scholarly journals Numerical investigation of the mechanical behaviour of a structural element containing a self-healing agent

2020 ◽  
Vol 1002 ◽  
pp. 012015
Author(s):  
T Zhelyazov ◽  
R Ivanov
Keyword(s):  
Numerical Investigation ◽  
Mechanical Behaviour ◽  
Self Healing ◽  
Structural Element ◽  
Healing Agent

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>

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>

Mechanical responses of microencapsulated self-healing cementitious composites under compressive loading based on a micromechanical damage-healing model

2021 ◽  
pp. 105678952110112
Author(s):  
Kaihang Han ◽  
Jiann-Wen Woody Ju ◽  
Yinghui Zhu ◽  
Hao Zhang ◽  
Tien-Shu Chang ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Compressive Strength ◽  
Micromechanical Model ◽  
Cementitious Composites ◽  
Self Healing ◽  
Damage Degree ◽  
Healing Efficiency ◽  
The Matrix ◽  
Healing Agent ◽  
Damage Healing

The cementitious composites with microencapsulated healing agents have become a class of hotspots in the field of construction materials, and they have very broad application prospects and research values. The in-depth study on multi-scale mechanical behaviors of microencapsulated self-healing cementitious composites is critical to quantitatively account for the mechanical response during the damage-healing process. This paper proposes a three-dimensional evolutionary micromechanical model to quantitatively explain the self-healing effects of microencapsulated healing agents on the damage induced by microcracks. By virtue of the proposed 3 D micromechanical model, the evolutionary domains of microcrack growth (DMG) and corresponding compliances of the initial, extended and repaired phases are obtained. Moreover, the elaborate studies are conducted to inspect the effects of various system parameters involving the healing efficiency, fracture toughness and preloading-induced damage degrees on the compliances and stress-strain relations. The results indicate that relatively significant healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will lead to a higher compressive strength and stiffness. However, the specimen will break owing to the nucleated microcracks rather than the repaired kinked microcracks. Further, excessive higher values of healing efficiency, preloading-induced damage degree and the fracture toughness of polymerized healing agent with the matrix will not affect the compressive strength of the cementitious composites. Therefore, a stronger matrix is required. To achieve the desired healing effects, the specific parameters of both the matrix and microcapsules should be selected prudently.

Numerical investigation into effect of self-healing composite microcapsules thickness and diameter on their failure strength

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Raj Kumar Pittala ◽  
Satish Ben B. ◽  
Syam Kumar Chokka ◽  
Niranjan Prasad
Keyword(s):  
Matrix Composite ◽  
Polymer Matrix ◽  
Shell Thickness ◽  
Polymer Matrix Composite ◽  
Thickness Effect ◽  
Failure Strength ◽  
Self Healing ◽  
Content Type ◽  
Reinforced Polymer ◽  
Healing Agent

Purpose Microcapsule-embedded autonomic healing materials have the ability to repair microcracks when they come into contact with the crack by releasing the healing agent. The microcapsules with specific shape and thickness effect in releasing healing agent to the cracked surfaces. Thus, the purpose of this paper is to know the load bearing capacity of the self-healing microcapsules and the stresses developed in the material. Design/methodology/approach In the present study, self-healing microcapsule is modelled and integrated with the polymer matrix composite. The aim of the present study is to investigate failure criteria of Poly (methyl methacrylate) microcapsules by varying the shell thickness, capsule diameter and loading conditions. The strength of the capsule is evaluated by keeping the shell thickness as constant and varying the capsule diameter. Uniformly distributed pressure loads were applied on the capsule-reinforced polymer matrix composite to assess the failure strength of capsules and composite. Findings It is observed from the results that the load required to break the capsules is increasing with the increase in capsule diameter. The failure strength of microcapsule with 100 µm diameter and 5 µm thickness is observed as 255 MPa. For an applied load range of 40–160 N/mm2 on the capsules embedded composite, the maximum stress developed in the capsules is observed as 308 MPa. Originality/value Failure strengths of microcapsules and stresses developed in the microcapsule-reinforced polymer composites were evaluated.

scholarly journals Reversible Assembly of Terpyridine Incorporated Norbornene-Based Polymer via a Ring-Opening Metathesis Polymerization and Its Self-Healing Property

