High-performance Reinforcement Research Articles

Optimization of a mono-composite leaf spring using a hybrid fiber-layup approach

Conventional leaf springs are simple in design, utilizing multiple metallic bars (leaves) with low geometrical moment of inertia to generate an economical and linear spring rate. In its early form, the leaf-spring was manufactured using metals like steel, but, in modern applications, there exist composite leaves reinforced by advance glass and carbon fibers. Benefits of composite spring designs include: high specific strength, ability to form complex profiles, and possibility of subcomponent consolidation to reduce assembly. Due to the bending characteristics of the leaf spring, the axial load decreases through the beam thickness, reaching a minimum at the neutral surface. Given this fact, a design optimization approach for mono-composite leaf springs is developed considering a hybrid fiber-layup. Initially, a detailed topology optimization is conducted to optimize the geometry of the leaf spring based on the Tsai-Wu failure model. This process yielded a unique spring design which reduced the mass of the spring by 29% compared to the initial non-optimized spring and 80–90% compared to a steel spring. Subsequently, the design is further optimized by replacing low stress, high modulus reinforcement with lower modulus and cost-effective materials to improve overall vehicle mass, efficiency, and operation. The second stage of the optimization based on the hybrid fiber-layup approach resulted in an additional 7% mass reduction. As there is a connection between fuel efficiency and vehicle mass, the significant reduction of spring mass has a positive impact on vehicle fuel consumption and leads to suspension responsiveness gains. Moreover, the possibility of swapping up to 20% of the middle plies reinforcement with commodity plastics demonstrates the cost benefits of the hybrid fiber-layup design approach considering the high cost of carbon and other high-performance reinforcements.

Environmentally Friendly and Controllable Pyrolysis Method to Synthesize Ni-Modified Graphene Nanosheets as Reinforcement of Lead-Free Solder

A tactic for the synthesis of Ni-modified graphene nanosheets (Ni-GNSs) as a high-performance reinforcement of a lead-free solder is proposed and achieved via an environmentally friendly and controllable pyrolysis method. The segmented pyrolysis processes of an Ni(CH3COO)2∙4H2O@GNSs hybrid are discussed. The morphology, microstructure, phase transition, and adsorption strength of nanoparticles on the surface of GNSs with various theoretical Ni loadings are characterized. The adsorption mechanism of a single Ni atom on the surface of perfect graphene and defective graphene was studied based on density functional theory. The corresponding underlying formation mechanisms of Ni-GNSs are analyzed. The results show that the grain size, distribution and phase composition of the nanoparticles on GNSs could be controlled by changing the theoretical Ni loading level. The morphology and dispersity of Ni nanoparticles on GNSs did not significantly change after long-time or high-power ultrasonic treatment, suggesting that the adsorption strength between Ni nanoparticles and GNSs was relatively large and belonged to chemical adsorption based on first-principle calculation. Ni atoms tend to adsorb in the center of the carbon six-membered ring. The obtained Ni-GNSs nanohybrid exhibited a small size, fewer defects, and higher crystallinity and adsorption strength when the theoretical Ni loading was 17 mol %. The results have potential applications in the design of the reinforced phase of composites.

Revealing the dependence of graphene concentration and physicochemical properties on the crushing strength of co-granulated fertilizers by wet granulation process

Granular fertilizers should have appropriate mechanical strength to resist significant fracturing during the handling and storage process. Graphene (GN) has the potential to act as a high-performance reinforcement for different composites. This paper provides a comprehensive study of the influence of GN concentration on the crushing strength of two fertilizers (monoammonium phosphate (MAP) and diammonium phosphate (DAP)) with different initial hardness. The results show differences in concentration dependence, with optimum concentration of 0.5% GN for MAP and 0.05% for DAP increasing their crushing strength by 1680% and 67.3%, respectively. The effect of different physicochemical properties of GN, such as method of preparation and specific surface area (SSA) on the crushing strength of the fertilizer was also investigated. Results showed dependence of granules’ crushing strength on the method of GN production and their SSA, while GN samples with a high degree of reduction and SSA were more effective than others.

