On the Modeling of Fibers Embedding in Aluminum Using Ultrasonic Consolidation

2017 ◽  
Vol 139 (3) ◽  
Author(s):  
Abba A. Abubakar ◽  
Shafique M. A. Khan ◽  
Samir Mekid
Keyword(s):  
Fiber Optics ◽  
Structural Model ◽  
Damage Model ◽  
Mechanical Analysis ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Ultrasonic Consolidation ◽  
Sic Fiber ◽  
Real Material ◽  
Extent Of Damage

Ultrasonic consolidation of fiber optics in metals is of major importance allowing surface embedding and protecting the fibers from exposure to open environment. The paper investigates the computational modeling of this process of embedding fibers at the aluminum subsurface. This new method provides an opportunity to develop sensory materials (Mekid et al., 2015, “Towards Sensor Array Materials: Can Failure be Delayed?” Sci. Technol. Adv. Mater., 16(3), p. 034607) and new types of nervous materials (Mekid and Kwon, 2009, “Nervous Materials: A New Approach for Better Control, Reliability and Safety of Structures,” Sci. Adv. Mater., 1(3), pp. 276–285) for structural health monitoring applications. A thermo-mechanical analysis of embedding SiC fiber in aluminum substrate has been conducted. The temperature distribution was obtained using a thermal model with process-dependent heat flux at the sonotrode/foil interface, which is coupled to the structural model in an iterative manner for simulating fiber embedment. The structural model uses a process-dependent plastic flow rule with an isotropic hardening model. A ductile damage model is employed for the first time in simulating such problems in addition to the use of real material properties of the fiber, which has resulted in better numerical results. Both of these factors help in determining the extent of damage particularly to the fiber/sensor being embedded. The experimental test has shown good agreement.

Micromechanics-Based Elastoplastic and Damage Modeling of Particle Reinforced Composites

Materials ◽  
2004 ◽  
Author(s):  
H. T. Liu ◽  
Lizhi Sun ◽  
J. W. Ju
Keyword(s):  
Damage Model ◽  
Local Stress ◽  
Damage Mechanism ◽  
Elastic Stiffness ◽  
Interfacial Debonding ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Elastoplastic Behavior ◽  
Micromechanical Damage ◽  
The Matrix

A micromechanical damage model is proposed to predict the effective elastoplastic behavior of ductile composites containing randomly dispersed particles. The interfacial debonding between particles and the matrix is considered as the primary micromechanical damage mechanism. The debonded isotropic elastic reinforcements are replaced by equivalent anisotropic elastic inclusions. The interfacial debonding process is simulated by three-dimensional debonding angles. After the local stress field in the matrix is calculated, the homogenization averaging procedure is employed to estimate the effective elastic stiffness and yield function of the composites. The associative plastic flow rule and the isotropic hardening law are postulated based on the continuum plasticity theory. As applications, the overall elastoplastic and damage constitutive behavior of the composites under various loading conditions is numerically simulated and compared with available experimental results.

scholarly journals Identification of Sudden Stiffness Change in the Acceleration Response of a Nonlinear Hysteretic Structure

2020 ◽  
Vol 2020 ◽  
pp. 1-20
Author(s):  
Sheng-Lan Ma ◽  
Shao-Fei Jiang ◽  
Chen Wu ◽  
Si-Yao Wu
Keyword(s):  
Structural Model ◽  
Dynamic Responses ◽  
Physical Parameters ◽  
Discrete Wavelet ◽  
Time Varying ◽  
Ground Acceleration ◽  
Structural Dynamic ◽  
Filter Tuning ◽  
Structural Responses ◽  
Extent Of Damage

The integration of discrete wavelet transform and independent component analysis (DWT-ICA) method can directly identify time-varying changes in linear structures. However, better metrics of structural seismic damage and future performance after an event are related to structural permanent and total plastic deformations. This study proposes a two-stage technique based on DWT-FastICA and improved multiparticle swarm coevolution optimization (IMPSCO) using a baseline nonlinear Bouc–Wen structural model to directly identify changes in stiffness caused by damage as well as plastic or permanent deflections. In the first stage, the measured structural dynamic responses are preprocessed firstly by DWT, and then the Fast ICA is used to extract the feature components that contain the damage information for the purpose of initially locating damage. In the second stage, the structural responses are divided at the identified damage instant into segments that are used to identify the time-varying physical parameters by using the IMPSCO, and the location and extent of damage can accordingly be identified accurately. The efficiency of the proposed method in identifying stiffness changes is assessed under different ground motions using a suite of two different ground acceleration records. Meanwhile, the effect of noise level and damage extent on the proposed method is also analyzed. The results show that in a realistic scenario with fixed filter tuning parameters, the proposed approach identifies stiffness changes within 1.25% of true stiffness within 8.96 s; therefore, it can work in real time. Parameters are identified within 14% of the actual as-modeled value using noisy simulation-derived structural responses. This indicates that, in accordance with different demands, the proposed method can not only locate and quantify damage within a short time with a high precision but also has excellent noise tolerance, robustness, and practicality.

