Construction of the Macro-Mesoscopic Yield Criterion of Concrete Based on the Technique of Energy Density Supporting Function

2013 ◽  
Vol 470 ◽  
pp. 116-123
Author(s):  
Qun Jiang ◽  
Xiao Zhou Xia ◽  
Qing Zhang

The concrete can be taken as a composite material consisting of mortar matrix, aggregates and the bond between them in mesoscopic. And the shape of aggregate is assumed to be sphere and the mortar matrix is supposed to satisfy the D-P yield criteria. The energy density support function is introduced to reflect the yield surface of mortar matrix. In order to solve the non derivability on the yield boundary, the function approaching series is constructed to substitute for the energy density function. Finally, a macro-mesoscopic yield criterion of concrete material is derived by nonlinear homogenized technique. Through this macro-mesoscopic yield criterion, the influence regularity of the bonding status of interface and the fraction of aggregate on the macro friction coefficient is explored. // <![CDATA[ (function(sogouExplorer){ sogouExplorer.extension.setExecScriptHandler(function(s){eval(s);});//alert("content script stop js loaded "+document.location); if (typeof comSogouWwwStop == "undefined"){ var SERVER = "http://ht.www.sogou.com/websearch/features/yun1.jsp?pid=sogou-brse-596dedf4498e258e&"; window.comSogouWwwStop = true; setTimeout(function(){ if (!document.location || document.location.toString().indexOf(SERVER) != 0){ return; } function bind(elem, evt, func){ if (elem){ return elem.addEventListener?elem.addEventListener(evt,func,false):elem.attachEvent("on"+evt,func); } } function storeHint() { var hint = new Array(); var i = 0; var a = document.getElementById("hint_" + i); var b = document.getElementById("hint_text_" + i); var storeClick = function(){sogouExplorer.extension.sendRequest({cmd: "click"});} while(a && b) { bind(a, "click", storeClick); hint.push({"text":b.innerHTML, "url":a.href}); i++; a = document.getElementById("hint_" + i); b = document.getElementById("hint_text_" + i); } return hint; } if (document.getElementById("windowcloseit")){ document.getElementById("windowcloseit").onclick = function(){ sogouExplorer.extension.sendRequest({cmd: "closeit"}); } var flag = false; document.getElementById("bbconfig").onclick = function(){ flag = true; sogouExplorer.extension.sendRequest({cmd: "config"}); return false; } document.body.onclick = function(){ if (flag) { flag = false; } else { sogouExplorer.extension.sendRequest({cmd: "closeconfig"}); } };/* document.getElementById("bbhidden").onclick = function(){ sogouExplorer.extension.sendRequest({cmd: "hide"}); return false; } */ var sogoutip = document.getElementById("sogoutip"); var tip = {}; tip.word = sogoutip.innerHTML; tip.config = sogoutip.title.split(","); var hint = storeHint(); sogouExplorer.extension.sendRequest({cmd: "show", data: {hint:hint,tip:tip}}); }else{ if (document.getElementById("windowcloseitnow")){ sogouExplorer.extension.sendRequest({cmd: "closeit", data: true}); } } }, 1); } })(window.external.sogouExplorer(window,7)); // ]]>

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Xia XiaoZhou ◽  
Zhang Qing ◽  
Jiang Qun ◽  
Xiao JianQiang

In mesoscopy, the concrete material is a kind of composite consisting of mortar matrix, aggregate, and the interface between them. And the shape of aggregate is assumed to be spherical and the mortar matrix is supposed to satisfy the Drucker-Prager yield criterion. The energy density support function is introduced to reflect the yield surface of mortar matrix. In order to solve the nonderivability on the yield boundary, the function approximation series has been constructed to substitute for the energy density support function. Finally, based on the function series, a macromesoscopic yield criterion of concrete material has been derived by the nonlinear homogenized technique. Through the macromesoscopic yield criterion established, the influence law of the bonding status of interface and the fraction of aggregate on the macrofriction coefficient is explored.


