Influence of Interphase Properties on the Macroscopic Response of Single- and Double-Walled CNT/Epoxy Nanocomposites: A Numerical Study

2012 ◽  
Vol 714 ◽  
pp. 3-11 ◽  
Author(s):  
David Weidt ◽  
Łukasz Figiel ◽  
Martin Buggy
Keyword(s):  
Shear Stress ◽  
Carbon Nanotube ◽  
Mechanical Performance ◽  
Numerical Study ◽  
Impact Resistance ◽  
Shear Stiffness ◽  
Epoxy Nanocomposites ◽  
Cfrp Laminates ◽  
The Impact ◽  
Walled Cnts

A concept for improving the impact resistance of carbon fibre reinforced plastic (CFRP) laminates by using a carbon nanotube (CNT)/epoxy surface coating is presented. An initial parametric numerical study shows the effects of interphase properties on the macroscopic stress-strain behaviour of carbon nanotube/epoxy nanocomposites. Finite element (FE) simulations carried out for fully aligned single-walled CNTs (SWCNTs) and double-walled CNTs (DWCNTs) investigated the influence of properties of the polymer/CNT interphase and the interwall phase of DWCNTs. They reveal that a high shear stiffness of the CNT/polymer interphase is essential to take the full advantage of the load-bearing ability of the inner wall of the DWCNT, and thus enhance the mechanical performance of the nanocomposite. Furthermore the interphase shear stress distributions in interwall and CNT/polymer interphase of a DWCNT point out the relationship between CNT/epoxy interphase damage propagation and shear stress in the interwall phase.

Experimental and Numerical Study of Basalt FRP Strip Strengthened RC Slabs under Impact Loads

2020 ◽  
Vol 20 (06) ◽  
pp. 2040001 ◽  
Author(s):  
Wensu Chen ◽  
Thong M. Pham ◽  
Mohamed Elchalakani ◽  
Huawei Li ◽  
Hong Hao ◽  
...  
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Numerical Study ◽  
Impact Resistance ◽  
Basalt Fiber ◽  
Impact Behavior ◽  
Impact Loads ◽  
Quantitative Measurements ◽  
Rc Slabs ◽  
The Impact

Basalt fiber-reinforced polymer (BFRP) has been applied for strengthening concrete structures. However, studies on reinforced concrete (RC) slabs strengthened by BFRP strips under impact loads are limited in open literature. This study investigates the efficiency of using BFRP strips with various strengthening layouts and anchoring schemes on the impact resistance of RC slabs. A total of 11 two-way square slabs were prepared and tested, including one reference specimen without strengthening and ten slabs strengthened with BFRP strips and/or anchors. The RC slabs were impacted by a drop weight with increasing height until slab failure. The observed failure modes include punching shear failure, BFRP sheet debonding and reinforcement fracture. The failure modes and the effects of using various strengthening schemes on the impact resistant capacity of RC slabs were examined. The quantitative measurements, such as impact velocity, indentation depth and diameter, were compared and discussed. In addition, numerical studies were carried out by using LS-DYNA to simulate the impact tests of RC slabs with and without BFRP strengthening. With the calibrated numerical model, the impact behavior of slabs with various dimensions and strengthening layouts under different impact intensities can be predicted with good accuracy.

Effects of Water-Borne Polyurethane on Calcium Silicate Hydrate and Toughness of Properties of Cementitious Composites

2012 ◽  
Vol 619 ◽  
pp. 545-552
Author(s):  
Bei Ding ◽  
Xia Zhang ◽  
Dong Liang Zhou ◽  
Chan Wen Miao
Keyword(s):  
Mechanical Performance ◽  
Concrete Strength ◽  
Harmful Effect ◽  
Impact Resistance ◽  
29Si Nmr ◽  
Size Change ◽  
Block Polymer ◽  
Chain Conformations ◽  
The Impact ◽  
Water Borne

A novel kind of block polymer with characteristics of rod-like chain conformations-water-borne polyurethane (PUA) was synthesized by incorporate polyacrylate (PA) into the PU chain to prepare an aqueous polyurethane-polyacrylate (PUA) hybrid emulsion with core-shell structure. The interactions between Water-borne PUA and C-S-H nanostructure, which include intercalation and the polymerization degree of C-S-H silicate chains, were studied by small angle X-ray diffraction spectra and 29Si NMR spectra, respectly. The influences of water-borne PUA on mechanical performance of C-S-H were investigated experimentally. The small XRD results show that no evidence is observed for any fundamental size change in the C-S-H particles that have been formed in the presence of polymer. The NMR results indicate that there is a significant increase in the Q2/Q1 ratio ranging from 0.5 for pure C-S-H to 2.2 for PUA-C-S-H, respectively. The degree of silicate polymerization increases from 3.0 for pure C-S-H to 6.4 for PUA-C-S-H by calculation. PUA had minimal harmful effect on the compressive strength whereas the flexural strength was increased by 23.2% with dosage of 0.5% and 23.3% with dosage of 1.0%, respectively.The fracture energy ratios of concrete with a dosage of PUA less than 1% are greatly improved more than double with the decreasing of concrete strength less than 10%. The water-borne PUA also enhances the impact resistance of concrete. The impact energy consumption of samples with PUA increase nearly three times more than reference samples, also better than samples with PP fiber.

