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Characterization of Formacell Lignin Derived from Black Liquor as a Potential Green Additive for Advanced Biocomposites 被引量:1
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作者 Sri Hidayati Eugenia Fonny Budiyanto +7 位作者 Hadi Saputra Sutopo Hadi Apri Heri Iswanto Nissa Nurfajrin Solihat Petar Antov Lee Seng Hua Widya Fatriasari MohdSapuan Salit 《Journal of Renewable Materials》 SCIE EI 2023年第6期2865-2879,共15页
Black liquor is obtained as a by-product of the pulping process,which is used to convert biomass into pulp by removing lignin,hemicelluloses and other extractives from wood to free cellulose fibers.Lignin represents a... Black liquor is obtained as a by-product of the pulping process,which is used to convert biomass into pulp by removing lignin,hemicelluloses and other extractives from wood to free cellulose fibers.Lignin represents a major constituent in black liquor,with quantities varying from 20%to 30%,of which a very low share is used for manufacturing value-added products,while the rest is mainly burned for energy purposes,thus underestimating its great potential as a raw material.Therefore,it is essential to establish new isolation and extraction methods to increase lignin valorization in the development of bio-based chemicals.The aim of this research work was to determine the effect of KOH or ethanol concentration as an isolation agent on lignin yields and the chemical characteristics of lignin isolated from formacell black liquor of oil palm empty fruit bunch(OPEFB).Isolation of lignin was carried out using KOH with various concentrations ranging from 5%to 15%(w/v).Ethanol was also used to precipitate lignin from black liquor at concentrations varying from 5%to 30%(v/v).The results obtained showed that the addition of KOH solution at 12.5%and 15%concentrations resulted in better lignin yield and chemical properties of lignin,i.e.,pH values of 3.86 and 4.27,lignin yield of 12.78%and 14.95%,methoxyl content of 11.33%and 10.13%,and lignin equivalent weights of 476.25 and 427.03,respectively.Due to its phenolic structure and rich functional groups that are favorable for modifications,lignin has the potential to be used as a green additive in the development of advanced biocomposite products in various applications to replace current fossil fuel-based material,ranging from fillers,fire retardants,formaldehyde scavengers,carbon fibers,aerogels,and wood adhesives. 展开更多
关键词 Formacell black liquor lignin properties KOH ETHANOL oil palm empty fruit bunch advanced biocomposite
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Recent applications of carbon-based composites in defence industry: A review 被引量:7
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作者 M.M.Harussani S.M.Sapuan +2 位作者 Gohar Nadeem Tahrim Rafin W.Kirubaanand 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2022年第8期1281-1300,共20页
Carbon-based composites, including carbon reinforced composites and carbon-matrix composites, in defence technologies have raised a lot of attention due to its significant physical capabilities, superior thermal and m... Carbon-based composites, including carbon reinforced composites and carbon-matrix composites, in defence technologies have raised a lot of attention due to its significant physical capabilities, superior thermal and mechanical stability, and its eco-friendly nature. Carbon-based composite which incorporating with various carbonaceous materials such as coke, char, black carbon, activated carbon, carbon fibre and other carbon nanomaterials (carbon nanotubes, carbon nanofibres, graphene and graphite) are the greatest viable option for the development of advanced defence technologies. In this review article the characteristics of carbon-based materials and its composites are discussed for their distinct application in defence sectors;aeronautics, maritime, automotive, electronics, energy storage, electromagnetic interference (EMI) shielding and structures. The origin of carbonaceous materials and its production techniques were discussed. Carbon-based composites have a promising future in defence technology, particularly in chemical sensors, drug delivery agents, radar technologies, and nanocomposites due to their low cost, easy availability, flexibility in design and processing. 展开更多
关键词 Carbon materials CHAR CARBON CNT GRAPHENE Composite Defence technology
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Physical and damping properties of kenaf fibre filled natural rubber/thermoplastic polyurethane composites 被引量:3
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作者 A.M.Noor Azammi S.M.Sapuan +1 位作者 Mohamad R.Ishak Mohamed T.H.Sultan 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第1期29-34,共6页
