Components Of Composite Materials Research Articles

In situ experimental mechanics of nanomaterials at the atomic scale

Sub-micron and nanostructured materials exhibit high strength, ultra-large elasticity and unusual plastic deformation behaviors. These properties are important for their applications as building blocks for the fabrication of nano- and micro-devices as well as for their use as components for composite materials, high-strength structural and novel functional materials. These nano-related deformation and mechanical behaviors, which are derived from possible size and dimensional effects and the low density of defects, are considerably different from their conventional bulk counterparts. The atomic-scale understanding of the microstructural evolution process of nanomaterials when they are subjected to external stress is crucial for understanding these ‘unusual’ phenomena and is important for designing new materials, novel structures and applications. This review presents the recent developments in the methods, techniques, instrumentation and scientific progress for atomic-scale in situ deformation dynamics on nanomaterials, including nanowires, nanotubes, nanocrystals, nanofilms and polycrystalline nanomaterials. The unusual dislocation initiation, partial-full dislocation transition, crystalline–amorphous transitions and fracture phenomena related to the experimental mechanics of the nanomaterials are reviewed. Current limitations and future aspects using in situ high-resolution transmission electron microscopy of nanomaterials are also discussed. A new research field of in situ experimental mechanics at the atomic scale is thus expected. The properties of a material depend not only on its composition but also on the exact arrangement of its atoms. In particular, nanostructured materials such as nanotubes, nanocrystals or polycrystalline materials are much stronger and more elastic than their bulk counterparts and exhibit different plastic deformations, making them suitable for a variety of applications. Lihua Wang and co-workers review how recent developments in transmission electron microscopy (TEM) techniques enable materials scientists to characterize, at the atomic scale, both the chemical composition of a nanomaterial and its deformation dynamics under stress and strain, in situ, and in real time. Some possible pitfalls and challenges remain — for example, over-irradiation with the TEM electron beam may damage the sample studied, and observations must typically be carried out under vacuum — but such detailed characterization provides a good understanding of the mechanisms at play. It therefore holds promise for the control of the mechanical, but also chemical and physical, properties of nanostructured materials through the application of stress or strain. Nanostructured materials always exhibit high strength, ultra-large elasticity and unusual plastic deformation behaviors. The atomic-scale understanding of the microstructure evolution process of nanomaterials when they are subjected to external stress is crucial for understanding these ‘unusual’ phenomena and is important for designing new materials and applications. In situ transmission electron microscopy (TEM) experiments provide the possibility for direct observation of the deformation mechanisms at the atomic scale. This review presents the recent developments of techniques and scientific progress for the atomic-scale in situ TEM deformation dynamics on nanomaterials. Current limitations and future aspects are also discussed.

Manufacturability analysis of composite component and its evaluation methodology

Manufacturability calculation of product’s design proposal often plays a vital role in many engineering applications, which is critical to achieve reduced time to market, high quality, and low cost. A methodology for the manufacturability evaluation of composite material components during preliminary stage of design is introduced and applied for the thermosetting composite laminated components produced by autoclave process in this article. The proposed methodology relies on the consideration that the component’s quality is a decisive index in the manufacturability evaluation of composite products. First, according to the analysis of composite product manufacturing processes, the concept of composite product manufacturability was proposed in this article. Second, the knowledge-based manufacturability evaluation flow is acquired based on the hierarchical indices setup of composite product manufacturability. Then, we mainly studied assessment model of composite product quality controllability: the quality controllability of composite product and its influencing factors were discussed. In addition, the quality controllability assessment model proposed was carried out step by step through the characteristic of multi-procedure in the production of composite product. In the end, an example of composite laminate component was provided to demonstrate the proposed model for evaluating the manufacturability.

A novel approach to composite preparation by direct synthesis of carbon nanomaterial on matrix or filler particles

Carbon nanotubes (CNTs), nanofibers (CNFs) and graphene are promising components for next-generation high-performance structural and multifunctional composite materials. One of the largest obstacles to creating strong, electrically or thermally conductive CNT/CNF or graphene composites is the difficulty of achieving a good dispersion of the carbon nanomaterials in a matrix. Typically, time-consuming steps of carbon nanomaterial purification, ultrasound treatment and functionalization are required. We utilized a novel approach to fabricate composite materials by growing CNTs/CNFs directly on the surface of matrix, matrix precursor or filler particles. As the precursor matrix and fillers we utilized cement (clinker), copper powder, fly ash particles, calcinated soil and sand. Carbon nanomaterials were successfully grown on these materials without additional catalyst. Investigations of the physical properties of the composite materials based on these carbon-modified particles revealed enhanced mechanical and electrical properties. The improvement in the mechanical properties of the C/Cu-based composite materials is attributed the crystallite or grain formation of the matrix material.

