Interface Transition Zone and the Elastic Modulus of Cement-Based Composites

1994 ◽  
Vol 370 ◽  
Author(s):  
Peter I. Simeonov ◽  
S.H. Ahmad
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Transition Zone ◽  
Material Properties ◽  
General Trend ◽  
Two Phase ◽  
Interface Transition Zone ◽  
The Matrix ◽  
Approach Zero ◽  
Highly Porous

AbstractThe influence of the Interface Transition Zone (ITZ) on the elastic modulus of concrete is demonstrated as a divergence of the experimental data from the general trend of the theoretical Hashin-Shtrikman bounds. This divergence is well related to the W/C of the composite. With reduction of W/C the influence of ITZ decreases and for values close to 0.4 and lower it is insignificant.The formation of the ITZ is characterized by a transfer of water from the matrix to the surface of the aggregates. As a result of this a highly porous ITZ is formed while the matrix remains with a reduced porosity. This process can also be described as a transfer of material properties. For some compositions the balance of this transfer can approach zero. The imbalance in this process is more pronounced at higher W/C.The effect of Interface Transition Zone can be successfully simulated by the help of recently derived Hashin's variational bounds for two-phase composites with imperfect interfaces.

scholarly journals Comparison Between Biphasic and Triphasic Model for Predicting the Elastic Modulus of Concrete

2018 ◽  
Vol 203 ◽  
pp. 06003
Author(s):  
Fatima Aouissi ◽  
Chung-Chia Yang ◽  
Abdelamalek Brahma ◽  
Omar Zorkane
Keyword(s):  
Composite Material ◽  
Elastic Modulus ◽  
Transition Zone ◽  
Predictive Models ◽  
Complex Structures ◽  
Biphasic Model ◽  
Interface Transition Zone ◽  
The Matrix ◽  
Combined Models ◽  
Voigt Model

The concrete is a composite material which, on the scale of the microstructure, can be considered as consisting of three phases: the matrix, the inclusions and the interface transition zone. The latter has features that reduce the properties of concrete and therefore limits its performance. Thus, with such complex structures, this zone is the weakest zone of the composite. The evaluation of the effective behavior of composite using predictive models requires a consideration of this zone. In this context an approach based on the model of double inclusion and on the Mori Tanaka theory to predict the elastic modulus of concrete are used. This approach will be compared with some analytical biphasic model such as Reuss model, Voigt model, the Voigt and Reus combined models and Hashin and Shtrikman (HδS) models. Many experimental results are considered in the confrontation. So the model developed predicts very satisfactorily the elastic modulus of the concrete unlike other models in which a discrepancy in the results is demonstrated in the majority of cases.

Simulation of sub-micron indentation tests with spherical and Berkovich indenters

2001 ◽  
Vol 16 (7) ◽  
pp. 2149-2157 ◽  
Author(s):  
A. C. Fischer-Cripps
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Material Properties ◽  
Indentation Testing ◽  
Depth Sensing ◽  
Displacement Response ◽  
Analysis Methods ◽  
Detailed Treatment ◽  
Indentation Tests ◽  
Load Displacement

The present work is concerned with the methods of simulation of data obtained from depth-sensing submicron indentation testing. Details of analysis methods for both spherical and Berkovich indenters using multiple or single unload points are presented followed by a detailed treatment of a method for simulating an experimental load–displacement response where the material properties such as elastic modulus and hardness are given as inputs. A comparison between simulated and experimental data is given.

Study on the Effects of the Nonhomogeneous Material Properties on the Structure Strength of the Induction Quenched Crankshaft

2014 ◽  
Vol 703 ◽  
pp. 400-405
Author(s):  
Ji Shan Li ◽  
Ri Dong Liao ◽  
Guo Hua Chen
Keyword(s):  
Elastic Modulus ◽  
Material Properties ◽  
Fem Model ◽  
Explosion Pressure ◽  
Nonhomogeneous Material ◽  
Linear Rule ◽  
Distribution Rule ◽  
The Matrix ◽  
Nonhomogeneous Properties ◽  
Structure Strength

To study the effects of the nonhomogeneous material properties on the stress in an induction quenched crankshaft, the FEM model considering the nonhomogeneous material properties was established to simulate the stress in the crankshaft under the explosion pressure. Results showed that the nonhomogeneous properties almost didn’t vary the Mises stress distribution rule in the crankshaft. The maximum Mises stress, the ratio of the elastic modulus of the surface layer and the matrix followed a linear rule nearly. Moreover, the maximum Mises stress increased with the ratio. Besides, effect of elastic modulus distribution in the transition layer on the maximum stress could be ignored. To simplify the establishment of the FEM model, the elastic modulus could be set to either equal to the surface layer’s or the matrix’s.

