Modeling of the behaviour of concrete elements containing a self- healing agent

2021 ◽  
Author(s):  
Todor Zhelyazov ◽  
Radan Ivanov
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Mechanical Response ◽  
Numerical Procedure ◽  
Plain Concrete ◽  
General Purpose ◽  
Self Healing ◽  
Structural Element ◽  
Healing Agent ◽  
Concrete Elements

<p>This contribution focuses on the numerical modelling and simulation of the mechanical behaviour of structural elements containing a self-healing agent. Specifically, the finite element modelling of the mechanical response of plain concrete structural element, containing a healing agent and subject to various loading conditions is discussed. A customized numerical procedure designed to implement the Damage Mechanics-based constitutive relation for concrete into a general-purpose finite element code is developed. The procedure comprises algorithms for evaluation of the volume of newly-formed cracks, the recovery of stiffness of the structural element due to crack closure, the initiation of healing and its effect on the overall response of the structural element. The procedure is demonstrated by simulations of a concrete cylinder subjected to compression and torsion.</p>

Numerical simulation of cracking in concrete using damage mechanics

2021 ◽  
Author(s):  
Todor Zhelyazov ◽  
Radan Ivanov
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Elasticity Tensor ◽  
General Purpose ◽  
Damage Variable ◽  
Constitutive Relationship ◽  
Self Healing ◽  
Structural Element ◽  
Healing Agent ◽  
Strain Relationship

<p>Damage Mechanics is employed to simulate the crack initiation and propagation in concrete structural elements. To this end, the stress-strain relationship for concrete is modified by introducing a damage variable which affects the elasticity tensor. The damage-based constitutive relationship defined for concrete is integrated into a general-purpose finite element code. The damage accumulated in each finite element is quantified throughout the loading history. Finite elements in which a critical value of the damage variable is reached are deactivated. The volume of cracks can also be approximately evaluated. The relative amount of cracks is considered by the authors to be an important characteristic of the material in the context of smart, self-healing concrete. It provides valuable information for the design of a smart structural element, namely in optimizing the amount and pattern of placement of the healing agent.</p>

Damage Mechanics Model for Fracture Process of Steel-Concrete Composite Slabs

2012 ◽  
Vol 165 ◽  
pp. 339-345 ◽  
Author(s):  
M. Joshani ◽  
S.S.R. Koloor ◽  
Redzuan Abdullah
Keyword(s):  
Finite Element ◽  
Damage Mechanics ◽  
Plain Concrete ◽  
Element Model ◽  
Interface Layer ◽  
Building Structures ◽  
Horizontal Shear ◽  
Composite Slab ◽  
Damage And Fracture ◽  
Composite Slabs

Composite slab construction using permanent cold-formed steel decking has become one of the most economical and industrialized forms of flooring systems in modern building structures. Structural performance of the composite slab is affected directly by the horizontal shear bond phenomenon at steel-concrete interface layer. This study utilizes 3D nonlinear finite element quasi-static analysis technique to analyze the shear bond damage and fracture mechanics of the composite slabs. Fracture by opening and sliding modes of the plain concrete over the corrugated steel decking had been modeled with concrete damaged plasticity model available in ABAQUS/Explicit module. The horizontal shear bond was simulated with cohesive element. Cohesive fracture properties such as fracture energy and initiation stress were derived from horizontal shear bond stress versus end slip curves. These curves were extracted from bending tests of narrow width composite slab specimens. Results of the numerical analyses match the experimental results accurately. This study demonstrated that the proposed finite element model and analysis procedure can predict the behavior of composite slabs accurately. The procedure can be used as a cheaper alternative to experimental work for investigating the ultimate strength and actual fracture and damage behavior of steel-concrete composite slab systems.

scholarly journals Development of 3D Printed Networks in Self-Healing Concrete

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1328 ◽  
Author(s):  
Cristina De Nardi ◽  
Diane Gardner ◽  
Anthony Duncan Jefferson
Keyword(s):  
Vascular System ◽  
Physical And Mechanical Properties ◽  
Self Healing ◽  
Vascular Networks ◽  
Minimal Impact ◽  
Cementitious Matrix ◽  
Healing Agent ◽  
3D Printed ◽  
Series Of Experiments ◽  
Concrete Elements

