scholarly journals NUMERICAL MODELLING OF THE SOIL BEHAVIOUR BY USING NEWLY DEVELOPED ADVANCED MATERIAL MODEL

2017 ◽  
Vol 57 (1) ◽  
pp. 58-70 ◽  
Author(s):  
Jan Veselý
Keyword(s):  
Numerical Modelling ◽  
Plastic Material ◽  
Material Model ◽  
Small Strain ◽  
Theoretical Background ◽  
Linear Elastic ◽  
In Situ Data ◽  
Modified Cam Clay ◽  
Soil Behaviour

This paper describes a theoretical background, implementation and validation of the newly developed Jardine plastic hardening-softening model (JPHS model), which can be used for numerical modelling of the soils behaviour. Although the JPHS model is based on the elasto-plastic theory, like the Mohr-Coulomb model that is widely used in geotechnics, it contains some improvements, which removes the main disadvantages of the MC model. The presented model is coupled with an isotopically hardening and softening law, non-linear elastic stress-strain law, non-associated elasto-plastic material description and a cap yield surface. The validation of the model is done by comparing the numerical results with real measured data from the laboratory tests and by testing of the model on the real project of the tunnel excavation. The 3D numerical analysis is performed and the comparison between the JPHS, Mohr-Coulomb, Modified Cam-Clay, Hardening small strain model and monitoring in-situ data is done.

A New Elasto-Plastic Critical State Model RU+MCC for Overconsolidated Soil

2016 ◽  
Vol 837 ◽  
pp. 68-74
Author(s):  
Rafal Uliniarz
Keyword(s):  
Critical State ◽  
Soil Mechanics ◽  
Small Strain ◽  
Computer Code ◽  
Constitutive Law ◽  
Isotropic Hardening ◽  
Loading Test ◽  
Modified Cam Clay ◽  
Soil Behaviour ◽  
Cam Clay

The paper presents a reasonably advanced constitutive law for soil – a hybrid of the Modified Cam Clay and a new RU development. The Modified Cam Clay model is an isotropic hardening elasto – plastic model originated by Burland in 1967 [1] within the critical state soil mechanics. This model describes realistically mechanical soil behaviour in normal consolidation states. The other one is designed to ensure more adequate soil responses to reloading paths, particularly in the range of small strains. The RU+MCC model has been implemented in the FEM computer code Z_SOIL.pc. To test the influence of the small strain nonlinearity on soil – structure interaction as well as to exhibit the ability of the proposed model to simulate realistically this effect, a comparative study based on the FEM solution has been carried out. As a benchmark a trial loading test of strip footing was used.

Observation of Micro-Tensile Behavior of Thin Film TiN and Au using ESPI Technique

2005 ◽  
Vol 875 ◽  
Author(s):  
Yong-Hak Huh ◽  
Dong-Iel Kim ◽  
Jun-Hee Hahn ◽  
Gwang-Seok Kim ◽  
Chang-Doo Kee ◽  
...  
Keyword(s):  
Thin Film ◽  
Tensile Strain ◽  
Plastic Material ◽  
Speckle Pattern ◽  
Electronic Speckle Pattern Interferometry ◽  
Linear Elastic ◽  
Specimen Width ◽  
Measurement Algorithm ◽  
Elastic Plastic Material

AbstractMicro-tensile properties of hard and soft thin films, TiN and Au, were evaluated by directly measuring tensile strain in film tension using the micro-ESPI(electronic Speckle Pattern Interferometry) technique. Micro-tensile stress-strain curves for these films were obtained and the properties were determined. TiN thin film 1 μm thick and Au films with two different thicknesses (t=0.5 μm and 1 μm) were deposited onto the silicon wafers, respectively, and micro-tensile specimens wide 50, 100 and 200 μm were fabricated using micromachining. In-situ measurement of the micro-tensile strain during tensile loading was carried out using the subsequent strain measurement algorithm and the ESPI system developed in this study. The micro-tensile curves showed that TiN thin film was a linear-elastic material showing no plastic deformation and Au thin film was an elastic-plastic material showing significant plastic flow. Effect of the specimen dimensions on mechanical properties was examined. It was revealed that tensile strengths for both films were slightly increased with increasing specimen width. Furthermore, variations of yielding strengths for the thin film Au with change of the dimension were investigated.

