Fiber reinforced polymer(FRP) composite materials are heterogeneous and anisotropic materials that do not exhibit plastic deformation. They have been used in a wide range of contemporary applications particularly in s...Fiber reinforced polymer(FRP) composite materials are heterogeneous and anisotropic materials that do not exhibit plastic deformation. They have been used in a wide range of contemporary applications particularly in space and aviation,automotive,maritime and manufacturing of sports equipment. Carbon fiber reinforced polymer(CFRP) and glass fiber reinforced polymer(GFRP) composite materials,among other fiber reinforced materials,have been increasingly replacing conventional materials with their excellent strength and low specific weight properties. Their manufacturability in varying combinations with customized strength properties,also their high fatigue,toughness and high temperature wear and oxidation resistance capabilities render these materials an excellent choice in engineering applications.In the present review study,a literature survey was conducted on the machinability properties and related approaches for CFRP and GFRP composite materials. As in the machining of all anisotropic and heterogeneous materials,failure mechanisms were also reported in the machining of CFRP and GFRP materials with both conventional and modern manufacturing methods and the results of these studies were obtained by use of variance analysis(ANOVA),artificial neural networks(ANN) model,fuzzy inference system(FIS),harmony search(HS) algorithm,genetic algorithm(GA),Taguchi's optimization technique,multi-criteria optimization,analytical modeling,stress analysis,finite elements method(FEM),data analysis,and linear regression technique. Failure mechanisms and surface quality is discussed with the help of optical and scanning electron microscopy,and profilometry. ANOVA,GA,FEM,etc. are used to analyze and generate predictive models.展开更多
Military missions in hostile environments are often costly and unpredictable,with squadrons sometimes facing isolation and resource scarcity.In such scenarios,critical components in vehicles,drones,and energy generato...Military missions in hostile environments are often costly and unpredictable,with squadrons sometimes facing isolation and resource scarcity.In such scenarios,critical components in vehicles,drones,and energy generators may require structural reinforcement or repair due to damage.This paper proposes a portable,on-site production method for molds under challenging conditions,where material supply is limited.The method utilizes large format additive manufacturing(LFAM)with recycled composite materials,sourced from end-of-life components and waste,as feedstock.The study investigates the microstructural effects of recycling through shredding techniques,using microscopic imaging.Three potential defense-sector applications are explored,specifically in the aerospace,automotive,and energy industries.Additionally,the influence of key printing parameters,particularly nonparallel plane deposition at a 45-degree angle,on the mechanical behavior of ABS reinforced with 20%glass fiber(GF)is examined.The results demonstrate the feasibility of this manufacturing approach,highlighting reductions in waste material and production times compared to traditional methods.Shorter layer times were found to reduce thermal gradients between layers,thereby improving layer adhesion.While 45-degree deposition enhanced Young's modulus,it slightly reduced interlayer adhesion quality.Furthermore,recycling-induced fiber length reduction led to material degradation,aligning with findings from previous studies.Challenges encountered during implementation included weak part adherence to the print bed and local excess material deposition.Overall,the proposed methodology offers a cost-effective alternative to traditional CNC machining for mold production,demonstrating its potential for on-demand manufacturing in resource-constrained environments.展开更多
The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolyme...The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.展开更多
文摘Fiber reinforced polymer(FRP) composite materials are heterogeneous and anisotropic materials that do not exhibit plastic deformation. They have been used in a wide range of contemporary applications particularly in space and aviation,automotive,maritime and manufacturing of sports equipment. Carbon fiber reinforced polymer(CFRP) and glass fiber reinforced polymer(GFRP) composite materials,among other fiber reinforced materials,have been increasingly replacing conventional materials with their excellent strength and low specific weight properties. Their manufacturability in varying combinations with customized strength properties,also their high fatigue,toughness and high temperature wear and oxidation resistance capabilities render these materials an excellent choice in engineering applications.In the present review study,a literature survey was conducted on the machinability properties and related approaches for CFRP and GFRP composite materials. As in the machining of all anisotropic and heterogeneous materials,failure mechanisms were also reported in the machining of CFRP and GFRP materials with both conventional and modern manufacturing methods and the results of these studies were obtained by use of variance analysis(ANOVA),artificial neural networks(ANN) model,fuzzy inference system(FIS),harmony search(HS) algorithm,genetic algorithm(GA),Taguchi's optimization technique,multi-criteria optimization,analytical modeling,stress analysis,finite elements method(FEM),data analysis,and linear regression technique. Failure mechanisms and surface quality is discussed with the help of optical and scanning electron microscopy,and profilometry. ANOVA,GA,FEM,etc. are used to analyze and generate predictive models.
