Resin Matrix／Fiber Reinforced Composite Material, Ⅱ： Method of Solution and Computer Code

According to a mathematical model which describes the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials, and the consolidation of the comopsites, the solution method to the model is made and a computer code is developed, which for flat-plate composites cured by a specified cure cycle, provides the variation of tenaperature distribution, the cure reaction process in the resin, the resin flow and fibers stress inside the composite, the void variation and the residual stress distribution.     

An Investigation of Stimulating the Autoclave Curing Process of Resin Matrix／Fiber Reinforced Composite Material, Ⅰ ： Process model

A mathematical model is made which describes the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials, and the consoli-dation of the composite is developed. The model provides the variation of temperature distribu-tion, the entre reaction process in the resin, the resin flow and fibers stress inside the composite,and the void variation and the residual stress distribution. It can be used to illustrate the mecha-nism of curing process and optimize the cure cycle of composite material in order to ensure the quality of a product.     

Anti-penetration performance of high entropy alloy-ceramic gradient composites

A high-entropy alloy-ceramic gradient composite of TiC-TiB₂/75vol% Al_0.3CoCrFeNi was successfully prepared by combustion synthesis under an ultra-high gravity field, which is a low-cost method with high efficiency. The ceramic particles were gradient distributed in the Al_0.3CoCrFeNi matrix, and the hardness of the composite material gradually decreased along the thickness direction. The anti-penetration performance of the gradient composites was simulated using the ANSYS/LS-DYNA explicit simulation program. The results demonstrate that the distribution of the ceramic particles strongly affected the mechanical properties and the anti-penetration performance of the composites. With the same total ceramic volume fraction, the gradient composites exhibit better anti-penetration performance than the corresponding ceramic-metal interlayer composites. The more uneven the ceramic distribution, the greater the elastic modulus and yield stress of the surface layer and, thus, the better the anti-penetration performance.     

Microstructure and mechanical properties of SiC-particle-strengthening tri-metal Al/Cu/Ni composite produced by accumulative roll bonding process

In this study, a multilayer Al/Ni/Cu composite reinforced with SiC particles was produced using an accumulative roll bonding (ARB) process with different cycles. The microstructure and mechanical properties of this composite were investigated using optical and scanning microscopy and hardness and tensile testing. The results show that by increasing the applied strain, the Al/Ni/Cu multilayer composite converted from layer features to near a particle-strengthening characteristic. After the fifth ARB cycle, a composite with a uniform distribution of reinforcements (Cu, Ni, and SiC) was fabricated. The tensile strength of the composite increased from the initial sandwich structure to the first ARB cycle and then decreased from the first to the third ARB cycle. Upon reaching five ARB cycles, the tensile strength of the composite increased again. The variation in the elongation of the composite exhibited a tendency similar to that of its tensile strength. It is observed that with increasing strain, the microhardness values of the Al, Cu, and Ni layers increased, and that the dominant fracture mechanisms of Al and Cu were dimple formation and ductile fracture. In contrast, brittle fracture in specific plains was the main characteristic of Ni fractures.     

Statistical Model of the 3-D Braided Composites Strength

Based on the statistical model for the tensile statistical strength of unidirectional composite materials and the stress analysis of 3-D braided composites, a new method is proposed to calculate the tensile statistical strength of the 3-D braided compos- ites. With this method, the strength of 3-D braided composites can be calculated with very large accuracy, and the statistical parameters of 3-D braided composites can be determined. The numerical result shows that the tensile statistical strength of 3-D braided composites can be predicted using this method.     

Design Optimization of RFI Parameters by Manufacturing T-shaped Composite Panel

The aim of this project is to develop a novel approach for optimizing design resin film infusion (RFI) processing parameters by manufacturing T-shaped composite panel. The dimensional accuracy was selected as the objective function. By investigating the rheological properties of resin film, the compaction behavior of fiber preform and characteristics of RFI process, an optimal mathematical model was established, it was found that the numerical results obtained from the RFICOMP program package have good consistency with the experimental results, and this optimization procedure can be applied to other composites manufacture processes.?AKeywords：Composites, Resin Film Infusion, Design Optimization, Accuracy.     

Insect population differentiation in response to enviromental thermal stress

Numerous studies reported the adaptation strategies adopted by ecthotherms to survive under environmental thermal stress. Geographic and seasonal variations in the thermal stress tolerance, which is closely associated with species' climatic adaptation and allopatric speciation, have been extensively investigated in insects. The variation patterns suggest directional selection for species' adaptive straits, and are used to predict the origin, distribution and dynamics of insect populations. These studies are becoming more and more important in the context of global warming. This paper discusses the process of adaptation to environmental thermal stress and the mechanisms underlying the differentiation in related adaptive straits of insect populations.     