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1173 ◽  
Author(s):  
Jookyeong Lee ◽  
Hwi Moon ◽  
Keewook Paeng ◽  
Changsik Song
Keyword(s):  
Ring Opening ◽  
Transition Metal Ions ◽  
Self Healing ◽  
Ring Opening Metathesis Polymerization ◽  
Metathesis Polymerization ◽  
Ligand Interactions ◽  
Healing Agent ◽  
Healing Property ◽  
External Stimuli ◽  
Metal Ligand

We induced a terpyridine moiety into a norbornene-based polymer to demonstrate its self-healing property, without an external stimulus, such as light, heat, or healing agent, using metal–ligand interactions. We synthesized terpyridine incorporated norbornene-based polymers using a ring-opening metathesis polymerization. The sol state of diluted polymer solutions was converted into supramolecular assembled gels, through the addition of transition metal ions (Ni2+, Co2+, Fe2+, and Zn2+). In particular, a supramolecular complex gel with Zn2+, which is a metal with a lower binding affinity, demonstrated fast self-healing properties, without any additional external stimuli, and its mechanical properties were completely recovered.

Microencapsulation of UV-Curable Self-healing Agent for Smart Anticorrosive Coating

2014 ◽  
Vol 27 (5) ◽  
pp. 607-615 ◽  
Author(s):  
Dong Zhao ◽  
Mo-zhen Wang ◽  
Qi-chao Wu ◽  
Xiao Zhou ◽  
Xue-wu Ge
Keyword(s):  
Self Healing ◽  
Uv Curable ◽  
Anticorrosive Coating ◽  
Healing Agent

scholarly journals Self-Healing Biogeopolymers Using Biochar-Immobilized Spores of Pure- and Co-Cultures of Bacteria

2020 ◽  
Author(s):  
Jadin Zam S. Doctolero ◽  
Arnel B. Beltran ◽  
Marigold O. Uba ◽  
April Anne S. Tigue ◽  
Michael Angelo B. Promentilla
Keyword(s):  
Image Analysis ◽  
Crack Width ◽  
Ultrasonic Pulse ◽  
Self Healing ◽  
Weak Effect ◽  
Bacterial Cultures ◽  
Healing Agent ◽  
Optimum Response ◽  
Maximum Crack ◽  
Cultured Bacteria

A sustainable solution for crack maintenance in geopolymers is necessary if they are to be the future of modern green construction. This study thus aimed to develop self-healing biogeopolymers that could potentially rival bioconcrete. First, a suitable healing agent was selected from Bacillus subtilis, B. sphaericus, and B. megaterium by directly adding their spores in the geopolymers and subsequently exposing them to a large amount of nutrients for 14 days. SEM-EDX analysis revealed the formation of biominerals for B. subtilis and B. sphaericus. Next, the effect of biochar-immobilization and co-culturing (B. sphaericus and B. thuringiensis) on the healing efficiencies of the geopolymers were tested and optimized by measuring their ultrasonic pulse velocities weekly over a 28-day healing period. The results show that using co-cultured bacteria significantly improved the observed efficiencies, while biochar-immobilization had a weak effect but yielded an optimum response between 0.3-0.4 g/mL. The maximum crack width sealed was 0.65 mm. Through SEM-EDX and FTIR analyses, the biominerals precipitated in the cracks were identified to be mainly CaCO3. Furthermore, image analysis of the XCT scans of some of the healed geopolymers confirmed that their pulse velocities were indeed improving due to the filling of their internal spaces with biominerals. With that, there is potential in developing self-healing biogeopolymers using biochar-immobilized spores of bacterial cultures.

Self-healing organic coatings based on microcapsules – A patent-based review

2021 ◽  
Vol 04 ◽  
Author(s):  
Diego Moreira Schlemper ◽  
Sérgio Henrique Pezzin
Keyword(s):  
Corrosion Protection ◽  
State Of The Art ◽  
Review Article ◽  
The State ◽  
Organic Coatings ◽  
Self Healing ◽  
Future Challenges ◽  
The Matrix ◽  
Healing Agent

: Self-healing coatings are intended to increase long-term durability and reliability and can be enabled by the presence of microcapsules containing a self-healing agent capable of interacting with the matrix and regenerating the system. This review article provides an overview of the state-of-the-art, focusing on the patents published in the field of microcapsule-based self-healing organic coatings, since the early 2000’s. A discussion about coatings for corrosion protection and the different self-healing approaches and mechanisms are also addressed, as well as future challenges and expectations for this kind of coatings.

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