The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide(NaOH) on physical and dynamic mechanical analysis(DMA) viscoelastic properties of kenaf fibre filled natural rubber(NR)/ther... The paper presents the investigation of the effect of alkaline treatment of sodium hydroxide(NaOH) on physical and dynamic mechanical analysis(DMA) viscoelastic properties of kenaf fibre filled natural rubber(NR)/thermoplastic polyurethane(TPU) composites.The treated kenaf fiber,NR and TPU were weighed and proportioned according to the required compositions and were blended using hot mixed Brabender machine.The polymer composites were then fabricated using the hot press to form a sample board.The sample was cut and prepared and water absorption,density,thickness swelling and DMA tests were performed.As far as physical properties are concerned,composites with the highest NR amount of shows the best results,which indicates good fiber bonding adhesion.The polymer composites with the highest amount of TPU shows the highest damping properties at high temperature. 展开更多
关键词 KENAF fiber ALKALINE treatment THERMOPLASTIC POLYURETHANE Natural rubber Dynamic mechanical analysis
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Conceptual Design of Natural Fiber Composites as a Side-Door Impact Beam Using Hybrid Approach 被引量:2
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作者 M.A.Shaharuzaman S.M.Sapuan +1 位作者 M.R.Mansor M.Y.M.Zuhri 《Journal of Renewable Materials》 SCIE EI 2020年第5期549-563,共15页
This paper presents the conceptual design stage in the product development process of a natural fiber composites of the side-door impact beam,which starts from idea generation to the selection of the best design conce... This paper presents the conceptual design stage in the product development process of a natural fiber composites of the side-door impact beam,which starts from idea generation to the selection of the best design concept.This paper also demonstrates the use of the integrated Theory of Inventive Problem Solving(Function-Oriented Search)(TRIZ(FOS))and Biomimetics method,as well as the VIseKriterijumska Optimizacija I Kompromisno Resenje(VIKOR)method.The aim of this study was to generate design concepts that were inspired by nature and to select the best design concept for the composite side-door impact beam.Subsequently,eight design concepts were generated using the TRIZ(FOS)-Biomimetics method and finite element analysis were used to analyse their performance and weight criteria using ANSYS software.VIKOR method was used as the multiple criteria decision making tools to compare their performances,weight and cost criteria.As a result,design concepts B-03 and C-02 were ranked as the first and second best,with VIKOR value of 0.0156 and 0.1178,respectively,which satisfied the conditions in VIKOR method.This paper shows that the integrated method of TRIZ(FOS)-Biomimetics and VIKOR can assist researchers and engineers in developing designs that are inspired by nature,as well as in selecting the best design concept using a systematic strategy and justified solutions during the conceptual design stage. 展开更多
关键词 Theory of inventive problem solving TRIZ(FOS) biomimetics VIseKriterijumska Optimizacija I Kompromisno Resenje VIKOR side-door impact beam
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Manufacturing Process Selection of “Green” Oil Palm Natural Fiber Reinforced Polyurethane Composites Using Hybrid TEA Criteria Requirement and AHP Method for Automotive Crash Box 被引量:2
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作者 N.S.B.Yusof S.M.Sapuan +1 位作者 M.T.H.Sultan M.Jawaid 《Journal of Renewable Materials》 SCIE EI 2020年第6期647-660,共14页
In this study,the best manufacturing process will be selected to build an automotive crash box using green oil palm natural fibre-reinforced polyurethane composite materials.This paper introduces an approach consist o... In this study,the best manufacturing process will be selected to build an automotive crash box using green oil palm natural fibre-reinforced polyurethane composite materials.This paper introduces an approach consist of technical aspects(T),the economic point of view(E)and availability(A),and it’s also called as TEA requirement.This approach was developed with the goal of assisting the design engineer in the selection of the best manufacturing process during the design phase at the criteria selection stage.In this study,the TEA requirement will integrate with the analytical hierarchy process(AHP)to assist decision makers or manufacturing engineers in determining the most appropriate manufacturing process to be employed in the manufacture of a composite automotive crash box(ACB)at the early stage of the product development process.It is obvious that a major challenge in the manufacturing selection process is lack of information regarding manufacturing of ACB using natural fibre composite(NFC).There have been no previous studies that examined ranking manufacturability processes in terms of their suitability.Therefore,the TEA-AHP hybrid method was introduced to provide unprejudiced criteria-ranking selection prior to evaluation of pairwise comparisons.At the end of this study,the pulforming process was selected as the best manufacturing process for fabrication of the ACB structural component. 展开更多
关键词 Manufacturing process selection automotive crash box natural fibre composites TEA requirement
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Decision Support Strategy in Selecting Natural Fiber Materials for Automotive Side-Door Impact Beam Composites 被引量:3