Pyrolytic densification of porous carbon-carbon composite materials

This paper examines the densification of the pore space of a carbon-carbon composite material through methane pyrolysis at a reduced pressure and the dynamics of the pyrolytic saturation process. The morphology and microstructure of the pyrolytic carbon are compared to those of the main components of the parent carbon-carbon composite material. The composite is characterized by hardness tests before and after the pyrolytic densification of the carbon matrix.

Study of the composition of low-molecular products of the thermal oxidative destruction of atactic polypropylene by gas chromatography/mass spectrometry

The paper presents the results of studying the composition of low-molecular products of the thermal oxidative destruction of atactic polypropylene by gas chromatography/mass spectrometry. Special attention has been paid to the investigation of the mass spectra of compounds dominating in the composition of low-molecular products of the incomplete oxidative destruction of the original polymer, carried out for the synthesis of components for composite materials of the new generation. The most probable molecular structures of the studied compounds are determined on the basis of fragmentation patterns.

Structure and Technics Research on Composite Ship T-Joint

T-joints between fiber reinforced composite material components are widely used in ship building. They are the weak positions in ship structure on mechanical properties aspect. Through experiments, the effects of structure size and technics on joint deformation and destructive strength were researched. Destructive strength first increases with the increase of T-joint fillet radius dimensions, then declines when radius dimensions over R50mm. Compared with control group, composite material components with surface sandblasting process has got superior performance, with destructive load improved by 2.1 times and displacement 1.16 times. With the increase of pressure and injection time of sandblasting process, the destructive strength of joints increases. While destructive strength increases slowly when pressure achieved 0.6 MPa and injection time achieved 100s.

Synthesis of dimethacrylates monomers with low polymerization shrinkage and its application in dental composites materials

In this work, a new dimethacrylate monomer named α,α′-Bis(4-(2′-hydroxy- 3′methacryloyloxy-propoxy)-3,5-dimethylphenyl)-1,4-diisopropyl-benzene (α,α′-BHMPDDB) was synthesized to replace 2,2-bis[4-(2′-hydroxy-3′-methacryloyloxy-propoxy)-phenyl]propane (Bis-GMA) as one component of dental composite materials. The structures of α,α′-BHMPDDB and its intermediate product α,α′-Bis(4-oxiranylmethoxy-3,5-dimethylphenyl)-1,4-diisopropylbenzene (α,α′-BODDB) were confirmed by FT-IR, 1H-NMR, and elemental analysis. α,α′-BHMPDDB was mixed with TEGDMA to form a new dental resin, and double bond conversion, polymerization shrinkage, contact angle, water sorption and solubility, flexural strength and modulus before and after water immersion of this new dental resin were studied. Compared with the commonly used Bis-GMA/TEGDMA dental resin, α,α′-BHMPDDB/TEGDMA had higher double bond conversion (60.5 ± 0.3 %), lower polymerization shrinkage (5.6 %), and comparable flexural strength before water immersion (94.1 ± 3.9 MPa), which made α,α′-BHMPDDB/TEGDMA having potential to replace Bis-GMA/TEGDMA as matrix phase of dental composites materials. However, α,α′-BHMPDDB/TEGDMA also had drawbacks, such as higher water sorption (5.06 ± 0.17 %), water solubility (2.37 ± 0.1 %), and lower flexural strength after water immersion (71.4 ± 14.6 MPa).

Fullerenes in matrices of different substances

Techniques for obtaining fullerene-containing materials based on metals and semiconductors, and also on polymers and ceramics, have been developed. It has been shown that fullerenes, on introduction into the matrices of different substances, produce substantial changes in their structure and properties. In some cases fullerenes act not only as the components of composite materials but also as the reagents of chemical reactions in obtaining new substances.

Preparation and Study to Core-Material of Microcapsule for Textiles Discoloration Finishes

Choose the organic thermochromic compo site materials as thermochromic microcapsule core-material，Using and studying crystal violet lactone 、bisphenol A and tetradecyl alcohol as the components of compo site materials according to the need of textiles finishies. We analysed the structure and capability of the compo site materials and identified 1:4:70 as the optimal ratio of the compo site materials could suitable for discoloration gradient of textiles，lay the foundation for preparation of microcapsule and textiles finishies. The discoloration fabric as functional textile has a tremendous market potential，its could using discoloration dress、materials-show and prevent bogus marker。Thermochromic fabrics is the intelligent textile and colour changed following the temperature changes. Generally，the Thermochromic materials was encased by microcapsule and using the finishing technology pasted the microcapsule on the surface of fabrics,so the fabric could has the discoloration function. Currently，thermochromic materials have organic、inorganic and Liquid crystal materials. Study to thermochromic materials and achieved a organic thermochromic compo site material in this paper，using the compo site material as the core-material of thermochromic microcapsule for the discolouration fabric finishes.

