials. The focus of this study encompasses a comprehensive examination of the physical and mechanical properties pertaining to asphalt concrete of Grade I, Type B. To enhance the performance attributes of asphalt concrete, an additive in the form of oil sludge sourced from ZhaikMunay LLP (Uralsk) was introduced. Various proportions of oil sludge, namely 5%, 10%, and 15%, were incorporated into the asphalt concrete mixture. The utilization of 5% oil sludge elicited negligible alterations in the properties of the asphalt concrete. However, with a 15% addition of oil sludge, discernible reductions were observed in maximum compressive efficiency (0.03% by volume) and shear resistance, indicated by the internal friction coefficient efficiency (0.01% by volume).

Influence of pore water pressure on concrete creep and a creep model considering the effect of cohesion and internal friction angle

AbstractA new nonlinear viscoplastic body considering cohesion and internal friction coefficient versus time is proposed by considering cohesion and internal friction angle. A new creep model for concrete considering cohesion and internal friction angle is obtained by interlocking it with the conventional model. The results show that the creep model can properly reflect the creep development of soft‐cut concrete at the pile head by comparing the creep model with the three‐dimensional creep test data trends under various levels of loading. The model can well describe the whole process of creep deformation and also better compensate for the shortcomings of the traditional creep model that cannot describe the characteristics of accelerated creep deformation.

Smoothed particle hydrodynamics approach for modelling submerged granular flows and the induced water wave generation

In this study, we develop a Smoothed Particle Hydrodynamics (SPH) 2D-model for simulating fully submerged granular flows and their arising water waves. The granular particles are characterised by a non-Newtonian flow pattern, following a Casson constitutive law, generalised by applying the infinitesimal strain theory to avoid numerical singularities inherited from the original law. The implementation of this rheological model on the weakly compressible viscous Navier-Stokes equations enables the simultaneous modelling of the motion of granular flows and their resulting water waves, establishing a monolithic representation of fluid-structure coupling. The novelty of this model lies in the numerical continuity of the generalised rheological model based mainly on the yield stress criterion, which is computed purely from the mechanical properties of granular materials, including internal friction, cohesion, and viscosity coefficients. The proposed SPH model is validated through two benchmarks available in the literature, representing a submarine landslide along an inclined plane and an immersed granular column collapse. The outcomes of our study illustrate the effectiveness of the proposed model in accurately predicting the motions of submerged granular masses and their resulting water waves, which is crucial for accurately predicting the behaviour of underwater landslides and other natural hazards.

Influence of open pit depth on the choice of conveyor transport type

Surface mining operations lead to an increase in the depth of open pits. As a result, there is a need to choose a conveyor transport, which allows transporting rock mass to a great height at high lifting angle. Conveyors with deep trough belts and tubular and steep incline belt conveyors are used to transport rock mass along curved and vertical routes. The use of conveyors adapted to the conditions of deep open pits allows to reduce the length of the route and to cut capital expenditures and energy costs for transporting rock mass. The main difference the existing types of steep incline conveyors is the way the cargo on the belt is kept from spontaneously moving downwards. In this work, the main types of steep incline conveyors, their advantages and disadvantages are considered. It is noted that in order to achieve maximum efficiency in transporting large pieces of rock mass in deep open pits, it is advisable to use double-circuit type "sandwich" belt conveyors, and partitions on the cargo belt. Steep incline conveyors and belts developed by Flexowell (USA), Savatech (Ukraine), Metso Outotec (Finland), ContiTech Transportbandsysteme GmbH (Germany), and steep incline conveyor with a double-circuit belt (Uzbekistan) are considered. Recommendations for choosing the type of steep incline conveyor are given. The main technical and technological parameters of tubular conveyors, which are currently in operation, are considered. It is noted that the maximum angle of inclination of tubular belt conveyors for transporting bulk cargoes depends on the coefficient of internal friction of the cargo, the coefficient of friction of the cargo on the belt and the rate of the belt filling. The ranges of change in the maximum angles of inclination of tubular conveyors are determined. Based on the analysis of the technical and technological parameters of the maximum angles of inclination of a tubular conveyor and a belt hold-down conveyor, it was found that the maximum angle of inclination of the hold-down conveyor is 5–10degrees higher than the maximum angle of inclination of the tubular conveyor. However, the cost and design complexity of the hold-down conveyor is higher than that of a tubular conveyor. It is recommended to use tubular conveyors on sections of the route with an inclination angle of up to 30 degrees. Keywords: open pit, steep incline conveyer, belt, angle of inclination, cargo.

