阶梯圆盘节圆偏离对辐射声场指向性的影响

摘要

In practical application,the location of a nodal circular and its pre-designed stepped location in a stepped circular plate can not be fully coincident for some reasons,i.e.,there is more or less deviation between then.Here,taking a central convex stepped circular plate for example,the stepped circular plate was divided into three parts according to the location of the nodal circular and its stepped one.Then,a method analytically calculating the three-part displacement distribution was proposed,and it was verified with the finite element method.On this basis,the expression of the radiated acoustic pressure was derived with the principle of superposition for an acoustic field,and the effect on its directivity pattern was calculated due to the deviation of the nodal circular location from its stepped one.The results showed that the deviation of the nodal circular location from its stepped location,leads to that the main lobe of the directivity pattern becomes wider,the main lobe of the directivity pattern bifurcates when the nodal circular is larger than its stepped location to a certain level,this makes the radiated energy of the sound field be relatively dispersed.%在实际应用中,阶梯圆盘节圆位置与预先设计的阶梯位置不可能实现真正意义上的重合,节圆会偏离阶梯位置.以带有一个中心上凸的阶梯圆盘为例,将阶梯圆盘按节圆及阶梯位置分成三个部分,提出了解析计算这三部分位移分布的方法,经有限元计算证实了这种方法的有效性.在此基础上,利用声场迭加的原理导出了辐射声压,并计算分析了节圆偏离对指向性的影响.结果表明:节圆偏离阶梯位置会导致阶梯圆盘的指向性主瓣的半开角变大,节圆比阶梯位置偏大到一定值时指向性主瓣分叉,这使得阶梯圆盘的辐射声场能量相对分散.