The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Stepan Vladimirovitch Lomov - One of the best experts on this subject based on the ideXlab platform.

  • coupled Meso macro simulation of woven fabric local deformation during draping
    Composites Part A-applied Science and Manufacturing, 2019
    Co-Authors: Akira Iwata, Takuya Inoue, Naim Naouar, Philippe Boisse, Stepan Vladimirovitch Lomov
    Abstract:

    Abstract The prediction of yarn buckling and distortions require detailed modelling of the fabric and yarns deformations on the Meso-Level (Level of the interlacing structure). In the current research, computationally viable Meso-Level simulation is achieved by coupling continuous macro draping simulation with a local Meso-modeling in the location where the defects are expected to occur. The macro-simulation uses a membrane-shell continuous model of the fabric. A hyperelastic constitutive model for the yarns (Charmetant – Boisse) is used in the Meso-modelling. The model parameters are identified and validated in independent tension, shear, compaction and bending tests of the yarn and the fabric. The simulation reproduces local yarn slippage and buckling, e.g., the yarn distortion on the 3D mould corner. The simulations are compared with the local fabric distortions observed during draping experiments for two carbon plain weave fabrics (12K carbon-fibre tows and with spread tows) on a hemispherical and on a box-shaped moulds.

  • Meso Level textile composites simulations open data exchange and scripting
    Journal of Composite Materials, 2014
    Co-Authors: Stepan Vladimirovitch Lomov, Dmitry Ivanov, Ignace Verpoest, Joerg Cichosz, C Hahn, Bart Verleye
    Abstract:

    The article presents a user interface for modelling of textile composites, which combines open XML input and output formats with scripting for definitions of the reinforcement models under (local) shear, tension and compression deformations. The open input format (parameters of the textile reinforcement) allows easy integration of a Meso-Level (unit cell) textile processor upstream – with, for example, textile process modelling software or forming models, which define local parameters of the textile reinforcement. The scripting command format makes possible automated processing of the information on local reinforcement deformation conditions, and offers itself to be integrated in user software without accessing or knowing internal computational procedures or native data formats of Meso-Level textile processor. The open output format allows transferring the results of the Meso-Level textile processor downstream to Meso-Level models of the micromechanics or the permeability of a textile composite unit cell....

  • on modelling of damage evolution in textile composites on Meso Level via property degradation approach
    Composites Part A-applied Science and Manufacturing, 2007
    Co-Authors: Larissa Gorbatikh, Dmitry Ivanov, Stepan Vladimirovitch Lomov
    Abstract:

    Abstract The continuous damage mechanics (CDM) approach is a popular tool for modelling of damage evolution in textile composites on the Meso-Level. It is based on the assumption that a material with defects can be replaced by a fictitious material with no defects but with degraded elastic constants. In such way the presence of defects is only reflected in the material elastic properties and damage evolution is recorded through the loss of these properties. The CDM approach incorporated into finite element analysis often predicts unphysically wide damage zones and in some cases failure across yarns – findings that are not supported by experimental data. The current work is geared toward identifying the source of inconsistencies between experiment and modelling by revisiting basic assumptions of CDM. A test problem is proposed to illustrate a break down of the CDM approach where a single crack-like defect in a yarn is modelled as an inhomogeneity with elastic constants reduced according to Murakami–Ohno model. It is shown that CDM in combination with local stress analysis of failure may predict a different direction of damage evolution as well as an incorrect failure mode in comparison with the crack problem. We also investigate whether the Murakami–Ohno model adopted for calculation of properties of a fictitious inhomogeneity contributes to the unphysical results. For this we compare contributions of a crack and an inhomogeneity into material elastic response. A new property degradation procedure is suggested (referred here as an effective elastic response model) where the size of an inhomogeneity and properties of the surrounding material are taken into account.

Abbas S Milani - One of the best experts on this subject based on the ideXlab platform.