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作者 M.A.Shaharuzaman S.M.Sapuan +1 位作者 M.R.Mansor M.Y.M.Zuhri 《Journal of Renewable Materials》 SCIE 2019年第10期997-1010,共14页
The enforcement on sustainable design and environmental-friendly products has attracted the interest of researchers and engineers in the context of replacing metals and synthetic fibers with natural based fibers,espec... The enforcement on sustainable design and environmental-friendly products has attracted the interest of researchers and engineers in the context of replacing metals and synthetic fibers with natural based fibers,especially in the automotive industry.However,studies on sustainable natural fiber material selection in the automotive industry are limited.Evaluation for the side-door impact beam was conducted by gathering product design specification from literature which amounted to seven criteria and it was forwarded to ten decision makers with automotive engineering and product design background for evaluation.The weightage required for decision-making was obtained using the Analytic Hierarchy Process(AHP)method based on six criteria.Following this,the best natural fiber materials to be used as reinforcement in polymer composites were selected using the VIseKriterijumska Optimizacija I Kompromisno Resenje(VIKOR)method.The results using both the AHP and VIKOR method showed that kenaf was the best natural fiber for the side-door impact beam composites.The result showed the lowest VIKOR value,QA1=0.0000,which was determined to be within the acceptable advantage and acceptable stability conditions.It can be concluded that the application of integrated AHP-VIKOR method resulted in a systematic and justified solution towards the decision-making process. 展开更多
关键词 Materials selection natural fiber side-door impact beam Analytic Hierarchy Process(AHP) VIseKriterijumska Optimizacija I Kompromisno Resenje(VIKOR)
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Effect of carbon nanotube and silicon carbide on microstructure and dry sliding wear behavior of copper hybrid nanocomposites 被引量:1
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作者 H.M.MALLIKARJUNA C.S.RAMESH +2 位作者 P.G.KOPPAD R.KESHAVAMURTHY K.T.KASHYAP 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第12期3170-3182,共13页
Microstructure and tribological properties of copper-based hybrid nanocomposites reinforced with copper coatedmultiwalled carbon nanotubes (MWCNTs) and silicon carbide (SiC) were studied. Carbon nanotube was varied fr... Microstructure and tribological properties of copper-based hybrid nanocomposites reinforced with copper coatedmultiwalled carbon nanotubes (MWCNTs) and silicon carbide (SiC) were studied. Carbon nanotube was varied from 1% to 4% withsilicon carbide content being fixed at 4%. The synthesis of copper hybrid nanocomposites involves ball milling, cold pressing andsintering followed by hot pressing. The developed hybrid nanocomposites were subjected to density, grain size, and hardness tests.The tribological performances of the nanocomposites were assessed by carrying out dry sliding wear tests using pin-on-steel disctribometer at different loads. A significant decrease in grain size was observed for the developed hybrid composites when comparedwith pure copper. An improvement of 80% in the micro-hardness of the hybrid nanocomposite has been recorded for 4% carbonnanotubes reinforced hybrid composites when compared with pure copper. An increase in content of CNTs in the hybridnanocomposites results in lowering of the friction coefficient and wear rates of hybrid nanocomposites. 展开更多
关键词 COPPER carbon nanotubes (CNTs) SiC MICROHARDNESS wear mechanisms NANOCOMPOSITE
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Characterization of Reinforced Carbon Composites with Full Field Measurements: Long Gauge Length Compressive Apparatus
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作者 Mathieu Colin de Verdiere Alexandros A. Skordos Andrew Walton 《Open Journal of Composite Materials》 2013年第1期7-15,共9页
A new compressive testing apparatus is developed and used in this research. It has long gauge length to allow digital image correlation monitoring and anti buckling guides to prevent buckling. It allows the optical re... A new compressive testing apparatus is developed and used in this research. It has long gauge length to allow digital image correlation monitoring and anti buckling guides to prevent buckling. It allows the optical recording of strains and displacements. The novel setup is used to study the compressive response of tufted and untufted Carbon non crimp fabric composites with full field measurements. Experimental results show that the specimens are not bending in the apparatus under compression. Results also show reduced strain concentrations and a large strain field that provides a good environment for material compressive stiffness characterization. The test proves particularly successful for bias direction layup of [+45/-45] for which large damage mechanism occurs. However for [0/90] specimens a scatter in compressive ultimate strength was noticed which is due to the difficulty to prepare specimens with best minute accurate geometry. The compressive apparatus has shown to be a good alternative to existing setups and to provide significantly more information as well as having the possibility to be used in dynamics with a drop tower. 展开更多
