Thermo-Mechanical Multiscale Modeling in Plasticity of Metals Using Small Strain Theory

2017 ◽  
Vol 34 (5) ◽  
pp. 579-589 ◽  
Author(s):  
N. Munjas ◽  
M. Čanađija ◽  
J. Brnić
Keyword(s):  
Local Level ◽  
Numerical Procedure ◽  
Strain Analysis ◽  
Numerical Differentiation ◽  
Small Strain ◽  
Forward Difference ◽  
Macro Scale ◽  
Isothermal Analysis ◽  
Standard Approximation ◽  
Fully Coupled

AbstractA numerical coupled thermoplasticity multiscale procedure for small strain analysis is developed in the finite element environment. It is suitable for simulation of thermo-mechanical behavior and overall response of metallic materials, using standard approximation method based on the concept of representative volume element (RVE). The local level isothermal analysis that models the micro-scale, is fully coupled to the global level non-isothermal analysis. The global macro-scale tangent stiffness operator is obtained using numerical differentiation procedure using the forward difference scheme. The numerical procedure is developed for two-dimensional problems, using Abaqus user-defined subroutines. Applicability of the proposed framework is presented on several representative examples.

Effect of Large Deformation Analysis for Site Investigation Tool - CPT in Layered Soils

2020 ◽  
Author(s):  
Qiang Xie ◽  
Yuxia Hu ◽  
Mark J. Cassidy
Keyword(s):  
Large Deformation ◽  
Strain Analysis ◽  
Small Strain ◽  
Deformation Analysis ◽  
Large Strains ◽  
Embedment Depth ◽  
Sand Layer ◽  
Clay Layer ◽  
Layered Soils ◽  
Soil Response

Abstract Cone penetration test (CPT) is regularly used during offshore site investigations to interpret soil stratification and soil characteristics due to its continuous penetration resistance profile. However, its use could be improved if better numerical methods to simulate its penetration could be developed. Finite element (FE) analysis, for instance, has the potential to provide insightful information on soil response and soil flow mechanisms. However, it is challenging to simulate CPT in layered soils, as the soil experiences extremely large strains around the cone and the simulation costs are high. In this study, the efficiency of using a partial large deformation FE (LDFE) approach was explored to examine the pre-embedment depth allowed for saving LDFE analysis cost. The LDFE analysis was conducted using the remeshing and interpolation technical with small strain (RITSS) method to model the large strain problem. Both soft-stiff-soft clays and clay-sand-clay soil were considered to study the thin stiff layer effect when it was sandwiched in soft clay. The LDFE/RITSS analysis compared a CPT penetrating from the soil surface with penetrations from a pre-embedded depth above the stiff layer. Pre-embedded small strain analysis was also conducted for comparison. The results show that the small strain analysis underestimated the resistance in both clay and sand. For the partial LDFE analysis with pre-embedment in the top clay layer, the CPT response in the middle stiff clay layer could be well captured regardless of the initial pre-embedment depth. However, for the middle medium dense sand layer (ID = 60%), the pre-embedment depth needs to have sufficient distance above it (10D, D is cone diameter) to capture the soil response in the sand layer correctly.

Analysis of Angular Velocities and Accelerations in Plane Linkages by Means of Numerical Procedure

1983 ◽  
Vol 105 (4) ◽  
pp. 624-630
Author(s):  
A. Di Benedetto ◽  
E. Pennestri´
Keyword(s):  
Numerical Method ◽  
Kinematic Analysis ◽  
Numerical Procedure ◽  
Numerical Differentiation ◽  
Mathematical Induction ◽  
Technical Literature ◽  
Numerical Example ◽  
Angular Velocities

Briefly recalling some of the latest procedures of kinematic analysis that technical literature records, a numerical method is proposed for approximate calculus of angular velocities and accelerations in plane mechanisms. The algorithm is obtained by mathematical induction through Newton’s formulae for repeating integrations and it consists of a four points formula of numerical differentiation which is also easily programmable on automatic computers. A numerical example illustrated below shows the degree of reliability of the method proposed.

