scholarly journals Study on the Effect of Amygdales on Mechanical Characteristics of Basalt Using the Combined Finite-Discrete Element Method

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Shirui Zhang ◽  
Shili Qiu ◽  
Ping Li ◽  
Yongyuan Kou ◽  
Pengfei Kou
Keyword(s):  
Growth Trend ◽  
Heterogeneous Model ◽  
Inverse Monte Carlo ◽  
Initiation And Propagation ◽  
Laboratory Test Results ◽  
Heterogeneous Rock ◽  
Heterogeneous Models ◽  
The Matrix ◽  
Tensile Fractures ◽  
Baihetan Hydropower Station

Amygdaloidal basalt, as a heterogeneous rock, is widely exposed at Baihetan hydropower station, China. The geometric effect of amygdales needs further studies and quantifying the shape, orientation, and statistical distribution of amygdales plays an important role in the laboratory and numerical experiments. Therefore, digital image processing (DIP) was first utilized to build a heterogeneous model (HM) to calibrate against the laboratory test results. Then, the heterogeneous models (HMs) with prescribed geometric features were generated by the inverse Monte-Carlo (IMC) algorithm. The uniaxial compression experiments based on HMs were conducted to study the mechanism of the crack initiation and propagation in the amygdaloidal basalt. The tensile fractures were mainly occurred in the matrix, and the shear fractures were mainly occurred in the amygdales. With the increase in the elliptic coefficient of amygdales, the uniaxial compressive strength (UCS) showed a linear growth trend. With the increase in the orientation of amygdales, the UCS exhibited a “V-shaped” distribution characteristic. This paper provides a numerical method for studying the mechanical properties of rocks with flaws.

scholarly journals Homogeneous Approach for Composite Under Dynamic Contact With Friction

2007 ◽  
Author(s):  
Guillaume Peillex ◽  
Laurent Baillet ◽  
Yves Berthier
Keyword(s):  
Elastic Properties ◽  
Coulomb Friction ◽  
Homogeneous Model ◽  
Dynamic Contact ◽  
Stick Slip ◽  
Heterogeneous Model ◽  
Friction Law ◽  
Heterogeneous Models ◽  
The Matrix ◽  
Coulomb Friction Law

An explicit dynamic 2D finite element model of a composite under dynamic tribological loading is proposed. The software used for this kind of application manages contact conditions thanks to the Lagrange multipliers. The kind of contact is a deformable against rigid surface one. First of all due to ill-posedness of the classical Coulomb friction law, a regularized Coulomb friction law that allows local and global convergence of the models even under the presence of contact instabilities is proposed. This friction law is experimentally motivated and is similar to the simplified “Prakash-Clifton” law. In a second time the dynamic tribological behavior of the composite is studied by the mean of different models where the heterogeneities of the material are explicitly introduced. Those heterogeneous models stand for a description of the microscopic scale of the composite. A comparison is made between the results given by these heterogeneous models and the results obtained by the analysis of a homogeneous model. The elastic properties of the homogeneous model are obtained through classical homogenization process which is suitable here because the scale separation, difference between the size of the heterogeneities and the wavelength of the loading, is sufficiently important. The homogeneous model represents the macroscopic scale of the composite. Equivalence between heterogeneous models and the homogeneous one is straightforward if the contrast of Young’s modulus between the heterogeneities and the matrix is sufficiently low and if the local contact dynamic is stable. This equivalence has been observed for different contact instabilities like slip-separated, and stick-slip-separated ones. When the equivalence between the models is not ensured, because of high contrast of elastic properties for example, an adaptation of the dynamic parameter of the friction law is necessary to retrieve this equivalence. Finally the determination of the stresses and their evolution along the time in the heterogeneities and in the matrix is performed thanks to the relocalization process. This process is mixing dynamic analysis of the homogeneous models and fast static calculations on heterogeneous model. This process has already been applied to structures submitted to static loading but to our knowledge this is the first attempt to use it for dynamic contact problems. So this work highlights a full multi-scale approach for composite under dynamic contact with friction loading.