scholarly journals A New 3D Empirical Plastic and Damage Model for Simulating the Failure of Concrete Structure

2019 ◽  
Vol 13 (1) ◽  
Author(s):  
Yan-tao Jiao ◽  
Bo Wang ◽  
Zhen-zhong Shen
Keyword(s):  
Damage Mechanics ◽  
Evolution Equations ◽  
Influence Factor ◽  
Yield Criterion ◽  
Kinematic Hardening ◽  
Damage Model ◽  
Nonlinear Behavior ◽  
Complex Stress State ◽  
Flow Rule ◽  
Wide Range

Abstract A new plastic–damage constitutive model based on the combination of damage mechanics and classical plastic theory was developed to simulate the failure of concrete. In order to explain different material behaviors of concrete under tensile and compressive loadings, the plastic yield criterion, the different kinematic hardening rule for tension and compressive and the isotropic flow rule were established in the effective stress space. Meanwhile, two different empirical damage evolution equations were adopted: one for compression and the other for tension. A multi-axial damage influence factor was also introduced to fully describe the anisotropic damage of concrete. Finally, the model response was compared with a wide range of experiment results. The results showed that the model could well describe the nonlinear behavior of concrete in a complex stress state.

Deriving Plastic Constitutive Equations of the Material in Complex Stress State by Means of Simple Test Results

2011 ◽  
Vol 109 ◽  
pp. 100-104 ◽  
Author(s):  
Xiao Jiu Feng ◽  
Li Fu Liang
Keyword(s):  
Stress State ◽  
Constitutive Equations ◽  
Complex Stress ◽  
Complex Stress State ◽  
One Dimension ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Test Results ◽  
Loading Function ◽  
Simple Tension

By conducting simple tension and torsion tests to material, constitutive equations of one dimension are obtained. Plastic theories of continuum mechanics are used for analyzing deformation behavior of the material after yielding. Here, material is presumed to have isotropic hardening characteristic. By using Mises loading function and the associative flow rule, the derivations are made to extend the constitutive equations of one dimension in the simple tension and torsion tests to that of multi-dimension and obtain the plastic constitutive equations of the material in complex stress state , respectively.

Significance of Lu¨der’s Plateau on Pipeline Fault Crossing Assessment

2010 ◽  
Author(s):  
Lanre Odina ◽  
Robert J. Conder
Keyword(s):  
Finite Element ◽  
Compressive Strain ◽  
Strain Curve ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Pipe Material ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Integrity Assessment ◽  
Analytical Approaches

When subjected to permanent ground deformations, buried pipelines may fail by local buckling (wrinkling under compression) or by tensile rupture. The initial assessment of the effects of predicted seismic fault movements on the buried pipeline is performed using analytical approaches by Newmark-Hall and Kennedy et al, which is restricted to cases when the pipeline is put into tension. Further analysis is then undertaken using finite element methods to assess the elasto-plastic response of the pipeline response to the fault movements, particularly the compressive strain limits. The finite element model is set up to account for the geometric and material non-linear parameters. The pipe material behaviour is generally assumed to have a smooth strain hardening (roundhouse) post-yield behaviour and defined using the Ramberg-Osgood stressstrain curve definition with the plasticity modelled using incremental theory with a von Mises yield surface, associated flow rule and isotropic hardening. However, material tests on seamless pipes (X-grade) show that the stress-strain curve typically displays a Lu¨der’s plateau behaviour (yield point elongation) in the post-yield state. The Lu¨der’s plateau curve is considered conservative for pipeline design and could have a significant impact on strain-based integrity assessment. This paper compares the pipeline response from a roundhouse stress-strain curve with that obtained from a pipe material exhibiting Lu¨der’s plateau behaviour and also examines the implications of a Lu¨der’s plateau for pipeline structural integrity assessments.

Theoretical and Numerical Predictions of Burst Pressure of Pipelines

2007 ◽  
Vol 129 (4) ◽  
pp. 644-652 ◽  
Author(s):  
Xian-Kui Zhu ◽  
Brian N. Leis
Keyword(s):  
Equivalent Stress ◽  
Failure Criteria ◽  
Burst Pressure ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Strain Criterion ◽  
Stress Criterion ◽  
Numerical Predictions ◽  
Yield Theory ◽  
Von Mises