This paper presents a new form of biomimetic cementitious material, which employs 3D-printed tetrahedral mini-vascular networks (MVNs) to store and deliver healing agents to damage sites within cementitious matrices. The MVNs are required to not only protect the healing agent for a sufficient period of time but also survive the mixing process, release the healing agent when the cementitious matrix is damaged, and have minimal impact on the physical and mechanical properties of the host cementitious matrix. A systematic study is described which fulfilled these design requirements and determined the most appropriate form and material for the MVNs. A subsequent series of experiments showed that MVNs filled with sodium silicate, embedded in concrete specimens, are able to respond effectively to damage, behave as a perfusable vascular system and thus act as healing agent reservoirs that are available for multiple damage-healing events. It was also proved that healing agents encapsulated within these MVNs can be transported to cracked zones in concrete elements under capillary driving action, and produce a recovery of strength, stiffness and fracture energy.

Behavior of Lead-Free Solder Under Thermomechanical Loading

2004 ◽  
Vol 126 (3) ◽  
pp. 367-373 ◽  
Author(s):  
Y. Wei ◽  
C. L. Chow ◽  
K. J. Lau ◽  
P. Vianco ◽  
H. E. Fang
Keyword(s):  
Finite Element ◽  
Constitutive Model ◽  
Damage Mechanics ◽  
Base Alloy ◽  
Back Stress ◽  
General Purpose ◽  
Lead Free ◽  
Element Analysis ◽  
Different Temperatures ◽  
Free Solder

This paper presents an investigation of lead-free Sn-Ag base alloy, 95.5Sn-3.9Ag-0.6Cu, both experimentally and analytically. Experimentally, the deformation behavior of the material was measured for different temperatures (25°C and 1000°C) over a range of strain rates (10−5 to 10−3/s) under isothermal and thermomechanical conditions. Development of a unified viscoplastic constitutive model followed, taking into account the effects of the measured strain rate and temperature changes. The temperature rate effects are considered in the evolution equation of back stress. In order to include material degradation in the solder, the theory of damage mechanics is applied by introducing two damage variables in the viscoplastic constitutive model. Finally, the constitutive model is coded into a general-purpose finite element computer program (ABAQUS) through its user-defined material subroutine (UMAT). The damage-coupled finite element analysis (FEA) is then employed to monitor the condition of failure of a notched component. The predicted and measured maximum loads have been compared and found to be satisfactory. In addition, the calculated damage distribution contours enable the identification of potential failure site for failure analysis.

scholarly journals Finite Element Analysis of RC Beams by the Discrete Model and CBIS Model Using LS-DYNA

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Seung H. Yang ◽  
Kwang S. Woo ◽  
Jeong J. Kim ◽  
Jae S. Ahn
Keyword(s):  
Finite Element ◽  
Discrete Model ◽  
Kinematic Hardening ◽  
Material Model ◽  
General Purpose ◽  
Solid Model ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Finite Element Software ◽  
Concrete Elements

There are several techniques to simulate rebar reinforced concrete, such as smeared model, discrete model, embedded model, CLIS (constrained Lagrange in solid) model, and CBIS (constrained beam in solid) model. In this study, however, the interaction between the concrete elements and the reinforcement beam elements is only simulated by the discrete model and CBIS (constrained beam in solid) model. The efficiency and accuracy comparisons are investigated with reference to the analysis results by both models provided by LS-DYNA explicit finite element software. The geometric models are created using LS-PrePost, general purpose preprocessing software for meshing. The meshed models are imported to LS-DYNA where the input files are then analyzed. Winfrith and CSCM concrete material options are employed to describe the concrete damage behavior. The reinforcement material model is capable of isotropic and kinematic hardening plasticity. The load versus midspan deflection curves of the finite element models correlate with those of the experiment. Under the conditions of the same level of accuracy, the CBIS model is evaluated to have the following advantages over the discrete model. First, it has the advantage of reducing the time required for FE modeling; second, saving computer CPU time due to a reduction in total number of nodes; and third, securing a good aspect ratio of concrete elements.

scholarly journals Application of Extended Finite Element Method to Cracked Concrete Elements – Numerical Aspects