Cleavage of catalytic ally grown carbon nanofibers into hydrophilic segments by oxidation in a mixture of concentrated HNO3-H2SO4 in an autoclave

The catalytically grown carbon nanofibers were treated by a mixture of concentrated nitric aid and sulfuric aid in an autoclave at temperature 333, 363 and 423 K. It was found that the samples treated at 363 K and 423 K were still well dispersed in water 15 hours later, indicating that carbon nanofibers can be made hydrophilicy. It was also found that the dispersion was destroyed when the pH value was lowered by adding acid. The results are significant when the carbon nanofibers are used as enhancing component in polymer composite material because several hundreds of nm are perfect size and the hydrophilicity controls the dispersion of CNFs in the polymer media. It is concluded that the amount of the oxygen-containing groups on the surface and the hydrophilicity of the carbon nanofibers can be controlled by the treatment temperature, and that the carbon nanofibers can be cleaved into uniform segments.

Metakaolinite/TiO2 composite: Photoactive admixture for building materials based on Portland cement binder

Novel latent hydraulic and photoactive admixture metakaolinite/TiO2 was prepared, characterized and evaluated as a partial replacement for the Portland cement in mortars. The main component of this novel composite material is metakaolinite containing the anatase nanoparticles anchored on its surface. The values of the compression strength measured for the mortars containing metakaolinite/TiO2 composites reached higher values in comparison to the mortar without this admixture. Photodegradation activity of the mortars with given amount of the metakaolinite/TiO2 admixture against nitric oxide (NO) was tested using the modified ISO standard. The results showed that the conversion of NO increases with the increasing content of TiO2. The synergistic effect of the photodegradation activity and the latent hydraulicity in this material can be utilized in building industry to decrease concentration of selected air pollutants e.g. in areas affected by traffic pollution.

In Situ Mechanical Analysis of Genetic Modification and Aging on Soft, Bilayered Drosophila Myocardium

Drosophila melanogaster is a genetically malleable organism with a short life span, making it a tractable system in which to study mechanical effects of genetic perturbation and aging on tissues, such as impaired heart function. However, Drosophila heart tube studies can be hampered by its bilayered structure: a ventral muscle layer covers the contractile cardiomyocytes. We have refined an atomic force microscopy-based analysis to measure individual mechanical components of soft composite materials. The technique was verified using bilayered polydimethylsiloxane. Its biological utility was further demonstrated by its ability to resolve stiffness changes due to cardiac-specific RNA interference to reduce cardiomyocyte myofibrillar assembly or due to aging in Drosophila myocardial layers. Female yellow-white (yw) flies experience decreased diastolic diameter with age (>20%) while cardiomyocytes stiffened more than two-fold with age (1.8± 0.1 vs. 3.8 ± 0.3 kPa in 1 and 5 week old flies, respectively) at cell-cell junctions. Cardiac-specific RNA-interference against myosin heavy chain severely impaired contraction and reduced stiffness after 1 week (1.0± 0.1 vs. 1.8 ± 0.1 kPa) without altering ventral muscle stiffness. This method provides a platform to assess the mechanics of soft biological composite systems and for the first time permits direct measurement of how genetic perturbations, aging, and disease can impact cardiac function in situ.

In Situ Mechanical Analysis of Myofibrillar Perturbation and Aging on Soft, Bilayered Drosophila Myocardium

Drosophila melanogaster is a genetically malleable organism with a short life span, making it a tractable system in which to study mechanical effects of genetic perturbation and aging on tissues, e.g., impaired heart function. However, Drosophila heart-tube studies can be hampered by its bilayered structure: a ventral muscle layer covers the contractile cardiomyocytes. Here we propose an atomic force microscopy-based analysis that uses a linearized-Hertz method to measure individual mechanical components of soft composite materials. The technique was verified using bilayered polydimethylsiloxane. We further demonstrated its biological utility via its ability to resolve stiffness changes due to RNA interference to reduce myofibrillar content or due to aging in Drosophila myocardial layers. This protocol provides a platform to assess the mechanics of soft biological composite systems and, to our knowledge, for the first time, permits direct measurement of how genetic perturbations, aging, and disease can impact cardiac function in situ.

High frequency soft phononics

Phononic crystals, the acoustic equivalents of the photonic crystals, are controlled by a larger number of material parameters. The study of hypersonic crystals imposes substantial demand on fabrication and characterization techniques. Colloid and polymer science offer methods to create novel materials that possess periodic variations of density and elastic properties at mesoscopic length scales commensurate with the wave length of hypersonic phonons and hence photons of the visible light. Polymer- and colloid-based phononics is an emerging new field at the interface of soft materials science and condensed matter physics with rich perspectives ahead. The key quantity is the dispersion of high frequency (GHz) acoustic excitations which is nowadays at best measured by high resolution spontaneous Brillouin light scattering. Depending on the components of the nanostructured composite materials, the resolved vibration eigenmodes of the individual particles sensitively depend on the particle architecture and their thermo-mechanical properties [T. Still et al., Nano Lett. 10, 3194 (2008)]. In periodic structures of polymer based colloids, the dispersion relation ω(k) between the frequency and the phonon wave vector k has revealed hypersonic phononic band gaps of different nature [T. Still et al., Phys. Rev. Lett. 106, 175505 (2011)].

