Correlation between bulk and interparticle contact forces for fine powders

Distinct element simulation was performed for direct shear box (DSB) tests on a dense and a loose two-dimensional (2D) sample of 3259 cylinders. Special attention was devoted to the effect that the frictional force between the inside surface of the upper shear box and the sample had on the measured shear strength in the DSB test. Some ways of minimizing this interface frictional force were introduced in the paper. Given that the deformation approximates simple shear within the deforming zone across the sample centre (referred to as the shear zone), a method was proposed to evaluate the overall strains in the DSB test. The numerically simulated data were used to interpret, on a microscopic scale, the angle of internal friction and a 2D stressdilatancy equation for the mobilized plane in granular material. It was found that the angle of internal friction in granular material is not directly related to the interparticle friction angle (ϕµ). Instead, it relates to the average interparticle contact angle ([Formula: see text]) on the mobilized plane and the ratio k/f0, representing the degree of the probability distribution of the interparticle contact forces that is biased toward the positive zone of the contact angle θ (along the shear direction), where k is the slope of the linear distribution of the average interparticle contact forces against the interparticle contact angle; and f0 is the average interparticle contact force.Key words: angle of internal friction, direct shear box test, distinct element method, friction, granular material, stressdilatancy.

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CORRELATION BETWEEN MICROSTRUCTURE AND YIELD STRESS IN MAGNETICALLY STABILIZED FLUIDIZED BEDS

Journal of Multiscale Modelling ◽

10.1142/s1756973710000400 ◽

2010 ◽

Vol 02 (03n04) ◽

pp. 185-198

Author(s):

J. M. VALVERDE ◽

M. J. ESPIN ◽

M. A. S. QUINTANILLA ◽

A. CASTELLANOS

Keyword(s):

Magnetic Field ◽

Tensile Strength ◽

Gas Flow ◽

Fine Particles ◽

Contact Forces ◽

Interparticle Contact ◽

Gas Velocity ◽

Jamming Transition ◽

Interparticle Contacts ◽

Different Response

A magnetofluidized bed consists of a bed of magnetizable particles subjected to a gas flow in the presence of an externally applied magnetic field. In the absence of magnetic field, there is a given gas velocity at which naturally cohesive fine particles can form a network of permanent interparticle contacts capable of sustaining small stresses. This gas velocity marks the jamming transition of the fluidized bed. For gas velocities above the jamming transition, the bed resembles a liquid. Below the jamming transition, the bed behaves as a weak solid and it has a nonvanishing tensile strength. In the absence of magnetic field, the tensile strength of the solidlike stabilized bed has its only origin in nonmagnetic attractive forces acting between particles. In the presence of a magnetic field, the gas velocity at the jamming transition and the tensile strength of the bed depend on the field strength as a consequence of the magnetostatic attraction induced between the magnetized particles. In this work we present experimental measurements on the jamming transition and tensile strength of magnetofluidized beds of linearly magnetizable fine powders. It is shown that powders with similar magnetic susceptibility but different strength of the nonmagnetic forces show a different response to the magnetic field. This finding can be explained by the influence of the nonmagnetic natural forces on the network of contacts. Thus, our experimental results reported in this paper reinforce the role of short-ranged interparticle contact forces on the behavior of the system, which contrasts with the usual modeling approach in which the magnetofluidized bed is viewed as a continuum medium and a fundamental assumption is that the fields can be averaged over large distances as compared with particle size.

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Interparticle contact forces in fine cohesive powders. Theory and experiments

PAMM ◽

10.1002/pamm.200310377 ◽

2003 ◽

Vol 3 (1) ◽

pp. 206-207 ◽

Cited By ~ 6

Author(s):

M. A. S. Quintanilla ◽

A. Castellanos ◽

J. M. Valverde

Keyword(s):

Contact Forces ◽

Interparticle Contact ◽

Cohesive Powders ◽

Theory And Experiments

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Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

Tire Science and Technology ◽

10.2346/1.2965832 ◽

2008 ◽

Vol 36 (3) ◽

pp. 211-226 ◽

Cited By ~ 9

Author(s):

F. Liu ◽

M. P. F. Sutcliffe ◽

W. R. Graham

Keyword(s):

High Speed ◽

Slip Rate ◽

Material Model ◽

Contact Forces ◽

Block Modeling ◽

Rate Dependent ◽

Linear Viscoelastic Material ◽

Linear Viscoelastic ◽

The Impact ◽

Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

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Modeling Vibration-Induced Tire-Pavement Interaction Noise in the Mid-frequency Range

