scholarly journals Finite element procedure for stress amplification factor recovering in a representative volume of composite materials

2011 ◽  
Vol 3 (3) ◽  
pp. 239-250 ◽  
Author(s):  
Paulo Cesar Plaisant Junior ◽  
Flávio Luiz de Silva Bussamra ◽  
Francisco Kioshi Arakaki
2021 ◽  
pp. 167-180
Author(s):  
M. A Tashkinov ◽  
A. D Dobrydneva ◽  
V. P Matveenko ◽  
V. V Silberschmidt

Сomposite materials are widely used in various industrial sectors, for example, in the aviation, marine and automotive industries, civil engineering and others. Methods based on measuring the electrical conductivity of a composite material have been actively developed to detect internal damage in polymer composite materials, such as matrix cracking, delamination, and other types of defects, which make it possible to monitor a composite’s state during its entire service life. Polymers are often used as matrices in composite materials. However, almost always pure polymers are dielectrics. The addition of nanofillers, such as graphene and its derivatives, has been successfully used to create conductive composites based on insulating polymers. The final properties of nanomodified composites can be influenced by many factors, including the type and intrinsic properties of nanoscale objects, their dispersion in the polymer matrix, and interphase interactions. The work deals with modeling of effective electric conductive properties of the representative volume elements of nanoscale composites based on a polymer matrix with graphene oxide particles distributed in it. In particular, methods for evaluating effective, electrically conductive properties have been studied, finite element modelling of representative volumes of polymer matrices with graphene oxide particles have been performed, and the influence of the tunneling effect and the orientation of inclusions on the conductive properties of materials have been investigated. The possibility of using models of resistive strain gauges operating on the principle of the tunneling effect is studied. Based on the finite-element modeling and graph theory tools, we created approaches for estimating changes in the conductive properties of the representative volume elements of a nanomodified matrix subjected to mechanical loading.


2008 ◽  
Vol 2008 (0) ◽  
pp. _OS0203-1_-_OS0203-2_
Author(s):  
Akinori TANIOKA ◽  
Yasutomo UETSUJI ◽  
Hiroyuki KURAMAE ◽  
Masaru ZAKO

2021 ◽  
Author(s):  
◽  
Mahshid Ranjbarestalkhjani

The objective of this work is to determine an e˙ective yield criteria for porous pressure sensitive solids and investigate the anisotropic yield behavior by employing a virtual testing strategy. The work is concerned with the pressure sensitivity typically displayed by geometarials, such as sandstone and composite materials consisting of a series of parallel layers, such as sedimentary rock and underground salt.Virtual testing strategy is based on computational homogenization approach for the definition of the elasto-plastic transition. Representative volume elements (RVEs) containing single-centered and distributed ellipsoidal voids are analyzed using three-dimensional finite element models under both small and finite strains. Yield curves are obtained following a unified variational formulation, which provides bounds on the e˙ective material properties for a given choice of the Representative Volume Element (RVE).In order to estimate the e˙ective properties of porous solid, the constitutive behavior of the continuum matrix is assumed to follow the standard Drucker-Prager elasto-plastic model. The computationally generated e˙ective yield criteria are compared against the recently proposed analytical estimates for Drucker-Prager type solids and the SR4 constitutive model for soft rocks. The developed computational approach is applied to estimate the e˙ective properties of a realistic rock sample. To illustrate a wide range of potential engineering applications, the computationally e˙ective yield surface are also obtained under the explicit finite element method.Finally, based on the simulated yield stress point of composite materials, the pa-rameters for proposed analytical models are acquired with ellipse fit by Taubin’s method.


2011 ◽  
Vol 368-373 ◽  
pp. 930-933
Author(s):  
Wei Hou ◽  
Shuan Hai He ◽  
Cui Juan Wang ◽  
Gang Zhang

Being aimed to deformation problem of pre-stressed concrete thin-walled multi-room box girders exposed to co-action of fire and load, on the basis of enthalpy conduction model and thermo-mechanics parameters, the finite element procedure was applied to analyze the deformation of three spans pre-stressed concrete thin-walled multi-room box girders exposed to co-action of fire and load. In conclusion, the deflection is obvious under action of the variation width and fire load model.


1998 ◽  
Vol 120 (1) ◽  
pp. 24-34 ◽  
Author(s):  
C. Fu ◽  
D. L. McDowell ◽  
I. C. Ume

A finite element procedure using a semi-implicit time-integration scheme has been developed for a cyclic thermoviscoplastic constitutive model for Pb-Sn solder and OFHC copper, two common metallic constituents in electronic packaging applications. The scheme has been implemented in the commercial finite element (FE) code ABAQUS (1995) via the user-defined material subroutine, UMAT. Several single-element simulations are conducted to compare with previous test results, which include monotonic tensile tests, creep tests, and a two-step ratchetting test for 62Sn36Pb2Ag solder; a nonproportional axial-torsional test and a thermomechanical fatigue (TMF) test for OFHC copper. At the constitutive level, we also provide an adaptive time stepping algorithm, which can be used to improve the overall computation efficiency and accuracy especially in large-scale FE analyses. We also compare the computational efforts of fully backward Euler and the proposed methods. The implementation of the FE procedure provides a guideline to apply user-defined material constitutive relations in FE analyses and to perform more sophisticated thermomechanical simulations. Such work can facilitate enhanced understanding thermomechanical reliability issue of solder and copper interconnects in electronic packaging applications.


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