Experimental Modal Analysis of Carbon Nanotubes-Reinforced Composite Plates

A combined experimental and numerical study of free vibration of carbon nanotube-reinforced composite (CNTRC) plates of different thickness and aspect ratios has been carried out under clamped and cantilever boundary conditions. CNTRC plates are prepared by mixing different weight percentages of multiwall carbon nanotube (MWCNT) with a polymer. The Young’s modulus and tensile strength of CNTRCs are experimentally determined following ASTM D-3039 and values are used in numerical analysis. Modal testing is conducted by impact excitation using Fast Fourier Transform (FFT) analyzer (Bruel and Kjaer) supporting Pulse platform to determine the frequency response functions (FRF) to extract the natural frequencies. A computer code based on the finite element method has been developed in MATLAB to determine the natural frequencies of vibration and to validate the experimental results. The theoretical and experimental results are found to be in good agreement. The results indicate a rise in Young’s modulus and natural frequencies with increased weight percentage of MWCNT to a critical value of 0.3% and fall thereafter for 0.5 wt. %, mainly due to the agglomeration of MWCNT in the hosting matrix.