scholarly journals Mechanical Behavior and Healing Efficiency of Microcapsule-Based Cemented Coral Sand under Various Water Environments

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5571
Author(s):  
Yue Qin ◽  
Qiankun Wang ◽  
Dongsheng Xu ◽  
Wei Chen
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Water Environment ◽  
Experimental Tests ◽  
High Porosity ◽  
Self Healing ◽  
Hopkinson Pressure Bar ◽  
Initial Strength ◽  
Rotating Speed ◽  
Coral Sand ◽  
Healing Efficiency

The cracks in the cemented coral sand (CCS) would result in significant damage for the marine structures. In this study, the effective and efficiency of microcapsules in self-healing CCS under various water environments were investigated with a series of experimental tests. Firstly, a new preparation method was proposed to fabricate the microcapsules with a wide particle size distribution, which was adapted to the high porosity, large difference in pore size, and uneven distribution of CCS. Secondly, the mechanical properties of microcapsule-based CCS were examined by the uniaxial compressive tests and split Hopkinson pressure bar (SHPB) tests. The results indicated that the microcapsule could improve the initial strength of CCS. The CCS mixed with 3% of the microcapsule that synthesized under a rotating speed of 450 rmp had the highest compressive strength at the initial strain state. Finally, the healing efficiency of microcapsule for CCS was investigated in various environmental conditions, which were freshwater, seawater, and water of various pH values. The non-destructive experiment approach of the piezoelectric transducer (PZT) test was adopted to evaluate the healing efficiency of microcapsules. Experimental results indicated that the healing efficiency of microcapsules in freshwater and seawater were 75% and 59.56%, respectively. In contrast, the acid and alkali water environment would greatly reduce the healing efficiency of microcapsules in CCS.

scholarly journals Stress Attenuation and Energy Absorption of the Coral Sand with Different Particle Sizes under Impacts

Proceedings ◽  
2018 ◽  
Vol 2 (8) ◽  
pp. 545
Author(s):  
Xiao Yu ◽  
Li Chen ◽  
Qin fang ◽  
Wuzheng Chen
Keyword(s):  
Energy Absorption ◽  
Stress Wave ◽  
Wave Attenuation ◽  
Split Hopkinson Pressure Bar ◽  
Particle Size Effect ◽  
Particle Sizes ◽  
Hopkinson Pressure Bar ◽  
Coral Sand ◽  
Stress Zone ◽  
Pressure Bar

The stress wave attenuation and energy absorption in the coral sand were respectively investigated. A series of experiments were carried out by using a new methodology with an improved split Hopkinson pressure bar (SHPB). Four types of coral sand, i.e., particle sizes of 1.18–0.60 mm, 0.60–0.30 mm, 0.30–0.15 mm, and 0.15–0.075 mm, were carefully sieved and tested. Significant effects of coral sand on stress wave attenuation and energy absorption were observed. Correlation between stress wave attenuation and energy absorption of coral sand was validated. Conclusions on particle size effect of stress wave attenuation and energy absorption, which support each other, were drawn. There existed a common critical stress zone for coral sand with different particle sizes. When the stress below this zone, sand with small particle sizes attenuates stress wave better and absorb energy more; when the stress beyond this zone, sand with larger particle sizes behave better on stress wave attenuation and energy absorption.

scholarly journals Numerical study for determination of pulse shaping design variables in SHPB apparatus

2013 ◽  
Vol 61 (2) ◽  
pp. 459-466 ◽  
Author(s):  
P. Baranowski ◽  
J. Malachowski ◽  
R. Gieleta ◽  
K. Damaziak ◽  
L. Mazurkiewicz ◽  
...  
Keyword(s):  
Pulse Shaping ◽  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Experimental Tests ◽  
Peak Shape ◽  
Hopkinson Pressure Bar ◽  
Design Variables ◽  
Split Hopkinson ◽  
Pulse Peak ◽  
Pressure Bar

Abstract High strain rate experimental tests are essential in a development process of materials under strongly dynamic conditions. For such a dynamic loading the Split Hopkinson Pressure Bar (SHPB) has been widely used to investigate dynamic behaviour of various materials. It was found that for different materials various shapes of a generated wave are desired. This paper presents a parametric study of Split Hopkinson Pressure Bar in order to find striker’s design variables, which influence the pulse peak shape in the incident bar. With experimental data given it was possible to verify the developed numerical model, which was used for presented investigations. Dynamic numerical simulations were performed using explicit LS-Dyna code with a quasi-optimization process carried out using LS-Opt software in order to find striker’s design variables, which influence the pulse peak shape.

scholarly journals Experimental and Numerical Study on the Behavior of Dyneema� HB26 Composite in Compression

2019 ◽  
Vol 57 (2) ◽  
pp. 113-122
Author(s):  
Florina Bucur ◽  
Adrian Rotariu ◽  
Liviu Matache ◽  
Florin Baciu ◽  
Gabriel Jiga ◽  
...  
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Numerical Study ◽  
Low Cost ◽  
Testing Machine ◽  
Compressive Load ◽  
High Strength ◽  
Experimental Tests ◽  
Hopkinson Pressure Bar ◽  
Course Of Action ◽  
Pressure Bar

