scholarly journals A numerical and experimental study of sand-rubber mixtures subjected to oedometric compression

2019 ◽  
Vol 92 ◽  
pp. 14010
Author(s):  
Pravin Badarayani ◽  
Patrick Richard ◽  
Bogdan Cazacliu ◽  
Riccardo Artoni ◽  
Erdin Ibraim
Keyword(s):  
Mechanical Response ◽  
Volume Fraction ◽  
Rubber Mixture ◽  
Uniaxial Load ◽  
Dem Simulations ◽  
Small Strains ◽  
Initial Volume Fraction ◽  
Landfill Sites ◽  
Recycled Rubber ◽  
Powdered Form

The stockpiling of waste tires at landfill sites has become a nuisance for the society. One of the alternatives could be converting the recycled rubber into powdered form and mixing it with soil to use it as the backfill of the retaining structures. This paper is based on the study of such sand-rubber mixtures. In this work, Discrete Element (DEM) simulations were employed to study the mechanical response of sand-rubber mixtures with respect to a column of grains enclosed within a rigid cylindrical confinement, and subjected to an oedometric compression by the fixed velocity displacement of one of the horizontal walls. Further, experimental analysis was also carried out by using a uniaxial load cell to load the sand-rubber mixtures under compression. Different initial packings of sand-rubber mixture were prepared by varying: (a) the packing volume fraction and (b) the volume fraction of rubber. The mechanical response at small strains was studied for these sand-rubber packings. The mixture behavior was observed to be more sand-dominant or rubber-dominant depending on the rubber fraction and the mixture quality. Moreover, variation in the initial volume fraction of the packing also caused a difference in the load bearing of the packings for a given strain and a given rubber fraction.

Initiation of underwater granular avalanches: Influence of the initial volume fraction

2008 ◽  
Vol 20 (11) ◽  
pp. 111701 ◽  
Author(s):  
M. Pailha ◽  
M. Nicolas ◽  
O. Pouliquen
Keyword(s):  
Volume Fraction ◽  
Initial Volume ◽  
Initial Volume Fraction

scholarly journals Mechanical Properties and Microstructural Aspects of Two High-Manganese Steels with TWIP/TRIP Effects: A Comparative Study

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 24
Author(s):  
Matías Bordone ◽  
Juan Perez-Ipiña ◽  
Raúl Bolmaro ◽  
Alfredo Artigas ◽  
Alberto Monsalve
Keyword(s):  
Mechanical Response ◽  
Volume Fraction ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Chemical Compositions ◽  
High Manganese ◽  
Microstructural Changes ◽  
Ε Martensite ◽  
High Manganese Steels ◽  
Manganese Steels

This article is focused on the mechanical behavior and its relationship with the microstructural changes observed in two high-manganese steels presenting twinning-induced plasticity (TWIP) and transformation-induced plasticity (TRIP), namely Steel B and Steel C, respectively. Chemical compositions were similar in manganese, but carbon content of Steel B approximately doubles Steel C, which directly impacted on the stacking fault energy (SFE), microstructure and mechanical response of each alloy. Characterization of as-cast condition by optical microscope revealed a fully austenitic microstructure in Steel B and a mixed microstructure in Steel C consisting of austenite grains and thermal-induced (εt) martensite platelets. Same phases were observed after the thermo-mechanical treatment and tensile tests, corroborated by means of X-Ray Diffraction (XRD), which confirms no phase transformation in Steel B and TRIP effect in Steel C, due to the strain-induced γFCC→εHCP transformation that results in an increase in the ε-martensite volume fraction. Higher values of ultimate tensile strength, yield stress, ductility and impact toughness were obtained for Steel B. Significant microstructural changes were revealed in tensile specimens as a consequence of the operating hardening mechanisms. Scanning Electron Microscopy (SEM) observations on the tensile and impact test specimens showed differences in fracture micro-mechanisms.

Architectural changes of trabecular bone caused by the remodeling process

2005 ◽  
Vol 874 ◽  
Author(s):  
Richard Weinkamer ◽  
Markus A. Hartmann ◽  
Yves Brechet ◽  
Peter Fratzl
Keyword(s):  
Trabecular Bone ◽  
Feedback Loop ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Bone Volume ◽  
Bone Architecture ◽  
Mechanical Problem ◽  
Bone Volume Fraction ◽  
Obvious Effect ◽  
Trabecular Bone Architecture

AbstractUsing a stochastic lattice model we have studied the architectural changes of trabecular bone occurring while the structure is remodeled. Our model considers the mechanical feedback loop, which control the remodeling process. A fast algorithm was employed to solve approximately the mechanical problem. A general feature of the model is that a networklike structure emerges, which further coarsens while the bone volume fraction remains unchanged. Decreasing the mechanical response of the system by either lowering the external load or the internal mechano-sensitivity leads not only to a reduction of the bone volume fraction, but results in topological changes of the trabecular bone architecture, where the loss of horizontal trabeculae is the most obvious effect.

