叶片非线性瞬态响应计算方法与参数选择

Selection of Methods and Parameters for Calculating Nonlinear Transient Response of Blade

在计算叶片的鸟撞击响应时，为提高计算精度及降低计算成本，需要为待解的非线性动力方程组制定一个合理的求解方案。这包括选择系数矩阵的算法与非线性动力方程组的解法，以及选择主要计算参数。本文介绍了当使用ＡＤＩＮＡ程序计算平板叶片在冲击载荷下的非线性瞬态响应时，对计算方法与计算参数的选择。算例说明了时间步长的重要影响作用。

When we calculate the blade response caused by bird impact with the finite element method,it is necessary to solve a set of nonlinear dynamic coupled equations. A reasonable plan for solving the coupled equations must be drawn up at first in order to improve the precision of the solution and to reduse the calculation cost. The following problems must be considered in making the plan,i.e., how to calculate the coefficient matrixes,how to select the method for solving the nonlinear dynamic coupled equations,and how to select the principal calculation parameters. When the nonlinear transient responses of flat blades under the impact loads are calculated by the program ADINA, the problems mentioned above are solved as follows.The mass matrix is established by the procedure of lumping mass. In establishing the stiffness matrix,the effect of both elastic-plastic and large deformation is considered. The nonlinear dynamic coupled equations are solved by the Newmark method,and the equilibrium iteration is conducted by the BFGS method. The selection of principal calculation parameters such as the time step,the convergence error,the maximum of iteration number and so on are also introduced,and the important effect of the time step on the response calculation is shown by the calculation process with an example.