scholarly journals Bounding the Multi-Scale Domain in Numerical Modelling and Meta-Heuristics Optimization: Application to Poroelastic Media with Damageable Cracks

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3974
Author(s):  
Albert Argilaga ◽  
Efthymios Papachristos
Keyword(s):  
Constitutive Law ◽  
Failure Envelope ◽  
Poroelastic Medium ◽  
Micro Structure ◽  
Asymptotic Homogenization ◽  
Micro Scale ◽  
Scale Parameters ◽  
Multi Scale ◽  
Poroelastic Media ◽  
Synthetic Materials

It is very common for natural or synthetic materials to be characterized by a periodic or quasi-periodic micro-structure. This micro-structure, under the different loading conditions may play an important role on the apparent, macroscopic behaviour of the material. Although, fine, detailed information can be implemented at the micro-structure level, it still remains a challenging task to obtain experimental metrics at this scale. In this work, a constitutive law obtained by the asymptotic homogenization of a cracked, damageable, poroelastic medium is first evaluated for multi-scale use. For a given range of micro-scale parameters, due to the complex mechanical behaviour at micro-scale, such multi-scale approaches are needed to describe the (macro) material’s behaviour. To overcome possible limitations regarding input data, meta-heuristics are used to calibrate the micro-scale parameters targeted on a synthetic failure envelope. Results show the validity of the approach to model micro-fractured materials such as coal or crystalline rocks.

Microstructure and Mechanical Properties of Multi-Scale Titanium Diboride Matrix Nanocomposite Ceramic Tool Materials

2010 ◽  
Vol 431-432 ◽  
pp. 523-526
Author(s):  
Han Lian Liu ◽  
Chuan Zhen Huang ◽  
Shou Rong Xiao ◽  
Hui Wang ◽  
Ming Hong
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Transgranular Fracture ◽  
Ceramic Tool ◽  
Tool Materials ◽  
Micro Scale ◽  
Multi Scale ◽  
Nano Scale ◽  
Matrix Nanocomposite

Under the liquid-phase hot-pressing technique, the multi-scale titanium diboride matrix nanocomposite ceramic tool materials were fabricated by adding both micro-scale and nano-scale TiN particles into TiB2 with Ni and Mo as sintering aids. The effect of content of nano-scale TiN and sintering temperature on the microstructure and mechanical properties was studied. The result showed that flexural strength and fracture toughness of the composites increased first, and then decreased with an increase of the content of nano-scale TiN, while the Vickers hardness decreased with an increase of the content of nano-scale TiN. The optimal mechanical properties were flexural strength 742 MPa, fracture toughness 6.5 MPa•m1/2 and Vickers hardness 17GPa respectively. The intergranular and transgranular fracture mode were observed in the composites. The metal phase can cause ductility toughening and crack bridging, while crack deflection and transgranular fracture mode could be brought by micro-scale TiN and nano-scale TiN respectively.

scholarly journals Serviceability and post-failure behaviour of laminated glass structural elements

2019 ◽  
Author(s):  
Lorenzo Ruggero Piscitelli
Keyword(s):  
Engineering Design ◽  
Structural Design ◽  
Laminated Glass ◽  
Structural Elements ◽  
Failure Behaviour ◽  
Multi Scale ◽  
Synthetic Materials ◽  
Cold Bending ◽  
The World ◽  
Safety Assessments

Glass structures are being built ever more frequently all over the world, in a growing architectural trend towards light, transparency and sustainability. The engineering design of laminated glass elements being profoundly influenced by properties of interlayers, this multi-scale research highlights some among the key elements on the hyperelastic and viscoplastic response of such synthetic materials. Results and new discoveries are interpreted to better model and predict the response of laminated glass structures: examples are provided for design applications to post-failure safety assessments, structural design and cold-bending techniques. Still, in a vastly unknown field, a growing market and foggy regulatory framework, many challenges and research opportunities remain to be dealt with.

scholarly journals Macro-meso scale simulations of 3D woven composite reinforcements during the forming process

2021 ◽  
Author(s):  
Jie Wang ◽  
Peng Wang ◽  
Nahiène Hamila ◽  
Philippe Boisse
Keyword(s):  
Computational Cost ◽  
Constitutive Law ◽  
Forming Process ◽  
Multi Scale ◽  
Rtm Process ◽  
Macroscopic Simulation ◽  
Deformations And Orientations ◽  
High Computational Cost ◽  
Meso Scale ◽  
Composite Reinforcements