  • Shear response of woven fabric composites under Meso-Level uncertainties
    Journal of Composite Materials, 2012
    Co-Authors: M Komeili, Abbas S Milani
    Abstract:

    Experimental results in the literature indicate notable non-repeatabilities during mechanical testing of woven fabrics, even under the same loading conditions, which may be linked to the presence of defects and uncertainties at Meso or micro Levels in yarns. Sources of such uncertainties can include both yarn dimensional tolerances and variations in the fiber/matrix material properties. The aim of this article is to conduct a systematic sensitivity analysis on the Meso-Level uncertainty factors in a typical woven fabric and identify the most significant factors and their interactions under a trellising mode. A finite element model capable of capturing behavior of dry yarns, along with a two-Level full-factorial design approach has been employed. Factorial designs are split into two categories of the geometrical and material factors. It is shown how the obtained range of variations from the above statistical designs may be used to capture non-repeatability in some trellising tests.

  • the effect of Meso Level uncertainties on the mechanical response of woven fabric composites under axial loading
    Computers & Structures, 2012
    Co-Authors: M Komeili, Abbas S Milani
    Abstract:

    First, a finite element unit cell model of a glass fibre plain weave has been developed via an implicit subroutine. Because of the complex behaviour of fibrous yarns, a user-defined constitutive model needed to be defined. Material properties of yarns in the dry fabric are extracted by fitting the numerical model to experimental data under the uni-axial and bi-axial extension modes. Subsequently, two sets of geometrical and material-related Meso-Level uncertainty factors are studied using two-Level factorial designs. Through the obtained half-normal probability plots, as well as the main and interaction factor effects, the most significant parameters are identified and discussed.

M Komeili - One of the best experts on this subject based on the ideXlab platform.

  • Shear response of woven fabric composites under Meso-Level uncertainties
    Journal of Composite Materials, 2012
    Co-Authors: M Komeili, Abbas S Milani
    Abstract:

    Experimental results in the literature indicate notable non-repeatabilities during mechanical testing of woven fabrics, even under the same loading conditions, which may be linked to the presence of defects and uncertainties at Meso or micro Levels in yarns. Sources of such uncertainties can include both yarn dimensional tolerances and variations in the fiber/matrix material properties. The aim of this article is to conduct a systematic sensitivity analysis on the Meso-Level uncertainty factors in a typical woven fabric and identify the most significant factors and their interactions under a trellising mode. A finite element model capable of capturing behavior of dry yarns, along with a two-Level full-factorial design approach has been employed. Factorial designs are split into two categories of the geometrical and material factors. It is shown how the obtained range of variations from the above statistical designs may be used to capture non-repeatability in some trellising tests.

  • the effect of Meso Level uncertainties on the mechanical response of woven fabric composites under axial loading
    Computers & Structures, 2012
    Co-Authors: M Komeili, Abbas S Milani
    Abstract:

    First, a finite element unit cell model of a glass fibre plain weave has been developed via an implicit subroutine. Because of the complex behaviour of fibrous yarns, a user-defined constitutive model needed to be defined. Material properties of yarns in the dry fabric are extracted by fitting the numerical model to experimental data under the uni-axial and bi-axial extension modes. Subsequently, two sets of geometrical and material-related Meso-Level uncertainty factors are studied using two-Level factorial designs. Through the obtained half-normal probability plots, as well as the main and interaction factor effects, the most significant parameters are identified and discussed.

Grégoire Croidieu - One of the best experts on this subject based on the ideXlab platform.

