scholarly journals Ultrahigh Ballistic Resistance of Twisted Bilayer Graphene

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 206
Author(s):  
Qing Peng ◽  
Sheng Peng ◽  
Qiang Cao
Keyword(s):  
Weight Ratio ◽  
High Strength ◽  
Bilayer Graphene ◽  
Energy Propagation ◽  
Dynamic Simulations ◽  
Protective Material ◽  
Impact Performance ◽  
Ballistic Resistance ◽  
Twisted Bilayer Graphene ◽  
The Impact

Graphene is a good candidate for protective material owing to its extremely high stiffness and high strength-to-weight ratio. However, the impact performance of twisted bilayer graphene is still obscure. Herein we have investigated the ballistic resistance capacity of twisted bilayer graphene compared to that of AA-stacked bilayer graphene using molecular dynamic simulations. The energy propagation processes are identical, while the ballistic resistance capacity of the twisted bilayer graphene is almost two times larger than the AA-bilayer graphene. The enhanced capacity of the twisted bilayer graphene is assumed to be caused by the mismatch between the two sheets of graphene, which results in earlier fracture of the first graphene layer and reduces the possibility of penetration.

scholarly journals Experimental Tests and Reliability Analysis of the Cracking Impact Resistance of UHPFRC

Fibers ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 74
Author(s):  
Hussain A. Jabir ◽  
Sallal R. Abid ◽  
Gunasekaran Murali ◽  
Sajjad H. Ali ◽  
Sergey Klyuev ◽  
...  
Keyword(s):  
High Performance ◽  
Steel Fiber ◽  
Impact Resistance ◽  
High Strength ◽  
Experimental Tests ◽  
Fiber Reinforced Concrete ◽  
Fiber Types ◽  
Impact Performance ◽  
High Performance Fiber ◽  
The Impact

Ultra-high performance (UHP) concrete is a special type of fibrous cementitious composite that is characterized by high strength and superior ductility, toughness, and durability. This research aimed to investigate the resistance of ultra-high performance fiber-reinforced concrete (UHPFRC) against repeated impacts. An adjusted repeated drop mass impact test was adopted to evaluate the impact performance of 72 UHPFRC disc specimens. The specimens were divided into six mixtures each of 12 discs. The only difference between the mixtures was the types of fibers used, while all other mixture components were the same. Three types of fibers were used: 6 mm micro-steel, 15 mm micro-steel, and polypropylene. All mixtures included 2.5% volumetric content of fibers, however with different combinations of the three fiber types. The test results showed that the mixtures with the 15 mm micro-steel fiber absorbed a higher number of impact blows until cracking compared to other mixtures. The mixture with pure 2.5% of 15 mm micro-steel fiber exhibited the highest impact resistance, with percentage increases over the other mixtures ranging from 25 to 140%. In addition, the Weibull distribution was used to investigate the cracking impact resistance of UHP at different levels of reliability.

scholarly journals Hyperelastic modelling of yarn structures for dynamic applications

2018 ◽  
Vol 183 ◽  
pp. 01031
Author(s):  
Pietro del Sorbo ◽  
Jeremie Girardot ◽  
Frederic Dau ◽  
Ivan Iordanoff
Keyword(s):  
High Performance ◽  
Three Dimensional ◽  
Weight Ratio ◽  
High Strength ◽  
Material Model ◽  
Linear Elastic ◽  
Mesoscopic Models ◽  
First Results ◽  
Hyperelastic Model ◽  
The Impact

Dry fabrics comprised of high performance polymeric fibers have been widely used as protection layers in structures submitted to high velocity impacts (HVI). Their outstanding impact energy dissipation ability combined with an high strength-to-weight ratio make them a preferable choice in different applications such as bullet vests or blade containment systems over standard materials. Among the different approaches adopted to study these structures numerical methods assume a central role. Thanks to their reduced costs and the related possibility of evaluating the effects of single phenomena, they are often used to predict the structure ballistic limits or to study the physical events which occur during the penetration. Among the different strategies adopted to model a fabric, mesoscopic models have been largely adopted by different authors. These models assume the yarns as a continuum body while the fabric geometry is explicitly described. Nowadays yarn material models are universally assumed to be linear elastic and orthotropic. This modelling approach mostly focuses on the longitudinal behaviour of the yarn, however fiber-scale analyses and experimental results shows the importance of three-dimensional stress state on the ballistic limit. In order to obtain a three-dimensional description of the yarn strain state during the impact, a novel hyperelastic model for yarn structures here is developed. In a first step, fiber-level preliminary analyses have been performed to obtain the effective behaviour of these structure under the projectile collision. In the second step, the hyperelastic model has been implemented and identified thanks to microscopic elementary tests. Finally, a continuum model of the yarn have been performed. First results show the relevance of the hyperelastic model compared to the fiber-level observation and enhance the limit of the classical linear elastic material model.

