scholarly journals DEVELOPMENT OF STATISTICALLY AVERAGED MODELS OF DEFORMATION OF MATERIALS WITH RANDOM NETWORK STRUCTURE OF DIFFERENTLY ORIENTED FIBERS

Author(s):  
Mykola M. Tkachuk

The paper describes the developed statistically averaged models of deformation of materials with a random network structure of differently oriented fibers. New methods of stress-strain analysis and micromacromechanical models of material deformation in the volume of bodies made of material with a network structure taking into account structural and physical nonlinearities have been created. These models are based on the micromechanics of network structures at the level of statistical sets of their chains. The novelty of approaches, models, methods and results is the creation of theoretical foundations for the analysis of the deformation of non-traditional network materials. Nonlinear mathematical models of material deformation in the form of a chaotic network structure of one-dimensional fragments are proposed, which are constructed involving fundamentally new approaches to the description of physical and mechanical properties at the micro level of statistical sets of fiber chains and spatial homogenization of their macroproperties. Compared to traditional models, they more adequately model the features of material deformation in the form of spatial chaotic and ordered network structures, as they do not involve a number of additional non-physical hypotheses. This creates fundamentally new opportunities not only for analyzing the properties of such materials, but also when creating new ones with specified properties. Using the created methods, models and research tools, the basis for solving a number of model and applied problems has been created. The nature of deformation of non-traditional materials with a network structure of one-dimensional elements is determined. The macro-properties of these materials are established on the basis of the developed micromechanical models, variational formulations and averaging methods. Keywords: stress-strain state, network structures, contact interaction, finite element method, contact pressure, machine parts, variational formulation

2019 ◽  
Vol 16 (1) ◽  
pp. 62-69
Author(s):  
SUBRAMANIAN RAVICHANDRAN ◽  
E. VENGATESAN ◽  
A. RAMAKRISHNAN

Composite materials are replacing traditional materials, because of their superior physical and mechanical properties. The main objective of the present work is to perform stress-strain analysis on Styrene-Ethylene-Butylene-Styrene (SEBS)-epoxy resin composites under reinforcement of fibres and dispersion of CuO, ZnO, MgO, SiO and TiO2nano metal oxides. Combination of glass fibre with particle reinforcement (GFRPs) applications has increased in recent days. In this study, glass fibre reinforced epoxy composites with different nano metal oxides are developed by compression moulding method and their mechanical properties such as breaking load, elastic limit, plastic range and fracture point are evaluated. The results indicate that the incorporation of nanophase material with glass fibre can improve the properties of composites.


TAPPI Journal ◽  
2012 ◽  
Vol 11 (1) ◽  
pp. 61-66 ◽  
Author(s):  
DOEUNG D. CHOI ◽  
SERGIY A. LAVRYKOV ◽  
BANDARU V. RAMARAO

Delamination between layers occurs during the creasing and subsequent folding of paperboard. Delamination is necessary to provide some stiffness properties, but excessive or uncontrolled delamination can weaken the fold, and therefore needs to be controlled. An understanding of the mechanics of delamination is predicated upon the availability of reliable and properly calibrated simulation tools to predict experimental observations. This paper describes a finite element simulation of paper mechanics applied to the scoring and folding of multi-ply carton board. Our goal was to provide an understanding of the mechanics of these operations and the proper models of elastic and plastic behavior of the material that enable us to simulate the deformation and delamination behavior. Our material model accounted for plasticity and sheet anisotropy in the in-plane and z-direction (ZD) dimensions. We used different ZD stress-strain curves during loading and unloading. Material parameters for in-plane deformation were obtained by fitting uniaxial stress-strain data to Ramberg-Osgood plasticity models and the ZD deformation was modeled using a modified power law. Two-dimensional strain fields resulting from loading board typical of a scoring operation were calculated. The strain field was symmetric in the initial stages, but increasing deformation led to asymmetry and heterogeneity. These regions were precursors to delamination and failure. Delamination of the layers occurred in regions of significant shear strain and resulted primarily from the development of large plastic strains. The model predictions were confirmed by experimental observation of the local strain fields using visual microscopy and linear image strain analysis. The finite element model predicted sheet delamination matching the patterns and effects that were observed in experiments.


2015 ◽  
Vol 9 (6) ◽  
pp. 583
Author(s):  
Dario German Buitrago ◽  
Luis Carlos Ruíz ◽  
Olga Lucia Ramos

2020 ◽  
Vol 26 (6) ◽  
pp. 613-618
Author(s):  
A. V. Altukhov ◽  
S. A. Tishchenko

The presented study reviews practically relevant research papers in the field of network structures, modern network business models and platforms.Aim. The study aims to elaborate and explain the concept of network structure and platform and to show the reasons for the progressiveness and potential of network organizational structure at the current stage of socio-economic and scientific development.Tasks. The authors highlight the main scientific ideas about network structures in business, including significant studies in this area; provide and explain the main terms and definitions and examine the key characteristics of network business structures; characterize “platforms” as an important concept for modern business and show the relationship between platforms and network structures.Methods. This study uses analysis of information and subsequent synthesis of new knowledge in the form of the authors’ conclusions and a wide range of relevant scientific publications of Russian and foreign authors, including original publications in English and French.Results. The history of network structures is briefly provided. Definitions and characteristics of such concepts as “network structure” and “platform” in relation to business are provided and explained by the authors.


Author(s):  
L. F. Sennikova ◽  
G. K. Volkova ◽  
V. M. Tkachenko

The results of studies of the stress-strain state of copper M0b after deformation under different schemes of equal channel angular pressing (ECAP) are presented. The level of macro and micro stresses in copper has been determined in various ECAP modes. It is shown that the strength properties, deformation porosity and parameters of the fine copper structure differ depending on the loading pattern.


Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1302
Author(s):  
Younggi Hong ◽  
Munju Goh

Epoxy resin (EP) is one of the most famous thermoset materials. In general, because EP has a three-dimensional random network, it possesses thermal properties similar to those of a typical heat insulator. Recently, there has been substantial interest in controlling the network structure of EP to create new functionalities. Indeed, the modified EP, represented as liquid crystalline epoxy (LCE), is considered promising for producing novel functionalities, which cannot be obtained from conventional EPs, by replacing the random network structure with an oriented one. In this paper, we review the current progress in the field of LCEs and their application to highly thermally conductive composite materials.


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