The Concrete Fracture Performance Response to the Interface Transition Zone Parameters Based on Mesoscopic Simulation

2012 ◽  
Vol 170-173 ◽  
pp. 3482-3486 ◽  
Author(s):  
Min Du ◽  
Liu Jin ◽  
Xiu Li Du ◽  
Yan Zhao
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Elastic Modulus ◽  
Fracture Energy ◽  
Transition Zone ◽  
Failure Process ◽  
Aggregate Model ◽  
Fracture Modes ◽  
Random Aggregate ◽  
Interface Transition Zone

The interface transition zone (ITZ) has a significant impact on the concrete’s mechanical properties and fracture modes. For the influence of ITZ’s strength and elastic modulus, the extended finite element method (XFEM) is adopted to simulate the mesostructure failure process by virtue of random aggregate model under uniaxial tension. The results show that ITZ’s strength and elastic modulus have a certain effect on the mechanical properties and fracture modes. With the tensile strength of ITZ increasing, the fractured modes transit from single coalescent crack to multiple non-coalescent cracks and the fracture energy increases, the ductility of concrete is enhanced. With the elastic modulus of ITZ increasing, the concrete’s elastic modulus increases, the tensile strength and the fracture energy decrease.

scholarly journals The Effect of Cooling Rate on Properties of Intermetallic Phase in a Complex Al-Si Alloy

2016 ◽  
Vol 16 (3) ◽  
pp. 125-128 ◽  
Author(s):  
M. Tupaj ◽  
A.W. Orłowicz ◽  
M. Mróz ◽  
A. Trytek ◽  
O. Markowska
Keyword(s):  
Elastic Modulus ◽  
Cooling Rate ◽  
Material Properties ◽  
Intermetallic Phase ◽  
Indentation Hardness ◽  
Instrumented Indentation ◽  
Silicon Alloy ◽  
The Matrix ◽  
Crystallisation Process ◽  
Technological Options

Abstract The cooling rate is one of the main tools available to the process engineer by means of which it is possible to influence the crystallisation process. Imposing a desired microstructure on a casting as early as in the casting solidification phase widens significantly the scope of technological options at disposal in the process of aluminium-silicon alloy parts design and application. By changing the cooling rate it is possible to influence the course of the crystallisation process and thus also the material properties of individual microstructure components. In the study reported in this paper it has been found that the increase of cooling rate within the range of solidification temperatures of a complex aluminium-silicon alloy resulted in a decrease of values of the instrumented indentation hardness (HIT) and the instrumented indentation elastic modulus (EIT) characterising the intermetallic phase occurring in the form of polygons, rich in aluminium, iron, silicon, manganese, and chromium, containing also copper, nickel, and vanadium. Increased cooling rate resulted in supersaturation of the matrix with alloying elements.

An elastic-plastic indentation model and its solutions

1996 ◽  
Vol 11 (9) ◽  
pp. 2358-2367 ◽  
Author(s):  
Weiping Yu ◽  
James P. Blanchard
Keyword(s):  
Experimental Data ◽  
Mechanical Properties ◽  
Elastic Modulus ◽  
Yield Stress ◽  
Material Properties ◽  
Hardness Test ◽  
Plastic Materials ◽  
Indentation Tests ◽  
Plastic Indentation ◽  
Comparison With Experimental Data

An analytical model of hardness has been developed. Four major indentation tests, namely indentation by cones, wedges, spheres, and flat-ended, axisymmetric cylinders have been analyzed based on the model. Analytical relationships among hardness, yield stress, elastic modulus, Poisson's ratio, and indenter geometries have been found. These results enable hardness to be calculated in terms of uniaxial material properties and indenter geometries for a wide variety of elastic and plastic materials. These relationships can also be used for evaluating other mechanical properties through hardness measurements and for converting hardness from one type of hardness test into those of a different test. Comparison with experimental data and numerical calculations is excellent.