FRP Application and Structural Engineering Innovation of High Performance Materials Based on Mechanical Analysis

FRP (Fiber Reinforced Composite) has been widely used in the reinforcement of concrete structures in recent years. FRP composites, as high strength, lightweight and high performance reinforcement materials, have been widely used not only in China, but also in foreign countries and in water and soil engineering. China has made a series of achievements in the development of high-performance FRP materials and their products suitable for civil engineering applications, and in the application of FRP key technologies in civil engineering. In the development of concrete structures in the new century, new requirements and challenges have been put forward for materials. Because FRP is a frontal composite material composed of many kinds of materials, its common advantages are light weight, high strength and elastic modulus, fatigue resistance, long service time, good corrosion resistance and low thermal expansion coefficient, etc. FPR is a new type of high performance material, which is of great significance to the sustainable development of civil engineering industry in our country. This paper introduces the properties and forms of FRP materials commonly used in structural engineering, puts forward the rational application of FRP and its structure, and analyses its advantages and disadvantages in order to promote the application and research of this new type of high performance material in civil engineering in China.

Fabrication and Property Evaluation of Hemp–flax Fiber Reinforced Hybrid Composite

In terms of innovative and high-performance reinforcement, hemp and flax solutions have not only met the technical requirements of composite manufacturers but also reduced environmental impacts. This paper aims to fabricate the hemp–flax fiber reinforced hybrid composite and to determine the mechanical properties such as flexural strength, flexural modulus along with moisture absorption performance. Hand lay-up method was used to fabricate the composites. The specimens were tested with the universal testing machine (UTM). Hybridization effect is clearly visible with the results. The results revealed that, the highest flexural strength (53.45Mpa) as well as flexural modulus (3.43Gpa) was exhibited by the sample composed of 30% hemp-10% flax reinforced hybrid composite. Water absorption behavior has shown that hybridization has increased the water uptake.

High strength Kevlar fiber reinforced advanced textile composites

A state of art on characterization of Kevlar fibers and Kevlar fiber reinforced polymer (KFRP) composites is presented to enunciate the limits of further researches in regard of its applicability with the optimized design in today’s high-tech era. A proper characterization is very important for enhancing material properties in various applications such as defense, industrial, marine and aerospace. In this review work, research works performed on the mechanical impact and deformation behavior of Kevlar fiber and KFRP composites have been focused. Kevlar fibers possess high fracture toughness and high strength to weight ratio, of high-performance reinforcement in polymer textile composites. Researchers using different modeling approaches such as homogeneous isotropic and orthotropic material model along with the effect of different parameters as fabric weaving pattern, matrix material, and composite fabrication techniques, working and loading conditions are discussed in detail. Due to anisotropic nature of Kevlar fibers; KFRP composites have high ratio of longitudinal tensile to compression strength whereas the compression strength is considerably found to increase after fiber surface treatment. The purpose of this study is to provide the reader with an overview of different strategies applied with the experimental and numerical investigations of high strength Kevlar fibers and KFRP composites at micro/meso/macroscale.

The Role of Advance Composite material In Contemporary Buildings

Composite materials have been used from the earliest times, from wood, which is a naturally occurring composite of lignin and cellulose, through straw reinforced clay bricks to reinforced concrete. In the 20th century, a new breed of composite materials was developed using polymer matrices with high-performance reinforcement fibres. The great effect and uncompromising properties of advance composite materials have enabled the emergence of composites cut across all fields of application and all areas of work, just to mention a few aeronautic engineering, automobile engineering, and medicine, military and building construction. Therefore, with emphasis on building construction, advance composite material has played a vital role in today’s contemporary building construction method, by presenting its self as an alternative building construction material, its application has made the contemporary building construction much more flexible and achievable, compared to traditional building materials and its methods of construction. It further offers the building construction industry the technical know-how of having new possibilities of design styles, shapes and forms. Therefore, advance composite material proves it’s self to be a better and a new alternative building construction material that remains construction friendly and flexible based on its properties. This study, therefore, tends to provide an overview of advance composite material, its application as well as its role in today’s contemporary building.