A Novel Method of Residual Strain Analysis Via a Non-Bonded Interface Technique in Combination With the Circular Grid Analysis Method

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Brandon Gorman ◽  
Zoheir Farhat ◽  
Andrew Warkentin
Keyword(s):  
Residual Strain ◽  
Strain Analysis ◽  
Homogeneous Material ◽  
Fe Model ◽  
Experimental Sample ◽  
Indentation Force ◽  
Bonded Interface ◽  
Macro Scale ◽  
Von Mises ◽  
Circular Grid

Abstract A novel non-bonded interface technique (NBIT) is used to analyze internal residual strain by combining a pre-split sample of AISI 4340 steel with the circular grid residual strain analysis technique. NBIT is compared with an implicit non-linear finite element (FE) model using LS-DYNA. A split FE model was compared with a quarter FE model to determine the split interface that causes an average difference of 9.0% on the residual von Mises strain field from a 588.6 N indentation. The homogeneous FE quarter model was then compared with the experimental split model using 588.6, 981.0, and 1471.5 N indentation forces. An average displacement difference of 3.92 µm was found when comparing the experimental split and FE homogeneous samples from a 588.6 N indentation. The internal residual major and minor principal strains from the split experimental sample and homogeneous FE model were compared for each indentation force. The minor principal strain results show the 588.6, 981.0, and 1471.5 N indentation forces resulted in a difference between the experimental split and homogeneous FE model of 28.5%, 34.8%, and 26.0%, respectively. The difference between the comparisons was explained by the inability of the FE model to simulate local non-homogeneous material properties such as grain composition and orientation whereas NBIT does. NBIT can be used for micro- or macro-scale residual strain analysis as the spatial resolution is highly adjustable.

Very Large Deformation but Small Strain Analysis of Plates and Folded Plates by Finite Strip Method

2005 ◽  
Vol 8 (6) ◽  
pp. 547-560 ◽  
Author(s):  
A. R. Shahidi ◽  
M. Mahzoon ◽  
M. M. Saadatpour ◽  
M. Azhari
Keyword(s):  
Large Deformations ◽  
Virtual Work ◽  
Strain Analysis ◽  
Small Strain ◽  
Linear Mapping ◽  
Thin Plates ◽  
Computational Domain ◽  
Finite Strip ◽  
Strip Method ◽  
Finite Strip Method

In this paper a Finite strip method is developed to analyze very large deformations of thin plates and folded plates by use of the elastic Cosserat theory. The principle of virtual work is exploited to present the weak form of the governing differential equations. Through a linear mapping, a rectangular strip is transformed into a standard square computational domain in which the deformation and director fields are developed together with the general forms of the uncoupled nonlinear equations. The geometric and material tangential stiffness matrices are formed through linearization, and a step by step procedure is presented to complete the scheme. The validity and the accuracy of the method are illustrated through certain numerical examples and comparison of the results with other researches. The method is shown to be capable of handling numerical analysis of plates experiencing very large deformations.

Numerical Simulation of the Installation and Extraction Process of Spudcan Foundations in Clay

2009 ◽  
Author(s):  
Jun Liu ◽  
Yuxia Hu
Keyword(s):  
Plastic Material ◽  
Yield Criterion ◽  
Strain Analysis ◽  
Small Strain ◽  
Extraction Process ◽  
Interface Roughness ◽  
Large Displacement ◽  
Centrifuge Model Test ◽  
Element Analysis ◽  
Perfectly Plastic

This paper presents results from large displacement finite element analysis for spudcan foundation penetrating into and extracting from normally consolidated (NC) clay. The soil was idealized as an elastic-perfectly plastic material obeying a Mohr-Coulomb yield criterion and the large displacement analysis was carried out using Remeshing and Interpolating Technique with Small Strain (RITSS) model to simulate the full installation and extraction process. The numerical results were compared with centrifuge model test data and existing analytical solutions. A full parametric study was undertaken to quantify the influence on spudcan extraction process from soil strength profile, foundation interface roughness and penetration depth. The extraction results showed that the normalized uplift resistance after spudcan installation was much lower than that from small strain analysis, and it was also lower than that of pre-embedded case. Thus it is necessary to apply RITSS method in spudcan extraction simulation after installation.

