Nonlinear free vibration analysis of variable stiffness symmetric skew laminates

•A skew p-element is developed for nonlinear free vibration of variable stiffness symmetric skew laminates.•The numerical results are validated with the help of convergence tests and comparisons with published data.•The linear frequency increases with increasing skew angle.•The variation in skew angle yields notable changes in curvature of normal modes.•The degree of hardening decreases with increasing skew angle.

A skew p-element is developed for the nonlinear free vibration of variable stiffness symmetric skew laminates. The governing equations are based on thin plate theory and Von Karman strains. The fundamental frequencies and normal modes are computed for fully clamped edge conditions. The equations of motion are derived using Lagrange's method. By employing the harmonic balance method, the transformation from time to frequency domain is facilitated. The nonlinear equations are solved using the iterative technique known as the linearized updated mode method. The numerical results are validated with the help of convergence tests and comparisons with published data. New results are presented for variable stiffness symmetric skew laminates with different fiber configurations showing the effects of variation in skew angle on frequency, normal mode, and degree of hardening.