THEORETICAL PREDICTION OF SOUND RADIATION FROM A HEAVY FLUID-LOADED CYLINDRICAL COATED SHELL

A theoretical model is developed to predict the sound radiation ability of a cylindrical thin elastic shell of finite length, covered with a damp layer and terminated with infinite cylindrical rigid baffles. This shell is immersed in a heavy fluid extending up to infinity, and excited by a constant point load continuously traveling along the circumferential direction. A frequency-domain representation of the rotating load and three equations of the vibroacoustic coupling problem are given. The equations are solved by means of modal analysis method and asymptotic expansion method. Also, a mathematical expression of modal amplitude of shell radial displacement is obtained. The sound radiation ability of this kind of shell is evaluated and the corresponding numerical results are given.

弹性支承上弹性转动约束矩形薄板线性荷载压屈分析

为探讨边界约束下不同刚度对受线性压力作用矩形板稳定性的影响,研究了弹性支承上弹性转动约束的矩形薄板线性压屈问题。采用基于能量变分原理的Ritz能量法,根据屈曲形变提出合适的挠曲面函数,由其能量变分推得临界屈曲荷载理论解。通过有限元分析得到此类矩形板压屈荷载数值解,结果表明:荷载梯度较小时误差不超过2.8%;荷载梯度较大时,通过回归得到修正系数,误差不超过4.7%。同时建立临界纵横比、荷载梯度与板的边界转动约束刚度和支承刚度之间的关系式,根据计算结果分析,边界转动约束刚度为0.8~100时对薄板受压稳定性影响显著。