scholarly journals Lamb-Wave-Based Method in the Evaluation of Self-Healing Efficiency

2020 ◽  
Vol 10 (7) ◽  
pp. 2585
Author(s):  
Maciej Radzieński ◽  
Paweł Kudela ◽  
Wiesław Ostachowicz ◽  
Patryk Bolimowski ◽  
Rafał Kozera ◽  
...  
Keyword(s):  
Lamb Wave ◽  
Composite Laminates ◽  
Impact Damage ◽  
Healing Process ◽  
Nondestructive Method ◽  
Laser Vibrometer ◽  
Self Healing ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Healing Efficiency

The aim of this research is a feasibility study of self-healing process monitoring in composite laminates. A novel nondestructive method based on the full wavefield of Lamb wave processing is proposed. Experimental verification is presented for glass-fiber-reinforced polymer plate with embedded self-healing function in the form of a dry microcapsule powder. After impacting the specimen to create barely visible impact damage, a series of laser vibrometer full wavefield measurements were carried out and processed to assess self-healing efficiency.

scholarly journals The Self-Healing Performance of Carbon-Based Nanomaterials Modified Asphalt Binders Based on Molecular Dynamics Simulations

2021 ◽  
Vol 7 ◽  
Author(s):  
Yan Gong ◽  
Jian Xu ◽  
Er-hu Yan ◽  
Jun-hua Cai
Keyword(s):  
Healing Process ◽  
Asphalt Binder ◽  
Mean Square Displacement ◽  
The Self ◽  
Asphalt Binders ◽  
Self Healing ◽  
Modified Asphalt ◽  
Healing Efficiency ◽  
Carbon Based Nanomaterials ◽  
Carbon Based

In this study, the molecular dynamics simulation was used to explore the effects of carbon-based nanomaterials as binder modifiers on self-healing capability of asphalt binder and to investigate the microscopic self-healing process of modified asphalt binders under different temperature. An asphalt average molecular structure model of PEN70 asphalt binder was constructed firstly. Further, three kinds of carbon-based nanomaterials were added at three different percentages ranging from 0.5 to 1.5% to the base binder to study their effects on the self-healing capability, including two carbon nanotubes (CNT1 and CNT2) and graphene nanoflakes. Combining with the three-dimensional (3D) microcrack model to simulate the asphalt self-healing process, the density analysis, relative concentration analysis along OZ direction, and mean square displacement analysis were performed to investigate the temperature sensitive self-healing characters. Results showed that the additions of CNTs were effective in enhancing the self-healing efficiency of the plain asphalt binder. By adding 0.5% CNT1 and 0.5% CNT2, about 652% and 230% of the mean square displacement of plain asphalt binder were enhanced at the optimal temperatures. However, the use of graphene nanoflakes as an asphalt modifier did not provide any noticeable changes on the self-healing efficiency. It can be found that the self-healing capability of the asphalt was closely related to the temperature. For base asphalt, the self-healing effect became especially high at the phase transition temperature range, while, for the modified asphalt, the enhancement of the self-healing capability at the low phase transition temperature (15°C) became negligible. In general, the optimal healing temperature range of the CNTs modified asphalt binders is determined as 45–55°C and the optimal dosage of the CNTs is about 0.5% over the total weight of the asphalt binder. Considering the effect of carbon-based nanomaterials on the self-healing properties, the recommended carbon-based nanomaterials modifier is CNT1 with the aspect ratio of 1.81.

Soluble Silicates as Additives for Self-Sealing and Self-Healing Concrete

2016 ◽  
Vol 1813 ◽  
Author(s):  
L. E. Rendon Diaz Miron ◽  
M. E. Lara Magaña
Keyword(s):  
Mechanical Properties ◽  
Crack Formation ◽  
Healing Process ◽  
Self Healing ◽  
Reaction Products ◽  
Calcium Carbonate Precipitation ◽  
Broad Perspective ◽  
Healing Efficiency ◽  
Tensile Forces ◽  
Solubility Ratio

ABSTRACTTensile strength of concrete is limited and therefore is sensitive to crack formation. Steel reinforcement is added to bear the tensile forces; nonetheless, this does not completely omit crack formation. Repair of cracks in concrete is time-consuming and expensive. Self-sealing and self-healing of cracks upon appearance would therefore be a convenient property. We propose a mechanism to obtain self-repair of the concrete by adding soluble silicates (ASS) which will induce a self-sealing and self-healing process catalyzed by natural periods of wet and dry states of the concrete. Self-sealing approaches prevent the ingress of harsh chemical substances which may deteriorate the concrete matrix. This can be achieved by self-healing of concrete cracks (e.g. further cement hydration, calcium carbonate precipitation) and autonomous healing (e.g. further hydration of partially soluble silicates added as healing agents). The autogenous healing efficiency depends on the amount of deposited reaction products (ASS), its solubility (ratio of calcium to sodium silicate), the availability of water, and the crack width (restricted by adding microfibers). The self-sealing efficiency is generally evaluated by measuring the decrease in water permeability and air flow through the crack. The healing efficiency is usually evaluated by testing concrete´s regain in mechanical properties after crack formation; by reloading the cracked and autonomously healed specimen and comparing the obtained mechanical properties with the original ones. Self-sealing and self-healing of concrete gives a broad perspective and new possibilities to make future concrete structures more durable.