关键词 CARBON COMPOSITE Compression Testing Full FIELD Measurements
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Material Selection of a Natural Fibre Reinforced Polymer Composites using an Analytical Approach
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作者 M.Noryani S.M.Sapuan +2 位作者 M.T.Mastura M.Y.M.Zuhri E.S.Zainudin 《Journal of Renewable Materials》 SCIE 2019年第11期1165-1179,共15页
Material selection has become a critical part of design for engineers,due to availability of diverse choice of materials that have similar properties and meet the product design specification.Implementation of statist... Material selection has become a critical part of design for engineers,due to availability of diverse choice of materials that have similar properties and meet the product design specification.Implementation of statistical analysis alone makes it difficult to identify the ideal composition of the final composite.An integrated approach between statistical model and micromechanical model is desired.In this paper,resultant natural fibre and polymer matrix from previous study is used to estimate the mechanical properties such as density,Young’s modulus and tensile strength.Four levels of fibre loading are used to compare the optimum natural fibre reinforced polymer composite(NFRPC).The result from this analytical approach revealed that kenaf/polystyrene(PS)with 40%fibre loading is the ideal composite in automotive component application.It was found that the ideal composite score is 1.156 g/cm^(3),24.2 GPa and 413.4 MPa for density,Young’s modulus and tensile strength,respectively.A suggestion to increase the properties on Young’s modulus are also presented.This work proves that the statistical model is well incorporated with the analytical approach to choose the correct composite to use in automotive application. 展开更多
关键词 Material selection natural fibre reinforced polymer composites rule of mixtures
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Microstructure and dry sliding wear behavior of Cu-Sn alloy reinforced with multiwalled carbon nanotubes 被引量:3
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作者 H.M.MALLIKARJUNA K.T.KASHYAP +2 位作者 P.G.KOPPAD C.S.RAMESH R.KESHAVAMURTHY 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2016年第7期1755-1764,共10页
Multiwalled carbon nanotubes (MWCNTs) reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocompo... Multiwalled carbon nanotubes (MWCNTs) reinforced Cu-Sn alloy based nanocomposite was developed by powder metallurgy route. The mass fraction of CNTs was varied from 0 to 2% in a step of 0.5%. The developed nanocomposites were subjected to density, hardness, electrical conductivity, and friction and wear tests. The results reveal that the density of nanocomposite decreases with the increase of the mass fraction of CNTs. A significant improvement in the hardness is noticed in the nanocomposite with the addition of CNTs. The developed nanocomposites show low coefficient of friction and improved wear resistance when compared with unreinforced alloy. At an applied load of 5 N, the coefficient of friction and wear loss of 2%CNTs reinforced Cu-Sn alloy nanocomposite decrease by 72% and 68%, respectively, compared with those of Cu-Sn alloy. The wear mechanisms of worn surfaces of the composites are reported. In addition, the electrical conductivity reduces with the increase of the content of CNTs. 展开更多
关键词 Cu-Sn alloy carbon nanotube NANOCOMPOSITES powder metallurgy MICROSTRUCTURE sliding wear
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Crashworthiness performance of hybrid kenaf/glass fiber reinforced epoxy tube on winding orientation effect under quasi-static compression load 被引量:5
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作者 A.B.M.Supian S.M.Sapuan +2 位作者 M.Y.M.Zuhri E.S.Zainudin H.H.Ya 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2020年第5期1051-1061,共11页
This research was aimed to study the effect winding orientation on the crashworthiness performance of hybrid tube.The specimens tested under quasi-static compression load involve of three winding parameters(q?30,45a... This research was aimed to study the effect winding orientation on the crashworthiness performance of hybrid tube.The specimens tested under quasi-static compression load involve of three winding parameters(q?30,45and 70)of hybrid kenaf/glass fiber reinforced epoxy and glass fiber reinforced epoxy as contrast specimen.The automated filament winding technique has been used in fabrication of hybrid and non-hybrid composite tube and crashworthiness performance was investigated experimentally.The effects of winding orientation on energy absorption capabilities and crashworthiness characteristic were investigated through quasi-static compression load and the result are compared with the glass fiber composite tube to justify the capability of hybrid natural/synthetic as energy absorption application.Hybridized samples proved to enhancing the progressive crushing capability as combination of local buckling,delaminate and brittle fracturing as progressive crushing modes.In the view of winding orientation aspect,the results of high winding orientation of hybrid composite tube elevated the crush load efficiency,specific energy absorption and energy absorption capability compared to glass composite tube(GFRP).The hybrid kenaf/glass composite tube with high winding orientation showed the best winding orientation to enhance the energy absorber characteristics as energy absorption application. 展开更多