During the forming stage in the RTM process, deformations and orientations of yarns at the mesoscopic scale are essential to evaluate mechanical behaviors of final composite products and calculate the permeability of the reinforcement. However, due to the high computational cost, it is very difficult to carry out a mesoscopic draping simulation for the entire reinforcement. In this paper, a macro-meso scale simulation of composite reinforcements is presented in order to predict mesoscopic deformations of the fabric in a reasonable calculation time. The proposed multi-scale method allows linking the macroscopic simulation of the reinforcement with the mesoscopic modelling of the RVE through a macromeso embedded analysis. On the base of macroscopic simulations using a hyperelastic constitutive law of the reinforcement, an embedded mesoscopic geometry is first deduced from the macroscopic simulation of the draping. To overcome the inconvenience of the macro-meso embedded solution which leads to unreal excessive yarn extensions, local mesoscopic simulations based on the embedded analysis are carried out on a single RVE by defining specific boundary conditions. Finally, the multi-scale forming simulations are investigated in comparison with the experimental results, illustrating the efficiency of the proposed approach, in terms of accuracy and CPU time.

Moment-Based Hybrid Polynomial Chaos Method for Interval and Random Uncertain Analysis of Periodical Composite Structural-Acoustic System with Multi-Scale Parameters

2020 ◽  
pp. 2050041
Author(s):  
Ning Chen ◽  
Jiaojiao Chen ◽  
Shengwen Yin
Keyword(s):  
Polynomial Chaos ◽  
Random Variable ◽  
Acoustic System ◽  
Passenger Compartment ◽  
Scale Parameters ◽  
Multi Scale ◽  
Arbitrary Polynomial ◽  
Random Moment ◽  
The Moment ◽  
Probability Density Function Pdf

An interval and random moment-based arbitrary polynomial chaos method (IRMAPCM) is proposed in this paper for the analysis of periodical composite structural-acoustic systems with multi-scale uncertain-but-bounded parameters. In IRMAPCM, the response of structural-acoustic system is approximated as moment-based arbitrary polynomial chaos (maPC) expansion. IRMAPCM can construct the polynomial basis according to the moment of the random variable without knowing the Probability Density Function (PDF), which can avoid the errors introduced by estimating the PDF. Numerical examples of a hexahedral box and an automobile passenger compartment are given to investigate the effectiveness of IRMAPCM for the prediction of the sound pressure response of structural-acoustic systems.

Multi-scale density detection for yarn-dyed fabrics with deformed repeat patterns

2016 ◽  
Vol 87 (20) ◽  
pp. 2524-2540 ◽  
Author(s):  
Dejun Zheng ◽  
Lingheng Wang
Keyword(s):  
Computation Time ◽  
Registration Method ◽  
Decomposition Approach ◽  
Micro Scale ◽  
Detection Model ◽  
Multi Scale ◽  
Fabric Density ◽  
Macro Scale ◽  
Dyed Fabrics ◽  
Dyed Fabric

A new method combining the characteristics of macro-scale texture repeat patterns and micro-scale interwoven yarns of fabric images was proposed for yarn-dyed fabric density detection. The method was formulated in a research framework of multi-scale image processing and analysis. Firstly, a structure–texture decomposition approach was used to extract texture information and woven pattern details from the macro-scale fabric image. Secondly, a texture unit detection model was proposed to extract the texture units and to detect the yarn skewness in these texture units. Thirdly, a simple yet effective image registration method and a lightness gradient projection method were adopted to analyze the micro-scale fabric image and obtain the yarn locations in a texture unit. Finally, the average fabric density was calculated by coupling the near-regular features of texture units and yarn locations. The experiments showed that the proposed method was effective in detecting hundreds of yarns in the fabric samples and the computation time was very reasonable.