Dynamic Analysis of Sandwiched Composite Foldable Structure under Heavy Vehicle Load

2011 ◽  
Vol 110-116 ◽  
pp. 2331-2336
Author(s):  
Norazman Mohamad Nor ◽  
S.T. Agusril ◽  
Mohamed Yusof Alias ◽  
A.M.A. Zaidi ◽  
Abdullah Shohaimi
Keyword(s):  
Weight Ratio ◽  
High Strength ◽  
Structural Element ◽  
Dynamic Simulations ◽  
Primary Material ◽  
Long Span ◽  
Disaster Relief Operations ◽  
Rapid Construction ◽  
Relief Operations ◽  
Strength And Stiffness

Foldable structures are very important for the purpose of rapid construction and bridging system. Such structural element can be utilized in disaster relief operations. In the early days, portable structure such as military bridges were made from steel, causing the weight of the structure to be huge, subsequently it will be costly to operate. To overcome these problems, aluminium and metal alloy were introduced to reduce the weight of such structure. Use of composite material such as Carbon Fiber Reinforced Polymer (CFRP) emerges as a lighter alternative being considered to be the primary material for the portable structure. The use of the CFRP as a primary material is due to its high strength to weight ratio, thus make it lighter than steel and other alloy. In this research, a long-span portable structure is analysed and designed using finite element method. Several dynamic simulations are made to test various possible lay-up including use of core in order to increase strength and stiffness of the member. From the trials it can be concluded that with proper design and fabrication, CFRP is capable of carrying the designed dynamic load. Furthermore, use of core layers for top flange can improve the performance of the structure significantly, while use of core to the webs stiffen the webs against buckling and further improve the overall performance of the structure.

scholarly journals Mechanical Characterization of TiO2 nanoparticles based on Glass Fiber Reinforced Polymer Composite

2021 ◽  
Vol 1206 (1) ◽  
pp. 012006
Author(s):  
Abhishek Singh ◽  
S. C. Jayswal
Keyword(s):  
Glass Fiber ◽  
Polymer Composite ◽  
Composite Laminates ◽  
Weight Ratio ◽  
High Strength ◽  
Bending Stiffness ◽  
Flexural Properties ◽  
Nano Composite ◽  
Set Up ◽  
The Impact

Abstract Nanotechnology has become the best truly developing innovation in the field of engineering science. Numerous examinations have been completed by different exploration researchers in the prior many years. In my examination work research, the impact of cross breed E-glass built up fiber with epoxy Nano composite. The Nano composite covers overlays were set up by hand layup procedures by shifting layers of Titanium Dioxide (TiO2) nanoparticles of 0.6% individually. The nano added substances are utilized to improve the strength from destroy opposition, hardness of the polymer composite and high strength to weight ratio. The Nano composite laminates this prepared are characterized by the compression and flexural test. The flexural properties of the glass fiber built up plastic improved with expansion of nanoTiO2 filler particles. At 0.6 wt% of TiO2 and having 12 layers the force at yield is 327.99N and bending stiffness 63.11 N/mm and in 9 layers force at yield is 149.06 and bending stiffness 36.22 N/mm. True interfacial bonding b/w the fiber and epoxy turned into the primary motive for reaching higher flexural properties.

scholarly journals Review on Multi-Pass Friction Stir Processing of Aluminium Alloys

2020 ◽  
Author(s):  
Oritonda Muribwathoho ◽  
Sipokazi Mabuwa ◽  
Velaphi Msomi
Keyword(s):  
Friction Stir Processing ◽  
Aluminium Alloys ◽  
Weight Ratio ◽  
High Strength ◽  
Fatigue Properties ◽  
Dissimilar Metals ◽  
Friction Stir ◽  
Aluminium Copper ◽  
The Impact ◽  
Welding Technique

