Journal of Composite Materials

In this paper, stainless steel–titanium carbonitride-based composites were fabricated and analyzed to utilize for bipolar plate in fuel cells. In order to study the size effect of titanium carbonitride on the mechanical and corrosion resistance properties of the composites, micro and nanosize titanium carbonitride powders were used. Stainless steel–carbonitride composites were prepared by spark plasma sintering and subsequently annealed at different temperatures up to 1100℃ to improve the morphological and mechanical properties. Various properties of the obtained samples were compared before and after annealing. It was shown that after heat treatment, the mechanical properties of the stainless steel–carbonitride composites improved due to the diffusion of titanium carbonitride particles into stainless steel. Addition of microsized titanium carbonitride powders was found to be effective to improve the mechanical properties, such as microhardness and compressive strength, of the composite. However, addition of nanosized titanium carbonitride powders led to an increase of corrosion resistivity of the composite. Physical properties, such as thermal and chemical stability of the obtained composite samples were investigated by microhardness tester, potentiostat, field emission-scanning electron microscope, EDX and X-ray diffraction.

As a renewable energy harvesting method, interest in piezoelectric energy harvesting has increased significantly. Despite the piezoelectric energy-harvesting technology expanding its area to the flexible (elastic, amendable) devices, striking use or application of the technology is hardly found in the market. Here, we report a novel flexible piezoelectric energy harvester fabricated by using an additive manufacturing process, which enables both effective and customized manufacturing technique. By taking advantages of additive manufacturing, further application of the piezoelectric energy-harvesting technology is highly expected. Particles of BaTiO₃, a ceramic with a large piezoelectric constant, were mixed with polyether block amide elastomer to form a flexible piezoelectric composite. The energy harvester was fabricated using an additive manufacturing process, by printing the piezoelectric composite on a laser-patterned flexible Indium-tin-oxide–coated polyethylene terephthalate substrate. Performance of fabricated energy harvester was evaluated by applying a mechanical stress to the energy harvester; voltage and current output were 2 V and 40 nA, respectively. An analytical model of the piezoelectric energy harvester was developed and discussed to explain the form of the voltage waveforms in response to the applied stress.

The SPHC/MgO composites were fabricated by friction stir welding (FSW) and then the mechanical property of the composites was investigated. MgO particles were flocculated on the advancing side in the stir zone (SZ) formed by one-pass processing. On the other hand, MgO particles were more homogenously distributed in the SZ formed by two-pass processing. Compared to the SZ without MgO particles, the hardness profile of the SZ with MgO particles was increased to 20–30 Hv due to refined grain by pinning effect. Grain growth in the SZ without MgO particles was observed at elevated temperature. On the other hand, the fine grain produced with MgO particles was maintained at elevated temperature (∼900℃) due to pinning effect by MgO particles.

To meet requirements of high performance and light weight of parts in equipment, automobile and mechanical industries, etc. coupled with problems during weaving such as simple structure, small size, complex process, low machine automation, poor fiber volume fraction of products, high void fraction of resin impregnation and difficulty of making large and complex structure, a new weaving method for three-dimensional hybrid woven with composite material is provided. Fibers are weaved to structures along with a digital guide template controlled by computer and parts are formed after resin being impregnated from outside to inside. Fabric of three-dimensional hybrid woven method based on the board, method of resin impregnation from outside to inside of three-dimensional hybrid woven fabricated part, and development of test platform for three-dimensional hybrid woven parts and fabric test for typical parts are mainly studied. This new forming technology improves flexibility and operability in forming process of large parts, and has great academic value, active meaning in science study and good foreground in engineering applications.