Mechanical Deformation of Field-Coupled Materials

2002 ◽  
Author(s):  
Pavel M. Chaplya ◽  
Geoffrey P. McKnight ◽  
Gregory P. Carman
Keyword(s):  
Shape Memory ◽  
Smart Materials ◽  
Residual Strain ◽  
Applied Load ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Mechanical Deformation ◽  
Passive Damping ◽  
Wide Range ◽  
Internal States

This article describes remarkable similarities in the nonlinear mechanical response of different active/smart materials despite fundamental differences in the underlying mechanisms associated with each material. Active/smart materials (i.e., piezoelectric (PZT-5H), magnetostrictive (Terfenol-D), and shape memory alloys (NiTi)) exhibit strong non-linear mechanical behavior produced by changing non-mechanical internal states such as polarization, magnetization, and phase/twin configuration. In active/smart materials the initial deformation proceeds linearly followed by a jump in strain associated with the transformation of an internal non-mechanical state. After the transformation, the mechanical response returns to linear elastic. Upon unloading, a residual strain is observed which can be recovered with the application of a corresponding external field (i.e., electric, magnetic, or thermal). Due to coupling between applied fields and non-mechanical internal states, mechanical deformation is also a function of applied external fields. At a critical applied field, the residual strain is eliminated, providing repeatable cyclic characteristics that can be used in passive damping applications. Even though different intrinsic processes (i.e., polarization, magnetization, and phase/twin variant composition) govern the deformation of each material, their macroscopic behavior is explained using a unified volume fraction concept. That is, the deformation of piezoelectric material is described in terms of the volume fraction of ferroelectric domains with polarization parallel or orthogonal to the applied load; the deformation of magnetostrictive materials is described in terms of the volume fraction of magnetic domains with magnetization parallel or orthogonal to the applied load; and the deformation of shape memory material is described in terms of the volume fraction of twin variants that are oriented favorably to the applied load. Although the qualitative behavior of each material is similar, the average magnitude of stress required to induce non-linearity varies from ~10 MPa for Terfenol-D to ~65 MPa for PZT-5H to ~300 MPa for NiTi shape memory alloy. It is hypothesized that a composite material made of these materials connected in series would exhibit passive damping over a wide range of applied stress.

scholarly journals Finite Element Simulation of the Thermo-mechanical Response of Graphene Reinforced Nanocomposites

2018 ◽  
Vol 188 ◽  
pp. 01016
Author(s):  
Androniki S. Tsiamaki ◽  
Nick K. Anifantis
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Matrix Material ◽  
Continuum Theory ◽  
Element Model ◽  
Multilayer Graphene ◽  
Temperature Changes ◽  
The Matrix

The research for new materials that can withstand extreme temperatures and present good mechanical behavior is of great importance. The interest is highly focused on the utilization of composites reinforced by nanomaterials. To cope with this goal the present work studies the mechanical response of graphene reinforced nanocomposite structures subjected to temperature changes. A computational finite element model has been developed that accounts for both the reinforcement and the matrix material phases. The model developed is based on both the continuum theory and the molecular mechanics theory, for the simulation of the three different material phases of the composite, respectively, i.e. the matrix, the intermediate transition phase and the reinforcement. Considering this model, the mechanical response of an appropriate representative volume element of the nanocomposite is simulated under various temperature changes. The study involves different types of reinforcement composed from either monolayer or multilayer graphene sheets. Apart from the investigation of the behavior of a nanocomposite with each particular type of the reinforcement, comparisons are also presented between them in order to reveal optimized material combinations. The principal parameters taken into consideration, which contribute also to the mechanical behavior of the nanocomposite, are its size, the sheet multiplicity as well as the volume fraction.

