单自由度体系动力学分析回顾 1.单自由度体系自由振动 (1)无阻尼时 mix+kx=0 k 元+2x=0 x(t)=(o cos ot +sin ot) (2)有阻尼时m+c+kx=0 x+2+m2x=0 5<1时 x()=e(x0c0s0+0+x2O二、单自由度体系动力学分析回顾 1.单自由度体系自由振动 (1)无阻尼时 m x + kx = 0 0 2 x + x = m k = 2 ( ) ( cos sin ) 0 0 t x x t x t = + m c m k 2 , 2 = = m x +cx + kx = 0 2 0 2 x + x + x = ( ) ( cos sin ) d d 0 0 0 t x x x t e x t d t + = + − 1 时 (2)有阻尼时