基金Generalitat Valenciana(GVA)and Spanish Ministry of Science and Innovation(Grant Nos.TED2021-130879 B-C21,CIACIF/2021/286,PID2023-151110OB-I00,and CIPROM/2022/3)to provide funds for conducting experiments and software licensessupported by the National Research Foundation,Prime Minister's Office,Singapore under its Campus for Research Excellence and Technological Enterprise(CREATE)programme。
文摘Military missions in hostile environments are often costly and unpredictable,with squadrons sometimes facing isolation and resource scarcity.In such scenarios,critical components in vehicles,drones,and energy generators may require structural reinforcement or repair due to damage.This paper proposes a portable,on-site production method for molds under challenging conditions,where material supply is limited.The method utilizes large format additive manufacturing(LFAM)with recycled composite materials,sourced from end-of-life components and waste,as feedstock.The study investigates the microstructural effects of recycling through shredding techniques,using microscopic imaging.Three potential defense-sector applications are explored,specifically in the aerospace,automotive,and energy industries.Additionally,the influence of key printing parameters,particularly nonparallel plane deposition at a 45-degree angle,on the mechanical behavior of ABS reinforced with 20%glass fiber(GF)is examined.The results demonstrate the feasibility of this manufacturing approach,highlighting reductions in waste material and production times compared to traditional methods.Shorter layer times were found to reduce thermal gradients between layers,thereby improving layer adhesion.While 45-degree deposition enhanced Young's modulus,it slightly reduced interlayer adhesion quality.Furthermore,recycling-induced fiber length reduction led to material degradation,aligning with findings from previous studies.Challenges encountered during implementation included weak part adherence to the print bed and local excess material deposition.Overall,the proposed methodology offers a cost-effective alternative to traditional CNC machining for mold production,demonstrating its potential for on-demand manufacturing in resource-constrained environments.
基金National Natural Science Foundation of China(Grant Nos.51908188 and 51938011).
文摘The recent increase in blast/bombing incidents all over the world has pushed the development of effective strengthening approaches to enhance the blast resistance of existing civil infrastructures.Engineered geopolymer composite(EGC)is a promising material featured by eco-friendly,fast-setting and strain-hardening characteristics for emergent strengthening and construction.However,the fiber optimization for preparing EGC and its protective effect on structural elements under blast scenarios are uncertain.In this study,laboratory tests were firstly conducted to evaluate the effects of fiber types on the properties of EGC in terms of workability,dry shrinkage,and mechanical properties in compression,tension and flexure.The experimental results showed that EGC containing PE fiber exhibited suitable workability,acceptable dry shrinkage and superior mechanical properties compared with other types of fibers.After that,a series of field tests were carried out to evaluate the effectiveness of EGC retrofitting layer on the enhancement of blast performance of typical elements.The tests include autoclaved aerated concrete(AAC)masonry walls subjected to vented gas explosion,reinforced AAC panels subjected to TNT explosion and plain concrete slabs subjected to contact explosion.It was found that EGC could effectively enhance the blast resistance of structural elements in different scenarios.For AAC masonry walls and panels,with the existence of EGC,the integrity of specimens could be maintained,and their deflections and damage were significantly reduced.For plain concrete slabs,the EGC overlay could reduce the diameter and depth of the crater and spallation of specimens.