It has been firmly realized that the dispersion of carbon nanotubes and their bonding with the matrix on the interfaces are two crucial problems need to be resolved to achieve the expected properties of nanocomposites. In view of the unsatisfactory interfacial bonding of the carbon nanotubes/epoxy composites, the complicated production procedure, and the high energy consuming of the conventional preparing method, the electron beam curing technology was used in preparing carbon nanotubes/epoxy composites in this study. The electron beam can realize the radiation curing of the nanocomposites; in the meantime, it also can enhance the concentration of unsaturated carbon atoms of the carbon nanotubes surface and strengthen the interphase interaction of carbon nanotubes and the matrix as well. It would improve the carbon nanotubes modification efficiency and composites properties and benefit the environment. In this article, to further improve the properties of the composites, the multi-walled carbon nanotubes were modified with polyethylene glycol diglycidyl ether, and then polyethylene glycol diglycidyl ether-functionalized multi-walled carbon nanotubes/epoxy composites were prepared by electron beam curing process. The results showed that polyethylene glycol diglycidyl ether-functionalized multi-walled carbon nanotubes do good to the improvement of the elongation at break of the corresponding composites. It also showed that the reinforcement effect of polyethylene glycol diglycidyl ether-functionalized multi-walled carbon nanotubes reached a maximum at the content of around 0.25 wt%, and at higher contents, the tensile modulus decreased with filler loading.

The aim of the present work is to study the influence of the mechanical and electrical imperfections in reinforced piezoelectric composite materials with unidirectional cylindrical fibers periodically distributed in rhombic cells under mechanical and electrical imperfect contacts. The behavior of the composites is studied through two approaches: the two-scale asymptotic homogenization method and the finite element method. The asymptotic homogenization method is applied to a two-phase composite with mechanical and electrical imperfect contacts and to a three-phase composite with perfect contact in the interphase. The constituents of the composite are homogeneous piezoelectric materials with transversely isotropic properties. The local problems are formulated for the spring-capacitor and three-phase models by the asymptotic homogenization method. The solution of each plane local problem is found using potential methods of a complex variable and the properties of doubly periodic Weierstrass elliptic functions. Closed-form formulae are obtained for the effective properties of the composites with both types of imperfect contacts and different configuration of the cells. The finite element method is implemented for analysis of piezoelectric composite materials with unidirectional cylindrical fibers periodically distributed in rhombic cells under mechanical and electrical imperfect contacts. Some numerical examples are given under the presence of both imperfect contacts and different arrangement of the cells. Comparisons between the numerical results reported by asymptotic homogenization method and finite element method are provided.

In this study, physical, mechanical, thermal, fire and biological properties of thermoplastic composites filled with fire retardant and tea mill waste fiber were investigated. The composites produced with the extrusion method were accomplished by using tea mill waste fiber as lignocellulosic materials and high-density polyethylene and polypropylene as thermoplastic polymer. Aluminum trihydrate and zinc borate were incorporated with different contents into polymer matrix for improving fire properties of the composites, and their effects on technological properties of the composites were evaluated. Aluminum trihydrate had a positive effect on the tensile modulus of the composites whilst zinc borate had adverse effect on that of the composites. The strength properties of the composites slightly decreased with usage of fire retardant. In the light of obtained results, it was specified that use of fire retardants improved physical, biological, thermal and fire properties of tea mill waste fiber-filled thermoplastic composites.

The objective of this study was to investigate the quasi-static and dynamic behaviors of three-dimensional carbon/epoxy braided composites under high strain rate punch shear loading. The punch shear tests were conducted at four strain rates, i.e. quasi-static, high strain rates ranging from 1320 s⁻¹ to 3109 s⁻¹, respectively. The meso-structure model of the three-dimensional braided composite was established based on the braided preform structure. The progressive damage and three-dimensional stress distribution in shear zone of the braided composite were numerically revealed with finite element method. The influences of braiding angles and strain rate sensitivity on the punch shear behaviors have been analyzed. There was good agreement between experimental and finite element method results. The finite element method results showed that the stress concentrated on the shear region. The braiding angle plays a significant role in the shear behaviors of the three-dimensional braided composites. It was also observed that the compression damage occurred on the front surface while tension damage occurred on the back surface. The fracture of three-dimensional braided composites under high strain rate shear loading increased with the strain rate increase.

