Our previous research found that CFRPs fabricated by the electrodeposition resin molding (ERM) method exhibited high damping properties. In this research, tailored fiber placement (TFP) was used to make curved fiber shapes, however, those shapes were limited to a parabola and a sine curve. Linear combination of radial basis functions (RBFs) were used to make more complex fiber shapes, and optimum fiber shapes are investigated to improve damping of CFRPs fabricated by the ERM method. Damping is modeled by the specific damping capacity (SDC) which is defined as the ratio of dissipated energy and maximum strain energy, and total damping properties of CFRPs are calculated using finite element analysis (FEA). Before optimization, material SDCs of a plain weave sheet and a TFP layer, which are compositions of CFRPs, are identified by particle swarm optimization (PSO) using the results of experimental modal analysis and FEA. Then, fiber shapes were optimized to maximize the first modal SDC of L-shaped and T-shaped plates using PSO with nonlinear dissipative term. Simultaneously, the thickness distribution which is caused by overlaps or gaps between curved fibers was estimated and applied to a finite element model for more accurate numerical estimation. The results showed that the present optimization of curved fiber shapes including estimation of thickness distribution improves the first modal SDC and decreases the volume of a TFP layer in comparison with unidirectional fiber shapes.
An autoclave molding with prepregs is the most general method of CFRP manufacturing. It is well known that this method is time and energy consuming and prevents the cost reduction of CFRPs. Therefore, aiming to improve CFRP productivity, some manufacturing methods without the autoclave have been proposed such as a vacuumed resin transfer molding(VaRTM)method. The authors have been also proposed a new CFRP manufacturing method that is an electro deposition resin molding(EDRM)method. The EDRM is an application of the electro deposition technology which has been used as a coating technology for automobiles, and it is suitable for mass productions. In our previous studies, static mechanical properties including stiffnesses and strength of CFRPs molded by the EDRM have been investigated, but their dynamic properties have not been done yet. Therefore, in this study, in order to evaluate the vibration characteristics of CFRPs produced by the EDRM, an experimental modal analysis and finite element analysis(FEA) were performed on CFRP specimens with straight and curved reinforcing fibers. The specimens were also manufactured by the VaRTM method and their vibration damping characteristics were compared. It was confirmed from numerical and experimental results that natural frequencies and eigenmode shapes agree well with high accuracy, and the FEA is useful for the specimen manufactured by the EDRM. It is also found that CFRPs produced by the EDRM has greater modal damping ratios than CFRPs by the VaRTM.