Visualization of the Microstructural Response of Lightly-Cemented Granular Soils Under Uniaxial Strain Conditions
The microstructural response of granular soil under uniaxial strain is being investigated through direct observation of micromotions. Two techniques are being refined to quantify individual...
Development of a Constitutive Model for Impact Limiters
A constitutive model is being developed for 'impact limiter' materials such as aluminum honeycombs and polyurethane foams. Among other applications, these materials...
Fracture Response of Cement Matrices Reinforced with High Volume Fiber Fraction
Toughening mechanisms of cement matrices reinforced with high volume fiber fraction have been experimentally studied by quantitative image analysis and laser holographic interferometry....
Material Testing at High Pressure
A static test cell has been designed and fabricated to apply a peak stress of up to 2 GPa to a 2.54 cm cylindrical specimen. The cell design was based on the 'belt'...
Mechanical Behavior of Composites with Interphases
The effect of interphases on the mechanical behavior of fiber-reinforced composites is studied. Two problems, a cracked fiber in a matrix, and a fiber pulled out of a matrix, are discussed....
On Statistical Micromechanical Process Damage Models for Brittle Solids with Interacting Microcracks
Two-dimensional micromechanical damage models with strongly interacting microcracks are presented to investigate the overall nonlinear mechanical responses of microcrack-weakened brittle...
Nonlocality of Continuum Approximation of Microcracked Materials
A continuum with nonlocal damage has recently been shown to be an effective approach for the analysis of strain-softening structures. The basic idea is that only the damage, normally caused...
Influence of Finite Deformations in the Stress-Strain Modelling of Granular Media
An incremental formulations of the stress-strain law is presented for quasi-static deformation of granular solids. The stress-strain relationship is derived for an element of granular...
Instability and Plastic Flow of Soils
Materials should according to Drucker's postulate become unstable when the second increment of plastic work is negative. Experimental observations however show otherwise....
Constitutive Relations for Large Deformation Plasticity
Influence of the choice of measures of stress and deformation upon the representation of constitutive relations for elasto-plastic solids undergoing finite deformation is discussed. The...
A Micromechanics Model for Rough Interfaces
A new constitutive model for transfer of interfacial tractions along rough cracks in strain softening composites is presented. The model relates the normal and shearing stresses on the...
Penetration Tests in a Particulate Calibration Chamber
A numerical technique which couples discrete element method with boundary element method has been developed to simulate a two dimensional particulate assembly. Soil particles in the near...
Comparison of a Microscopic Model and a Macroscopic Model Predictions on the Stress-Strain Behavior of a Soil
The stress-strain behavior of a soil under drained triaxial conditions was simulated using the Microscopic constitutive model TRUBAL. The model parameters for the Macroscopic constitutive...
Constitutive Relations for Granular Solids Accounting for Heterogeneous Deformation Fields
Under high deviatoric stress levels corresponding to large strains, the deformation of granular media is highly heterogeneous. A micro-mechanical approach is developed here to model the...
A Time-Dependent Microplane Model for Creep of Cohesive Soils
The microplane model is used in this paper to describe the time-dependent (creep) behavior of cohesive soils (clays). The constitutive equations are defined on each of a set of microplanes...
Factors Affecting the Incremental Stiffness of Particle Assemblies
A simple numerical experiment was performed on an assembly of densely packed spheres in order to investigate the factors that affect an assembly's incremental stiffness. The...
Numerical Undrained Cyclic Loading Simulations Using the Discrete Element Method
Three dimensional numerical experiments on random arrays of rough spheres were performed using the discrete element method to study the behavior of granular soil and the results were compared...
Numerical Experiments for Anisotropic Behavior of Granular Materials
A three dimensional discrete element computer code 'TRUBAL' is used to investigate the effect of initial anisotropy on stress-strain and volume change characteristics...
Microstructure and Stress Differences in Shearing Flows
Steady shearing flows of highly inelastic particles are simulated using rigid and slightly deformable sphere models. Large first normal stress differences in small systems are observed,...
Interparticle Sliding and Rolling
Numerical experiments are done with a continuum plasticity program in order to study the initiation and evolution of shear bands. Many elements are used in order to resolve families of...
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