The influence of the carbon nanotubes (CNTs) content on the fiber/matrix interfacial shear strength (IFSS) in glass/fiber epoxy composites was measured by means of push-in and push-out tests. Both experimental methodologies provided equivalent values of the IFSS for each material. It was found that the dispersion of CNTs increased in IFSS by 19% in average with respect to the composite without CNTs. This improvement was reached with 0.3 wt.% of CNTs and increasing the CNT content up to 0.8 wt.% did not improve the interface strength.

This study consists in the evaluation of the use of an artificial neural network of modular architecture in building probabilistic constant life diagrams. Therefore, an algorithm developed in previous studies which was applied to achieve deterministic values has proved itself viable when at least three S-N curves were used. For this case, the probability S-N curves were used for training and validation of the modular network based on the generalized power law and a probability of 5% for failure has been considered. In addition, three composite materials were evaluated with a considerable number of tests to better assess the model.

Chicken feathers waste from poultry industry was incorporated in poly(lactic acid) matrix to obtain an environmental friendly biocomposite taking advantage of the unique properties of chicken feathers, such as low density, biodegradability and good thermal and acoustic properties, and of the biodegradability of the poly(lactic acid). The effect of manufacturing conditions on the final properties of the composite and on the matrix–fiber compatibility was studied. Optimal manufacturing conditions, in order to obtain the best mechanical results, were found at a temperature of 170–180℃ for a processing time of 5 min and a speed of mixing of 50 r/min. Young’s modulus was not very affected by the chicken feather’s content showing a maximal variation of less than 8%, indicating that is possible to include chicken feathers in a composite maintaining its stiffness. However, tensile strength and elongation decreased up to 58 and 12%, respectively, when chicken feather content was 25% because of the restraining effect of the fibers. Moreover, dimensional stability was negatively affected with the inclusion of chicken feathers. Infrared spectroscopy and scanning electron microscopy studies show that fiber–matrix interaction exists but it is weak.

Aluminium matrix composites have been extensively studied for several decades due to the potential advantages over classical low-density materials. Low-density composites can offer high wear and corrosion resistance, high strength, and favorable thermal electrical properties that attract the attention of various industries such as aerospace and automotive. This study investigates the dry sliding wear behavior of AlB₂–Al–4Cu composites with 5, 10, 20, and 30% weight reinforcement. In situ developed AlB₂ flakes were incorporated as the reinforcing compound in the Al–4Cu matrix. The composite samples were tested against a steel disk using a pin-on-disk wear rig. The effect of reinforcement ratio, applied load, sliding velocity on the wear rate and friction coefficient of the composite samples was investigated. In addition, the worn surfaces have been characterized in terms of wear patterns. Compared to the matrix alloy, composite samples exhibited better wear resistance and lower friction coefficient to varying degrees of magnitudes.

In this study, hybrid yarns were developed by commingling the continuous polypropylene and glass fibers using air jet and direct twist preparation techniques. The non-crimp fabrics were obtained with ± 45 ° fiber orientation from these hybrid yarns. The fabrics were prepared with fiber sizings that are compatible and incompatible with polypropylene matrix to investigate the effect of interfacial adhesion on the properties of the thermoplastic composites. Composite panels were produced from the developed fabrics by hot press compression method and microstructural and mechanical properties of the composites were investigated. It was found that type of the hybrid yarn preparation technique and glass fiber sizing applied on the glass fibers have some important role on the properties of the composites. Composites made of fabrics produced by air jet hybrid yarn preparation technique exhibited better results than those produced by direct twist covering (single or double) hybrid yarn preparation techniques. The highest flexural properties (99.1 MPa flexural strength and 9.55 GPa flexural modulus) were obtained from the composites manufactured from fabric containing compatible sizing, due to better adhesion at the interface of glass fibers and polypropylene matrix. The composite fabricated from fabric with polypropylene compatible sizing also exhibited the highest peel resistance (interlaminar peel strength value of 5.87 N/mm). On the other hand, it was found that hybrid yarn preparation technique and type of the glass fiber sizing have insignificant effect on the impact properties of the glass fiber/polypropylene composites.