In order to investigate the effect of autoclave process on the stiffness properties of thermoplastic composite truncated cones made by automated fiber placement technique (AFP), two short truncated cones were made out of advanced thermoplastic composite material (carbon fiber/PEEK). Then, the truncated cones were tested by impulse excitation of vibration to get experimental natural frequencies. Tensile and compression test coupons were made out of the same material using hand layup and autoclave process, and stiffness properties were characterized experimentally. Furthermore, finite element analysis was performed to extract theoretical natural frequencies using material properties obtained from coupon testing. Comparison between the natural frequencies obtained using the finite element method and experimental modal analysis was conducted. Furthermore, the two truncated cones were treated inside the autoclave, and changes in the thickness and density were measured. After autoclave treatment, experimental modal analysis was repeated to investigate the possible changes in natural frequencies. The finite element model was also updated upon the changes in thickness and density of the truncated cones, and consequently, comparison between the theoretical and experimental natural frequencies was carried out again. Also, micrographs of two truncated cones were taken before and after autoclave treatment to examine the autoclave effect on the quality of the samples.
Science and Engineering of Composite Materials22, no. 2 (March 2015): 175–186.