Journal of Reinforced Plastics and Composites

Polyurethane (PU)/E-glass composites with different reinforcement contents are prepared. The compression strength and hardness of these composites are evaluated. These properties are found to be enhanced by the reinforcement with glass.

Theoretical analysis is developed for an infinite composite hollow cylinder constructed of elastic and pyroelectric layers subjected to axisymmetric dynamic thermal loads. The solutions are based on piezothermoelastic theory. In terms of the charge equation of electrostatics, the radial electric displacement is first expressed as a product of a known function of radial coordinate and an unknown function of time. Then, the solution for the elastic field is obtained by the method of superposition. Finally, by means of the electric potential boundary conditions, a second kind of Volterra integral equation, which can be solved by the interpolation method, is derived to determine the unknown function of time. As a numerical experiment, the transient responses for the uniformly heated steel/CdSe composite hollow cylinder are illustrated graphically.

This article is concerned with the experimental and numerical results of the stress analysis in woven-glass fiber-reinforced conveying chain components. The effects of various loading conditions on the stress of a pin-loaded composite component are investigated. For the experimental study, an apparatus had been developed to simulate chain components in real motion, and two different loading conditions of the chain component have been investigated. The first condition represents the movement of the chain components without loading, while in the second condition, the chain component tand moves the load. The finite element code ANSYS has been used to perform the numerical analysis using three-dimensional eight-noded layered structural solid elements. The chain tensile forces loaded through pins are chosen to be 300, 600, 900, and 1200 N for the two conditions of the chain components. Comparisons are made between the numerical and the experimental studies for the two different conditions. The experimental and numerical results show that at the second loading condition the stress values increase by increasing the tensile force.

In this study, an elastoplastic thermal stress analysis has been carried out on a thermoplastic composite disc that is unidirectionally reinforced by steel fibers. The finite element method (FEM) was used to compute thermal elastic and elastoplastic stress distributions in the model of the composite disc. The solution is performed using the ANSYS program. In order to evaluate the effects of uniform temperature, different temperature loadings are applied to the disc model uniformly. Both radial and tangential stresses are calculated under a uniform temperature loading which is chosen from between 80 to 120 C. Due to the composite disc having different thermal expansions in radial and tangential directions, thermal stresses were calculated by applying uniform temperature loading. The magnitude of tangential stress components for both elastic and elastoplastic solutions is higher than that of radial stress components. Moreover, residual stress components are obtained using the results of elastic and elastoplastic solutions. The calculated results point out that distributions and values of improved thermal stresses and residual stresses are considerably influenced with increasing uniform temperature loading.

This article studies the possibility of making a cork fiber to reinforce plastics (polypropylene, PP). The thermal and structural properties of natural fibers are determined. The hydrophilic character of cork and the hydrophobic character of PP eliminate all chemical adhesion between the fiber and the matrix. This article gives a method of surface modification of cork which ameliorates the fiber-matrix adhesion (their results effects on the mechanical properties of composites). The method consists of hot water treatment. First, the influence of water treatment on the mechanical, thermal, and structural properties of the cork used to reinforce the composites is studied. This study is used to prepare a composite material with good mechanical and thermal properties without destruction of the cellular structure. The specimens of cork are treated with boiling water at ambient pressure for 1, 2 and 3 h and then washed with cold water. The specimens are dried in a dry oven at 70 C for 3 h. The results obtained show that density decreases as a function of water treatment time. This study also describes the influence of water treatment on the thermal behavior of the cork. An increase in thermal stability with water treatment time, in a nitrogen atmosphere, is noticed. In an isothermal study, a loss of mass of 5% after 30 min at 180 Cis observed. The specimens of treated and untreated cork are used to reinforce the PP matrix. The tensile test shows the importance of the surface modification of cork used in composites, particularly after treatment for 1 h. The adhesion properties of PP-cork are described with scanning electron microscopy (SEM).

In this study, the corrosion behavior of Al 6092/17.5 SiC(p) alloy is investigated. The alloy offers a good resistance to corrosion in 3.5 wt% NaCl as shown by weight loss and electrochemical studies conducted in a smoothly stirred condition up to 70 C. The alloy also offered a strong resistance to corrosion in a salt spray chamber. The corrosion behavior of the alloy, however, declined with an increase in velocity, temperature, and addition of polystyrene particles in the electrolyte. The declining corrosion resistance is attributed to the cracking and breakdown of the protective boehmite layer at elevated temperatures, higher velocities, and impact of polystyrene particles. Microanalytical studies reveal the intermetallic precipitates to be the preferred sites for initiation of pits. The alloy offers good service prospects in a marine environment at controlled flow velocities and temperatures.

This study reports the method of recovery of glass fibers from glass/epoxy composites through the solvent method. It is possible to decompose epoxy resin with a yield of more than 99 wt% soluble products in a nitric acid solution (8 M) at 90 C for 5 h. The decomposition rate of epoxy resin increases with an increase in temperature and concentration of acid solution. The glass fibers can be recovered with very little contamination and they have a tensile strength reduction of 3.5% under decomposition conditions of T = 70°C, t = 250 h, C = 6 M and α= 6 g/100 mL. These fibers can be used as reinforcement to prepare new composites. The interlaminar shear strength (ILSS) of recovered short fiber-reinforced composites produce strength reductions of only 2.5% compared with pristine composites.

Buckling analysis of symmetric and antisymmetric cross-ply laminated hybrid composite plates with an inclined crack subjected to a uniform compression is investigated in this article. The first-order shear deformation theory in conjunction with the variational energy method is employed in the mathematical formulation. The effects of crack size, crack inclination angle, and lay-up sequences on the buckling loads are investigated. The results are shown in graphical form for various conditions.