Loading...

**Search for:**strain-energy

0.009 seconds

Total 74 records

#### A hyperelastic constitutive model for rubber-like materials

, Article European Journal of Mechanics, A/Solids ; Volume 38 , 2013 , Pages 144-151 ; 09977538 (ISSN) ; Arghavani, J ; Naghdabadi, R ; Sharif University of Technology
2013

Abstract

Hyperelastic behavior of isotropic incompressible rubbers is studied to develop a strain energy function which satisfies all the necessary characteristic properties of an efficient hyperelastic model. The proposed strain energy function includes only three material parameters which are somehow related to the physical quantities of the material molecular network. Moreover, the model benefits from mathematical simplicity, well suitting in all ranges of stretch and possessing the property of deformation-mode-independency. This reduces the required number of experimental tests for parameter calibration of the model. Results of the proposed model are compared with results of some available models...

#### A strain energy function for rubber-like materials

, Article Constitutive Models for Rubber VIII - Proceedings of the 8th European Conference on Constitutive Models for Rubbers, ECCMR 2013 ; 2013 , Pages 205-210 ; 9781138000728 (ISBN) ; Naghdabadi, R ; Arghavani, J ; Sharif University of Technology
2013

Abstract

Hyperelastic behavior of isotropic incompressible rubbers are studied to develop a strain energy function. The proposed function includes only three material parameters which are related to physical properties of the material molecular network. Furthermore, the model benefits from well suitting in all ranges of stretch as well as possessing the property of deformation mode independency. This reduces the required number of experimental tests for parameter calibration. Results of the model are compared with results of Mooney-Rivlin, Arruda-Boyce, Gent and Gao models as well as the experimental data

#### Hyperelastic materials behavior modeling using consistent strain energy density functions

, Article Acta Mechanica ; Volume 213, Issue 3-4 , 2010 , Pages 235-254 ; 00015970 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
Springer-Verlag Wien
2010

Abstract

Hyperelastic materials have high deformability and nonlinearity in load-deformation behavior. Based on a phenomenological approach, these materials are treated as a continuum, and a strain energy density is considered to describe their hyperelastic behavior. In this paper, the mechanical behavior characterization of these materials is studied from the continuum viewpoint. For this purpose, the strain energy density is expressed as sum of independent functions of the mutual multiple of principal stretches. These functions are determined by applying the governing postulates on the form of the strain energy density. It is observed that a consistent strain energy density is expressible in terms...

#### A Hierarchy of Plate Models Derived from Nonliinear Elasticity by T-Convergence

, M.Sc. Thesis Sharif University of Technology ; Bahraini, Alireza (Supervisor)
Abstract

In this thesis the elastic energy of plates is computed. Primarily, some physical related concepts such as stress, strain and strain energy density are defined. Then based on rigidity estimate theorem, the gradient map on bounded Lipschitz domains is approximated by a constant rotation map R.Thanks to this approximation theorem,we prove the precompactness of sequences of finite bending energy, and the limiting energy of two dimensional thin plates is shown to be an elastic energy. This limit innovation is called Γ –convergence introduced in 1993. It will indeed be revealed that the induced elastic energy of a deformable body is the limit of the sequence of stored energy of body under...

#### A visco-hyperelastic constitutive model for rubber-like materials: A rate-dependent relaxation time scheme

, Article International Journal of Engineering Science ; Volume 79, June , 2014 , Pages 44-58 ; ISSN: 00207225 ; Arghavani, J ; Naghdabadi, R ; Sohrabpour, S ; Sharif University of Technology
Abstract

A three-dimensional visco-hyperelastic constitutive model is developed to describe the rate-dependent behavior of rubber-like materials at large deformations. The model encompasses a hyperelastic part which uses the "Exp-Ln" strain energy function to characterize the equilibrium response and a viscous part capturing the rate sensitivity using a hereditary integral form which links the overstress to the history of stored strain energy. A physically consistent rate-dependent relaxation time scheme is introduced which reduces the number of required material parameters and also facilitates the calibration process. The proposed model is verified using various uniaxial experimental data in...