To accurately characterize plastic yield behavior of metals in multiaxial stress states, a new yield theory, i.e., the average shear stress yield (ASSY) theory, is proposed in reference to the classical Tresca and von Mises yield theories for isotropic hardening materials. Based on the ASSY theory, a theoretical solution for predicting the burst pressure of pipelines is obtained as a function of pipe diameter, wall thickness, material hardening exponent, and ultimate tensile strength. This solution is then validated by experimental data for various pipeline steels. According to the ASSY yield theory, four failure criteria are developed for predicting the burst pressure of pipes by the use of commercial finite element softwares such as ABAQUS and ANSYS, where the von Mises yield theory and the associated flow rule are adopted as the classical metal plasticity model for isotropic hardening materials. These failure criteria include the von Mises equivalent stress criterion, the maximum principal stress criterion, the von Mises equivalent strain criterion, and the maximum tensile strain criterion. Applications demonstrate that the proposed failure criteria in conjunction with the ABAQUS or ANSYS numerical analysis can effectively predict the burst pressure of end-capped line pipes.

Ductile Fracture Modeling of DH36 Grade Steels

2018 ◽  
Author(s):  
Burak Can Cerik ◽  
Sung-Ju Park ◽  
Joonmo Choung
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Fracture Surface ◽  
Ductile Fracture ◽  
Stress Triaxiality ◽  
Local Stress ◽  
Fracture Initiation ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Element Analysis

A Hosford-Coulomb type ductile fracture surface was developed for DH36 grade steels. The fracture experiments reported in the literature, which consist of tests with notched tensile specimens, tensile specimens with a central hole, shear specimen and disc specimens for punch specimens, were utilized in a detailed finite element analysis of each experiment to evaluate the evolution of local stress and strain fields and identify plasticity and fracture response of DH36. The developed plasticity model consists of a von Mises yield surface, an associated flow rule and a combined Swift-Voce type isotropic hardening rule. The loading paths to fracture initiation were determined in terms of stress triaxiality and normalized Lode angle parameter histories. Finally, the Hosford-Coulomb fracture surface was calibrated using the finite element analysis results and adapting a linear damage accumulation law.

Coupling Analysis between Stress Induced Anisotropic Damage and Permeability Variation in Brittle Rocks

2007 ◽  
Vol 340-341 ◽  
pp. 1133-1138 ◽  
Author(s):  
Hui Zhou ◽  
Jian Fu Shao ◽  
Xia Ting Feng ◽  
Da Wei Hu
Keyword(s):  
Damage Model ◽  
Coupling Model ◽  
Mechanical Analysis ◽  
Effective Porosity ◽  
Anisotropic Damage ◽  
Permeability Evolution ◽  
Coupling Analysis ◽  
Brittle Rocks ◽  
Permeability Variation ◽  
Set Up

In this paper, a coupling constitutive model is proposed for anisotropic damage and permeability variation in brittle rocks before cracks fully coalesce. In this coupling model, an anisotropic damage model is employed to perform the mechanical analysis, and a statistical penetration model is set up to describe the effective porosity and permeability evolution in brittle rocks. For the coupling analysis, anisotropic damage model offers statistical penetration model the crack length in various directions, and statistical penetration model inversely provides anisotropic damage model with permeability of rock for coupling hydro-mechanical analysis. The proposed coupling model is applied to Lac du Bonnet granite, and generally a good agreement is obtained between numerical simulations and experimental data.

Quasi-statically growing crack tip fields in plastically compressible hardening-softening-hardening solid

2018 ◽  
Vol 9 (4) ◽  
pp. 532-547 ◽  
Author(s):  
Sushant Singh ◽  
Debashis Khan
Keyword(s):  
Constitutive Relation ◽  
Numerical Study ◽  
Crack Tip ◽  
Small Scale ◽  
Isotropic Hardening ◽  
Flow Rule ◽  
Hardening Material ◽  
Static Mode ◽  
Content Type ◽  
Crack Tip Fields

Purpose As the normality concept for frictional dilatant material has a serious drawback, the key feature in this numerical study is that the material here is characterized by elastic-viscoplastic constitutive relation with plastic non-normality effect for two different hardness functions. The paper aims to discuss this issue. Design/methodology/approach Quasi-static, mode I plane strain crack tip fields have been investigated for a plastically compressible isotropic hardening–softening–hardening material under small-scale yielding conditions. Finite deformation, finite element calculations are carried out in front of the crack with a blunt notch. For comparison purpose a few results of a hardening material are also provided. Findings The present numerical calculations show that crack tip deformation and the field quantities near the tip significantly depend on the combination of plastic compressibility and slope of the hardness function. Furthermore, the consideration of plastic non-normality flow rule makes the crack tip deformation as well as the field quantities significantly different as compared to those results when the constitutive equation exhibits plastic normality. Originality/value To the best of the authors’ knowledge, analyses, related to the constitutive relation exhibiting plastic non-normality in the context of plastic compressibility and softening (or softening hardening) on the near tip fields, are not explored in the literature.

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