Aluminium alloys have evolved as suitable materials for automotive and aircraft industries due to their reduced weight, excellent fatigue properties, high-strength to weight ratio, high workability/formability, and corrosion resistance. Recently, the joining of similar and dissimilar metals have achieved huge success in various sectors. The processing of soft metals like aluminium, copper, iron and nickel have been fabricated using friction stir processing. Friction stir processing (FSP) is a microstructural modifying technique that uses the same principles as the friction stir welding technique. In the majority of studies on FSP, the effect of process parameters on the microstructure was characterized after a single pass. However, multiple passes of FSP is another method to further modify the microstructure in aluminium castings. This study is aimed at reviewing the impact of multi-pass friction stir processed joints of aluminium alloys and to identify a knowledge gap. From the literature that is available on multi-pass FSP, it has been observed that the majority of the literature focused on the processing of plates than the joints. There is limited literature reporting on multi-pass friction stir processed joints. This then creates a need to study further on multi-pass friction stir processing on dissimilar aluminium alloys.

scholarly journals Impact Performance of Steel Fiber-Reinforced Self-Compacting Concrete against Repeated Drop Weight Impact

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 91
Author(s):  
Sallal R. Abid ◽  
Murali Gunasekaran ◽  
Sajjad H. Ali ◽  
Ahmed L. Kadhum ◽  
Thaar S. Al-Gasham ◽  
...  
Keyword(s):  
Steel Fiber ◽  
Impact Resistance ◽  
High Strength ◽  
Steel Fibers ◽  
Test Results ◽  
Fiber Reinforced ◽  
Self Compacting Concrete ◽  
Impact Performance ◽  
Free Falling ◽  
The Impact

The self-compacting concrete (SCC) was invented to overcome the compaction problems in deep sections, owing to its perfect workability characteristics. Steel fibers when used with SCC would affect the required fluidity characteristics but improve its impact resistance. In this research, an experimental work was conducted to evaluate the impact response of micro-steel fiber-reinforced SCC, under flexural impact. A 5.47 kg free-falling mass was dropped repeatedly from 100 mm height on the top center of 270 mm-length beam specimens. Eight mixtures with two design grades of 30 and 50 MPa were prepared to distinguish the normal and high-strength SCCs. The distinguishing variable for each design grade was the fiber content, where four volumetric contents of 0%, 0.5%, 0.75%, and 1.0% were used. The test results showed that the impact resistance and ductility were significantly improved due to the incorporation of micro-steel fibers. The percentage improvements were noticeably higher at failure stage than at cracking stage. For the 30 MPa mixtures, the maximum percentage improvements at cracking and failure stages were 543% and 836%, respectively. Weibull’s linear correlations with R2 values of 0.84 to 0.97 were obtained at the failure stage, which meant that the impact failure number followed the Wiebull distribution.

Stream of Variation Modeling and Analysis for Compliant Composite Part Assembly—Part I: Single-Station Processes

2016 ◽  
Vol 138 (12) ◽  
Author(s):  
Tingyu Zhang ◽  
Jianjun Shi
Keyword(s):  
New York ◽  
Composite Structures ◽  
Weight Ratio ◽  
High Strength ◽  
Laminated Plates ◽  
Composite Part ◽  
Modeling And Analysis ◽  
Single Station ◽  
Assembly Deviation ◽  
The Impact

Composite structures are widely used due to their superior properties, such as low density, high strength, and high stiffness-to-weight ratio (Mallick, 1993, Fiber-Reinforced Composites: Materials, Manufacturing, and Design, Marcel Dekker, New York). However, the lack of methodologies for variation modeling and analysis of composite part assembly has imposed a significant constraint on developing dimensional control for composite assembly processes. This paper develops a modeling method to predict assembly deviation for compliant composite parts in a single-station assembly process. The approach is discussed in two steps: considering the part manufacturing error (PME) only and considering both the PME and the fixture position error (FPE). Finite element method (FEM) and homogenous coordinate transformation are used to reveal the impact of the PME and the FPE. The validity of the method is verified with two case studies on assembly deviation prediction of two composite laminated plates considering the PME only and both the PME and the FPE, respectively. The proposed method provides the basis for assembly deviation prediction in the multistation composite assembly.