#### Modal-based damage identification for the nonlinear model of modern wind turbine blade

, Article Renewable Energy ; Volume 94 , 2016 , Pages 391-409 ; 09601481 (ISSN) ; Behzad, M ; Moradi, H ; Haddadpour, H ; Sharif University of Technology
Elsevier Ltd

Abstract

In this paper, the modal-based indices are used in damage identification of the wind turbine blade. In contrast of many of previous researches, the geometric nonlinearity due to the large structural deformation of the modern wind turbines blade is considered. In the first step, the finite element model (FEM) of the rotating blade is solved to obtain the modal features of the deformed structure under operational aerodynamic loading. Next, the accuracy and efficiency of the various modal-based damage indices including the frequency, mode shape, curvature of mode shape, modal assurance, modal strain energy (MSE) and the difference of indices (between the intact and damaged blades) are...

#### Damage detection of offshore jacket structures using frequency domain selective measurements

, Article Journal of Marine Science and Application ; Volume 12, Issue 2 , June , 2013 , Pages 193-199 ; 16719433 (ISSN) ; Golafshani, A. A ; Ghodrati, E ; Sharif University of Technology
2013

Abstract

The development of damage detection techniques for offshore jacket structures is vital to prevent catastrophic events. This paper applies a frequency response based method for the purpose of structural healthCgreater detection efficiency. In addition, the performance of the proposed method was evaluated in relation to multiple damages. The aforementioned points are illustrated using the numerical study of a two dimensional jacket platform, and the results proved to be satisfactory utilizing the proposed methodology

#### Energy pairs in the micropolar continuum

, Article International Journal of Solids and Structures ; Volume 44, Issue 14-15 , 2007 , Pages 4810-4818 ; 00207683 (ISSN) ; Naghdabadi, R ; Sharif University of Technology
2007

Abstract

In this paper, the concept of energy pairs in the micropolar continuum is introduced. A brief review of the micropolar continuum theory is presented for using in the subsequent derivations. A mathematical Lagrangian strain and a wryness tensor for the micropolar continuum are introduced. Using the first law of thermodynamics and for isothermal processes, the power of deformation is obtained and the energy pairs in the Eulerian and Lagrangian descriptions are defined. Also, the micropolar stress and couple stress tensors which are energy pairs to the micropolar Lagrangian strain and wryness measures are determined. © 2006 Elsevier Ltd. All rights reserved

#### Visco-hyperelastic constitutive law for modeling of foam's behavior

, Article Materials and Design ; Volume 32, Issue 5 , 2011 , Pages 2940-2948 ; 02641275 (ISSN) ; Alizadeh, Y ; Sharif University of Technology
2011

Abstract

This paper proposes a new visco-hyperelastic constitutive law for modeling the finite-deformation strain rate-dependent behavior of foams as compressible elastomers. The proposed model is based on a phenomenological Zener model, which consists of a hyperelastic equilibrium spring and a Maxwell element parallel to it. The hyperelastic equilibrium spring describes the steady state response. The Maxwell element, which captures the rate-dependency behavior, consists of a nonlinear viscous damper connected in series to a hyperelastic intermediate spring. The nonlinear damper controls the rate-dependency of the Maxwell element. Some strain energy potential functions are proposed for the two...

#### Constitutive modeling of rubberlike materials based on consistent strain energy density functions

, Article Polymer Engineering and Science ; Volume 50, Issue 5 , 2010 , Pages 1058-1066 ; 00323888 (ISSN) ; Naghdabadi, R ; Kargarnovin, M. H ; Sharif University of Technology
Abstract

Rubberlike materials are characterized by high deformability and reversibility of deformation. From the continuum viewpoint, a strain energy density function is postulated for modeling the behavior of these materials. In this paper, a general form for the strain energy density of these materials is proposed from a phenomenological point of view. Based on the Valanis-Landel hypothesis, the strain energy density of incompressible materials is expressed as the sum of independent functions of the principal stretches meeting the essential requirements on the form of the strain energy density. It is cleared that the appropriate mathematical expressions for constitutive modeling of these materials...