scholarly journals Mechanical Properties Assessment of Low-Content Capsule-Based Self-Healing Structural Composites

2020 ◽  
Vol 10 (17) ◽  
pp. 5739
Author(s):  
Xenia Tsilimigkra ◽  
Dimitrios Bekas ◽  
Maria Kosarli ◽  
Stavros Tsantzalis ◽  
Alkiviadis Paipetis ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Flexural Strength ◽  
Mechanical Performance ◽  
Urea Formaldehyde ◽  
Healing Process ◽  
Experimental Results ◽  
Self Healing ◽  
Healing Efficiency ◽  
A Minor

Microcapsule-based carbon fiber reinforced composites were manufactured by wet layup, in order to assess their mechanical properties and determine their healing efficiency. Microcapsules at 10%wt. containing bisphenol-A epoxy, encapsulated in a urea formaldehyde (UF) shell, were employed with Scandium (III) Triflate (Sc (OTf)3) as the catalyst. The investigation was deployed with two main directions. The first monitored changes to the mechanical performance due to the presence of the healing agent within the composite. More precisely, a minor decrease in interlaminar fracture toughness (GIIC) (−14%), flexural strength (−12%) and modulus (−4%) compared to the reference material was reported. The second direction evaluated the healing efficiency. The experimental results showed significant recovery in fracture toughness up to 84% after the healing process, while flexural strength and modulus healing rates reached up to 14% and 23%, respectively. The Acoustic Emission technique was used to support the experimental results by the onsite monitoring.

EFFECT OF HYBRIDIZATION ON OPEN-HOLE TENSION PROPERTIES OF WOVEN KEVLAR/GLASS FIBER HYBRID COMPOSITE LAMINATES

2015 ◽  
Vol 76 (9) ◽  
Author(s):  
Norazean Shaari ◽  
Aidah Jumahat ◽  
Shahrul Azam Abdullah ◽  
Ahmad Zariff Hadderi
Keyword(s):  
Tensile Strength ◽  
Glass Fiber ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Open Hole ◽  
Strength And Stiffness

Hybrid laminates consisting of woven Kevlar/glass fiber composite plies were studied in terms of their residual tensile strength, stiffness and fracture surface.  Residual tensile strength and stiffness were determined from the open hole tension test according to ASTM D5766. The laminates of Kevlar fiber reinforced polymer (KFRP), glass fiber reinforced polymer (GFRP) and hybrid of Kevlar-glass fiber reinforced polymer (KGFRP) were fabricated using a vacuum bagging process. Three different ratios of Kevlar to glass fiber plies were prepared in this study which were 20:80, 50:50, and 80:20. Results showed that hybrid laminate consisting of 80:20 Kevlar to glass fiber plies, produced higher residual tensile strength and stiffness when compared to the other hybrid system. Furthermore, strength and stiffness of hole specimens were reduced within 50-63% when compared to unhole specimens due to existence of the hole. In addition, the effect of adding nanosilica to the hybrid system was also studied. 5 wt% of nanosilica was added to the hybrid composite laminates and results showed that higher tensile strength and stiffness was observed in GFRP and 20:80 KGFRP specimens, while the tensile strength was decreased with an increased number of Kevlar fiber. This research was conducted as there are limited number of studies that have been done on the tensile strength of woven hybrid composite laminates so far, especially on hybridization of Kevlar and glass fiber with consideration on the effect of hole and addition of nanofillers.

scholarly journals Numerical and Experimental Investigation of the Through-Thickness Strength Properties of Woven Glass Fiber Reinforced Polymer Composite Laminates under Combined Tensile and Shear Loading

2020 ◽  
Vol 4 (3) ◽  
pp. 112
Author(s):  
Teruyoshi Kanno ◽  
Hiroki Kurita ◽  
Masashi Suzuki ◽  
Hitoshi Tamura ◽  
Fumio Narita
Keyword(s):  
Finite Element ◽  
Composite Laminates ◽  
Strength Properties ◽  
Shear Loading ◽  
Fiber Reinforced Polymer ◽  
Glass Fiber Reinforced Polymer ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Gfrp Composite ◽  
Woven Glass Fiber