关键词 composite LAMINATE WINDING
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Conceptual design of oil palm fibre reinforced polymer hybrid composite automotive crash box using integrated approach 被引量:5
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作者 N S B YUSOF S M SAPUAN +1 位作者 M T H SULTAN M JAWAID 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第1期64-75,共12页
A hybrid conceptual design approach was introduced in this study to develop a conceptual design of oil palm polymer composite automotive crash box(ACB). A combination of theory of inventive problem solving(TRIZ), morp... A hybrid conceptual design approach was introduced in this study to develop a conceptual design of oil palm polymer composite automotive crash box(ACB). A combination of theory of inventive problem solving(TRIZ), morphological charts and biomimetics was applied where the foremost requirements in terms of the material characteristics, function specifications, force identification, root cause analysis, geometry profile and design selection criteria were considered. The strategy was to use creations of nature to inspire five innovative conceptual designs of the ACB structure and the AHP method was applied to perform the pairwise analysis of selecting the best ACB conceptual design. A new conceptual design for a composite ACB was conceived bearing in mind the properties of natural fibre, unlike those of conventional materials such as steel alloys and aluminium alloys. The design with the highest ranking(26.6 %) was chosen as the final conceptual design, which was the one with a honeycomb structure for the outermost profile, reinforced with a spider web structure inside the part, supported by fibre foam structure extracted from the woodpecker sponge tissue at the centre to maximize the energy absorption capability. The new design could solve the problem of bending collapse which is a major cause of failure to absorb maximum impact energy for ACB during collision. However, the final conceptual design will still need several modifications for production and assembly purposes, which will be completed in a further study. 展开更多
关键词 conceptual design automotive crash box hybrid method concept selection method
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Damage Monitoring in Composite Stiffened Skin Using Fiber Bragg Grating under Tensile and Three-Point Loading 被引量:1
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作者 Agus Trilaksono Naoyuki Watanabe +3 位作者 Hikaru Hoshi Atsushi Kondo Yutaka Iwahori Shinichi Takeda 《Journal of Mechanics Engineering and Automation》 2013年第4期227-237,共11页
One of the problems associated with loading a fully composite structure with joints is that the loads are not linear through the neutral axis of the structure but are collinear; this induces additional moment and crea... One of the problems associated with loading a fully composite structure with joints is that the loads are not linear through the neutral axis of the structure but are collinear; this induces additional moment and creates a load in the normal direction, which is typically a critical load because it can create delamination and can only be withstood if it is small. Another problem is that the structure is difficult to inspect using conventional methods because of limited accessibility. With fiber Bragg grating (FBG), the problem can potentially be solved in structures with a stiffness mismatch. The model used to represent the problem above is a composite stiffened skin with two loading cases: tensile and three-point bending. Additionally, FBG is used to monitor and characterize the delamination caused by both loading cases. Finite element modeling (FEM) with traction versus separation theory is performed to determine the critical area on the specimen for placement of the FBG before manufacturing and testing. In this research, FBG can successfully monitor and characterize delamination caused by both loading cases in structures that have mismatched stiffnesses. Also, FBG can predict the delamination growth quantitatively. A spectrum graph of the FBG results can be used to replace a conventional mechanical graph for use in structural health monitoring. 展开更多
关键词 Carbon fiber composite structural health monitoring DELAMINATION joints/joining smart structure
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Composites for electric vehicles and automotive sector: A review 被引量:2
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作者 Adil Wazeer Apurba Das +2 位作者 Chamil Abeykoon Arijit Sinha Amit Karmakar 《Green Energy and Intelligent Transportation》 2023年第1期86-108,共23页