scholarly journals Process Knowledge Graph Modeling Techniques and Application Methods for Ship Heterogeneous Models

2021 ◽  
Author(s):  
Jinfeng Liu ◽  
Jianwei Dong ◽  
Xuwen Jing ◽  
Xuwu Cao ◽  
Chenxiao Du ◽  
...  
Keyword(s):  
Process Design ◽  
Welding Process ◽  
Mapping Method ◽  
Knowledge Graph ◽  
Case Based Reasoning ◽  
Test Model ◽  
Process Knowledge ◽  
Heterogeneous Model ◽  
Heterogeneous Models ◽  
Component Assembly

Abstract In the process design and reuse of marine component products, there are a lot of heterogeneous models, causing the problem that the process knowledge and process design experience contained in them are difficult to express and reuse. Therefore, a process knowledge representation model for ship heterogeneous model is proposed in this paper. Firstly, the multi-element process knowledge graph is constructed, and the heterogeneous ship model is described in a unified way. Then, the multi-strategy ontology mapping method is applied, and the semantic expression between the process knowledge graph and the entity model is realized. Finally, by obtaining implicit semantics based on case-based reasoning and checking the similarity of the matching results, the case knowledge reuse is achieved, to achieve rapid design of the process. This method provides reliable technical support for the design of ship component assembly and welding process, greatly shortens the design cycle, and improves the working efficiency. In addition, a case study of the test model is carried out to verify the feasibility and efficiency of the proposed method.

Microstructure and Tensile Deformation Features of Tandem Hot Rolling GH4169 Superalloy

2014 ◽  
Vol 33 (2) ◽  
pp. 131-136
Author(s):  
Zhenrong Li ◽  
Chunlei Ma ◽  
Sugui Tian ◽  
Liqing Chen ◽  
Xianghua Liu
Keyword(s):  
Hot Rolling ◽  
Tensile Deformation ◽  
Solution Treatment ◽  
Microstructure Observation ◽  
Large Numbers ◽  
Initiation And Propagation ◽  
The Matrix ◽  
Deformation Features ◽  
Δ Phase ◽  
Property Measurement

AbstractBy means of solution treatment, microstructure observation and mechanical property measurement, the microstructure and tensile deformation features of tandem hot rolling GH4169 alloy have been investigated. Results shown that, after solution treatment and aging, large numbers of the spherical γ′ phase and the flat-ellipsoidal γ″ phase dispersedly precipitate in the matrix, and acicular or short rod-like δ-phase discontinuously distribute along grain boundaries. As the tensile temperatures increases, the tensile strength and yield strength of the alloy gradually decrease. The tensile deformation features of the alloy are that the twinning and slipping dislocations with double orientations are activated in the matrix. In the later tension, the deformed dislocations pile up near the grain boundary to induce initiation and propagation of cracks due to stress concentration.

scholarly journals SBML2Modelica: integrating biochemical models within open-standard simulation ecosystems

2019 ◽  
Vol 36 (7) ◽  
pp. 2165-2172 ◽  
Author(s):  
F Maggioli ◽  
T Mancini ◽  
E Tronci
Keyword(s):  
State Of The Art ◽  
General Purpose ◽  
Heterogeneous Model ◽  
Simulation Languages ◽  
Experimental Campaign ◽  
Heterogeneous Models ◽  
Open Standard ◽  
Level 3 ◽  
Model Networks ◽  
Definition Of

