%A Quoc Quan Tran %A Hui - Shen Shen %A Dinh Duc Nguyen %T Nonlinear Dynamic and Vibration of Imperfect Sigmoid-Functionally Graded Double Curved Shallow Shells Resting on Elastic Foundations using the First Order Shear Deformation Theory %C Hanoi, Vietnam %D 2014 %L SisLab1233