Effect of End Restraint on High Pressure Tests of Granular Materials

1971 ◽  
Vol 8 (4) ◽  
pp. 579-588 ◽  
Author(s):  
M. Roy ◽  
K. Y. Lo
Keyword(s):  
High Pressure ◽  
Granular Materials ◽  
Volume Change ◽  
Triaxial Tests ◽  
Stress Strain ◽  
End Conditions ◽  
Pressure Tests ◽  
Confining Pressures ◽  
End Restraint ◽  
Distribution Of Stress

Comparative drained triaxial tests at high confining pressures were carried out on a strong- and weak-grained granular material with 'rough' and 'lubricated' ends. The results indicated that the stress-strain relationships are significantly influenced by the end conditions. The use of 'lubricated' ends for high pressure tests results in much more uniform distribution of stress, strain, volume change, and crushing of particles throughout the samples.

A numerical assessment of strain rate effects on the critical state of crushable granular materials

2022 ◽  
Vol 12 (1) ◽  
pp. 1-19
Author(s):  
S.K. Das ◽  
S.K. Verma ◽  
A. Das
Keyword(s):  
Strain Rate ◽  
Granular Materials ◽  
Critical State ◽  
Triaxial Tests ◽  
Particle Crushing ◽  
Confining Stress ◽  
Stress Strain ◽  
Strain Rate Effects ◽  
Coral Sand ◽  
Rate Effects

The present study highlights the effects of strain rate on the critical state response of crushable granular materials. A set of drained triaxial tests is simulated using the discrete element method (DEM) to understand the rate effects on the stress-strain and volumetric behaviour of the granular sample. The DEM parameters are obtained by comparing the stress-strain and particle crushing behaviour of in-house experimental analysis on crushable coral sand under a slow strain rate. In DEM, the particles are subjected to varied strain rates under different initial confining pressures and initial densities to capture the rate effects on the macroscopic responses until the critical state. It is seen that crushing increases with increasing confining stress. However, a higher strain rate induces relatively lower crushing and higher strength in terms of both peak stress and residual stress. It is observed that in pressure-volume space, the critical state line alters with the increasing strain rate of the crushable samples, especially at high confining conditions, whereas strain rate effect on critical state seems to be negligible at low confining conditions due to the absence of particle crushing.

Development of a New Technique for Measuring Volume Change of Dry Particulate Systems Under Very Low Confining Pressures

2000 ◽  
Author(s):  
Ali I. Abdel-Hadi ◽  
N. D. Cristescu ◽  
O. Cazacu ◽  
Ray A. Bucklin
Keyword(s):  
Volume Change ◽  
Flow Behavior ◽  
New Technique ◽  
Triaxial Tests ◽  
Accurate Information ◽  
Confining Stress ◽  
Confining Pressures ◽  
A New Technique ◽  
Cross Calibration ◽  
Particulate Systems

Abstract A new technique has been developed to measure volume change at very low confining pressures. Such low confining stress levels may be experienced in typical powder technology applications (storage and transport of particulate systems). The aim of this technique is to obtain more accurate information on the deformation, failure and flow behavior of cohesive powders under a variety of loading conditions and deformation rates. The technique allows covering the entire pressure regime that is covered by commercially available and industrially applied powder flow testers. It bridges the gap of multiple devices, whose ranges of test conditions do not overlap, thus facilitating cross-calibration of equipment and increases confidence (and reliability) of all compaction data obtained. The investigation of the effect of initial porosity on powder flowability was chosen to test the new experimental setup. In particular, triaxial tests have been carried out on samples of different particulate systems and the results have been presented at different confining pressures and on samples of different initial porosities.

A normalizing relation for granular materials

1990 ◽  
Vol 27 (1) ◽  
pp. 68-78 ◽  
Author(s):  
Colin L. Y. Wong
Keyword(s):  
Shear Stress ◽  
Granular Material ◽  
Granular Materials ◽  
Volume Change ◽  
Void Ratio ◽  
Axial Strain ◽  
Strain Curve ◽  
Shear Behavior ◽  
Stress Strain ◽  
Testing Procedures

It is hypothesized that a normalized shear stress – strain curve for granular materials can be obtained by accounting fully for the effects of volume change. In this sense, volume change behavior is a factor that controls the shear stress – strain behavior of a granular material. This hypothesis is applied to Rowe's stress-dilatancy theory to include slip, rolling, rearrangement, and crushing strains, and a theoretical normalizing relation is obtained. The relation is demonstrated to be reasonably correct for the published test data utilized in this study. Differing fabrics of a granular material at the same void ratio can be corrected for by the normalizing relation. The hypothesis is also applied to simple shear behavior and an empirical normalizing relation is obtained.On the basis of the success of the normalizing relation, it is suggested that the volume change rate at 4% axial strain may be, in relation to shear behavior, a more appropriate characterizing parameter than void ratio. However, owing to the long-standing use and acceptance of void ratio, the concept of a reference void ratio, determined by specific sample preparation and testing procedures, is introduced as a characterizing parameter for granular materials. Key words: volume change, dilatancy, normalization, fabric, stress, strain, deformation, sand, granular material.