#### Hyperelastic materials modelling using a strain measure consistent with the strain energy postulates

, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 224, Issue 3 , 2010 , Pages 591-602 ; 09544062 (ISSN) ; Naghdabadi, R ; Kargarnovin, M. H ; Sharif University of Technology
Abstract

In this article, a strain energy density function of the Saint Venant-Kirchhoff type is expressed in terms of a Lagrangian deformation measure. Applying the governing postulates to the form of the strain energy density, the mathematical expression of this measure is determined. It is observed that this measure, which is consistent with the strain energy postulates, is a strain type with the characteristic function more rational than that of the Seth-Hill strain measures for hyperelastic materials modelling. In addition, the material parameters are calculated using a novel procedure that is based on the correlation between the values of the strain energy density (rather than the stresses)...

#### Predicting fracture of solder joints with different constraint factors

, Article Fatigue and Fracture of Engineering Materials and Structures ; 2018 ; 8756758X (ISSN) ; Mirmehdi, S ; Farrahi, G. H ; Soroush, F ; Sharif University of Technology
Blackwell Publishing Ltd
2018

Abstract

Double cantilever beam (DCB) specimens of 2.5-mm-long SAC305 solder joints were prepared with thickness of copper adherends varying from 8 to 21 mm each. The specimens were tested under mode I loading conditions (ie, pure opening mode with no shear component of loading) with a strain rate of 0.03 second−1. The measured fracture load was used to calculate the critical strain energy release rate for crack initiation, Jci, in each case. Fracture behaviour showed a significant dependence on the adherend thickness; the Jci and plastic deformation of the solder at crack initiation decreased significantly with increase in adherend thickness. This behaviour was attributed to changes in stress...

#### A hierarchical thermo-mechanical multi-scale technique for modeling of edge dislocations in nano-crystalline structures

, Article Computational Materials Science ; Volume 141 , 2018 , Pages 360-374 ; 09270256 (ISSN) ; Khoei, A. R ; Heidarzadeh, N ; Jafarian, N ; Sharif University of Technology
Elsevier B.V
2018

Abstract

In this paper, a hierarchical multi-scale technique is developed to investigate the thermo-mechanical behavior of nano-crystalline structures in the presence of edge dislocations. The primary edge dislocations are generated by proper adjustment of atomic positions to resemble discrete dislocations. The interatomic potential used to perform atomistic simulation is based on the Finnis-Sinclair embedded-atom method as many-body potential and, the Nose-Hoover thermostat is employed to control the effect of temperature. The strain energy density function is obtained for various representative volume elements under biaxial and shear loadings by fitting a fourth order polynomial in the atomistic...

#### Predicting fracture of solder joints with different constraint factors

, Article Fatigue and Fracture of Engineering Materials and Structures ; Volume 42, Issue 2 , 2019 , Pages 425-438 ; 8756758X (ISSN) ; Mirmehdi, S ; Farrahi, G ; Soroush, F ; Sharif University of Technology
Blackwell Publishing Ltd
2019

Abstract

Double cantilever beam (DCB) specimens of 2.5-mm-long SAC305 solder joints were prepared with thickness of copper adherends varying from 8 to 21 mm each. The specimens were tested under mode I loading conditions (ie, pure opening mode with no shear component of loading) with a strain rate of 0.03 second−1. The measured fracture load was used to calculate the critical strain energy release rate for crack initiation, Jci, in each case. Fracture behaviour showed a significant dependence on the adherend thickness; the Jci and plastic deformation of the solder at crack initiation decreased significantly with increase in adherend thickness. This behaviour was attributed to changes in stress...

#### Predicting crack initiation of solder joints with varying sizes under bending

, Article Journal of Electronic Materials ; 2019 ; 03615235 (ISSN) ; Farrahi, G. H ; Nourani, A ; Soroosh, F ; Sharif University of Technology
Springer New York LLC
2019

Abstract

The critical strain energy release rate for crack initiation, J ci , was measured under mode I loading for SAC305 solder joints between two copper substrates. Fracture tests were performed using double cantilever beam specimens at a strain rate of 0.03 s −1 . Different bond-line widths (i.e., joint size in the out-of-plane dimension) and thicknesses, were examined. The fracture force per unit width and J ci (the average value of four J-integral contours encircling the crack tip) were relatively insensitive to the width of the joint ranging from 8 mm to 21 mm. Variations in bond-line thickness (i.e., 150 μm, 250 μm and 450 μm) also had an insignificant influence on the fracture energy of...