The purpose of this paper is to investigate the through-thickness stresses of woven glass fiber reinforced polymer (GFRP) composite laminates under combined tensile and shear loading. Tensile tests were carried out with cross specimens at room temperature under various stacking angles, and the through-thickness strength properties of the woven GFRP laminates were evaluated. The failure characteristics of the woven GFRP laminates were also studied by optical microscopy observations. A three-dimensional finite element analysis (FEA) was carried out to calculate the stress distributions in the cross specimens, and the failure conditions of the specimens were examined. The numerically determined interlaminar tensile and shear stresses at failure location were consistent with Hoffman and Mohr-Coulomb failure criteria when the stacking angle was relatively small. This work is the first attempt to quantify the relation between interlaminar tensile and shear strengths of GFRP composite laminates under tensile and shear loading simultaneously using a combined numerical and experimental approach. A method based on finite element stress analysis was developed for estimating the through-thickness strength of the composite laminates using the experimentally determined fracture load and location. The results suggest that the through-thickness strength under combined tensile and shear loading can be determined effectively by this approach for relatively small stacking angles.

Analytical and experimental investigation of tensile properties of cross-ply and angle-ply GFRP composite laminates

2015 ◽  
Vol 22 (3) ◽  
pp. 297-301 ◽  
Author(s):  
Mostefa Bourchak ◽  
Wail Harasani
Keyword(s):  
Tensile Properties ◽  
Composite Laminates ◽  
Composite Laminate ◽  
Analytical Technique ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Gfrp Composite ◽  
Laminate Theory ◽  
Static Tensile ◽  
Ultimate Failure

AbstractThe static tensile properties in the form of ultimate failure stress, ultimate failure strain and Young’s modulus of a cross-ply glass fiber-reinforced polymer (GFRP) composite laminate [904, 04]s and an unconventional angle-ply GFRP composite laminate [+67.54, -67.54]s were investigated using the netting analysis, the laminate mixture rule (Hart-Smith 10% rule) and the classical laminate theory (CLT). The findings were then compared to experimental results to determine the accuracy of each analytical technique. It was found that the netting analysis was the best overall method for estimating the cross-ply laminate tensile properties, whereas neither the CLT nor the 10% rule were appropriate for estimating the tensile properties of the unconventional ply angle laminate.

scholarly journals Healable thermoset polymer composite embedded with stimuli-responsive fibres

2012 ◽  
Vol 9 (77) ◽  
pp. 3279-3287 ◽  
Author(s):  
Guoqiang Li ◽  
Harper Meng ◽  
Jinlian Hu
Keyword(s):  
Mechanical Properties ◽  
Human Skin ◽  
Biological Systems ◽  
Healing Process ◽  
Self Healing ◽  
Stimuli Responsive ◽  
Closed Crack ◽  
Healing Efficiency ◽  
Thermoset Polymer ◽  
Crack Interface

Severe wounds in biological systems such as human skin cannot heal themselves, unless they are first stitched together. Healing of macroscopic damage in thermoset polymer composites faces a similar challenge. Stimuli-responsive shape-changing polymeric fibres with outstanding mechanical properties embedded in polymers may be able to close macro-cracks automatically upon stimulation such as heating. Here, a stimuli-responsive fibre (SRF) with outstanding mechanical properties and supercontraction capability was fabricated for the purpose of healing macroscopic damage. The SRFs and thermoplastic particles (TPs) were incorporated into regular thermosetting epoxy for repeatedly healing macroscopic damages. The system works by mimicking self-healing of biological systems such as human skin, close (stitch) then heal, i.e. close the macroscopic crack through the thermal-induced supercontraction of the SRFs, and bond the closed crack through melting and diffusing of TPs at the crack interface. The healing efficiency determined using tapered double-cantilever beam specimens was 94 per cent. The self-healing process was reasonably repeatable.

scholarly journals Preparation and Properties of Self-Healing Waterborne Polyurethane Based on Dynamic Disulfide Bond

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2936
Author(s):  
Gongbo Ye ◽  
Tao Jiang
Keyword(s):  
Particle Size ◽  
Tensile Strength ◽  
Healing Process ◽  
Waterborne Polyurethane ◽  
The Self ◽  
Polymer Materials ◽  
Self Healing ◽  
Heat Treated ◽  
Healing Efficiency ◽  
Excellent Stability

A self-healing waterborne polyurethane (WPU) materials containing dynamic disulfide (SS) bond was prepared by introducing SS bond into polymer materials. The zeta potential revealed that all the synthesized WPU emulsions displayed excellent stability, and the particle size of them was about 100 nm. The characteristic peaks of N-H and S-S in urethane were verified by FTIR, and the chemical environment of all elements were confirmed by the XPS test. Furthermore, the tensile strength, self-healing process and self-healing efficiency of the materials were quantitatively evaluated by tensile measurements. The results showed that the self-healing efficiency could reach 96.14% when the sample was heat treated at 70 °C for 4 h. In addition, the material also showed a good reprocessing performance, and the tensile strength of the reprocessed film was 3.39 MPa.

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