Abstract： Free vibration behavior of laminated composite cylindrical helical springs with rectangular cross-section is studied. The effect of the warping deformation of wire cross-section on natural frequencies and vibration mode shapes is first considered in the formulation. The differential equations of motion for the springs including warping, which consist of 14 first-order partial differential equations, are derived using naturally curved and twisted anisotropic beam theory. The natural frequencies of the springs are determined by the use of improved Riccati transfer matrix method. The element transfer matrix used in the solution is calculated using the Scaling and Squaring method and Pad´e approximations. Calculations show that the warping deformation has a certain influence on the natural frequencies, which should be considered in the free vibration analysis of the springs. Finally, the effects of various parameters on the natural frequencies have been investigated, and some properties, different from those of isotropic cylindrical helical springs with rectangular cross-section, have been found.
2012, Vol. 31 
