Techno Press

Steel and Composite Structures   Volume 26, Number 6, March25 2018, pages 771-791
Low velocity impact response and dynamic stresses of thick high order laminated composite truncated sandwich conical shell based on a new TDOF spring.mass.damper model considering structural damping
A. Azizi, S.M.R. Khalili and K. Malekzadeh Fard

Abstract     [Full Text]
    This paper deals with the low velocity impact response and dynamic stresses of composite sandwich truncated conical shells (STCS) with compressible or incompressible core. Impacts are assumed to occur normally over the top face-sheet and the interaction between the impactor and the structure is simulated using a new equivalent three-degree-of-freedom (TDOF) spring-mass-damper (SMD) model. The displacement fields of core and face sheets are considered by higher order and first order shear deformation theory (FSDT), respectively. Considering continuity boundary conditions between the layers, the motion equations are derived based on Hamilton's principal incorporating the curvature, in-plane stress of the core and the structural damping effects based on Kelvin-Voigt model. In order to obtain the contact force, the displacement histories and the dynamic stresses, the differential quadrature method (DQM) is used. The effects of different parameters such as number of the layers of the face sheets, boundary conditions, semi vertex angle of the cone, impact velocity of impactor, trapezoidal shape and in-plane stresses of the core are examined on the low velocity impact response of STCS. Comparison of the present results with those reported by other researchers, confirms the accuracy of the present method. Numerical results show that increasing the impact velocity of the impactor yields to increases in the maximum contact force and deflection, while the contact duration is decreased. In addition, the normal stresses induced in top layer are higher than bottom layer since the top layer is subjected to impact load. Furthermore, with considering structural damping, the contact force and dynamic deflection decrees.
Key Words
    low velocity impact; STCS; structural damping; dynamic stresses; higher order theory
(1) A. Azizi:
Department of Mechanical and Aerospace Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran;
(2) S.M.R. Khalili:
Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran, Iran;
(3) S.M.R. Khalili:
Department of Applied Mechanics, Indian Institute of Technology Delhi, New Delhi, 110016, India;
(4) S.M.R. Khalili:
Center of Excellence for Research in Advanced Materials and Structures, Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Pardis Street, Molassadra Avenue, Vanak Square, Tehran, Iran;
(5) K. Malekzadeh Fard:
Malek Ashtar University of Technology, Department of Mechanical Engineering, 4th Kilameter, Makhsous RD, Tehran, Iran.

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