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In the present study, filament wound pipes were fabricated by glass and polypropylene (PP) yarns with the three different filament winding angles 55°, 70°, and 82°. Glass and PP yarns were wound around the pipe with two methods; layered and hybrid. Epoxy resin was applied as a matrix to manufacture composite samples. It should be mentioned that composite samples were made in different layers. The three-point bending test was carried out on all samples to investigate the bending behavior of the composites. The experimental results showed that the winding angle 55° is better than other angles in terms of improving the flexural strength of the composite. Moreover, using hybrid yarn to fabricate the composite sample increases the flexural strength and energy absorption of the composite. In the next step, a multi-scale finite element model was applied to predict the flexural behavior of the composites. In this model, a unit-cell of each composite structure was modeled at the meso scale and elastic constants of the composites were extracted by a Python code. In addition, failure parameters for the composites were determined according to micromechanical equations. All elastic and failure parameters were utilized for the macro model and simulation three-point bending test. The numerical results were compared with the experimental and a good agreement could be observed between numerical and experimental results. So, the proposed model is proper to predict the mechanical behavior of the filament wound composite with high accuracy.

This study investigated the directional warpage on bi-convex and bi-concave spherical lenses by experimentally monitoring the changes in the pressure and temperature of mold cavity and comparing them with the simulation results. Warpage was investigated in the direction of the introduction of molten materials into the cavity of the mold, and when it was perpendicular to the direction of the fluid wave front. Packing conditions, including packing time and packing pressure, and mold temperatures are among the important factors influencing lens warpage and their geometric quality. In this research, these factors were investigated in a full factorial design of experiment. Also, simulation results are in good agreement with the experimental results obtained by the vision measuring machine apparatus. According to the results of this study, the least warpage values in bi-convex and bi-concave lenses in the direction of the fluid wave front were 180 and 200 microns, respectively; while these values were 172 and 198 microns when the lenses were perpendicular to the fluid wave front. The experimental values of these in the direction of the melt in the entrance of the mold for bi-convex and bi-concave lenses were 149 and 186 microns, respectively, while these values were 143 and 180 microns when the lenses were perpendicular to the flow front direction. In addition, the results of the pressure diagram inside the mold cavities indicated the correlation with the warpage, such that when the slope of the pressure graph was lower, the lens warpage was less too.