飞机冲击载荷等效静载的确定方法研究

A method to determine the equivalent static load of aircraft shock load

摘要:

如何确定冲击载荷的等效静载对飞机结构的强度设计和验证具有重要意义。基于经典冲击载荷时域曲线后峰锯齿波、单自由度冲击动响应理论和位移等效原则，建立冲击载荷动态缩放系数求解公式。基于三角函数不等式关系，推导出动态缩放系数与冲击载荷作用时间、结构固有频率乘积的函数关系。建立求解冲击载荷等效静载方法的实施流程。以简化拦阻钩系统的冲击缩比模型的水上迫降为例，对所提方法的有效性进行验证。结果表明：拦阻冲击载荷动态缩放系数的理论估计值与仿真计算值的相对误差小于4%；水上迫降等效静压与选用的设计压力相对误差为1.6%。

Abstract:

It is significant to determine the equivalent static load of impact load for the strength design and verification of aircraft structures. The formula to calculate shock load dynamic effect coefficient is established basing on terminal peak saw-tooth shock pulse describing the time history of shock load, single freedom dynamic response model and the equivalent principle of model displacement. Then the function relationship between dynamic effect coefficient and the product of shock load duration and model natural frequency is deduced from trigonometric function inequality. The flow chart to determine equivalent static load of shock load is drawn according to the above theory. Finally this method is used to predict the equivalent static load of arresting hook system and aircraft model ditching process. The comparative results show that the maximal relative error of dynamic effect coefficient of arresting impact load is below 4% between theoretic estimated values and numerical simulated values by FEM, the relative error of equivalent static pressure during model ditching test is below 1.6% between theoretic estimated value and determined design value.