Plastic Response Estimation in Repeated Elastic Analyses for Strain Hardening Material Model

2013 ◽  
Vol 135 (5) ◽  
Author(s):  
S. L. Mahmood ◽  
R. Adibi-Asl ◽  
C. G. Daley
Keyword(s):  
Strain Hardening ◽  
Strain Energy ◽  
Plastic Material ◽  
Limit Load ◽  
Material Model ◽  
Element Analysis ◽  
Hardening Material ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

Simplified limit analysis techniques have already been employed for limit load estimation on the basis of linear elastic finite element analysis (FEA) assuming elastic-perfectly-plastic material model. Due to strain hardening, a component or a structure can store supplementary strain energy and hence carries additional load. In this paper, an iterative elastic modulus adjustment scheme is developed in context of strain hardening material model utilizing the “strain energy density” theory. The proposed algorithm is then programmed into repeated elastic FEA and results from the numerical examples are compared with inelastic FEA results.

Structural Integrity Evaluation for the Analysis of Corroded Pipelines With Multiple Corrosion Defects

2006 ◽  
Author(s):  
Alejandro Andueza ◽  
Thiago Pontual
Keyword(s):  
Structural Integrity ◽  
Plastic Material ◽  
Material Model ◽  
Model Generation ◽  
The Finite Element Method ◽  
Failure Pressure ◽  
Linear Elastic ◽  
Asme Code ◽  
Corrosion Defects ◽  
Elastic Plastic Material

The structural integrity evaluation of corroded pipelines is very important for the management of systems that are in operation in order to help managers in the important decision of repairing the line. The required models for the analysis of corroded pipelines with multiple corrosion defects are in many cases a hard task to be generated. This paper presents a new methodology for the generation of full 3D hex meshes for the analysis using the Finite Element Method. The algorithm, developed specifically for the analysis of corroded pipelines, makes the task of model generation with multiple corrosion defects easier and faster. Examples with one and two corrosion defects are presented using a linear-elastic material model and the corresponding results compared to the criteria established by ASME code sec. VIII div. 2. The same models are analyzed using ideal elastic-plastic material model in order to determine the minimum failure pressure for the corroded pipes. The numerical failure pressures obtained are also compared to the values obtained from DNV RP-F101 method for single defects and experimental results. Finally, a new repairing methodology that allows the continuous operation of the pipeline in a safer way is presented. This methodology can help managers in the undertaking of scheduling a full repair of the pipeline in a much more flexible way.

Stress and Strain Analysis of Waste Dam and Stability Analysis of Landfill

2015 ◽  
Vol 744-746 ◽  
pp. 702-705 ◽  
Author(s):  
Li Hua Liang ◽  
Su Lin Kuang ◽  
Zhi Jun Diao
Keyword(s):  
Strain Analysis ◽  
Material Model ◽  
In Situ Stress ◽  
Stress And Strain ◽  
Linear Elastic ◽  
Construction Design ◽  
Dam Stability ◽  
The Stability ◽  
In Situ Stress Field

Stress and strain of waste dam were analyzed based on the construction design and situations in the field. In situ stress field was calculated according to linear elastic material model and deformation was simulated according to hyperbolic nonlinear plastic model. On the basis of the deformation and stress analysis, dam stability was evaluated according to the deformation by total stress method. The result shows that the stability of the dam can meet the specification requirements and be operated normally even if the deformation occurs when solid waste are heaped up to 0-12 m according to the preliminary design scheme.

Measuring the In-Situ Matrix Properties in Fiber Reinforced Composites

2009 ◽  
Author(s):  
Christian Heinrich ◽  
Anthony M. Waas
Keyword(s):  
Surrogate Model ◽  
Plastic Material ◽  
Matrix Material ◽  
Material Model ◽  
Fe Analysis ◽  
Fiber Reinforced Composites ◽  
Average Error ◽  
Reinforced Composites ◽  
Matrix Properties

A new methodology to extract viscoelactic-plastic material properties of a matrix material in a composite through Nanoindentation is discussed in this study. A material model is developed to account for viscoelastic-plastic effects and is incorporated in a parametric Finite Element (FE) analysis. The results from this analysis are used to construct a surrogate model to allow for fast evaluations of the simulated experiments, which in turn can be used to match calculations with real experiments. The surrogate model predicts the FE results within an average error of 2.9%. The viscoelastic properties are recovered with an error of 9.4% and 9.8% respectively, when comparing the surrogate model with FE simulations.

scholarly journals Finite Element modeling of Mechanical Loading-Pumpkin Peel and flesh

2017 ◽  
Vol 13 (5) ◽  
Author(s):  
Maryam Shirmohammadi ◽  
Prasad KDV Yarlagadda
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Plastic Material ◽  
Material Model ◽  
Mean Square ◽  
Fe Modeling ◽  
Material Models ◽  
Linear Elastic Material ◽  
Error Indicator ◽  
Linear Elastic

