Study on Fractal Elastic Damage Constitutive Law for Concrete Material under Static Load

2011 ◽  
Vol 138-139 ◽  
pp. 1269-1273
Author(s):  
Ming Xie ◽  
Shan Suo Zheng
Keyword(s):  
Fracture Surface ◽  
Damage Mechanics ◽  
Constitutive Law ◽  
Uniaxial Test ◽  
Fractal Characteristic ◽  
Mechanics Model ◽  
Evolution Characteristics ◽  
Mesoscopic Level ◽  
Fractal Characteristics ◽  
Stochastic Properties

The stochastic properties and discreteness of macroscopic property for concrete appear on mechanical property and fracture surface. In consideration of stochastik and discreteness of fracture surface, a class of mesoscopic damage mechanics model of concrete based on spring model, are put forward to understand the real damage evolution characteristics of concrete at the level of constitutional law. A kind of spring-slipper model is introduced to reflect the elastic-plastic damage behavior. It has been confirmed that fracture surface of concrete has self-affine fractal characteristic only on a certain spatial scale, but the actual fracture surface of concrete is a stochastic surface with multi-fractal characteristics. Uniaxial test was operated, combined with the Computerized Tomography test of concrete, to study the evolution of crack surface from mesoscopic level to macroscopic level. Compared with the existing damage constitutive law and experimental results preliminarily, the feasibility of fractal damage constitutive law is verified.

Elastic-Plastic Fractal Damage Constitutive Law for Concrete

2011 ◽  
Vol 382 ◽  
pp. 348-351
Author(s):  
Ming Xie ◽  
Shan Suo Zheng
Keyword(s):  
Damage Mechanics ◽  
Crack Surface ◽  
Constitutive Law ◽  
Test Results ◽  
Uniaxial Test ◽  
Elastic Plastic ◽  
Mechanics Model ◽  
Plastic Damage ◽  
Evolution Characteristics ◽  
Mesoscopic Level

In consideration of stochastik and discreteness of fracture surface, a class of mesoscopic damage mechanics model of concrete based on spring model, are put forward to understand the real damage evolution characteristics of concrete at the level of constitutional law. A kind of spring-slipper model is introduced to reflect the elastic-plastic damage behavior. Uniaxial test was operated, combined with the Computerized Tomography test of concrete, to study the evolution of crack surface from mesoscopic level to macroscopic level. And the rationality of fractal damage constitutive law was verified with their theoretical calculation result and test results. Compared with the existing damage constitutive law and experimental results preliminarily, the feasibility of fractal damage constitutive law is verified.

Homogenization Based 3D Continuum Damage Mechanics Model for Composites Undergoing Microstructural Debonding

2008 ◽  
Vol 75 (3) ◽  
Author(s):  
Jayesh R. Jain ◽  
Somnath Ghosh
Keyword(s):  
Fourth Order ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Interfacial Debonding ◽  
Material Behavior ◽  
Constitutive Law ◽  
Continuum Damage ◽  
Loading History ◽  
Model Framework ◽  
Mechanics Model

This paper develops a microscopic homogenization based continuum damage mechanics (HCDM) model framework for fiber reinforced composites undergoing interfacial debonding. It is an advancement over the 2D HCDM model developed by Raghavan and Ghosh (2005, “A Continuum Damage Mechanics Model for Unidirectional Composites Undergoing Interfacial Debonding,” Mech. Mater., 37(9), pp. 955–979), which does not yield accurate results for nonproportional loading histories. The present paper overcomes this shortcoming through the introduction of a principal damage coordinate system (PDCS) in the HCDM representation, which evolves with loading history. The material behavior is represented as a continuum constitutive law involving a fourth order orthotropic tensor with stiffness characterized as a macroscopic internal variable. The current work also extends the model of Raghavan and Ghosh to incorporate damage in 3D composites through functional forms of the fourth order damage tensor in terms of macroscopic strain components. The model is calibrated by homogenizing the micromechanical response of the representative volume element (RVE) for a few strain histories. This parametric representation can significantly enhance the computational efficiency of the model by avoiding the cumbersome strain space interpolations. The proposed model is validated by comparing the CDM results with homogenized micromechanical response of single and multiple fiber RVEs subjected to arbitrary loading history.