Formability Characteristics of Hot Stamped Ti6Al4V Sheets Electro-Chemically Modified on Surface for Biomedical Applications

2015 ◽  
Vol 639 ◽  
pp. 301-308
Author(s):  
Beatrice Valoppi ◽  
Stefania Bruschi ◽  
Andrea Ghiotti
Keyword(s):  
Chemical Composition ◽  
Biomedical Applications ◽  
Hot Stamping ◽  
Weight Ratio ◽  
High Strength ◽  
Acid Etching ◽  
Chemical Treatments ◽  
Chemically Modified ◽  
Surface Modified ◽  
The Impact

Over these last decades Ti6Al4V has been largely employed for biomedical applications because of its biocompatibility and high strength-to-weight ratio. According to several studies, the implantation success is strongly dependent on the characteristics of its surface, since the roughness and the chemical composition of the surface play an important role in the osseointegration of the implant and in its bioactivity, respectively.In this paper different thermo-electro-chemical treatments were applied to Ti6Al4V sheets to increase their roughness for biomedical applications. The Ti6Al4V sheets underwent three different treatments, namely acid etching, acid etching followed by anodization and etching in a hydrothermal reactor, and finally furnace annealing.After the etching and annealing treatments, the surface morphology of the samples were analysed through Scanning Electron Microscopy, while its chemical composition was identified through the Energy Dispersive Spectroscopy. The surface roughness and topography were evaluated by using a 3D profilometer. Furthermore, the bioactivity of the treated samples was evaluated by diving them in Simulated Body Fluid and then analysed through SEM and EDS analyses.Based on these results, the treatment assuring the best performance in terms of roughness and bioactivity was identified and then applied to tensile samples tested at 700°C and strain rates of 0.1 and 1s-1 to evaluate the impact of the surface treatment on the material formability and, therefore, to prove the feasibility of applying the hot stamping process to surface modified sheets.

scholarly journals The Impact Behaviour of Carbon Fiber-Epoxy Composite Leading Edge using Finite Element Method

2019 ◽  
Vol 8 (2) ◽  
pp. 2617-2622
Keyword(s):  
Finite Element ◽  
Weight Ratio ◽  
Leading Edge ◽  
High Strength ◽  
Failure Criteria ◽  
High Energy ◽  
Rigid Sphere ◽  
Impact Behaviour ◽  
Finite Element Software ◽  
The Impact

Composite material has been widely used in aircrafts due to its high strength to weight ratio that leads to weight saving of the aircrafts. Equally important, aircraft material should be tough i.e. it should have the ability to absorb high energy and thus resist fracture. The aircraft’s wing design requires the material to have high toughness as parts of the wing especially its leading edge is subjected to impact loadings. Using finite element software of LS-DYNA, this research focuses on studying the impact behaviour of composite panels that represent the leading edges of wings when the panels are subjected to rigid sphere projectile. Three shapes of panels are used: flat, semi-circular and semi ellipse while panels can be of 2, 4 and 8 layers to vary its thickness. The panels are made of laminated composites with woven carbon fibres and the angle of orientations are [0/90] n, [0/45]n and [45/-45]n where n will give the number of layer for the composite. The Mat-58 material type suitable for woven type fibre is used where failure criteria of Hashin is applied. It was found that the simulation results are in a very close agreement with the finding from experiments conducted earlier. Furthermore, the optimum stacking sequence was found to be the [0/45]2 stacking sequences

scholarly journals Impact of cutting parameters on machining of Ti-6Al-4V alloy: an experimental and FEM approach

2021 ◽  
Vol 12 ◽  
pp. 2
Author(s):  
Kathirvel Gobivel ◽  
Krishnaraju Srinivasaraju Vijaysekar ◽  
Gopalakrishnan Prabhakaran
Keyword(s):  
Three Dimensional ◽  
Cutting Speed ◽  
Weight Ratio ◽  
High Strength ◽  
Cutting Parameters ◽  
Von Mises Stress ◽  
Aerospace Material ◽  
Feed Force ◽  
Von Mises ◽  
The Impact

Titanium alloys are used as an aerospace material due to their inherent properties such as high strength to weight ratio, corrosion, and fracture resistance. However, the low conductivity and reactivity towards plastic deformation causes these materials to be difficult to cut category. The prediction of various parameters like chip formation and actual cutting forces are important factors for better machinability which involves lot of resources. To overcome such issues, this work proposes three-dimensional FE approach to simulate the machinability behavior of Ti-6Al-4V especially on conventional turning. The impact of cutting speed and feed rate on the cutting force, thrust force, feed force and surface roughness were analyzed experimentally for various conditions. The predicted machining forces showed strong correlation with the experimental results and the effective von mises stress were examined.

Sign in / Sign up

Export Citation Format

Share Document