Abstract Finite element (FE) models of uniaxial loading of pumpkin peel and flesh tissues were developed and validated using experimental results. The tensile model was developed for both linear elastic and plastic material models, the compression model was developed only with the plastic material model. The outcomes of force versus time curves obtained from FE models followed similar pattern to the experimental curves; however the curve resulted with linear elastic material properties had a higher difference with the experimental curves. The values of predicted forces were determined and compared with the experimental curve. An error indicator was introduced and computed for each case and compared. Additionally, Root Mean Square Error (RMSE) values were also calculated for each model and compared. The results of modeling were used to develop material model for peel and flesh tissues in FE modeling of mechanical peeling of tough skin vegetables. The results presented in this paper are a part of a study on mechanical properties of agricultural tissues focusing on mechanical peeling methods using mathematical, experimental and computational modeling.

An Experimental/Analytical Study of Strains in Encapsulated Assemblies

1993 ◽  
Vol 115 (3) ◽  
pp. 298-304
Author(s):  
T. R. Guess ◽  
S. N. Burchett
Keyword(s):  
Analytical Study ◽  
Material Model ◽  
Strain Gages ◽  
Finite Element Analyses ◽  
Temperature Dependent ◽  
Transition Range ◽  
Linear Elastic ◽  
Cure Temperature ◽  
Good Agreement

A combined experimental and analytical study of strains that develop in encapsulated assemblies during casting, curing, and thermal excursions is described. The experimental setup, designed to measure in situ strains, consisted of thin, closed-end, metal tubes that were instrumented with strain gages and thermocouples before being over-potted with an encapsulant. Three epoxy-based materials were studied. After cure of the encapsulant, tube strains were measured over the temperature range of −55°C to 90°C. The thermal excursion experiments were then numerically modeled using finite element analyses and the results were compared to the experimental results. The predicted strains were overestimated (conservative) when a linear, elastic, temperature-dependent material model was assumed for the encapsulant and the stress free temperature was assumed to correspond to the cure temperature of the encapsulant. Very good agreement was obtained with the linear elastic calculations provided that the stress free temperature corresponded to the onset of the glassy-to-rubbery transition range of the encapsulant. Finally, very good agreement was obtained when a viscoelastic material model was utilized and a stress free temperature corresponding to the cure temperature was assumed.

scholarly journals Improving the Numerical Modelling of In-Situ Rock Bolts Using Axial and Bending Strain Data from Instrumented Bolts

2022 ◽  
Author(s):  
Prasoon Singh ◽  
Hyongdoo Jang ◽  
A. J. S. Sam Spearing
Keyword(s):  
Numerical Modelling ◽  
Rock Bolt ◽  
Sensitivity Analyses ◽  
Rock Bolts ◽  
In Situ Data ◽  
Bending Strain ◽  
Data Source ◽  
Bolt Reinforcement ◽  
Reinforcement Design

AbstractNumerical modelling has become an important tool in the underground rock bolt reinforcement designing process. Numerical modelling provides the advantage of easily and quickly simulating complex underground geometries and mechanisms with sensitivity analyses. However, a numerical model needs to be calibrated using mathematical solutions, lab testing or with actual in-situ observations and measurements (which is the preferred method) before its results can be quantitatively applied to reinforcement design. Instrumented rock bolts provide a useful data source for calibrating in-situ rock bolt models. In this work, procedures have been presented to identify and determine the orientation of structures in the rock mass based on the strains on the instrumented rock bolts. A method to calibrate the rock bolt model with in-situ data is also presented. The results of the presented procedures have been validated with laboratory tests and numerical modelling. The procedures have been applied to create and calibrate an in-situ rock bolt model in FLAC3D and the results are validated using in-situ data.

scholarly journals Verification of Ram-Press Pipe Bending Process using Elasto-Plastic FEM Model

2017 ◽  
Vol 11 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Paweł Sidun ◽  
Andrzej Łukaszewicz
Keyword(s):  
Numerical Modelling ◽  
Numerical Simulations ◽  
Plastic Material ◽  
Material Model ◽  
Numerical Analyses ◽  
Fem Model ◽  
Proposed Model ◽  
Bending Process ◽  
Pipe Bending

Abstract In this paper selected aspects of numerical modelling of bending pipes process are described. Elasto-plastic material model was used in COMSOL FEM environment. The results of numerical analyses of two kinds of steel were presented. The correctness of the proposed model was verified based on comparison shapes of deformed pipe profile obtained at the ending step of bending both from numerical simulations and experiment.

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