Effect of silica nanoparticles on mechanical properties of Kevlar/epoxy hybrid composites

The addition of nanofillers in high-performance reinforcement results in the formation of hybrid composites. The objective of this research is to determine the effect of silica nanofillers loading on the mechanical properties of Kevlar/epoxy composites for ballistic use. Produced hybrid composite laminates were tested for flexural properties, tensile Properties and impact energy absorption. DMA analyses were performed to investigate composite properties at elevated temperatures. It was observed that introduction of silica nanofillers enhanced flexural properties, tensile strength, and storage modulus of composites. Impact energy absorption was increased up to a specific extent of nanofiller addition. The findings of this study indicate that introduction of silica nanofillers on Kevlar fabrics is a promising method for enhancing mechanical properties of hybrid composite laminates.

Characterization of dimensional stability in flax fiber reinforced polypropylene composites

Flax fibers are a sustainable and high performance reinforcement for polymer composites. Molding polymers and polymer composites nearly always results in warpage or compromised “dimensional stability” of the part. However, there are very few reports on the quantitative analysis of dimensional stability, especially for natural fiber reinforced polymer composites. A systematic study of the dimensional stability of flax fiber reinforced polypropylene (PP) composites is undertaken by measuring the shrinkage of the composites after molding. Shrinkage is directly related to dimensional stability. Using flax fibers decreases part shrinkage or increases dimensional stability. Shrinkage in the molding flow direction is less than shrinkage perpendicular to it, which is shown to be a result of fiber orientation in that direction. Using maleic anhydride modified PP as a coupling agent further decreases the shrinkage. It is found that less shrinkage occurs in composites of higher modulus. POLYM. COMPOS., 40:132–140, 2019. © 2017 Society of Plastics Engineers

Graphene nanoplatelet-modified epoxy: effect of aspect ratio and surface functionality on mechanical properties and toughening mechanisms

Graphene has the potential to act as a high-performance reinforcement for adhesives or fibre composites when combined with epoxy polymer. However, it is currently mostly available not as single high aspect ratio sheets but as graphene nanoplatelets (GNPs), comprising stacks of graphene sheets. GNPs of a range of lateral size, thickness, aspect ratio and surface functionality were used to modify an anhydride-cured epoxy polymer. The morphology, mechanical properties and toughening mechanisms of these modified epoxies were investigated. The GNPs were sonicated in tetrahydrofuran (THF) or n-methyl-pyrrolidone (NMP) to facilitate dispersion in the epoxy. The use of THF resulted in large agglomerates, whereas more finely dispersed stacks of GNPs were observed for NMP. The maximum values of modulus (3.6 GPa at 1 wt%) and fracture energy (343 J/m\(^2\) at 2 wt%) were measured for the epoxy modified with an intermediate platelet size of approximately 4 \(\upmu \)m, compared to 2.9 GPa and 96 J/m\(^2,\) respectively, for the unmodified epoxy. The Young’s modulus was highly dependent on the dispersion quality, whereas the fracture energy was independent of the degree of GNP dispersion. The larger agglomerates of the GNPs which were dispersed in THF toughened the epoxy by crack deflection, whereas the GNPs dispersed in NMP showed platelet debonding, pull-out and plastic void growth of the epoxy. This work indicates that reinforcement and toughening can be achieved at much lower contents than for conventional modifiers. Further, achieving a good dispersion is crucial to the engineering application of these materials, and intermediate-sized graphene achieves the best balance of properties.

The Effect of the Melt Viscosity and Impregnation of a Film on the Mechanical Properties of Thermoplastic Composites.