Modelling the asymmetric tension–compression properties of additively manufactured alloys using continuum damage mechanics

2021 ◽  
pp. 146442072110134
Author(s):  
A Nayebi ◽  
H Rokhgireh ◽  
M Araghi ◽  
M Mohammadi
Keyword(s):  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Element Model ◽  
Continuum Damage ◽  
Compression Tests ◽  
Compression Properties ◽  
Mechanics Model ◽  
Stress Components ◽  
Tension And Compression ◽  
Closure Effect

Additively manufactured parts often comprise internal porosities due to the manufacturing process, which needs to be considered in modelling their mechanical behaviour. It was experimentally shown that additively manufactured parts’ tensile and compressive mechanical properties are different for various metallic alloys. In this study, isotropic continuum damage mechanics is used to model additively manufactured alloys’ tension and compression behaviours. Compressive stress components can shrink discontinuities present in additively manufactured alloys. Therefore, the crack closure effect was employed to describe different behaviours during uniaxial tension and compression tests. A finite element model embedded in an ABAQUS’s UMAT format was developed to account for the isotropic continuum damage mechanics model. The numerical results of tension and compression tests were compared with experimental observations for additively manufactured maraging steel, AlSi10Mg and Ti-6Al-4V. Stress–strain curves in tension and compression of these alloys were obtained using the continuum damage mechanics model and compared well with the experimental results.

Predicting the wear coefficient and friction coefficient in dry point contact using continuum damage mechanics

2018 ◽  
Vol 233 (3) ◽  
pp. 447-455 ◽  
Author(s):  
Sahar Ghatrehsamani ◽  
Saleh Akbarzadeh
Keyword(s):  
Friction Coefficient ◽  
Damage Mechanics ◽  
Point Contact ◽  
Continuum Damage Mechanics ◽  
Continuum Damage ◽  
Wear Coefficient ◽  
Mechanics Model ◽  
Pin On Disk ◽  
Disk Test ◽  
The Continuum

Wear coefficient and friction coefficient are two of the key parameters in the performance of any tribo-system. The main purpose of the present research is to use continuum damage mechanics to predict wear coefficient. Thus, a contact model is utilized that can be used to obtain the friction coefficient between the contacting surfaces. By applying this model to the continuum damage mechanics model, the wear coefficient between dry surfaces is predicted. One of the advantages of using this model is that the wear coefficient can be numerically predicted unlike other methods which highly rely on experimental data. In order to verify the results predicted by this model, tests were performed using pin-on-disk test rig for several ST37 samples. The results indicated that the wear coefficient increases with increasing the friction coefficient.

scholarly journals Development of Back-calculation Model for Aggregate Gradation Determination Using Fractal Theory

2018 ◽  
Vol 159 ◽  
pp. 01006
Author(s):  
Bagus Hario Setiadji ◽  
Supriyono ◽  
Djoko Purwanto
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Asphalt Mixture ◽  
Fractal Dimensions ◽  
Calculation Model ◽  
Careful Consideration ◽  
Upper And Lower Bounds ◽  
Aggregate Gradation ◽  
Fractal Characteristic ◽  
Fractal Characteristics

Several studies have shown that fractal theory can be used to analyze the morphology of aggregate materials in designing the gradation. However, the question arises whether a fractal dimension can actually represent a single aggregate gradation. This study, which is a part of a grand research to determine aggregate gradation based on known asphalt mixture specifications, is performed to clarify the aforementioned question. To do so, two steps of methodology were proposed in this study, that is, step 1 is to determine the fractal characteristics using 3 aggregate gradations (i.e. gradations near upper and lower bounds, and middle gradation); and step 2 is to back-calculate aggregate gradation based on fractal characteristics obtained using 2 scenarios, one-and multi-fractal dimension scenarios. The results of this study indicate that the multi-fractal dimension scenario provides a better prediction of aggregate gradation due to the ability of this scenario to better represent the shape of the original aggregate gradation. However, careful consideration must be observed when using more than two fractal dimensions in predicting aggregate gradation as it will increase the difficulty in developing the fractal characteristic equations.

