结构水下爆炸响应的恢复与冲击谱计算

由于传感器受高强度冲击作用,实测的结构水下爆炸响应信号可能偏离正常特征,为进一步分析响应信号带来困难.文中针对实测加速度信号的噪声特征,对信号采用SVD及ARMA滤波处理,先恢复真实的响应信号,然后在此基础上,给出正确的冲击谱计算结果.计算结果说明了SVD结合无相差滤波能够准确分离具有阶跃特征的低频噪声信号,对低频段的冲击响应谱计算精度有利.     

舰船水下非接触爆炸响应的数值模拟

通过数值模拟研究舰船结构水下非接触爆炸载荷下的响应，以有限元方法建立有限水域中的整船结构的有限元模型，并应用声固耦合算法模拟整船的水下爆炸响应，得到结构的冲击加速度响应和冲击响应谱、瞬态应力／应变分布以及结构易于损坏的部位。     

基于相关序列的在线频率估计方法

给出一种在线频率估计的时域算法.从Hankel矩阵与可控矩阵的隐含关系出发,利用可控矩阵的shift结构,推导出系统矩阵特征根与相关序列的显式关系,从而得到信号频率估计的简单公式.对于二阶系统,或可分解为并联二阶系统的高阶系统,特征频率可由信号分量的相关序列估计得到.对定常系统和时变系统的频率估计进行仿真,结果表明频率估计值可以快速逼近真实值,而且稳态误差小于1%.     

Finite Element Modeling of a Fluid Filled Cylindrical Shell with Active Constrained Layer Damping

On the basis of the piezoelectric theory, Mindlin plate theory, viscoelastic theory and ideal fluid equation, the finite element modeling of a fluid-filled cylindrical shell with active constrained layer damping （ACLD） was discussed. Energy methods and Lagrange＇s equation were used to obtain dynamic equations of the cylindrical shell with ACLD treatments, which was modeled as well with the finite element method. The GHM （Golla-Hughes-McTavish） method was applied to model the frequency dependent damping of viscoelastic material. Ideal and incompressible fluid was considered to establish the dynamic equations of the fluid-filled cylindrical shell with ACLD treatments, Numerical results obtained from the finite element analysis were compared with those from an experiment. The comparison shows that the proposed modeling method is accurate and reliable.