Tire Science and Technology ◽

10.2346/tire.20.190222 ◽

2020 ◽

Author(s):

Sterling McBride ◽

Ricardo Burdisso ◽

Corina Sandu

Keyword(s):

Sound Intensity ◽

Element Model ◽

Dominant Frequency ◽

Contact Forces ◽

Surface Velocity ◽

New Wave ◽

Normal Surface ◽

Radiated Noise ◽

Physical Effects ◽

Effects Of Rotation

ABSTRACT Tire-pavement interaction noise (TPIN) is one of the main sources of exterior noise produced by vehicles traveling at greater than 50 kph. The dominant frequency content is typically within 500–1500 Hz. Structural tire vibrations are among the principal TPIN mechanisms. In this work, the structure of the tire is modeled and a new wave propagation solution to find its response is proposed. Multiple physical effects are accounted for in the formulation. In an effort to analyze the effects of curvature, a flat plate and a cylindrical shell model are presented. Orthotropic and nonuniform structural properties along the tire's transversal direction are included to account for differences between its sidewalls and belt. Finally, the effects of rotation and inflation pressure are also included in the formulation. Modeled frequency response functions are analyzed and validated. In addition, a new frequency-domain formulation is presented for the computation of input tread pattern contact forces. Finally, the rolling tire's normal surface velocity response is coupled with a boundary element model to demonstrate the radiated noise at the leading and trailing edge locations. These results are then compared with experimental data measured with an on-board sound intensity system.

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Effect of Operational Conditions on the Formation of Ultra Fine Powders by a Reciprocating Friction Mill

Journal of the Society of Materials Science Japan ◽

10.2472/jsms.22.689 ◽

1973 ◽

Vol 22 (238) ◽

pp. 689-692 ◽

Cited By ~ 8

Author(s):

Syoichi MOROHASHI ◽

Yasushi SAWAHATA ◽

Saburo YASHIMA

Keyword(s):

Operational Conditions ◽

Fine Powders

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OLIN C197

Alloy Digest ◽

10.31399/asm.ad.cu0627 ◽

1999 ◽

Vol 48 (1) ◽

Keyword(s):

Thermal Conductivity ◽

Wear Resistance ◽

Physical Properties ◽

Tensile Properties ◽

High Performance ◽

Corrosion And Wear ◽

Contact Forces ◽

High Current ◽

Lower Strength ◽

Current Carrying Capability

Abstract Olin C197 is a second-generation high performance alloy developed by Olin Brass. It has a strength and bend formability similar to C194 (see Alloy Digest Cu-360, September 1978), but with 25% higher electrical and thermal conductivity. High conductivity allows C197 to replace brasses and bronzes in applications where high current-carrying capability is required. Also, the strength of C197 provides higher contact forces when substituted for many lower strength coppers. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion and wear resistance as well as forming and joining. Filing Code: CU-627. Producer or source: Olin Brass.

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Design and Calibration of a Force/Tactile Sensor for Dexterous Manipulation

Sensors ◽

10.3390/s19040966 ◽

2019 ◽

Vol 19 (4) ◽

pp. 966 ◽

Cited By ~ 6

Author(s):

Marco Costanzo ◽

Giuseppe De Maria ◽

Ciro Natale ◽

Salvatore Pirozzi

Keyword(s):

Experimental Validation ◽

Sensory System ◽

Tactile Sensor ◽

Contact Forces ◽

Dexterous Manipulation ◽

Soft Contact ◽

Grasping Force ◽

Sense Of Touch ◽

Human Sense ◽

Robotic Applications

This paper presents the design and calibration of a new force/tactile sensor for robotic applications. The sensor is suitably designed to provide the robotic grasping device with a sensory system mimicking the human sense of touch, namely, a device sensitive to contact forces, object slip and object geometry. This type of perception information is of paramount importance not only in dexterous manipulation but even in simple grasping tasks, especially when objects are fragile, such that only a minimum amount of grasping force can be applied to hold the object without damaging it. Moreover, sensing only forces and not moments can be very limiting to securely grasp an object when it is grasped far from its center of gravity. Therefore, the perception of torsional moments is a key requirement of the designed sensor. Furthermore, the sensor is also the mechanical interface between the gripper and the manipulated object, therefore its design should consider also the requirements for a correct holding of the object. The most relevant of such requirements is the necessity to hold a torsional moment, therefore a soft distributed contact is necessary. The presence of a soft contact poses a number of challenges in the calibration of the sensor, and that is another contribution of this work. Experimental validation is provided in real grasping tasks with two sensors mounted on an industrial gripper.

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