This study conducted several tensile tests to determine the effect of 20-30 nm silicon dioxide nanopowder on the mechanical properties of composite material polyester/carbon fiber. Samples were prepared at weight fractions of carbon fibers (i.e. 25, 40, and 55%), with different weights of silica nanoparticles (i.e. 0.16, 0.2, and 0.24%). The experimental results showed that the mechanical properties improved at various ratios as a result of increasing the weight fraction of the carbon fibers and the ratio of the silicon dioxide nanopowder in the composition of the composite samples. The maximum increase by 33.49% resulting from increasing the weight fraction from 25% to 40% at 0.16% silicon dioxide nanopowder. The maximum effect of increasing the weight of the silicon dioxide nanopowder from 0.2 to 0.24 resulted from increasing the stress by 33.53% at weight fraction of 25%. The SEM images of the structure showed the distribution of nanoparticles and crack growth in the region neighboring the fracture after the tensile test at different weight fractions of carbon fibers and nano-silica particles. The improvement in the mechanical properties of this low-cost composite material when using nanomaterials has potential for use in multiple applications, including boat hulls.

The study investigates the improvement of the mechanical properties of the acrylic layer by creating a crack according to polynomial’s function by using the CO2- laser and without additives. The cracks were created by the laser at different powers and different speeds. The shape of the cracks was created according to six degree polynomial’s function by using CNC-laser machine. The study focused on the effects of creating an edge on both sides of the crack generated from the laser heat helping to change the microstructure on it to resist the failure crack growth. The study adopts a laser beam path according to equation g(x) to show the effect of the shape of the laser beam on improving the properties of the acrylic specimens. The experimental results have shown the effect of laser beam speed and laser beam power on the stress-strain. The experimental results shown increasing in the stress with average rate (12.25%) due to increasing laser beam power at (40, 50 and 60). The experimental results of specimens type (O and A4) shown improving in the stress at average rate (12.87%) and copmaring the experimental results of specimens type ( O, A5 and A6) has revealed an incresing in the tensile stress with average rate (14.088%).

No abstract

No abstract

No abstract