Generally, to produce film-type thermoplastic composites with good mechanical properties, high-performance reinforcement films are used. In this case, films used as a matrix are difficult to impregnate into tow due to their high melt viscosity and high molecular weight. To solve the problem, in this paper, three polypropylene (PP) films with different melt viscosities were used separately to produce film-type thermoplastic composites. A film with a low melt viscosity was stacked so that tow was impregnated first and a film with a higher melt viscosity was then stacked to produce the composite. Four different composites were produced by regulating the pressure rising time. The thickness, density, fiber volume fraction (Vf), and void content (Vc) were analyzed to identify the physical properties and compare them in terms of film stacking types. The thermal properties were identified by using differential scanning calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The tensile property, flexural property, interlaminar shear strength (ILSS), and scanning electron microscopy (SEM) were performed to identify the mechanical properties. For the films with low molecular weight, impregnation could be completed fast but showed low strength. Additionally, the films with high molecular weight completed impregnation slowly but showed high strength. Therefore, appropriate films should be used considering the forming process time and their mechanical properties to produce film-type composites.

Flocculation kinetics of precipitated calcium carbonate induced by electrosterically stabilized nanocrystalline cellulose

Abstract The interactions between precipitated calcium carbonate (PCC) and electrosterically stabilized nanocrystalline cellulose (ENCC), dissolved carboxylated cellulose (DCC), and a mixture of DCC and ENCC have been studied. ENCC can be produced by periodate, chlorite and TEMPO oxidations of cellulose fibers. It has a large surface area, a high carboxylated content and can be used as a high-performance reinforcement material. It is likely to effectively bind and flocculate with PCC to improve the properties of filled paper. Dissolved carboxylated cellulose (DCC) is produced together with ENCC in the oxidation reactions, and also has a high charge density. The flocculation of PCC induced by ENCC/DCC was measured by photometric dispersion analysis (PDA). It was demonstrated that ENCC or DCC adsorbed first on PCC particle surfaces due to electrostatic attractions, and subsequently ENCC or DCC induces flocculation between PCC. The repulsive electrostatic force reduces to zero when the isoelectric point of PCC particles is reached, allowing attractive van de Waals forces to dominate, resulting in maximum PCC flocculation. After the charge neutralization point was reached, more dissolved carboxylated cellulose adsorbed on the PCC particles, resulting in net negative charges on PCC surfaces, and dispersion of flocs due to electrostatic repulsion. For mixtures of dissolved carboxylated cellulose (DCC) and ENCC, DCC adsorbed faster on PCC than ENCC. Excess ENCC resulted in the exchange of DCC with ENCC, with ENCC particles able to bridge PCC. This mechanism was proved by photometric dispersion analysis and dynamic light scattering experiments.

Synergistic strengthening effect of graphene-carbon nanotube hybrid structure in aluminum matrix composites

High-performance reinforcement and tailored architecture are currently explored to develop advanced metal matrix composites. In this work, aluminum (Al) matrix composite reinforced by hybrid carbon nanofillers was fabricated by a composite flake assembly process. It was found that for various carbon nanofiller volume fractions, a striking synergistic strengthening effect was achieved by employing graphene (reduced graphene oxide, RGO) and carbon nanotube (CNT) hybrid structure as reinforcement in the Al matrix. Particularly, a tensile strength of 415 MPa was achieved with the addition of 1.5 vol.% of RGO-CNT hybrid, which is significantly higher than those reinforced by individual CNT or RGO (326 and 331 MPa, respectively). The synergistic strengthening effect was attributed to the formation of a planar network of RGO and CNT, which improves the load transfer efficiency between the matrix and the reinforcement in composites. Our study highlights the importance of reinforcement architecture for enhancing the strengthening ability in composites, and provides an effective route to fully take the advantage of the superior properties of various reinforcements.

A facile hydrothermal method for synthesis of submillimeter-long octacalcium phosphate and hydroxyapatite as drug carriers with sustained release behaviors

A facile hydrothermal method was employed to synthesize submillimeter-long octacalcium phosphate (OCP) and hydroxyapatite (HAp) crystals as drug carriers. After hydrolysis reaction of urea, calcium phosphate fibers grew preferentially along c-axis due to modulation of crystallization by glutamic acid. With increasing addition of urea, OCP and HAp precipitated with decreased values of crystallite size and aspect ratio. It was found that the conversion of OCP to HAp was completed after hydrothermal treatment at 160°C for 6h. The formation of fibrous crystals and adsorption of water-insoluble drugs were accomplished in one-step synthesis process with presence of ibuprofen molecules. The sustained-release behavior of ibuprofen could be described by a Higuchi model. HAp and OCP fibers might be simultaneously used for high-performance reinforcements to improve mechanical properties of composite materials and sustained-release drug carriers to cure postoperative infection of bone replacement.

