Mechanics of Advanced Materials and Structures (2014) 21, 263–272 Copyright C  Taylor & Francis Group, LLC ISSN: 1537-6494 print / 1537-6532 online DOI: 10.1080/15376494.2012.680671 Local Buckling of Rectangular Viscoelastic Composite Plates Using Finite Strip Method NASRIN JAFARI 1 , MOJTABA AZHARI 1 , and AMIN HEIDARPOUR 2 1 Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran 2 Department of Civil Engineering, Monash University, Melbourne, VIC, Australia Received 22 February 2011; accepted 27 June 2011. This article presents the stability analysis of reinforced viscoelastic composite plates subjected to in-plane loading using a finite strip method. The equations governing the stiffness and geometry matrices of moderately thick rectangular plates in the time domain are presented using higher-order shear deformation theory and effective moduli method. The critical buckling loads of viscoelastic plates are determined through solving the eigenvalue problems related to the global stiffness and geometry matrices. The accuracy of the developed model is verified against the results reported elsewhere while a comprehensive parametric study is presented to show the effects of different variables on local buckling coefficients. Keywords: local buckling, effective moduli, shear deformation, viscoelasticity, finite strip method 1. Introduction The increasing applications of advanced composites in the aerospace industry and the growing use of polymeric materials in recent years have given rise to increased application of the linear viscoelastic theory. The state of strain in viscoelastic materials depends on the present stress as well as the stress history such that this type of materials exhibit time-dependent properties. On the other hand, the state of stress depends on the present strain and the strain history, and therefore this property of viscoelastic materials is named ‘memory effect’ [1]. The viscoelastic buckling response of laminated plates was investigated by Wilson and Vinson [2], in which the critical buckling load for a simply supported plate subjected to the biaxial in-plane loading was obtained. Oliveira and Creus [3] developed a numerical method for modeling the viscoelastic failure of composite plates and shells where the effects of large displacements and creep were taken into account. A modified stiffness matrix was calculated using the incremental damage while the thermal, hygroscopic, and viscoelastic effects were considered into the material modeling. Buckling problem of the elastic and viscoelastic rotationally symmetric thick cir- cular plate with a penny-shaped crack was investigated by Akbarov and Rzayev [4]. Likewise, using three-dimensional linearized theory of stability, the statement of the problem of stability loss of a circular plate made from a viscoelastic com- posite material was suggested by Kutug et al. [5] for which Address correspondence to Amin Heidarpour, Department of Civil Engineering, Building 60, Monash University, Melbourne, VIC 3800, Australia. E-mail: amin.heidarpour@monash.edu Laplace transform and finite element method were employed while it was assumed that the plate had an insignificant initial rotationally symmetrical imperfection. The quasi-static stability analysis of fiber reinforced vis- coelastic composite plates subjected to in-plane edge load sys- tems was performed by Zenkour [6]. The formulation was based on a shear-deformable plate theory while the proposed model enabled the testing of different through-thickness trans- verse shear-strain distribution. The equations governing the stability of simply supported fiber-reinforced viscoelastic com- posite plates were solved using the effective moduli method, and the solution was used to determine the critical in-plane edge loads associated with the asymptotic instability of plates. Hatami et al. [7] employed an exact finite strip method for the free vibration analysis of axially moving viscoelastic plates. The exact stiffness matrix of a finite strip of plate was extracted in the frequency domain using the differential equation that governs the vibration of plates traveling at a constant axial speed, while the rheological models were utilized to model the viscoelastic behavior of materials. By assembling the stiff- ness matrices of the finite strips, the global stiffness matrix of a plate moving on intermediate rollers was obtained, from which the eigenvalues defining the free vibration of the plate were extracted within the domain of complex numbers. Based on the two-dimensional viscoelastic differential con- stitutive relation, the differential equation of motion of the axially moving viscoelastic rectangular plates constituted by the Kelvin–Voigt model with parabolically varying thickness in the y-direction was developed by Zhou and Wang [8]. Zhen et al. [9] investigated the effect of higher-order shear defor- mations on bending, vibration, and buckling forces of mul- tilayered plates. The mth-order global-local theory satisfying