A Damage Mechanics Model for Creep and Oxygen Embrittlement in Metals

2005 ◽  
Vol 14 (2) ◽  
pp. 101-126 ◽  
Author(s):  
Xiaomin Deng ◽  
Fashang Ma ◽  
Michael A. Sutton
Keyword(s):  
Damage Mechanics ◽  
Mechanics Model

A controlled fractal interpolation method based on random midpoint displacement for coastline

GEOMATICA ◽  
2017 ◽  
Vol 71 (2) ◽  
pp. 89-99
Author(s):  
Baode Jiang ◽  
Dongqi Wei ◽  
Zhong Xie ◽  
Zhanlong Chen
Keyword(s):  
Spatial Data ◽  
Interpolation Method ◽  
Fractal Interpolation ◽  
Quality Requirements ◽  
One Dimensional ◽  
Fractal Characteristic ◽  
Fractal Interpolation Function ◽  
Proper Order ◽  
Fractal Characteristics ◽  
Original Scale

Coastline has different geographical bending characteristics in different coastal geomorphic regions. The existing fractal interpolation methods for coastline mostly focus on how to simulate its fractal characteristic but neglect the geographical bending characteristic. This study presents an improved controlled fractal inter polation method based on one-dimensional Random Midpoint Displacement (RMD) that aims to preserve both the bending characteristics and fractal characteristics of coastline. First, the coastline is divided into sev eral parts based on its bending characteristics, in order to conserve the geographical bending struc ture of the coastline and change the uncontrollable general fractal interpolation into a combination of sev er al piece-wise interpolation units. Second, the fractal interpolation function of one-dimensional RMD is used for each divided bending unit of the coastline, and the parameters of RMD function are restricted by the con straints of each unit bending characteristics. Third, the results of fractal interpolation of each unit are linked together in proper order to obtain the approximate coastline. The experiments show that this method can maintain the geographical bending characteristics and fractal characteristics of coastline, and when the ratio of target scale to the original scale is not more than 3 times, the accuracy of interpolation spatial coor di nates can meet the quality requirements of spatial data.

Stochastic Continuum Damage Mechanics Using Spring Lattice Models

2015 ◽  
Vol 784 ◽  
pp. 350-357 ◽  
Author(s):  
Sohan Kale ◽  
Seid Koric ◽  
Martin Ostoja-Starzewski
Keyword(s):  
Damage Mechanics ◽  
Lattice Models ◽  
Continuum Damage Mechanics ◽  
Constitutive Law ◽  
Disordered Media ◽  
Length Scale ◽  
Continuum Damage ◽  
Perfectly Plastic ◽  
Discrete Nature ◽  
Plastic Responses

In this study, a planar spring lattice model is used to study the evolution of damage variabledLin disordered media. An elastoplastic softening damage constitutive law is implemented which introduces a cohesive length scale in addition to the disorder-induced one. The cohesive length scale affects the macroscopic response of the lattice with the limiting cases of perfectly brittle and perfectly plastic responses. The cohesive length scale is shown to affect the strength-size scaling such that the strength increases with increasing cohesive length scale for a given size. The formation and interaction of the microcracks is easily captured by the inherent discrete nature of the model and governs the evolution ofdL. The proposed method provides a way to extract a mesoscale dependent damage evolution rule that is linked directly to the microstructural disorder.

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