Sea Water Ageing of Composites for Ocean Energy Conversion Systems: Influence of Glass Fibre Type on Static Behaviour

Composite material components will be an essential part of ocean energy recovery devices, and their long term durability in sea water must be guaranteed. Despite extensive experience for boat structures and wind turbines few data exist to design structures subjected to a combination of mechanical loads and sea water immersion. This paper presents the first results from an experimental study, performed jointly with fibre manufacturers, and a resin supplier, to fill this gap. The experimental study is completed by numerical modelling to simulate the coupling between water absorption and mechanical behaviour. Sea water ageing is shown to result in a drop in quasi–static mechanical properties and a change in flexural mode from compression to tension at longer ageing times, which is consistent with results from the numerical simulations.

New Technology Research of Nondestructive Testing for Aero Aircraft Composite Materials

Composite materials have many advantages such as big specific strength, high specific stiffness, good disrepair safety characteristic, large area molding conveniently and easy to forming complex shape. It becomes important structural materials of aero aircraft equipment necessarily and is used widely in aviation industry. Composite materials components of aero aircraft with complex and delicate structure chronically work in harsh environment. Early testing of its key component’s minute defects has been an urgent and necessary task. In this paper, its damage model and characteristic are analyzed and studied. Considering the limitation of composite materials structure’s detection methods at present, a number of existing problems are presented and development directions are pointed out. Laser ultrasound detection technique, continuous distribution sensing technique and optical fiber sensing technique are studied. The method of damage detection of aero aircraft’s composite materials components is put forward based on the organic combination of the three techniques. The results show that the system can be used to detect multi-ultrasound signals of large composite materials structure. Its structure is simple. It has small bulk and low cost. It is characterized by easy realization.

Modeling of self-organization of two-dimensional ordered structures

The problem of the search of biostructures capable to self-organization is quite urgent considering the prospects of application of nanostructured biomaterials as components of composite materials in transplantology and optics as well as "scaffolds" for the synthesis of nanostructured materials based on inorganic particles. The given study focuses on modeling of the growth of structures using the cellular automata with a set of states of the two values (0 and 1), with the value corresponding to the state is determined by the contribution of "the closest neighbor" (by the probability of induction of the state of the nextgeneration in the direction of the interaction) and the geometry of the field isdetermined by the vector of the direction of the particle and the direction of the interaction.

Wind Erosion Prevention and Repair of Composite Material Components of Civil Aircraft

This paper addresses how to discover wind erosion of aircraft components in time and to take appropriate measures to repair and prevent damage, thereby reducing the cost of aircraft maintenance and prolonging aircraft service life. The authors of this paper have extensively compiled and studied civilian aircraft maintenance data in the recent years from Guangzhou Aircraft Maintenance Engineering Co. Ltd. In this paper they discuss the aircraft components most susceptible to wind erosion, as well as repair methods and prevention mechanisms. These findings can serve as a reference and a guide to civilian aircraft flight maintenance, repair, and routine inspections.

Structural transformation of graphite by arc-discharge

The formation of novel structures by the passage of an electric current through graphite is described. These structures apparently consist of hollow three-dimensional graphitic shells bounded by curved and faceted planes, typically made up of two graphene layers. The curved structures were frequently decorated with nano-scale carbon particles, or short nanotubes. In some cases, nanotubes were found to be seamlessly connected to the thin shells, indicating that the formation of the shells and the nanotubes is intimately connected. Small nanotubes or nanoparticles were also sometimes found encapsulated inside the hollow structures, while fullerene-like particles were often seen attached to the outside surfaces. With their high surface areas and structural perfection, the new carbon structures may have applications as anodes of lithium ion batteries or as components of composite materials.

Calculation of composition in LaB 6–TiB 2 and LaB 6–ZrB 2 eutectics by means of pseudopotential method

A method of aprioristic pseudo-potential and an internal energy of individual components of composite materials are introduced that allows prediction of eutectic composition for the eutectic invariant point of LaB 6–TiB 2 and LaB 6–ZrB 2 system. The numerical predictions agreed well with the experimental data for eutectic composition. We determined the crystal lattice parameters and demonstrated the insolubility of the constituent phases of LaB 6–TiB 2 and LaB 6–ZrB 2 eutectic systems. The experimental results validated the predictions for the lattice constants of the constituent phases. The transferability of these potentials by including kinetic energy components has been discussed.