#### Predicting crack initiation of solder joints with varying sizes under bending

, Article Journal of Electronic Materials ; 2019 ; 03615235 (ISSN) ; Farrahi, G. H ; Nourani, A ; Soroosh, F ; Sharif University of Technology
Springer New York LLC
2019

Abstract

The critical strain energy release rate for crack initiation, J ci , was measured under mode I loading for SAC305 solder joints between two copper substrates. Fracture tests were performed using double cantilever beam specimens at a strain rate of 0.03 s −1 . Different bond-line widths (i.e., joint size in the out-of-plane dimension) and thicknesses, were examined. The fracture force per unit width and J ci (the average value of four J-integral contours encircling the crack tip) were relatively insensitive to the width of the joint ranging from 8 mm to 21 mm. Variations in bond-line thickness (i.e., 150 μm, 250 μm and 450 μm) also had an insignificant influence on the fracture energy of...

#### A hierarchical hyperelastic-based approach for multi-scale analysis of defective nano-materials

, Article Mechanics of Materials ; Volume 140 , January , 2020 ; Ahmadi, H ; Khoei, A. R ; Sharif University of Technology
Elsevier B.V
2020

Abstract

In this paper, a continuum–atomistic multi-scale method is presented in modeling the nonlinear behavior of nano-materials under large deformation. In order to identify an appropriate strain energy function for crystalline nano-structures with different percentages of spherical voids, the hyperelastic method is employed for specimen whose behavior is determined based on the molecular dynamics analyses. In the atomistic level, the EAM many-body potential is employed to model the interactions between the atoms of Al RVEs. The atomistic strain energy density curves and surfaces are generated by applying the uniaxial, biaxial and simple shear deformations to the boundaries of RVEs. The material...

#### Modeling of visco-hyperelastic behavior of foams

, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 12 , 2009 , Pages 425-433 ; 9780791848739 (ISBN) ; Asghari, M ; Naghdabadi, R ; Sharif University of Technology
2009

Abstract

In this paper, a new visco-hyperelastic constitutive law for describing the rate dependent behavior of foams is proposed. The proposed model was based on a phenomenological Zener model: a hyperelastic equilibrium spring, which describes the steady-state, long-term response, parallel to a Maxwell element, which captures the rate-dependency. A nonlinear viscous damper connected in series to a hyperelastic intermediate spring, controls the rate-dependency of the Maxwell element. Therefore, the stress is the sum of equilibrium stress on the equilibrium spring and overstress on the intermediate spring. In hyperelastic theory stress is not calculated directly as in the case of small-strain, linear...

#### Consistent Strain Energy Functions for Transversely Isotropic and Orthotropic Hyperelastic Materials

, M.Sc. Thesis Sharif University of Technology ; Naghdabadi, Reza (Supervisor) ; Sohrabpour, Saeed (Supervisor) ; Arghavani, Jamal (Co-Advisor)
Abstract

Process Variation is seen as statistical variations in leakage current and delay of transistors in nano-scale technologies. The amount of process variations increase as the size of transistors decrease by technology scaling such that those effects can be seen in frequency of MPSoC (Multi-Processor System-on-Chip) cores and their leakage power deviation. These variations cause the tasks duration and power consumption fluctuate in different processors in an MPSoC instance. Consequently, some chip instances of the same MPSoC may consume more time and power than their considered limitations. Hence considering the process variation is necessary and required for MPSoC optimization at different...

#### Delamination Modeling In Composite Material Under The First Failure Mode

, M.Sc. Thesis Sharif University of Technology ; Hosseini Kordkheyli, Ali (Supervisor)
Abstract

In this research, delamination in compound laminated materials under the I mode loading is studied. In this way, a Double Cantilever Beam is investigated, which is the only experiment to study delamination in standard compound laminated materials. At first, a survey and comprehension of the failure of these materials is performed and the major mode of failure, which is named Delamination Mode is understood. Next, a survey on the possible methods of investigating the delamination phenomena is presented. In the next chapter, possible numerical methods are analysed, and the better performance of Cohesive Zone Model and Virtual Crack Closure Technique is studied. In this research, using the...