The automotive sector is undergoing a significant transformation to address critical challenges affecting consumers and the climate.One of the most difficult tasks is reducing the weight of vehicles in order to minim... The automotive sector is undergoing a significant transformation to address critical challenges affecting consumers and the climate.One of the most difficult tasks is reducing the weight of vehicles in order to minimize energy consumption.A ten percent decrease in curb weight is predicted to result in a six to eight percent reduction in energy consumption.Composite materials having better strength to weight ratio are one of the finest options for planning,designing and manufacturing of the lightweight components.In automobile sector,employment of composite materials would reduce the weight of electric vehicles as well as influence their aerodynamic properties.Therefore,it would decrease the consumption of fuel as well by cutting down harmful emissions and particulate matter.Numerous developments in such technologies are studied over the last decade by automobile establishments and academic researchers.Fiber-reinforced polymers,particularly those established on glass and carbon fibers,have attracted attention of the automobile sector due to their high performance and lesser weight.This paper reviews the applications of various types of composite materials and the fabrication techniques of such composites in electric vehicles and automobiles.Furthermore,a comprehensive data breakdown of the lightweight materials statistics and figures on market analysis of high performance composite is presented.Finally,a discussion is made on the different applications of these composites.Hence,the details presented in this study should be useful for automobile companies to align with NET ZERO global mission while sustaining their businesses. 展开更多
关键词 COMPOSITES Electric vehicles Fabrication techniques Hybrid vehicles
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Vibration of Three-Layered FGM Cylindrical Shells with Middle Layer of Isotropic Material for Various Boundary Conditions
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作者 Muhammad Nawaz Naeem Awais Gul Khan +2 位作者 Shahid Hussain Arshad Abdul Ghafar Shah Madiha Gamkhar 《World Journal of Mechanics》 2014年第11期315-331,共17页
In the present study, vibration analysis of a three-layered cylindrical shell is performed whose inner and outer layers are composed of functionally graded materials whereas the middle one is assumed to be of isotropi... In the present study, vibration analysis of a three-layered cylindrical shell is performed whose inner and outer layers are composed of functionally graded materials whereas the middle one is assumed to be of isotropic material. This formation of a cylindrical shell influences stiffness modulii and the resultant material properties. The shell problem is formulated from the constitutive relations of stresses and strains with the displacement deformations and they are taken from Love’s thin shell theory. This problem is transformed into the integral form by evaluating the expressions for the strain and kinetic energies of the shell. Rayleigh-Ritz method is employed to solve the shell dynamic equations. Vibration characteristics of these cylindrical shells are investigated for a number of physical parameters and configurations of the fabrication of shells. The axial modal dependence is approximated by the characteristic beam functions that satisfy the boundary conditions. Results evaluated, show good agreement with the open literature. 展开更多
关键词 Functionally Graded MATERIAL ISOTROPIC MATERIAL Three-Layered Cylindrical SHELL Love’s Thin SHELL Theory Rayleigh-Ritz Method Natural Frequency
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Automatic Damage Detection and Monitoring of a Stitch Laminate System Using a Fiber Bragg Grating Strain Sensor
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作者 Agus Trilaksono Naoyuki Watanabe +2 位作者 Atsushi Kondo Hikaru Hoshi Yutaka Iwahori 《Open Journal of Composite Materials》 2014年第1期47-60,共14页
There are numerous aspects and questions related to the use of composite materials for primary structures in aircraft where the structural integrity is the most important factor. This is especially true if the main co... There are numerous aspects and questions related to the use of composite materials for primary structures in aircraft where the structural integrity is the most important factor. This is especially true if the main concerns are that the material should have good reliability and durability for the primary structural application. Composite laminates are highly sensitive to out-of-plane failure due to their low inter laminar fracture toughness. An alternate method to increase the damage resistance is through three-dimensional fibrous reinforcement such as through-the-thickness stitching with a single fiber as the thread. Recent studies have shown that the stitching of standard laminates can enhance damage tolerance to levels obtainable with toughened resin systems. However, for next-generation aircraft, material improvement alone is not enough to assure or increase the safety and reliability of the structure. Continuous damage monitoring during operation will become an