Quasi-Static Impact Response of Single-Curved Foldcore Sandwich Shells

2014 ◽  
Author(s):  
Joseph M. Gattas ◽  
Zhong You
Keyword(s):  
Energy Absorption ◽  
Mechanical Performance ◽  
Numerical Models ◽  
Preliminary Investigation ◽  
Impact Resistance ◽  
Absorption Capacity ◽  
Future Research ◽  
Initial Strength ◽  
Sandwich Shells ◽  
The Impact

Honeycomb core sandwich shells are used for many applications, but available unit architectures and global curvatures are limited. Numerous origami-core sandwich shells, known as foldcores, have been proposed as alternatives, but studies into their mechanical performance are few. This paper conducts a preliminary investigation into the impact resistance and energy absorption of single-curved foldcore sandwich shells that utilise Miura-derivative patterns as their core geometry. A numerical analysis on three Miura-derivative core patterns, the Arc-Miura (AM), Non-Developable Miura (ND), and Non-Flat Foldable Miura (NF) patterns, shows that ND and AM-type shells have similar impact resistance to each other, and superior impact resistance to NF-type shells. Prototypes of aluminium ND and AM-type foldcores are constructed and used to validate numerical models. Numerical models were then used to draw comparisons with an over-expanded honeycomb (OX-core) sandwich shell. It was seen that the OX-core had a better energy absorption capacity than either of the foldcores. However the AM-type foldcore possessed superior initial strength, and the ND-type possessed superior response uniformity, attributes that might be exploitable with future research. A brief parametric study on ND-type shells suggested that in general, for a given design radius and density, a foldcore shell configuration with a lower unit cell area-to-height ratio will have a higher energy absorption capability.

scholarly journals Preparation of poly(ionic liquid)/multi-walled carbon nanotube fillers using divinylbenzene as a linker to enhance the impact resistance of polyurethane elastomers

RSC Advances ◽  
2022 ◽  
Vol 12 (3) ◽  
pp. 1777-1787
Author(s):  
Zehui Xiang ◽  
Fan Hu ◽  
Xueyan Wu ◽  
Fugang Qi ◽  
Biao Zhang ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Carbon Nanotube ◽  
High Speed ◽  
Impact Resistance ◽  
Polyurethane Elastomers ◽  
High Speed Impact ◽  
Multi Walled Carbon Nanotube ◽  
Carbon Nanotube Composite ◽  
Poly Ionic Liquid ◽  
The Impact

Schematic diagram of multi-walled carbon nanotube composite ionic liquid synergistically enhancing the high-speed impact resistance of polyurethane elastomer.

scholarly journals Properties of core-half wrapped shell structure wood-polymer composites containing glass fiber-reinforced shells

BioResources ◽  
2020 ◽  
Vol 15 (4) ◽  
pp. 9088-9102
Author(s):  
Runzhou Huang ◽  
Xian Zhang ◽  
Zhuangzhuang Teng ◽  
Fei Yao
Keyword(s):  
Thermal Expansion ◽  
Glass Fiber ◽  
Polymer Composites ◽  
Mechanical Performance ◽  
Impact Resistance ◽  
Shell Layer ◽  
Flame Resistance ◽  
Wood Polymer ◽  
Wood Polymer Composites ◽  
The Impact

Glass fiber (GF) is commonly applied as a filler in the preparation of polymer composites. Due to the presence of GF, composite mechanical performance, flame resistance, and thermal performance could be greatly improved. The influence of a GF-filled polymer shell layer was investigated relative to the morphology, mechanical, thermal, and fire flammability performance of the core-half wrapped shell structured wood high-density polyethylene (HDPE) composites prepared via co-extrusion. The use of the relatively less-stiff pure HDPE with high linear coefficients of thermal expansion (LCTEs) lowered the general thermal stability and modulus of the wood polymer composites (WPCs). Flexural and thermal expansion properties were improved for the GF-filled HDPE shells in comparison to the unmodified material, enabling a well-balanced performance of this novel core–shell material. Implementation of GF-modified HDPE or unmodified HDPE layers as a shell for WPC core remarkably improved the impact resistance of the co-extruded WPCs. In comparison with composites possessing unmodified HDPE shell, the flame resistance performance of the shell layer was slightly improved in case that the GF content was below 25 wt%. A slight decrease in composite general heat release and rate was discovered in case that the GF content was greater than 25 wt%.

