چكيده به لاتين
Low-energy, low-velocity impacts, including the impact of repair tools and impacts caused by the impact of foreign objects on parts made of polymer-based composites, in most cases cause defects that are not detectable by visual inspection but reduce mechanical properties and Performance constructs. On the other hand, in some applications, composite parts are exposed to constant temperature changes, which affects their mechanical properties, including impact resistance properties. The aim of this dissertation is to use clay nanoparticles to improve the properties of carbon/ epoxy plates under low impact velocity and thermal cycles. The research method in this dissertation is based on laboratory observations and interpretation and quantification of results. First, epoxy samples containing 3% by weight of 0.2, 0.4 and 0.8% were made of nanoclay and based on the tensile and flexural properties of the samples, the optimal percentage of nanoclay in epoxy resin was 0.2%. Then, carbon/ epoxy plates without nanoclay and containing 0.2% of nanoclay were made by vacuum infusion method and were subjected to low velocity impact test by drop weight method and at three impact energy levels of 10, 15 and 20 joules. Addition of nanoclay increased the maximum contact force of the impact and the residual compressive strength on average by 22.11% and 20.77% in the samples, respectively. Next, carbon/ epoxy composite plates with and without nanoclay are subjected to 200 thermal cycles between -30 and +65 degrees Celsius in a thermal oven. Exposure of the multilayers under thermal cycle conditions resulted in an increase of 19.34%, 14.61%, 14.8% and 30.3% stiffness of the damaged samples with energies of 0, 10, 15 and 20 joules. And the residual compressive strength increased by 15.72%, 8.19%, 19.29% and 13.76% at the levels of 0, 10, 15 and 20 joules, respectively. Scanning electron and CT scan, failure mechanisms due to low velocity impact and thermal cycles have been studied on the samples. Finally, the parameters of the Caprino model are used to predict the residual compressive strength of carbon / epoxy samples with and without nanoclay at room temperature and thermal cycle conditions using the experimental results.
