A new elastoplastic constitutive model for coarse granular aggregates incorporating particle breakage

2004 ◽  
Vol 41 (4) ◽  
pp. 657-671 ◽  
Author(s):  
Wadud Salim ◽  
Buddhima Indraratna
Keyword(s):  
Constitutive Model ◽  
Plastic Flow ◽  
Current Model ◽  
Particle Breakage ◽  
Flow Rule ◽  
Peak Strain ◽  
Stress Strain ◽  
Coarse Aggregates ◽  
Stress Changes ◽  
Plastic Flow Rule

A new elastoplastic stress–strain constitutive model is developed for granular coarse aggregates incorporating the degradation of particles during triaxial shearing. Coarse granular aggregates are subjected to breakage during excessive stress changes. Most of the available constitutive models do not consider the degradation of particles during shearing. In the current model, a plastic flow rule has been developed incorporating the energy consumption due to particle breakage during shear deformation. A non-associated flow and a kinematic type yield locus have been adopted in the model. A general formulation for the rate of particle breakage during shearing has been developed and incorporated in the plastic flow rule. The effects of particle breakage on the plastic distortional and volumetric deformations are incorporated in the current model. The stress–strain formulations are developed within the general critical state framework. The model can accurately predict the stress–strain and volume change behaviour of coarse granular aggregates. The plastic dilation and contraction features of coarse aggregates at various confining pressures are well captured, and the strain-hardening and post-peak strain-softening behaviour of coarse granular media is adequately represented. A particular feature of the model is its capability to predict the degree of particle breakage at any stage of shear deformation.Key words: constitutive modelling, coarse granular aggregates, particle breakage, dilatancy, non-associated flow, plasticity.

scholarly journals Non-orthogonal elastoplastic constitutive model for sand with dilatancy

2021 ◽  
Author(s):  
Jingyu Liang ◽  
Dechun Lu ◽  
Xiuli Du ◽  
Wei Wu ◽  
Chao Ma
Keyword(s):  
Constitutive Model ◽  
Plastic Flow ◽  
Flow Direction ◽  
Model Performance ◽  
Yield Function ◽  
Flow Rule ◽  
Shear Process ◽  
Hardening Parameter ◽  
Elastoplastic Constitutive Model ◽  
Plastic Flow Rule

A non-orthogonal elastoplastic constitutive model for sand with dilatancy is presented in the characteristic stress space. Dilatancy of sand is represented by the direction of plastic flow, which can be directly determined by applying the non-orthogonal plastic flow rule to an improved elliptic yield function. A new hardening parameter is developed to describe the contractive and dilative volume change during the shear process, which is co-ordinated with the non-orthogonal plastic flow direction. The combination of the non-orthogonal plastic flow rule and the proposed hardening parameter renders the proposed model with the ability to reasonably describe the stress-strain relationship of sand with dilatancy. The model performance is evaluated by comparing with the experimental data of sand under triaxial stress conditions.

Generalized plastic flow rule

2005 ◽  
Vol 21 (2) ◽  
pp. 321-351 ◽  
Author(s):  
K HASHIGUCHI
Keyword(s):  
Plastic Flow ◽  
Flow Rule ◽  
Plastic Flow Rule

scholarly journals Non-orthogonal elastoplastic constitutive model with the critical state for clay

2021 ◽  
Author(s):  
Jingyu Liang ◽  
Dechun Lu ◽  
Xin Zhou ◽  
Xiuli Du ◽  
Wei Wu
Keyword(s):  
Plastic Flow ◽  
Critical State ◽  
Flow Direction ◽  
Volumetric Strain ◽  
Yield Function ◽  
Triaxial Tests ◽  
Flow Rule ◽  
Model Framework ◽  
Plastic Strain Increment ◽  
Plastic Flow Rule

A non-orthogonal elastoplastic model for clay is proposed by combining the non-orthogonal plastic flow rule with the critical state concept, and the model framework is presented from the perspective of the magnitude and direction of the plastic strain increment. The magnitude is obtained based on the improved elliptical yield function and the plastic volumetric strain dependent hardening parameter. The direction is determined by ap-plying the non-orthogonal plastic flow rule with the Riemann-Liouville fractional derivative to the yield function without the necessity of additional plastic potential function. The presented approach gives rise to a simple model for soil with five parameters. All parameters have clear physical meaning and can be easily identified by triaxial tests. The model performance is shown by analyzing the evolution process of the yield surface, the hardening rule and the plastic flow direction. The capability of the proposed model to capture the mechanical behaviours of clay with different stiffness is also confirmed by predicting test results from the literature.

Uniaxial compression mechanical properties and damage constitutive model of limestone under osmotic pressure

2021 ◽  
pp. 105678952110454
Author(s):  
Zhanping Song ◽  
Tong Wang ◽  
Junbao Wang ◽  
Kehui Xiao ◽  
TengTian Yang
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Osmotic Pressure ◽  
Uniaxial Compression ◽  
Influencing Factor ◽  
Peak Strain ◽  
Strain Response ◽  
Test Results ◽  
Stress Strain ◽  
Compaction Factor

To study the influence of osmotic pressure on the uniaxial compression mechanical properties of limestone, uniaxial compression tests were carried out on limestone specimens under different osmotic water pressure. The test results show that with the increase of osmotic pressure, the closure strain, yield strain and peak strain of limestone gradually increase, while the closure stress, yield stress, peak stress and elastic modulus gradually decrease. To describe the stress-strain response of limestone during uniaxial compression failure, the concepts of compaction factor and osmotic pressure influencing factor were proposed, and a constitutive model of rock compaction stage was established by integrating the relationship between the compaction factor and osmotic pressure influencing factor and the tangent modulus of compaction section. On this basis, combining the continuum damage mechanics theory, and assuming that the rock micro-unit strength obeys the compound power function distribution, a constitutive model reflecting the uniaxial compression mechanical properties of rock under osmotic pressure was established by the statistical method. The rationality of the model was verified using the results of the uniaxial compression test of limestone under different osmotic pressures. The results show that the test results under different osmotic pressures are in good agreement with the theoretical curves, and the model in this paper can reflect the stress-strain response of limestone before its failure under different osmotic pressures.

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