In the last decades as the need for high economical and technical efficiency items/applications became acute, lightweight, high strength and low-cost materials development and investigation emerged as a logical and promising course of action. With high potential for both military and civil sector, the ultra-high molecular weight polyethylene (UHMWPE) is considered a new class of material. Among this class, the Dyneema� HB26 composite is of most interest for the present study. The present paper focuses on the static and dynamic investigation of the HB26 mechanical behavior experiencing an out of plane compressive load. For experimental purposes, using a 15 mm thickness panel two types of samples (cylindrical and cubic samples) were processed. For compression test Instron Testing Machine and the Split Hopkinson Pressure Bar (SHPB) were used. The experimental tests were then compared against the numerical findings highlighting a good consistency.

scholarly journals On the study of the dynamic response in 3D additively manufactured auxetic structures

2021 ◽  
Vol 250 ◽  
pp. 06004
Author(s):  
Niklas Fjeldberg ◽  
Jesús Pernas ◽  
David Varas ◽  
Jordi Martín
Keyword(s):  
Dynamic Response ◽  
Split Hopkinson Pressure Bar ◽  
Deformation Behaviour ◽  
Experimental Tests ◽  
Hopkinson Pressure Bar ◽  
Deformation Response ◽  
Unit Cells ◽  
Auxetic Structures ◽  
Split Hopkinson ◽  
Pressure Bar

The main aim of this work is to analyse the quasi-static and the dynamic response and deformation behaviour of polymeric auxetic structures manufactured with an SLA (stereolitography) additive manufacturing technique. To this end, different experimental tests were performed using a universal servo-hydraulic instron machine and a Split Hopkinson Pressure Bar (SHPB). The study focuses on the understanding of the mechanical deformation response of the metamaterial depending on the type of load, the amount and distribution of the unit cells and the strain rate applied.

Analysis of the Impact of the Frequency Range of the Tensometer Bridge and Projectile Geometry on the Results of Measurements by the Split Hopkinson Pressure Bar Method

2013 ◽  
Vol 20 (4) ◽  
pp. 555-564 ◽  
Author(s):  
Wojciech Moćko
Keyword(s):  
Test Bench ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Deformation ◽  
Spectral Width ◽  
Hopkinson Pressure Bar ◽  
Computing Environment ◽  
Split Hopkinson ◽  
Pressure Bar ◽  
The Impact ◽  
Bench Model

Abstract The paper presents the results of the analysis of the striker shape impact on the shape of the mechanical elastic wave generated in the Hopkinson bar. The influence of the tensometer amplifier bandwidth on the stress-strain characteristics obtained in this method was analyzed too. For the purposes of analyzing under the computing environment ABAQUS / Explicit the test bench model was created, and then the analysis of the process of dynamic deformation of the specimen with specific mechanical parameters was carried out. Based on those tests, it was found that the geometry of the end of the striker has an effect on the form of the loading wave and the spectral width of the signal of that wave. Reduction of the striker end diameter reduces unwanted oscillations, however, adversely affects the time of strain rate stabilization. It was determined for the assumed test bench configuration that a tensometric measurement system with a bandwidth equal to 50 kHz is sufficient

scholarly journals Ultrarobust, tough and highly stretchable self-healing materials based on cartilage-inspired noncovalent assembly nanostructure

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuyan Wang ◽  
Xin Huang ◽  
Xinxing Zhang
Keyword(s):  
Spider Silk ◽  
Self Healing ◽  
High Toughness ◽  
Healing Efficiency ◽  
Strong Interfacial Interaction ◽  
Highly Stretchable ◽  
Noncovalent Bonds ◽  
Actuation Devices ◽  
Noncovalent Bonding ◽  
Polyurethane Matrix

AbstractSelf-healing materials integrated with excellent mechanical strength and simultaneously high healing efficiency would be of great use in many fields, however their fabrication has been proven extremely challenging. Here, inspired by biological cartilage, we present an ultrarobust self-healing material by incorporating high density noncovalent bonds at the interfaces between the dentritic tannic acid-modified tungsten disulfide nanosheets and polyurethane matrix to collectively produce a strong interfacial interaction. The resultant nanocomposite material with interwoven network shows excellent tensile strength (52.3 MPa), high toughness (282.7 MJ m‒3, which is 1.6 times higher than spider silk and 9.4 times higher than metallic aluminum), high stretchability (1020.8%) and excellent healing efficiency (80–100%), which overturns the previous understanding of traditional noncovalent bonding self-healing materials where high mechanical robustness and healing ability are mutually exclusive. Moreover, the interfacical supramolecular crosslinking structure enables the functional-healing ability of the resultant flexible smart actuation devices. This work opens an avenue toward the development of ultrarobust self-healing materials for various flexible functional devices.

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