Abstract Motivation SBML is the most widespread language for the definition of biochemical models. Although dozens of SBML simulators are available, there is a general lack of support to the integration of SBML models within open-standard general-purpose simulation ecosystems. This hinders co-simulation and integration of SBML models within larger model networks, in order to, e.g. enable in silico clinical trials of drugs, pharmacological protocols, or engineering artefacts such as biomedical devices against Virtual Physiological Human models. Modelica is one of the most popular existing open-standard general-purpose simulation languages, supported by many simulators. Modelica models are especially suited for the definition of complex networks of heterogeneous models from virtually all application domains. Models written in Modelica (and in 100+ other languages) can be readily exported into black-box Functional Mock-Up Units (FMUs), and seamlessly co-simulated and integrated into larger model networks within open-standard language-independent simulation ecosystems. Results In order to enable SBML model integration within heterogeneous model networks, we present SBML2Modelica, a software system translating SBML models into well-structured, user-intelligible, easily modifiable Modelica models. SBML2Modelica is SBML Level 3 Version 2—compliant and succeeds on 96.47% of the SBML Test Suite Core (with a few rare, intricate and easily avoidable combinations of constructs unsupported and cleanly signalled to the user). Our experimental campaign on 613 models from the BioModels database (with up to 5438 variables) shows that the major open-source (general-purpose) Modelica and FMU simulators achieve performance comparable to state-of-the-art specialized SBML simulators. Availability and implementation SBML2Modelica is written in Java and is freely available for non-commercial use at https://bitbucket.org/mclab/sbml2modelica.

A Theoretical Model for Water Flux Through the Artery Wall

1987 ◽  
Vol 109 (4) ◽  
pp. 311-317 ◽  
Author(s):  
R. Jain ◽  
G. Jayaraman
Keyword(s):  
Water Flux ◽  
Pressure Gradients ◽  
Artery Wall ◽  
Seepage Velocity ◽  
Heterogeneous Model ◽  
Large Pressure ◽  
The Matrix ◽  
Fluid Seepage ◽  
Two Layer Model ◽  
Water Saturated

A two layer model for water flux through the artery is studied using a matematical model based on the theory for the consolidation of water saturated soils. The matrix is considered to be constituted by two layers with different permeabilities and different elastic constants and the two systems of equations are coupled with the condition of continuity of pressure, total stress, solid displacement and fluid seepage velocity at the interface. The luminal pressure is considered to be harmonic in time. Exact solutions are obtained for displacements and pressures in both the layers. For large consolidation times, large pressure gradients are found to exist near the boundaries and at the interface. The heterogeneous model may not only be useful to understand the mechanics of transport in the physiological system but it will also help the bioengineers to choose proper implant materials to design artificial vascular organs for the purpose of prosthesis.

scholarly journals Numerical Study of Rock Fragmentation Process and Acoustic Emission by FDEM Based on Heterogeneous Model

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Qi Liu ◽  
Penghai Deng
Keyword(s):  
Acoustic Emission ◽  
Mechanical Response ◽  
Numerical Study ◽  
High Energy ◽  
Uniaxial Compression Test ◽  
Rock Damage ◽  
Heterogeneous Model ◽  
Damage And Fracture ◽  
Heterogeneous Rock ◽  
Rock Model

Rock has the characteristics of natural heterogeneity and discontinuity. Its failure phenomenon induced by external force involves complex processes, including the microcrack initiation, propagation, coalescence, and the macrocrack formation. In this study, the Weibull random distribution based on the rock microstructure characteristics is introduced into the combined finite-discrete element method (FDEM) to establish the heterogeneous rock model, and the mechanical response and damage evolution of rock samples in uniaxial compression test are simulated. The results show that FDEM simulation with loaded heterogeneous rock model can reflect the progressive development of rock damage, fracture, and acoustic emission (AE) activity in real rock well. Meanwhile, the statistical analysis indicates that the number and energy evolution of AE events with different fracture modes in the model are consistent with the macroscopic failure mode of rock. The change of b-value also agrees with the increasing trend of high-energy events in the loading process. This method provides a new tool for the analysis of rock damage and fracture evolution.

