Nonlinear oscillation analysis by an orthogonal function method

In this paper, an orthogonal function method is presented based on the idea to suppose periodic solution with the method of harmonic balance. The displacement is expressed in the form of trigonometric functions, a group of simplified eigenequations are obtained by the use of orthogonarity of trigonumetric functions and linear modes. The method overcomes the difficulty of a drift term existing ht systems with quadratic nonlinearities. The calculation examples show that the method has the advantages of high calculation precision, high convergence speed and little calculation work.