Hygrothermal effects on the free vibration characteristics of delaminated composite pretwisted rotating conical shells

2014 Mechanical Engineering Journal  
determine the natural frequencies of stationary plates. Liew, et al. (1994) and McGee and Chu (1994) have investigated the vibration characteristics of pretwisted conical shell by Ritz method while Lee, et al. (2002) have analyzed the vibration characteristics of twisted cantilevered conical composite shell by using finite element method. Shen and Grady (1992) and Krawczuk, et al. (1997) focused on the effect of delamination on natural frequencies of composite beam and plate respectively using
more » ... nalytical, experimental and finite element methods. Tracy and Pardoen (1989) and Paolozzi and Peroni (1992) studied the effect of delamination on laminated beam and plate respectively. Tenek, et al. (1993) have studied the impact of delaminations on the natural frequencies of composite plates. Later on, Karmakar and Kishimoto (2006) extended this analysis for delaminated composite cylindrical shells based on finite element method. The effect of moisture and temperature on the free vibration response of laminated composite plates was analyzed by Whitney and Ashton (1971) , Dhanaraj and Palaninathan (1989) and Sai Sinha (1992b). But Parhi, et al. (2001) investigated the hygrothermal effects on the dynamic behavior of multiple delaminated composite plates and shells. In addition, the hygrothermal effects on the bending characteristics (Sai Ram and Sinha, 1991) and the buckling (Sai Ram and Sinha, 1992a) of laminated composite plates have also been analyzed. Naidu & Sinha (2005) studied the non-linear free vibration of laminated composite shells in hygrothermal environment incorporating the Green-Lagrange type nonlinear strains. Kumari & Sinha (2002) demonstrated the hygrothermal effects on the behavior of composite T-joints using a modified thick shell element. Recently Anup Ghosh (2008) analyzed the hygrothermal effects on the initiation and propagation of damage in composite shells due to low-velocity impacts. The literature survey thus suggests that so far no attempt has been made to investigate hygrothermal effects on the free vibration characteristics of delaminated composite conical shells with initial stresses arising out of its rotation. The present work is aimed at finite-element based analysis to determine the natural frequencies of carbonepoxy composite rotating shallow conical shells ( Fig. 1) with delamination at varying temperature and moisture concentration. Numerical results are obtained corresponding to various twist angles, rotational speeds, fiberorientation angles and location of delamination. The present work is limited to the extent of not considering the contact between the delaminated layers. 3
doi:10.1299/mej.2014smm0059 fatcat:dgm7qsutlfgb3mvewvco4uujnu