Analysis of Interfacial Debonding in Three-Dimensional Composite Microstructures

2005 ◽  
Vol 128 (1) ◽  
pp. 96-106 ◽  
Author(s):  
Shriram Swaminathan ◽  
N. J. Pagano ◽  
Somnath Ghosh
Keyword(s):  
Cohesive Zone ◽  
Volume Fraction ◽  
Three Dimensional ◽  
Interfacial Debonding ◽  
Fiber Model ◽  
Unidirectional Fibers ◽  
Fiber Spacing ◽  
Commercial Code ◽  
Initiation And Propagation ◽  
The Matrix

This paper is aimed at analyzing stresses and fiber-matrix interfacial debonding in three-dimensional composite microstructures. It incorporates a 3D cohesive zone interface model based element to simulate interfacial debonding in the commercial code ABAQUS. The validated element is used to examine the potential debonding response in the presence of fiber–fiber interactions. A two-fiber model with unidirectional fibers is constructed and the effect of relative fiber spacing and volume fraction on the stress distribution in the matrix is studied. In addition, the effect of fiber orientation and spacing on the nature of initiation and propagation of interfacial debonding is studied in a two-fiber model. These results are expected to be helpful in formulating future studies treating optimal fiber orientations and payoff in controlling fiber spacing and alignment.

scholarly journals Usefulness of porphyry and amphibolites as a component of concrete for airfield pavements

2018 ◽  
Vol 163 ◽  
pp. 07002
Author(s):  
Małgorzata Linek ◽  
Piotr Nita ◽  
Paweł Wolka ◽  
Wojciech Żebrowski
Keyword(s):  
Bulk Density ◽  
Internal Structure ◽  
Coarse Aggregate ◽  
Cement Matrix ◽  
Physical Parameters ◽  
Hardened Concrete ◽  
Test Results ◽  
Laboratory Test Results ◽  
The Matrix

Coarse aggregate used as part of cement concrete is of primary significance for the obtained parameters of hardened concrete. In case of concretes intended for airfield pavements, the application of granite grit is recommended. Alternative to this type of aggregate in the form of porphyry and amphibolites aggregate was suggested. In order to assess the suitability of different aggregate types for concrete mixes, their bulk density, absorbability, polishing resistance, abrasion and crushing resistance were determined. Also, the internal structure of the suggested aggregates and its influence on changes of hardened concrete composite structure were subject to the assessment. The influence of aggregate type on the structure of cement matrix and contact areas between the matrix and aggregate grains were specified. The observed changes, in case of the internal structure of concretes based on porphyry and amphibolites aggregates, with reference to granite aggregate, resulted in changes of mechanical and physical parameters. Analyses included the determination of bulk density, absorbability, compression, bending and splitting resistance. According to the obtained laboratory test results, the significant influence of the aggregate type applied to the mix on parameters of hardened concrete, with regard to the application thereof to the airfield pavements was proved.

Analysis of Mechanical Properties and Exploration of Failure Mechanism for Nonwoven Reinforced Composites

2013 ◽  
Vol 791-793 ◽  
pp. 480-485 ◽  
Author(s):  
Gang Chen ◽  
Zhao Fang Du ◽  
Zhen Li ◽  
Wei Min Song
Keyword(s):  
Mechanical Properties ◽  
Glass Fiber ◽  
Failure Mechanism ◽  
Hot Rolling ◽  
Reinforced Composites ◽  
The Matrix ◽  
Tensile Fractures ◽  
Relative Analysis

This experiment made use of hand lay-up to generate nonwoven reinforced composites which used glass fiber nonwovens, glass fiber felt and PE hot rolling nonwovens as the reinforcement, thermosetting unsaturated resin as the matrix, and tested their tensile and bending mechanical properties, then analyzed mechanical properties by gray relative analysis. The results show that when glass fiber felt is used as reinforcement and its content greater than 60%, the comprehensive mechanical properties of the composite are the best. At the same time, we observed the tensile fractures to analyze the failure mechanism of the composites.

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