No abstract

This research offers an experimental and numerical study on the influence of multi-wall carbon nanotubes (MWCNTs) addition with different weight fractions on the dynamic characteristics of the unsaturated polyester (UP) reinforced by hybrid laminate composites. The laminate composites were prepared for only three layers as a total number of layers in such composites using Kevlar fibers and/or carbon fibers with different volume fractions. Both types of fibers were in the form of plain woven at (0°/90°) angle direction. Hand lay-up method was used to prepare the test samples. It was found that The best mechanical and dynamic properties based on the experimental study have been obtained for unsaturated polyester reinforced with (MWCNTs) particles at weight fraction (0.4% wt). Composite material made of unsaturated polyester reinforced with (MWCNTs) particles was also prepared with the same weight fraction of MWCNTs. Finite element method was used to model the free vibration of a cantilever beam made of composite material. ANSYS software composite Prep-Post (ACP) integrated within ANSYS Workbench software (18.2) was used to solve the FE problem. Field emission scanning electron microscopy (FESEM) and scanning electron microscopy (SEM) are applied to check the morphological properties of the composite material and the dispersion of MWCNT nanoparticles in the polymer matrix. Experimental and numerical Results obtained in the present work showed that the natural frequency and damping ratio of nano composite specimens increase with increasing weight fraction of MWCNTs. The results also showed that composite and hybrid composite materials with (0.4% wt) MWCNTs have higher values of natural frequency and damping ratio. It was found that the natural frequency for the hybrid nano composite with stacking sequence (UP+K/K/ K+MWCNT) increased by about 10.4% when adding MWCNTs compared with (UP+K/K/K) laminated composite while it becomes 13.82% and 5.8% for (UP+K/C/K+MWCNT) and (UP+C/K/C+MWCNT) hybrid nano composite material in comparison with that without MWCNTs. The increase percentages of the damping ratio of the such materials have been calculated and it was found to be, 12.23%, 15.9% and 8.6%, respectively. An agreement between the experimental and numerical results has been obtained from flexural and vibration tests with maximum errors not exceeded 3.4% and 9.34%, respectively.