Internal dissipative waves in poroelastic media

1987 ◽  
Vol 413 (1845) ◽  
pp. 383-405 ◽  
Keyword(s):  
Internal Waves ◽  
Wave Solution ◽  
Plane Waves ◽  
Displacement Discontinuity ◽  
Poroelastic Medium ◽  
Zero Dynamic ◽  
Poroelastic Media ◽  
Pressure Fields ◽  
Wave Solutions ◽  
Wavelength Scale

Free internal-wave solutions in poroelastic media are found by allowing for dilatational discontinuities in both the solid and fluid displacements. Physically, the displacement discontinuity sheet is shown to represent a thin layer in the state of dynamic liquefaction (i.e. a layer with zero dynamic solid-stress tensor) so that across the layer the porous medium is dynamically supported by pore pressure. Because of the associated relative motion between the viscous pore fluid and the porous solid, the resulting internal waves are dissipative in character. However, the dissipation rates are not necessarily similar for all obtained waves. In fact, two distinct wave types can be identified. One is characterized by having a dissipation-length scale that is much longer than the wavelength scale, and hence may be termed a propagating wave solution, while the other type has comparable dissipation and wave lengths, i. e. a non-propagating wave solution. It is shown that both types of waves can simultaneously exist in a poroelastic medium. Solutions are obtained for plane waves in a whole homogeneous space, giving the phase speeds, damping rates and velocity and pressure fields for both types of internal waves.

Large-Scale Assembly of Carbon Nanotubes

2004 ◽  
Author(s):  
T. El-Aguizy ◽  
Sang-Gook Kim
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Large Scale ◽  
Small Scale ◽  
Manufacturing Processes ◽  
Micro Scale ◽  
Multi Scale ◽  
Novel Method ◽  
Functionalization Of Carbon Nanotubes

The scale decomposition of a multi-scale system into small-scale order domains will reduce the complexity of the system and will subsequently ensure a success in nanomanufacturing. A novel method of assembling individual carbon nanotube has been developed based on the concept of scale decomposition. Current technologies for organized growth of carbon nanotubes are limited to very small-scale order. The nanopelleting concept is to overcome this limitation by embedding carbon nanotubes into micro-scale pellets that enable large-scale assembly as required. Manufacturing processes have been developed to produce nanopellets, which are then transplanted to locations where the functionalization of carbon nanotubes are required.

Multi-Scale Analysis of Viscoelastic Behavior of Laminated Composite Structures

2010 ◽  
Vol 430 ◽  
pp. 115-132
Author(s):  
Y. Shibuya ◽  
Hideki Sekine
Keyword(s):  
Viscoelastic Properties ◽  
Composite Structures ◽  
Viscoelastic Behavior ◽  
Laminated Composite ◽  
Scale Analysis ◽  
Scale Level ◽  
Micro Scale ◽  
Multi Scale ◽  
Laminated Composite Structures ◽  
Multi Scale Analysis

For high temperature applications of laminated composite structures, viscoelastic behavior of laminated composite structures is investigated by multi-scale analysis based on a homogenization theory. Effective viscoelastic properties of the laminas are evaluated by a boundary integral method at a micro-scale level, and viscoelastic analysis for laminated composite structures is performed by a finite element method at a macro-scale level using the effective viscoelastic properties of lamina obtained by the micro-scale analysis. In the multi-scale analysis, the Laplace transformation is adopted and the correspondence principle between elastic and viscoelastic solutions in the Laplace domain is applied. The inverse Laplace transform is formulated by the Duhamel integral, and is calculated numerically. As a numerical example, a laminated composite plate with a hole is treated and the viscoelastic behavior of the laminated composite structure is elucidated.

A Micro-Scale Model for Fiber Tow Characterization under Nondeterministic Assumption: Longitudinal and Transverse Permeability

2013 ◽  
Vol 554-557 ◽  
pp. 2348-2354 ◽  
Author(s):  
Pierpaolo Carlone ◽  
Gaetano S. Palazzo
Keyword(s):  
Scale Model ◽  
Liquid Composite Molding ◽  
Trial And Error ◽  
Flow Simulations ◽  
Micro Scale ◽  
Multi Scale ◽  
Representative Cell ◽  
Transverse Permeability ◽  
Composite Molding ◽  
Cure Models

Liquid Composite Molding processes are characterized by the impregnation of a dry fibrous perform by means of injection or infusion of a catalyzed resin. In recent years computational flow and cure models allowed for a remarkable time and cost compression in process planning with respect to trial and error procedures. In this contest multi-scale simulative approaches are gaining considerable attention and intriguing results have been recently presented. Most of the proposed models, however, rely on deterministic hypothesis, assuming perfect fiber packing and neglecting dimensional variations between fibers, in strong contrast with experimental observations. In this paper the influence of the stochastic variability of the fiber packing on tow permeability has been investigated by means of a CFD micro scale model. The variability of the microstructure defining the Representative Volume Element has been considered introducing random perturbations of the fiber packing. The components of the permeability tensor, in each case, have then been derived applying the Darcy model to flow simulations through the representative cell.

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