Steady-State Response Evaluation of Shape Memory Alloy Wire Under Resistive Heating Using a Newly Developed Element-Free Galerkin Meshless Method

2006 ◽  
Author(s):  
A. Ghazavi ◽  
H. A. Sepiani ◽  
F. Ebrahimi ◽  
A. Rastgo
Keyword(s):  
Shape Memory ◽  
Meshless Method ◽  
Resistive Heating ◽  
State Response ◽  
Element Free Galerkin ◽  
Extended Application ◽  
Macro Scale ◽  
Element Free ◽  
Fully Coupled ◽  
Good Agreement

The studies on shape memory alloys show their much extended application field. Nowadays, many researches are carried out to solve constitutive equations of various models of SMAs. In this research, a macro-scale, phenomenological constitutive model for SMAs is used in conjunction with energy balance equations to study the evolution of temperature and deformation profiles seen in SMA wires under specific thermal and mechanical boundary conditions. In this way, the general fully-coupled thermomechanical formula for resistive heating of an SMA wire-initial detwined martensite leads to strain recovery on heating is used and numerical results are obtained with use of “Meshless” method. Comparisons have been made between the results predicted by proposed EFG method and available reference solutions in the literature, generated either analytically or numerically. A good agreement is obtained between the achieved results and the literature.

scholarly journals Strain measurements with fibre Bragg grating sensors under inhomogeneous deformations

2021 ◽  
Vol 3 (1) ◽  
pp. 50-59
Author(s):  
Susann Hannusch ◽  
Edgar Peretzki ◽  
Katharina Schich ◽  
Thomas Lehmann ◽  
Jörn Ihlemann
Keyword(s):  
Strain Gradient ◽  
Strain Analysis ◽  
Small Strain ◽  
Bending Test ◽  
Hole Drilling ◽  
Bragg Grating ◽  
Fibre Bragg Grating ◽  
Peak Splitting ◽  
Hole Drilling Method ◽  
Fbg Sensors

Bragg grating sensors are fibre optic sensors for strain and temperature investigations with many advantages: the sensors can be embedded in plastic materials or composites and several gratings can be inscribed in one sensor. However, inhomogeneous deformation or transversal loading cause widening and splitting of the reflected wavelength peak of a fibre Bragg grating (FBG) sensor. These effects are shown in a residual stress analysis, in which the hole drilling method is adapted for FBG sensors. Additionally, a four-point bending test on three different notched aluminium beams is used to investigate the widening and splitting of the reflected peaks and their effects on the strain analysis. At each sample, a reference strain gauge sensor and two FBG sensors are applied. The two FBG sensors are loaded with different strain gradients. The unnotched beam and the beam with small strain gradient show the accuracy and reproducibility of the experiment. The beam with medium strain gradient shows no peak splitting, but the widening does influence the strain analysis. The results of the beam with high strain gradient demonstrate the peak splitting and the failure of the strain analysis methods. Initial approaches on how to deal with this widening and splitting are discussed.

scholarly journals Small and Medium Sizes Enterprises (SMEs) and Foreign Trade Policy

2015 ◽  
Author(s):  
İlkay Noyan Yalman ◽  
Mutlu Türkoğlu ◽  
Yalçın Yalman
Keyword(s):  
Foreign Trade ◽  
Trade Policy ◽  
Raw Materials ◽  
Local Level ◽  
Trade Policies ◽  
Foreign Trade Policy ◽  
Foreign Earnings ◽  
Macro Scale ◽  
Trade Potential ◽  
High Level

A high level of a country’s foreign trade is related to the growth of foreign earnings, to the acceleration of investments, to increase employment and contributes significantly to the growth of the country's economy. In this context, SMEs as one of the mile stones of the economy, foreign trade and economic growth are located in the leading roles. Especially SMEs sufficiently developed oppressed against strong opponents abroad, government policies or practices in trade restrictive policies are some of the reasons for this downside. SMEs that exports goods, or the infrastructure needed to produce goods for SMEs who import raw materials as well as the country's foreign trade policies and developments in the world economy is important. SMEs to follow the development, recognizing competitors, new markets, new products is very important in terms of growth both business and the countries. In this study, SMEs engaged in foreign trade in Sivas Province performing an application on in terms of both the business and government policy at the local level status will be examined. Data will be obtained on issues such as ultimately foreign trade potential of existing SMEs while doing foreign trade problems they face, strengths and weaknesses, market policies at national and international levels, the opinions about the state's foreign trade policy. The results obtained from the data on SMEs engaged in foreign trade by making general inferences about the data obtained on a micro scale, will allow making inferences on the macro scale.

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