Rapid Tooling Technique Based on Stereolithograph Prototype

Rapid tooling technique based on the sterelithograph prototype is investigated. The epoxy tooling technological process was elucidated. It is analyzed in detail that the epoxy resin formula is easy to cast, curing process, and release agents. The transitional plaster model is also proposed. The mold to encrust mutual-inductors with epoxy and mold to inject plastic soapboxes was made with the technique. The tooling needs very little time and cost, for the process is only to achieve the nice replica of the prototype. It is benefit for the trial and small batch of production.     

Fabrication and densification enhancement of SiC-particulate-reinforced copper matrix composites prepared via the sinter-forging process

The fabrication of copper (Cu) and copper matrix silicon carbide (Cu/SiC_p) particulate composites via the sinter-forging process was investigated. Sintering and sinter-forging processes were performed under an inert Ar atmosphere. The influence of sinter-forging time, temperature, and compressive stress on the relative density and hardness of the prepared samples was systematically investigated and subsequently compared with that of the samples prepared by the conventional sintering process. The relative density and hardness of the composites were enhanced when they were prepared by the sinter-forging process. The relative density values of all Cu/SiC_p composite samples were observed to decrease with the increase in SiC content.     

A Study of Melt Flow Analysis of an ABS-Iron Composite in Fused Deposition Modelling Process

Fused deposition modelling (FDM) is a filament based rapid prototyping system which offers the possibility of introducing new composite material for the FDM process as long as the new material can be made in feedstock filament form. Swinburne has been undertaking extensive research in development of new composite materials involving acrylonitrile-butadiene-styrene (ABS) and other materials including metals. In order to predict the behaviour of new ABS based composite materials in the course of FDM process, it is necessary to investigate the flow of the composite material in liquefier head. No such study is available considering the geometry of the liquefier head. This paper presents 2-D and 3-D numerical analysis of melt flow behaviour of a representative ABS-iron composite through the 90-degree bent tube of the liquefier head of the fused deposition modelling process using ANSYS FLOTRAN and CFX finite element packages. Main flow parameters including temperature, velocity, and pressure drop have been investigated. Filaments of the filled ABS have been fabricated and characterized to verify the possibility of prototyping using the new material on the current FDM machine. Results provide promising information in developing the melt flow modelling of metal-plastic composites and in optimising the FDM parameters for better part quality with such composites.     

Processing of nanostructured metallic matrix composites by a modified accumulative roll bonding method with structural and mechanical considerations

Particulate reinforced metallic matrix composites have attracted considerable attention due to their lightweight, high strength, high specific modulus, and good wear resistance. Al/B₄C composite strips were produced in this work by a modified accumulative roll bonding process where the strips were rotated 90° around the normal direction between successive passes. Transmission electron microscopy and X-ray diffraction analyses reveal the development of nanostructures in the Al matrix after seven passes. It is found that the B₄C reinforcement distribution in the matrix is improved by progression of the process. Additionally, the tensile yield strength and elongation of the processed materials are increased with the increase of passes.     

Novel Ag nanocrystals based dental resin composites with enhanced mechanical and antibac terial propert ies

The aim of this work was to investigate the effect of trace addition of oleic acid coated Ag nanocrystals(Ag NCs) on mechanical and antibacterial properties of dental resin composites.Composites(70 wt%of silica loading) with 25 ppm,50 ppm,75 ppm and 100 ppm(wt) Ag NCs were prepared and the composite without Ag NCs served as a control.The experimental results showed that the addition of Ag NCs significantly improved the strength and modulus of the resin composite without compromising the shade.For the composite with 50 ppm Ag NCs,fiexural strength(140.3 MPa),modulus(13.2 GPa)and compressive strength(347.2 MPa) were increased by 4.1%,22.2%,13.3%,respectively,compared with the control.The antibacterial test demonstrated that trace Ag NCs provided the resin composites with an antibacterial effect.Such strong and antibacterial dental resin composites might be advantageous to prevent secondary caries and be potential for future clinical applications.     

Effect of Sedimentation on the Microwave Permeability of FeSiAl Composites

In order to achieve an easy fabrication and considerable directional orientation, we use a sedimentation method to prepare composites consisting of Fe Si Al flakes. The flakes are dispersed in hydroxylated acrylic resin solution in sonication and natural form into laminated composite samples. Then, the toroidal rings are made with the prepared laminated composite samples. Compared with random orientational Fe Si Al flakes in the composite, the complex permeability of laminated sample has been obviously improved when microwave frequency is below 4 GHz, especially for the imaginary part. A model is proposed to explain the formation reason of aligned Fe Si Al composite by this method. Damping factor(α) is calculated by the combination of the effective medium theory and Landau-Lifshitz-Gilbert equation, and the permeability of the samples is verified by these theories.     

Enhanced dielectric properties of polypropylene based composite using Bi2S3 nanorod filler

A novel two-phase composite system using polypropylene(PP) as matrix and semiconductor bismuth sulfide(Bi_2S_3) as filler,was prepared by a simple process.Surfactant KH550 was chosen to modify the interface between inorganic fillers and organic PP matrix.The variations of dielectric properties of the Bi_2S_3/PP composites with the volume fraction of Bi_2S_3,frequency and temperature were discussed.The results reveal a percolative behavior of the composites with the threshold of 0.08.The composite is demo...     