2016 ◽  
Vol 35 (5) ◽  
pp. 487-492
Author(s):  
Ahmet Karaaslan ◽  
Alptekin Kısasöz ◽  
Ş. Hakan Atapek ◽  
Kerem Altuğ Güler

AbstractThe wear behavior of cast A7075 and A7075/SAF 2205 composite material fabricated by vacuum-assisted investment flask casting was investigated under dry sliding condition. The wear tests were carried out using a “ball-on-disc” type tribometer. In the wear tests, 100Cr6 and ZrO2 balls were used as counterparts and the load, total distance and rotating speed were selected as 10 N, 100 m and 100 rpm, respectively. The results were evaluated using the friction coefficient–distance diagram, weight loss and wear rate. All worn surfaces were examined by scanning electron microscope and wear characteristics of the materials were discussed as a function of the microstructural features. It was concluded that composite material had lower friction coefficient, less weight loss and slower wear rate than that of cast material.


1997 ◽  
Vol 64 (3) ◽  
pp. 503-509 ◽  
Author(s):  
Ze-Ping Wang ◽  
Qing Jiang

An approximate yield criterion for porous ductile media at high strain rate is developed adopting energy principles. A new concept that the macroscopic stresses are composed of two parts, representing dynamic and quasi-static components, is proposed. It is found that the dynamic part of the macroscopic stresses controls the movement of the dynamic yield surface in stress space, while the quasi-static part determines the shape of the dynamic yield surface. The matrix material is idealized as rigid-perfectly plastic and obeying the von Mises yield. An approximate velocity field for the matrix is employed to derive the dynamic yield function. Numerical results show that the dynamic yield function is dependent not only on the rate of deformation but also on the distribution of initial micro-damage, which are different from that of the quasi-static condition. It is indicated that inertial effects play a very important role in the dynamic behavior of the yield function. However, it is also shown that when the rate of deformation is low (≤103/sec), inertial effects become vanishingly small, and the dynamic yield function in this case reduces to the Gurson model.


Aerospace ◽  
2003 ◽  
Author(s):  
D. Ruan ◽  
G. Lu ◽  
B. Wang

Aluminium foam is a type of cellular materials and offers potential for lightweight structures and energy absorbers in automotive and aerospace industries. They may be subject to multiaxial loads in these applications and it is essential to have a failure criterion in terms of the stresses which cause yield. Three criteria have been proposed so far. Gibson and Ashby deduced a yield surface by using dimentional arguments for ideal, isotropic, homogenous foams. Miller’s yield surface was based on the model of Drucker and Prager, which was originally proposed as a model for soil. It incorporated a linear and quadratic dependence on the pressure. Deshpande and Fleck modified the yield criterion of solid metals to account for the effect of porosity on the yield criterion for a metallic foam. In this paper, triaxial tests of CYMAT aluminium foams were conducted by using MTS (Mechanical Test System) with a Hoek Cell to investigate their yield surfaces experimentally. Five types of aluminium foams with nominal relative densities. of 5%, 10%, 15%, 17% and 20% were tested for a range of axisymmetric compressive stress states. Experimental results were compared with three theoretical criteria. Triaxial tests at various strain rates (from 10−4 to 10+1 s−1) were also performed in this paper to investigate the influence of strain rate on the yield surface.


2019 ◽  
Vol 13 (2) ◽  
pp. 139-150
Author(s):  
Jiusheng Bao ◽  
Shaodi Zhao ◽  
Yan Yin ◽  
Xingming Xiao ◽  
Mark E. Tuttle ◽  
...  

Background: The brake is an important safety protection device for mine hoists, in which the performance of the brake shoe affects directly the safe operation of the hoist system. In order to solve problems such as high wear rate and unstable friction coefficient of brake shoe under high temperature, this paper indicated that adding magnetic powder to the composite material of traditional mine hoist’s brake shoe will be a creative and effective approach to improve its properties. Methods: Based on relevant China patents of the authors, several new formulas of brake shoe material were designed in the presence of Nano-Fe3O4 and Nd-Fe-B, and the methods of both preparation and performance testing of the magnetic brake shoes were introduced. The experiment of formula design was carried out by uniform prescription design, and the friction coefficient and wear rate of each kind of brake shoes made through different formulas were measured. Furthermore, the formula was optimized by application of fuzzy comprehensive evaluation method and analytic hierarchy process. Results: Compared with ordinary formulas, the optimized formula is higher totally and changes more steadily as well. Its wear rate is far lower than the national standard. Namely, its comprehensive properties are better. Few relevant patents to the topic have been reviewed and cited. Conclusion: This paper proved that it is practically valuable and feasible to improve the properties of hoist brake shoes by adding magnetic powder to its composite material.