Methods to assess the impact of UV irradiation on the surface chemistry and structure of multiwall carbon nanotube epoxy nanocomposites

Carbon ◽  
2014 ◽  
Vol 69 ◽  
pp. 194-205 ◽  
Author(s):  
Elijah J. Petersen ◽  
Thomas Lam ◽  
Justin M. Gorham ◽  
Keana C. Scott ◽  
Christian J. Long ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Surface Chemistry ◽  
Uv Irradiation ◽  
Multiwall Carbon Nanotube ◽  
Epoxy Nanocomposites ◽  
The Impact ◽  
Surface Chemistry And Structure ◽  
Multiwall Carbon

scholarly journals Crushing of Single-Walled Corrugated Board During Converting: Experimental and Numerical Study

2021 ◽  
Author(s):  
Tomasz Garbowski ◽  
Tomasz Gajewski ◽  
Damian Mrówczyński ◽  
Radosław Jędrzejczak
Keyword(s):  
Numerical Study ◽  
Shear Stiffness ◽  
Calculation Model ◽  
Basic Material ◽  
Corrugated Board ◽  
Material Stiffness ◽  
Residual Thickness ◽  
Corrugated Cardboard ◽  
Recycled Fibers ◽  
The Impact

Corrugated cardboard is an ecological material, mainly because, in addition to virgin cellulose fibers also the fibers recovered during recycling process are used in its production. However, the use of recycled fibers causes slight deterioration of the mechanical properties of the corrugated board. In addition, converting processes such as printing, die-cutting, lamination, etc. cause micro-damage in the corrugated cardboard layers. In this work, the focus is precisely on the crushing of corrugated cardboard. A series of laboratory experiments were conducted, in which the different types of single-walled corrugated cardboards were pressed in a fully controlled manner to check the impact of the crush on the basic material parameters. The amount of crushing (with a precision of 10 micrometers) was controlled by a precise FEMat device, for crushing the corrugated board in the range from 10 to 70 % of its original thickness. In this study, the influence of crushing on bending, twisting and shear stiffness as well as a residual thickness and edge crush resistance of corrugated board was investigated. Then, a procedure based on a numerical homogenization, taking into account a partial delamination in the corrugated layers to determine the degraded material stiffness was proposed. Finally, using the empirical-numerical method, a simplified calculation model of corrugated cardboard was derived, which satisfactorily reflects the experimental results.

Based on the Digital Design of the Pneumatic Pick Force Analysis and Research of Key Parts

2013 ◽  
Vol 753-755 ◽  
pp. 1347-1350
Author(s):  
Chen Shen ◽  
Hua Liang Gui ◽  
Ming Ming Wu
Keyword(s):  
Mechanical Performance ◽  
Raw Materials ◽  
Design Method ◽  
Impact Resistance ◽  
Digital Design ◽  
Working Process ◽  
Air Power ◽  
Power Machinery ◽  
Resistance Performance ◽  
The Impact

Pick is a hand-held machine of the air power machinery, using compressed air as power, hit a rundown coal and ore body or other objects. In the working process of the pneumatic pick, pick cylinder under different loading easily lead to early obsolescence. In order to improve the impact resistance performance to pick picks, prolong the service life of pneumatic pick, based on the digital design method for pneumatic pick pick cylinder is modeled, and based on the simulated stress analysis, for the process improvement, improve its mechanical performance, reduce the waste of raw materials.

scholarly journals Impact of Competitive Flow on Hemodynamics in Coronary Surgery: Numerical Study of ITA-LAD Model

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Jinli Ding ◽  
Youjun Liu ◽  
Feng Wang ◽  
Fan Bai
Keyword(s):  
Shear Stress ◽  
Coronary Artery ◽  
Wall Shear Stress ◽  
Numerical Study ◽  
Artery Bypass ◽  
Bypass Graft ◽  
Coronary Bypass ◽  
Coronary Artery Bypass Grafts ◽  
Wall Shear ◽  
The Impact

Competitive flow from native coronary artery is considered as a major factor in the failure of the coronary artery bypass grafts. However, the physiological effects are not very clear. The aim is to research the impact of competitive flow caused by different left anterior descending (LAD) artery stenosis degrees on hemodynamics in internal thoracic artery (ITA) bypass graft. An idealized ITA-LAD model was built in CAD tools. The degree of the competitive flow was divided into five classes according to different LAD stenosis degrees: higher (no stenosis), secondary (30% stenosis), reduced (50% stenosis), lower (75% stenosis) and no competitive flow (fully stenosis). Finite volume method was employed for the numerical simulation. The flow velocity distributions, wall shear stress and oscillatory shear index were analyzed. Results showed that higher competitive flow in the bypass graft would produce unbeneficial wall shear stress distribution associating with endothelial dysfunction and subsequent graft failure. The coronary bypass graft surgery was preferred to be carried out when the LAD stenosis was higher than 75%.

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