Five-Phase Sphere Model for Elastic Modulus of FRP-Confined Concrete

2012 ◽  
Vol 204-208 ◽  
pp. 3707-3711
Author(s):  
Ming Hui Liu ◽  
Yuan Feng Wang ◽  
Han Liang Wu
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Transition Zone ◽  
Volume Fraction ◽  
Aggregate Size ◽  
Interfacial Transition Zone ◽  
Confined Concrete ◽  
Sphere Model ◽  
Frp Sheet

Based on the four-phase sphere model, a five-phase sphere model predicting the elastic modulus of FRP-confined concrete was built up, by considering the effect of FRP sheet. The model can describe the elastic modulus of the FRP, the stirrup ratio, the aggregate volume fraction, the aggregate size and the interfacial transition zone (ITZ), et al. on the development of the elastic modulus of FRP-confined concrete with age. By comparing with the experimental data, the five-phase sphere model evaluates the tests well

Transition alpha structure in beta-isomorphous Nb-Hf alloys

1987 ◽  
Vol 45 ◽  
pp. 232-233
Author(s):  
R.W. Carpenter ◽  
Changhai Li ◽  
David J. Smith
Keyword(s):  
Solid Solution ◽  
Solution Phase ◽  
Miscibility Gap ◽  
Large Strains ◽  
Solid Solution Phase ◽  
Two Phase ◽  
Diffuse Intensity ◽  
Metastable Form ◽  
The Matrix ◽  
Equilibrium Morphology

Binary Nb-Hf alloys exhibit a wide bcc solid solution phase field at temperatures above the Hfα→ß transition (2023K) and a two phase bcc+hcp field at lower temperatures. The β solvus exhibits a small slope above about 1500K, suggesting the possible existence of a miscibility gap. An earlier investigation showed that two morphological forms of precipitate occur during the bcc→hcp transformation. The equilibrium morphology is rod-type with axes along <113> bcc. The crystallographic habit of the rod precipitate follows the Burgers relations: {110}||{0001}, <112> || <1010>. The earlier metastable form, transition α, occurs as thin discs with {100} habit. The {100} discs induce large strains in the matrix. Selected area diffraction examination of regions ∼2 microns in diameter containing many disc precipitates showed that, a diffuse intensity distribution whose symmetry resembled the distribution of equilibrium α Bragg spots was associated with the disc precipitate.

Using crystallographic symmetry in diffraction and contrast analysis

1989 ◽  
Vol 47 ◽  
pp. 504-505
Author(s):  
U. Dahmen ◽  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
High Symmetry ◽  
Two Phase ◽  
Tem Analysis ◽  
Crystallographic Symmetry ◽  
The Matrix ◽  
Contrast Analysis ◽  
Practical Tool ◽  
Convergent Beam ◽  
Beam Diffraction

Despite the increased use of convergent beam diffraction, symmetry concepts in their more general form are not commonly applied as a practical tool in electron microscopy. Crystal symmetry provides an abundance of information that can be used to facilitate and improve the TEM analysis of crystalline solids. This paper draws attention to some aspects of symmetry that can be put to practical use in the analysis of structures and morphologies of two-phase materials.It has been shown that the symmetry of the matrix that relates different variants of a precipitate can be used to determine the axis of needle- or lath-shaped precipitates or the habit plane of plate-shaped precipitates. By tilting to a special high symmetry orientation of the matrix and by measuring angles between symmetry-related variants of the precipitate it is possible to find their habit from a single micrograph.

Effect Of Elevated Temperatures On Complete Concrete Deformation Diagrams

2019 ◽  
pp. 9-14
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Elevated Temperatures ◽  
Peak Load ◽  
Relative Deformation ◽  
Deformation Characteristics ◽  
Compression Tests ◽  
Strain Behavior ◽  
Different Temperatures ◽  
Deformation Diagrams

The analysis of the previous results of the study on concrete stress-strain behavior at elevated temperatures has been carried out. Based on the analysis, the main reasons for strength retrogression and elastic modulus reduction of concrete have been identified. Despite a significant amount of research in this area, there is a large spread in experimental data received, both as a result of compression and tension. In addition, the deformation characteristics of concrete are insufficiently studied: the coefficient of transverse deformation, the limiting relative compression deformation corresponding to the peak load and the almost complete absence of studies of complete deformation diagrams at elevated temperatures. The two testing chambers provided creating the necessary temperature conditions for conducting studies under bending compression and tension have been developed. On the basis of the obtained experimental data of physical and mechanical characteristics of concrete at different temperatures under conditions of axial compression and tensile bending, conclusions about the nature of changes in strength and deformation characteristics have been drawn. Compression tests conducted following the method of concrete deformation complete curves provided obtaining diagrams not only at normal temperature, but also at elevated temperature. Based on the experimental results, dependences of changes in prism strength and elastic modulus as well as an equation for determining the relative deformation and stresses at elevated temperatures at all stages of concrete deterioration have been suggested.

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