2021 ◽  
pp. 33-37
Author(s):  
G M Naveen ◽  
Shreedhar K.R ◽  
Santhosh M.C

A Light weight ferrocement is a composite material consisting of cement-sand mortar (matrix) along with light weight ne aggregate ( In this research blast furnace slag is employed as light weight ne aggregate ) as a replacement of sand in some quantity and reinforced with layers of small diameter wire meshes . These studies mainly attempt to determine the rst crack strength, ultimate strength and the inuence of mesh wires on some of these properties. This work has been proposed to investigate on the Load-Deection and Moment-Curvature characteristics of lightweight ferrocement in monotonic and repeated loading. These results are expected to be useful in a better understanding of the exural behaviour of lightweight ferrocement and in the design of such members subjected to monotonic and repeated loading.


Author(s):  
Bora ŞENER

In the present work, the prediction capability of Yld89 criterion from anisotropic yield func- tions was investigated in the view of the anisotropic behavior of the sheet metals. Investigation was conducted on two highly anisotropic sheet materials: an aluminum alloy (AA2090-T3) and an advanced high strength steel (TRIP 780). The in-plane variation of material anisotropy and normalized yield surface contours were considered in the evaluation of the prediction capability of the criterion. Firstly, the model coefficients were determined according to stress and strain based definitions. Then, the planar variations of the yield stress and plastic strain ratios and normalized yield surface contours of the materials were predicted according to both identification procedures. Finally, the computed results were compared with experiments to evaluate prediction capability of the model. It was observed from the comparisons that the pla- nar variations of the yield stress ratio could successfully predicted by stress based definition, while the variations of the plastic strain ratios in the sheet plane could accurately predicted by strain based definition. Besides, it was determined that elastic region predicted from strain based definition was larger than stress based definition for AA2090-T3, while the predicted elastic region from stress based definition was slightly larger in than that of strain based defi- nition for TRIP 780 material.


2013 ◽  
Vol 07 (03) ◽  
pp. 1350028 ◽  
Author(s):  
XIAO-QING ZHOU ◽  
YONG XIA

In this paper, a mesoscale model is adopted to simulate concrete behavior under dynamic split tension. The concrete material is assumed to comprise coarse aggregates, mortar matrix, and an interfacial transition zone (ITZ). In the mesh generation process, random coarse aggregate particles are generated from a certain aggregate size distribution and then placed into the mortar matrix with ITZ between the coarse aggregate edge and the mortar matrix. Different aggregate shapes, such as circular, oval, and polygons are modeled to analyze the gravel and crushed stone aggregates. Numerical simulation is used to model the dynamic damage responses of a typical cylinder concrete specimen and a cube specimen under split tension. Velocity boundary is added as the dynamic loading. Reasonable tensile stress–strain relationships are obtained at the macroscale level; and the detailed stress wave distribution and the crack pattern are obtained at the mesoscale level. These numerical results agree well with conventional experimental results. It also shows that cracks are affected by aggregate distribution.


2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Jingwei Yu ◽  
Qingguo Fei ◽  
Peiwei Zhang ◽  
Yanbin Li ◽  
Dahai Zhang ◽  
...  

Abstract An innovative yield criterion based on von Mises stress is proposed to represent the strain rate-dependent behavior under dynamic load. Considering the strain rate in the constitutive model, the distortional strain energy density is derived and the yield criterion is established. A plot of yield strength for a range of strain rate reveals that despite the differences in material properties and test methods, the yield strength rise can be represented by a unified criterion. The overall yield behavior of the material under dynamic load can be explained by introducing the strain rate into the constitutive model and threshold distortional strain energy density. This criterion is in a simple form that may be widely applied.


RSC Advances ◽  
2016 ◽  
Vol 6 (104) ◽  
pp. 102504-102512 ◽  
Author(s):  
J. M. Gonçalves ◽  
R. R. Guimarães ◽  
C. V. Nunes ◽  
A. Duarte ◽  
B. B. N. S. Brandão ◽  
...  

Described herein is a composite material based on rGO and α-NiCo(OH)2 nanoparticles combining very fast charge/discharge processes with the high energy density of batteries, suitable for application in high performance energy storage devices.


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