Impact Performance of 3D Integrated Cellular Woven Composite Panel

This paper studied the impact resistance of 3D integrated cellular woven composite panel under persudo-static impact, comprised the test result with property of typical 3D woven composites, analyzed some parameters that maybe affect composites＇ impact resistance and at last used SEM to observe the damage process and mechanism of samples. The result shows that the impact resistance of 3D integrated cellular woven composites is much better than the performance of typical 3D woven composites; it is an active method to improve the impact resistance of composites that developing preform with cellular on the basis of typical 3D woven structure; for different 3D integrated cellular woven structure, the value of absorbed-energy is increasing with the hollow percentage; tiny deformatlen will not emerge on samples until the acting force gets to 85% of the maximum; similar with typical 3D woven composites, the delaminated phenomenon of 3D integrated cellular woven composites is also unapparent during impact process.     

Facile hydrothermal and sol-gel synthesis of novel Sn-Co/C composite as superior anodes for Li-ion batteries

As an anode material in lithium ion battery, the Sn-Co/C composite electrode materials have been successfully synthesized by hydrothermal and solgel methods, respectively. The resultant composites were mainly composed of Snbased oxides, nanometer Sn-Co alloy and carbon. Carbon and Co, acting as buffer materials, can accommodate to the large volume change of active Sn during the discharge-charge process, thus improving the cycling stability. Although charge/discharge curves revealed the excellent cycle performance for samples synthesized by both methods, composites obtained by the sol-gel showed a better dispersion effect of nanoparticles on the carbon matrix and possessed much more improved stable capacity with 624.9 mAh g-1 over 100 cycles and that by hydrothermal method only exhibited ～299.3 mAh g-1. Therefore, the Sn-Co/C composites obtained by solgel synthesis method could be a perfect candidate for anode material of Liion storage battery.     

Effect of sintering on the relative density of Cr-coated diamond/Cu composites prepared by spark plasma sintering

Cr-coated diamond/Cu composites were prepared by spark plasma sintering. The effects of sintering pressure, sintering temperature, sintering duration, and Cu powder particle size on the relative density and thermal conductivity of the composites were investigated in this paper. The influence of these parameters on the properties and microstructures of the composites was also discussed. The results show that the relative density of Cr-coated diamond/Cu reaches ~100% when the composite is gradually compressed to 30 MPa during the heating process. The densification temperature increases from 880 to 915℃ when the diamond content is increased from 45vol% to 60vol%. The densification temperature does not increase further when the content reaches 65vol%. Cu powder particles in larger size are beneficial for increasing the relative density of the composite.     

Comparison of methods for determining orthotropic axes in 3D femur remodeling

The density distribution and internal structure of trabecular bone are modulated by local mechanical environment. In this study, an orthotropic adaptation algorithm was applied to the 3D femur model to simulate the variations of stiffness and orientation of trabecular bone under multi-loading conditions. This algorithm includes the determination of orthotropic axes and the stiffness modification of trabecular bone. Three methods were used to determine the orthotropic axes, i.e. the maximal cycle method, the stress maximum method, and the composite method. We found that the composite method was better than the other two. Firstly, the characteristics of density distribution obtained by using the composite method agreed better with those in real proximal femur. Secondly, the material orientation aligned with the known trabeculaer pattern. Finally, the ratios of the longitudinal modulus to the transverse modulus were also shown to be realistic in three local regions of the proximal femur.     

Deposition of crackless freestanding diamond films on Mo substrates with Zr interlayer

The Mo substrate with Zr interlayer, namely composite substrate, was employed to solve the problem of crack formation in the freestanding diamond film deposition. Freestanding diamond films deposited on the composite substrates by the direct current arc plasma jet chemical vapor deposition (CVD) method were investigated with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. In addition, the stress distribution during the large area freestanding diamond film deposition on the composite substrate was analyzed based on the finite element model ANSYS. The results reveal that Zr interlayer can be easily destroyed during the post-deposition cooling process, which is helpful for stress release and crack avoiding in diamond films.     

Grading Standards of the Coefficient of Variation in the Electronic Raw Silk Size Testing

In order to shorten the difference between the raw silk size grading standards of the world and that of China, to quicken the step of the electronic raw silk testing process, the distribution of the coefficient of variation （CV50m%） of the raw silk size in the electronic testing and the development of the new standards are studied according to the sampling and grading theory. By the theoretical deduction and the simulating experiments, the distribution of the coefficient of variation of the raw silk size is given, and the grading scheme whose quality index is the coefficient of variation（CV50m%）of the raw silk size and the grading precisions of all grades are proposed. Moreover, the rightness and the feasibility of the grading scheme are testified by the sampling and grading simulation.