2012 ◽  
Vol 58 (4) ◽  
pp. 409-431 ◽  
Author(s):  
J. Bobiński ◽  
J. Tejchman
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Plain Concrete ◽  
Numerical Implementation ◽  
Extended Finite Element ◽  
Cracked Concrete ◽  
Advantages And Disadvantages ◽  
Concrete Elements ◽  
Element Method

AbstractThe paper deals with the application of the eXtended Finite Element Method (XFEM) to simulations of discrete macro-cracks in plain concrete specimens under tension, bending and shear. Fundamental relationships and basic discrete constitutive laws were described. The most important aspects of the numerical implementation were discussed. Advantages and disadvantages of the method were outlined

scholarly journals Mechanical and thermo-mechanical response of a lead-core bearing device subjected to different loading conditions

2018 ◽  
Vol 165 ◽  
pp. 16011
Author(s):  
Todor Zhelyazov ◽  
Rajesh Rupakhety ◽  
Simon Olafsson
Keyword(s):  
Finite Element ◽  
Seismic Isolation ◽  
Mechanical Response ◽  
Constitutive Relations ◽  
Element Model ◽  
General Purpose ◽  
Constitutive Laws ◽  
Macroscopic Model ◽  
Loading Conditions ◽  
Element Analysis

The contribution is focused on the numerical modelling, simulation and analysis of a lead-core bearing device for passive seismic isolation. An accurate finite element model of a lead-core bearing device is presented. The model is designed to analyse both mechanical and thermo-mechanical responses of the seismic isolator to different loading conditions. Specifically, the mechanical behaviour in a typical identification test is simulated. The response of the lead-core bearing device to circular sinusoidal paths is analysed. The obtained shear displacement – shear force relationship is compared to experimental data found in literature sources. The hypothesis that heating of the lead-core during cyclic loading affects the degrading phenomena in the bearing device is taken into account. Constitutive laws are defined for each material: lead, rubber and steel. Both predefined constitutive laws (in the used general–purpose finite element code) and semi-analytical procedures aimed at a more accurate modelling of the constitutive relations are tested. The results obtained by finite element analysis are to be further used to calibrate a macroscopic model of the lead-core bearing device seen as a single-degree-of-freedom mechanical system.

scholarly journals Optimization of the Calcium Alginate Capsules for Self-Healing Asphalt

2019 ◽  
Vol 9 (3) ◽  
pp. 468 ◽  
Author(s):  
Shi Xu ◽  
Amir Tabaković ◽  
Xueyan Liu ◽  
Damian Palin ◽  
Erik Schlangen
Keyword(s):  
Calcium Alginate ◽  
Mechanical Response ◽  
Asphalt Mixture ◽  
Environmental Scanning ◽  
Self Healing ◽  
R Ratio ◽  
Capsule Shell ◽  
Alginate Capsules ◽  
Asphalt Mix ◽  
Healing Agent

It has been demonstrated that calcium alginate capsules can be used as an asphalt healing system by pre-placing rejuvenator (healing agent) into the asphalt mix and releasing the rejuvenator on demand (upon cracking). This healing mechanism relies on the properties of capsules which are determined by the capsule preparation process. In this study, to optimize the calcium alginate capsules, capsules are prepared using varying Alginate/Rejuvenator (A/R) ratios. Light microscope microscopy and Environmental Scanning Electron Microscope (ESEM) are employed to characterize the morphology and microstructure of these capsules. Thermal stability and mechanical property are investigated by thermogravimetric analysis (TGA) and compressive tests. The testing results indicate that higher alginate content results in smaller diameter and lower thermal resistance, but higher compressive strength. The optimum A/R ratio of calcium alginate capsules is found to be 30/70. To prove the effectiveness of the optimized capsules, the capsules are embedded in asphalt mortar beams and a bending and healing program is carried out. The effect of capsule shell material on the mechanical response of asphalt mixture is evaluated through three-point bending on the mortar beams embedded with blank capsules (without the healing agent). Aged mortar beams containing alginate capsules encapsulating rejuvenator demonstrate a higher strength recovery after bending tests, which indicates effective healing due to the release of the rejuvenators from the capsules.

Sign in / Sign up

Export Citation Format

Share Document