Effect of Brownian and Thermophoretic Diffusions of Nanoparticles on Nonequilibrium Heat Conduction in Nanofluids

2008 ◽  
Author(s):  
Yuwen Zhang ◽  
Ling Li ◽  
H. B. Ma
Keyword(s):  
Heat Flux ◽  
Heat Conduction ◽  
Initial Temperature ◽  
Volume Fraction ◽  
Density Ratio ◽  
Lewis Number ◽  
Soret Coefficient ◽  
Transfer Enhancement ◽  
Initial Volume Fraction ◽  
Periodic Heat

Effects of Brownian and thermophoretic diffusions on nonequilibrium heat conduction in a nanofluid layer with periodic heat flux on one side and specified temperature on the other side are investigated numerically. The problem are described by eight dimensionless parameters: density ratio, heat capacity ratio, Lewis number, Soret coefficient, initial volume fraction of nanoparticles, initial temperature, Sparrow number, and period of the surface heat flux. Effects of Brownian and thermophoretic diffusions of nanoparticles on nonequilibrium heat conduction in nanofluid obtained by dispersing copper nanoparticles into ethylene glycol are investigated. The results showed that the Brownian and thermophoretic diffusions only affect the nanoparticle temperature but their effect on the heat transfer enhancement is negligible.

scholarly journals Granular Stack Density’s Influence on Homogeneous Fluidization Regime: Numerical Study Based on EDEM-CFD Coupling

2021 ◽  
Vol 11 (18) ◽  
pp. 8696
Author(s):  
Aboubacar Sidiki Drame ◽  
Li Wang ◽  
Yanping Zhang
Keyword(s):  
Volume Fraction ◽  
Numerical Study ◽  
Initial Density ◽  
Strong Impact ◽  
Fast Kinetics ◽  
Bed Height ◽  
Initial Volume Fraction ◽  
Fluidization Regime ◽  
Original Observation ◽  
Initial Packing

FLUENT and EDEM were applied to simulate liquid–solid coupling in a 3D homogenous fluidization. The dynamics of destabilization of the granular material immersed by homogeneous fluidization were observed. The effect of initial packing density of granular stack and fluidization rate on the fluidization’s transient regime, the configuration of particles in the fluidized bed and the variation of bed height were analyzed and discussed. According to the results, there was an original observation of a strong impact of the initial density of an initially static granular stack on the transient fluidization regime. Depending on the material initial volume fraction, there was a difference in grain dynamics. For an initially loose stack, a homogeneous turbulent fluidization was observed, whereas for an initially dense stack, there was a mass takeoff of the stack. The propagation of wave porosity instability, from the bottom to the top of the stack with fast kinetics that decompacted the medium, followed this mass takeoff.

scholarly journals Bending of Symmetric Sandwich FGM Beams with Shear Connectors

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Dung Nguyen Thai ◽  
Phung Van Minh ◽  
Cuong Phan Hoang ◽  
Tam Ta Duc ◽  
Nhung Nguyen Thi Cam ◽  
...  
Keyword(s):  
Finite Element ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Beam Theory ◽  
Numerical Data ◽  
Functionally Graded ◽  
Engineering Practice ◽  
Graded Materials ◽  
Shear Connectors ◽  
The Impact

This paper carries out the static bending analysis of symmetric three-layer functionally graded sandwich beams, in which each layer is made from different functionally graded materials, and they are connected by shear connectors due to sliding movement. The finite element formulations are based on Timoshenko’s first-order shear deformation beam theory (FSDT) and the finite element method to establish the equilibrium equation of beams. The calculation program is coded in the MATLAB environment, and then verification examples are given out to compare the numerical data of present work with those of exact open sources. The impact of several geometrical and material parameters on the mechanical response of the structure, such as the height-to-length ratio, boundary conditions, volume fraction index, and especially the shear coefficient of connectors, is being explored. When designing and using these types of structures in engineering practice, the computed results can be utilized as a valid reference.

Fully Coupled Three-Scale Finite Element Model for the Mechanical Response of a New Bio-Inspired Composite

2011 ◽  
Author(s):  
Erick I. Saavedra Flores ◽  
Senthil Murugan ◽  
Michael I. Friswell ◽  
Eduardo A. de Souza Neto
Keyword(s):  
Finite Element ◽  
Magnesium Alloy ◽  
Finite Element Model ◽  
Large Scale ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Element Model ◽  
Crystalline Cellulose ◽  
Gauss Point ◽  
Fully Coupled

This paper proposes a fully coupled three-scale finite element model for the mechanical description of an alumina/magnesium alloy/epoxy composite inspired in the mechanics and architecture of wood cellulose fibres. The constitutive response of the composite (the large scale continuum) is described by means of a representative volume element (RVE, corresponding to the intermediate scale) in which the fibre is represented as a periodic alternation of alumina and magnesium alloy fractions. Furthermore, at a lower scale the overall constitutive behavior of the alumina/magnesium alloy fibre is modelled as a single material defined by a large number of RVEs (the smallest material scale) at the Gauss point (intermediate) level. Numerical material tests show that the choice of the volume fraction of alumina based on those volume fractions of crystalline cellulose found in wood cells results in a maximisation of toughness in the present bio-inspired composite.

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