important issue in aircraft safety. Embed ding fiber Bragg grating (FBG) technology into the composite structure as strain sensors could potentially solve the above problem because the FBG can be used to detect and characterize the damage before it reaches a critical stage. The model used to represent this problem is a 6 × 6 Vectran stitched carbon/ epoxy laminate under tension loading, and the real-time monitoring using the FBG strain sensors is combined with acoustic emissions that were conducted during the test. A numerical laminate theory using a rebar element and first-ply failure criterion is performed to determine the preferred area on the specimen for the placement of the FBG before manufacturing and testing. Experiments are presented to determine the damage growth that was quantified with an ultrasonic (water immersion) c-scan. In this research, the FBG successfully detected and characterized the damage in the carbon/epoxy stitch laminate caused in tension loading cases. The FBG is enhanced with acoustic emission data and can quantitatively predict the damage growth. 展开更多
关键词 Carbon Fiber STITCH LAMINATE DAMAGE TOLERANCE Structural HEALTH MONITORING
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Investigation of the Mechanical Behavior of a Thin Composite Stiffened Skin with a Combined Joint
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作者 Agus Trilaksono Naoyuki Watanabe +3 位作者 Hikaru Hoshi Atsushi Kondo Yutaka Iwahori Shinichi Takeda 《Journal of Mechanics Engineering and Automation》 2013年第7期428-440,共13页
Many joint models available to predict secondary bending moments in the structure have a stiffness mismatch, while this type of structure widely used in aircraft. To determine how to represent a structure with a stiff... Many joint models available to predict secondary bending moments in the structure have a stiffness mismatch, while this type of structure widely used in aircraft. To determine how to represent a structure with a stiffness mismatch in a combined joint (bonded/riveted), a non-linear finite element analysis was performed. The detailed validation of this analysis identified the composite stiffened skin as the most suitable model in three dimensions. The use of this model for validating the secondary bending moment to calculate the behavior of the stiffener edge is straightforward and reliable. Experiments were performed to determine the distribution of the load in a combined joint under a tensile load that creates a secondary bending moment in a structure with a stiffness mismatch. The influence of related joint design considerations on the load transferred by the joint were examined through a finite element parameter analysis. The results are compared to determine best approach to predict the mechanical behavior at the edge of the stiffener. A close agreement between the finite element analysis and experimental results was obtained. Test observations using a C-scan compared well with the predictions of the onset of crack growth. 展开更多
关键词 Carbon fiber DELAMINATION joints/joining cohesive elements secondary bending moment.
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EMI shielding effectiveness of silver nanoparticle-decorated multi-walled carbon nanotube sheets
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作者 Wenming Zhao Mei Li +1 位作者 Zhongyi Zhang Hua-Xin Peng 《International Journal of Smart and Nano Materials》 SCIE EI 2010年第4期249-260,共12页
With the aim of exploring the excellent properties of multi-walled carbon nanotubes(MWNTs)in modern composite technologies,various macrostructures of nanotubes have been developed from one to three dimensions,e.g.fibe... With the aim of exploring the excellent properties of multi-walled carbon nanotubes(MWNTs)in modern composite technologies,various macrostructures of nanotubes have been developed from one to three dimensions,e.g.fibers,networks,sheets(buckypapers)and pellets.The MWNT sheets discussed here were fabricated by a vacuum filtration procedure,a process that has potential for large-scale manufacturing.In order to further enhance the transport properties of MWNT sheets by reducing the contact resistance between nanotubes,highly conductive silver nanoparticles were introduced by an in situ photochemical reduction method.TEM analysis showed that highly acid-treated MWNTs dispersed in the presence of Triton X-100(TX-100)under UV light was a controllable processing method for preparation of a narrow size distribution of silver nanoparticles that were anchored onto the nanotubes.The free-standing MWNT/Ag nanohybrid sheets possessed a sharp increase in electrical conductivity from 27.7 to 40.0 S/cm,which consequently led to a much improved electromagnetic interference shielding effectiveness(SE).In principle,the SE could reach 3500 dB/cm with a thickness of 110µm,which matched the experimental results well.In addition,the nanohybrid sheets are robust and can be folded with a thickness of 30µm,which opens a promising way to integrate MWNT sheets into conventional composite laminates. 展开更多
关键词 carbon nanotube silver nanoparticle electromagnetic shielding effectiveness NANOHYBRID
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