  • Untapped Riches of Meso-Level Applications in MultiLevel Entrepreneurship Mechanisms
    Academy of Management Perspectives, 2016
    Co-Authors: Phillip H. Kim, Karl Wennberg, Grégoire Croidieu
    Abstract:

    Entrepreneurial action is embedded within a variety of complex social structures, not all of which can be as easily defined or measured as macro-institutional or micro-individual characteristics. Nonetheless, these multilayered structures collectively hold rich insights—before now underexamined—into the actual causal mechanisms that affect entrepreneurial actions and outcomes. To address this problem, we call on researchers to broaden their Levels of analysis and direct their focus to Meso-Level structures. Although Meso-Level social structures are widely studied independently, these intermediate Levels are seldom integrated into existing multiLevel models. We argue that Meso-Level structures offer untapped riches for enhancing multiLevel entrepreneurial mechanisms and discuss how social groups, associations, and other collectives operating at a Meso Level can play a more distinct, integrative role between the two ends of the institutional spectrum. To provide practical guidance for pursuing such investigations, we adapt Coleman's bathtub model to form a robust framework that integrates micro, Meso, and macro Levels of analysis. Our framework helps alleviate the shortcomings produced by an overdependence on either solely macro- or micro-Level entrepreneurial mechanisms and offers fresh insights, as the intermediate Level is more deeply integrated into this new framework.

  • untapped riches of Meso Level applications in multiLevel entrepreneurship mechanisms
    Academy of Management Perspectives, 2016
    Co-Authors: Phillip H. Kim, Karl Wennberg, Grégoire Croidieu
    Abstract:

    Entrepreneurial action is embedded within a variety of complex social structures, not all of which can be as easily defined or measured as macro-institutional or micro-individual characteristics. N...

D Assimacopoulos - One of the best experts on this subject based on the ideXlab platform.

  • systemic eco efficiency assessment of Meso Level water use systems
    Journal of Cleaner Production, 2016
    Co-Authors: Athanasios Angelisdimakis, George Arampatzis, D Assimacopoulos
    Abstract:

    Eco-efficiency has recently become an important concept of environmental decision making, serving as a policy objective and, if linked with resource efficiency, can be a measure of progress towards sustainability. The need for improving eco-efficiency leads to the challenge of identifying the most promising alternative solutions which improve both the economic and the environmental performance of a given system (“eco-innovations”). A methodological framework for the eco-efficiency assessment of a water use system at the Meso Level has been developed in the context of the EcoWater research project and consists of four distinct steps. The first step leads to a clear, transparent mapping of the system at hand and the respective value chain, while the second step provides the means to assess its eco-efficiency, following a life-cycle oriented approach using the midpoint impact categories. An important novelty is the distribution of economic costs/benefits and environmental pressures over different stages and stakeholders in the value chain. The third step includes the selection of innovative technologies, which are assessed in the last step and combined with mid-term scenarios in order to determine the feasibility of their implementation. The proposed methodological framework has been applied to eight alternative water use systems, revealing all their environmental weaknesses and identifying potential opportunities for eco-efficiency improvement. At the same time, through the systemic approach all the involved actors are urged to cooperate in order to (a) propose and build innovative technological solutions that will improve the overall eco-efficiency of the system; and (b) make suggestions on the necessary policy framework that will facilitate and promote their uptake. This ensures that upstream decisions in the value chain are coordinated with downstream activities and all potential synergies are identified, leading to the creation of “Meso-Level closed resource loops” and thus the promotion of a circular economy.

  • process eco innovation assessing Meso Level eco efficiency in industrial water service systems
    Journal of Cleaner Production, 2016
    Co-Authors: Les Levidow, Palle Lindgaardjorgensen, Asa Nilsson, Sara Alongi Skenhall, D Assimacopoulos
    Abstract:

    Eco-innovation combines economic advantage with lower ecological-resource burdens. Eco-innovation has been generally directed at energy input-substitutes, component recycling, etc. Some companies have made investments reducing resource burdens in the production process. This study investigated options for eco-efficiency improvement in two large manufacturing companies, Volvo and Arla Foods. Their impetus for eco-innovation comes from the companies' environmental policies, as well as from external drivers such as future higher costs and resource scarcity. Relative to their respective industrial sector, these companies represent strong prospects for reducing resource burdens in water-service processes, especially from chemical inputs and wastewater. Such eco-innovations involve more com- plex interactions beyond the production site, so the options warrant a whole-system comparative assessment.