Shear strength, interparticle locking, and dilatancy of granular materials

2007 ◽  
Vol 44 (5) ◽  
pp. 579-591 ◽  
Author(s):  
Peijun Guo ◽  
Xubin Su
Keyword(s):  
Granular Materials ◽  
Stress Ratio ◽  
Peak Stress ◽  
Friction Angle ◽  
Substantial Effect ◽  
Triaxial Tests ◽  
Ottawa Sand ◽  
Confining Pressures ◽  
Limestone Sand ◽  
Crushed Limestone

The effect of particle angularity on the strength and dilation of granular materials is investigated through a series of laboratory tests on two materials, Ottawa standard sand (Sand O) and crushed limestone (Sand L), that are made up of rounded and angular particles, respectively. Triaxial tests on both materials at different confining pressures and initial void ratios show that particle angularity has a substantial effect on both the peak friction angle ϕp and the mobilized friction angle at the onset of dilation, ϕf. It is found that ϕf is smaller than the critical friction angle ϕcv for Ottawa sand; nevertheless ϕf is larger than ϕcv for Sand L owing to interparticle locking induced by particle angularity. The experimental results clearly show the contributions to shear resistance from both dilation and interlocking, with interlocking still largely existing at the peak stress ratio but not at the critical state. Suggestions are made to modify the stress–dilatancy formulations for sand to take into account the effect of interparticle locking associated with particle angularity.Key words: granular material, dilatancy, interlocking, and particle shape.

Experimental study of the strength and durability of metal-composite high-pressure tanks

2019 ◽  
Vol 85 (1(I)) ◽  
pp. 49-56 ◽  
Author(s):  
A. M. Lepikhin ◽  
V. V. Moskvichev ◽  
A. E. Burov ◽  
E. V. Aniskovich ◽  
A. P. Cherniaev ◽  
...  
Keyword(s):  
High Pressure ◽  
Strain State ◽  
Full Scale ◽  
Fracture Mechanisms ◽  
Metal Composite ◽  
Test Results ◽  
Stress Strain ◽  
Pneumatic Pressure ◽  
Stress Strain State ◽  
Composite Tank

The results of unique experimental studies of the strength and service life of a metal-composite high-pressure tank are presented. The goal of the study is to analyze the fracture mechanisms and evaluate the strength characteristics of the structure. The methodology included tests of full-scale samples of the tank for durability under short-term static, long-term static and cyclic loading with internal pneumatic pressure. Generalized test results and data of visual measurements, instrumental and acoustic-emission control of deformation processes, accumulation of damages and destruction of full-scale tank samples are presented. Analysis of the strength and stiffness of the structure exposed to internal pneumatic pressure is presented. The types of limiting states of the tanks have been established experimentally. Change in the stress-strain state of the tank under cyclic and prolonged static loading is considered. Specific features of the mechanisms of destruction of a metal-composite tank are determined taking into account the role of strain of the metal liner. The calculated and experimental estimates of the energy potential of destruction and the size of the area affected upon destruction of the tank are presented. Analysis of test results showed that the tank has high strength and resource characteristics that meet the requirements of the design documentation. The results of the experiments are in good agreement with the results of numerical calculations and analysis of the stress-strain state and mechanisms of destruction of the metal-composite tank.

Stress-Strain and Volume Change Characteristics of an Assemblage of Polymer Pellets

1998 ◽  
Vol 13 (4) ◽  
pp. 347-357 ◽  
Author(s):  
D. Penumadu ◽  
J. A. Yamamuro ◽  
A. E. Abrantes ◽  
G. A. Campbell
Keyword(s):  
Volume Change ◽  
Stress Strain ◽  
Change Characteristics

scholarly journals Role of temperature in the numerical analysis of CaO under high pressure

2010 ◽  
Vol 8 (1) ◽  
pp. 126-133 ◽  
Author(s):  
Purvee Bhardwaj ◽  
Sadhna Singh
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Numerical Analysis ◽  
Thermodynamic Properties ◽  
Elastic Constants ◽  
Volume Change ◽  
Thermodynamical Properties ◽  
Phase Transition Pressure ◽  
Different Temperatures

AbstractIn this paper we focus on the elastic and thermodynamic properties of the B1 phase of CaO by using the modified TBP model, including the role of temperature. We have successfully obtained the phase transition pressure and volume change at different temperatures. In addition elastic constants and bulk modulus of B1 phase of CaO at different temperatures are discussed. Our results are comparable with the previous ones at high temperatures and pressures. The thermodynamical properties of the B1 phase of CaO are also predicted.

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