54-2一维非线性振动及其微分方程的近似解法 初始条件x(0)=A(0)=0 x(0)=Ax0(0)=0 x1(0)=0x(0)=0 x2(0)=0x2(0)=0 x tox=0 A cos ot x+ox=A cos ot-aAcos at A-d, A)cos at +AcoS 3at§4-2 一维非线性振动及其微分方程的近似解法 初始条件 x(0) = A x (0) = 0 x0 (0) = A x  0 (0) = 0 x1 (0) = 0 x  1 (0) = 0 x2 (0) = 0 (0) 0 x  2 = 0 0 2  x  0 + x = x Acost 0 = x  x A cos t  Acost 1 3 3 1 2  1 + = − A  A t A cos3t 4 1 ) cos 4 3 ( 3 1 3 = − +