Linear free vibration analysis of cross-ply laminated cylindrical helical springs

A linear free vibration analysis of symmetric cross-ply laminated cylindric al helical springs is performed based on the first-order shear deformation theory. Considering the rotary inertia, the shear and axial deformation eff ects, governing equations of symmetric laminated helical springs made of a linear, homogeneous, and orthotropic material are presented in a straightfo rward manner based on the classical beam theory. The free vibration equatio ns consisting of 12 scalar ordinary differential equations are solved by th e transfer matrix method, The overall transfer matrix of the helix is compu ted up to any desired accuracy. The soundness of the present results are ve rified with the reported values which were obtained theoretically and exper imentally. After presenting the non-dimensional graphical forms of the free vibrational characteristics of (0 degrees/90 degrees/90 degrees/0 degrees) laminated helical spring made of graphite-epoxy material (AS4/3501-6) with fixed-fixed ends, a non-dimensional parametric study is worked out to exam ine the effects of the number of active turns, the shear modulus in the 1-2 plane (G(12)), the ratio of the cylinder diameter to the thickness (D/d), and Young's moduli ratio in 1 and 2 directions (E-1/E-2) on the first six n atural frequencies of a uniaxial composite helical spring with clamped-free , clamped-simple, and clamped-clamped ends. (C) 2000 Elsevier Science Ltd. All rights reserved.