The Progress and Prospects of the Research on Reinforcing RC Column with High Strength Steel Wire Mesh and High-Performance Mortar

The high strength stainless steel wire mesh and high-performance mortar reinforcement has been gradually applied in construction, bridge reinforcement project. Study of the reinforcement at home and abroad mainly focus on research of strengthening RC beam shear, bending, and seismic performance. Although the application of RC column has already been carried out, there is also a short of basic technical an applied research for further study. After looking through a large amount of references, this article gives a summary of the present study about reinforcing RC column with the reinforcement, draws some conclusions and predicts the prospect of development.

Robust high performance reinforcement learning through weighted k-nearest neighbors

The aim of this paper is to present (jointly) a series of robust high performance (award winning) implementations of reinforcement learning algorithms based on temporal-difference learning and weighted k - nearest neighbors for linear function approximation. These algorithms, named k NN‐TD ( λ ) methods, where rigorously tested at the Second and Third Annual Reinforcement Learning Competitions (RLC2008 and RCL2009) held in Helsinki and Montreal respectively, where the k NN‐TD ( λ ) method (JAMH team) won in the PolyAthlon 2008 domain, obtained the second place in 2009 and also the second place in the Mountain-Car 2008 domain showing that it is one of the state of the art general purpose reinforcement learning implementations. These algorithms are able to learn quickly, to generalize properly over continuous state spaces and also to be robust to a high degree of environmental noise. Furthermore, we describe a derivation of k NN‐TD ( λ ) algorithm for problems where the use of continuous actions have clear advantages over the use of fine grained discrete actions: the Ex 〈 a 〉 reinforcement learning algorithm.

Carbon fibre composites poised for dramatic growth

Richard Stewart reports on the tremendous potential for growth that carbon fibre represents and the innovative processing techniques and production advances that make the use of these high-performance reinforcements practical for applications in industries which have previously considered them a luxury they could not afford.

Evaluation of impact damage mechanism of multi-axial stitched CFRP laminate

This study focuses on multi-axial stitched fabric, which is a thick, high performance reinforcement for large-scale composite structures. The effects of impact damage on multi-axial stitched CFRP laminates molded by vacuum-assisted resin transfer molding (VARTM) method were evaluated. Impact damage within material was evaluated by ultrasonic scanning device and optical cross-sectional observations. Probed images obtained by both non-destructive and destructive methods were compared, and internal damage distributions of multi-axial stitched CFRP laminates were clarified. In addition, residual compressive strength and fatigue property of impact-damaged CFRP laminates were evaluated by in situ damage growth monitoring using the thermo-elastic stress analyzer (TESA). Three-dimensional damage distribution of impacted CFRP laminate was obtained from ultrasonic C-scan images and cross-sectional photographs. Damage progress behavior was observed on a destructive and non-destructive basis by post-impact fatigue (PIF) test.

High performance reinforcements for advanced structural composites : Dauksys, R. J. SAMPE Quarterly, Vol 3, No 2, pp 1–6 (January 1972)

High performance reinforcements for advanced structural composites : Dauksys, R. J. SAMPE Quarterly, Vol 3, No 2, pp 1–6 (January 1972)

Elastic stiffness and the economics of fibre-reinforced plastics

Present-day knowledge of the relationships between some mechanical properties of a fibre-reinforced composite and those of its components is briefly reviewed. On the basis of this knowledge estimates can be made of the elastic stiffness likely to be achieved for polymeric resins containing the new high-performance fibrous reinforcements. Using these estimates, the cost-effectiveness of such composites in meeting several different rigidity criteria has been investigated.