Development of technology for obtaining asphalt concrete mixture using oil sludge as an additive

Oil sludge is similar in composition to the composition of bitumen, which is one of the important components of asphalt concrete mixture. Therefore, oil waste can be used in the production of asphalt concrete, both as an organic binder to strengthen local soils and as a binder to produce organomineral mixtures. The use of oil sludge in road construction helps preserve natural resources, improve the environmental situation, and reduce the cost of building materials. In this work, physical and mechanical properties of asphalt concrete mixture of grade I type B were researched. To improve the performance characteristics of asphalt concrete oil sludge from oil company Zhaik Munay LLP (Uralsk) was used as an additive. Oil sludge was added to the asphalt concrete mixture in amounts of 5, 10 and 15%. When using 5% oil sludge, no significant changes in the properties of asphalt concrete are observed. An addition of 15% of oil went to the reduction of maximum efficiency during compression (0.03% by volume) and shear resistance by the efficiency of internal friction coefficient (0.01% by volume). The optimal amount is to use 10% oil sludge, at the same time, the compressive strength increases by 0.07% by volume, water resistance increases (0.02% by volume), water saturation decreases by 0.28% by volume, which has a positive effect on the quality of asphalt concrete. The properties of asphalt concrete before and after adding oil sludge were studied: compressive strength, water resistance, water saturation, shear resistance. It was concluded that it is advisable to use oil sludge as an additive. A technology for producing asphalt concrete mixture using oil sludge has been developed, which allows reducing its cost.

Deformation evolves from shear to extensile in rocks due to energy optimization

Determining how fracture network development leads to macroscopic failure in heterogeneous materials may help estimate the timing of failure in rocks in the upper crust as well as in engineered structures. The proportion of extensile and shear deformation produced by fracture development indicates the appropriate failure criteria to apply, and thus is a key constraint in such an effort. Here, we measure the volume proportion of extensile and shear fractures using the orientation of the fractures that develop in triaxial compression experiments in which fractures are identified using dynamic in situ synchrotron X-ray imaging. The fracture orientations transition from shear to extensile approaching macroscopic, system-size failure. Numerical models suggest that this transition occurs because the fracture networks evolve in order to optimize the total mechanical efficiency of the system. Our results provide a physical interpretation of the empirical internal friction coefficient in rocks.

Universal behavior in fragmenting brittle, isotropic solids across material properties.

A bonded particle model is used to explore how variations in the material properties of brittle, isotropic solids affect critical behavior in fragmentation. To control material properties, a model is proposed which includes breakable two- and three-body particle interactions to calibrate elastic moduli and mode I and mode II fracture toughnesses. In the quasistatic limit, fragmentation leads to a power-law distribution of grain sizes which is truncated at a maximum grain mass that grows as a nontrivial power of system size. In the high-rate limit, truncation occurs at a mass that decreases as a power of increasing rate. A scaling description is used to characterize this behavior by collapsing the mean-square grain mass across rates and system sizes. Consistent scaling persists across all material properties studied, although there are differences in the evolution of grain size distributions with strain as the initial number of grains at fracture and their subsequent rate of production depend on Poisson's ratio. This evolving granular structure is found to induce a unique rheology where the ratio of the shear stress to pressure, an internal friction coefficient, decays approximately as the logarithm of increasing strain rate. The stress ratio also decreases at all rates with increasing strain as fragmentation progresses and depends on elastic properties of the solid.

Cohesion and aggregates in unsaturated wet granular flows down a rough incline

Multi-phase flows, encountered in nature or in industry, exhibit non-trivial rheological properties, which we attempt to better understand thanks to model materials and appropriate rheometers. Unsaturated wet granular flows down a rough inclined plane turn out to be steady and uniform for a wide range of parameters, despite the cohesion and the grain aggregates. The cohesive Mohr–Coulomb yield criterion extended to inertial granular flows, with a cohesion stress dependent on the liquid content and an internal friction coefficient dependent on the inertial number, allows for predictions in good agreement with our experimental measurements, when one introduces a grain aggregate size, which defines the appropriate length and relaxation time scales in the inertial number. We found that the grain aggregate size depends not monotonically on the liquid content and does not scale with the cohesion length induced by the cohesion stress, due to the non-trivial distribution of the liquid within the granular material.