弱非线性、可变方向的大面积大功率高指向性辐射体研究

To separate the intervals between the resonant mode and near its promiscuous ones, and to reduce the influence on the resonant mode for minimizing the phenomenon of nonlinear vibration to the weakest degree, how to design the grooved（including its dimension, such as its depth, width etc.） at the bottom of appropriate location of the circular and the rectangle plates will be studied; How to influence the radiated directivity by deformation of the nodal lines at rectangular plate with stripe-mode vibration will be calculate in analytical way, how much is the scope of the driving source area corresponds to the little position changes of nodal lines for the radiator capable of generating highly directive will be studied; The sound source has a structure in which a transducer, a solid horn to magnify vibration amplitudes to excite radiator, and a radiated plate ( or radiator) with extensive surface area are connected in series. For the purpose of reducing the length of sound source, multi-directional radiation and utilizing the full performance of the radiator, in this project, the solider horn will be divided into three sections, that is to say, LA part,directional change device and LB part. The parts of LA and LB have a certain angle θ (through directional change device)by combining directional change device to change the transmission direction of longitudianl vibration. Based on the methods of analytical and finite element numerical calculations, combining with experimental tests, the relations of θ in directional change device and amplitude ratios between two ends of the sections LA and LB will be studied to generate high-amplitude ratio to excite the radiator along certain vibration transformation direction. Resolution of the above issues raised in this subject can provide beneficial reference for such as the problems of weakening of nonlinear vibration ,or of change of the transmission direction in other vibrating systems, and of the something like that relevant questions.

研究在大面积盘或板辐射体底端的恰当位置处开一定深度、宽度的槽体，以便拉开谐振模态与其附近处杂乱模态之间的间隔，减小杂乱模态对谐振模态的影响，将非线性振动减小到最弱程度；在一定激振源面积的激励下，解析计算矩形板条纹振动节线变形后对辐射声场指向性的影响，保证指向性尖锐的前提下，确定节线变化不大对应的激振源面积变化的范围；将连接换能器和大面积辐射体之间的变幅杆分解为"LA杆件-振动方向变换体-LB杆件（LB与LA有一定的夹角θ）"三部分，利用解析、有限元数值计算方法结合实验测试，研究纵向振动转换装置中夹角θ与振幅比（LB末端与LA入端振幅之比）之间的关系，使单向的纵振动可变换为沿不同方向输出高振幅比的纵振动，以此作为大面积辐射体的激振源，目的为发挥辐射体最大潜能前提下，既便于安装、又能实现多方向辐射。本申请项目中所提问题的解决，也能为诸如振动方向变换、弱化振动系统的非线性振动等相关问题提供参考。

研究了高辐射效率下的弯曲振动圆盘、多阶梯弯振圆盘的设计方法，提出了多阶梯圆盘辐射阻抗的计算方法。基于中厚板理论，研究了厚跨比较大时厚圆盘的设计方法,推导出了三种边界条件下的频率方程. 理论计算和实验研究了矩形板的条纹节线与激振源面积之间的变化关系，以及在具有一定纵振面积的振源的激励下，矩形条纹振动模式的节线位置将会发生位置的变化及对辐射声场的影响。实验测试了矩形平板、阶梯板、平圆盘和阶梯圆盘的辐射声场指向性，得到了轴向辐射声压与输入电功率、圆盘的阶梯数目之间的关系：阶梯圆盘轴向声压和输入有效电功率成正比；输入电功率一定时，轴向辐射声压与圆盘阶梯数目成正比. 研究了辐射体在大功率工作状态下，在辐射体背面开槽的槽位置、槽宽度、槽深度与工作频率前后相邻频率之间的间距的关系，由此提供了一种拉宽与工作频率前后相邻频率之间的间距的方法，以减弱非线性振动的方法。研究了超声变幅杆的节点与应变极大位置之间的关系，得出了一般规律。为了得到更大的振幅放大系数的变幅杆，研究了相同几何尺寸的输入、输出端面条件下，内部开锥形空心孔和开柱形锥形孔的变幅杆。提出并研究了用螺栓连接的直孔指数形型变幅杆。从声传播的角度，提出并推导了具有夹角的纵振动变幅杆件的频率方程。还研究了夹角型超声变幅杆的矩阵及有限元设计方法。对加工的数个有关振动变换体的部件进行了有关的试验研究。测试表明，谐振频率、输出端与输入端之比的振幅放大系数与解析计算、数值计算计算值相吻合。在此基础上，提出了一端输入、多端等幅输出的纵振动转换体，由输入杆、半球形过渡体和多个输出杆组成。利用自由边界条件，以及各组件连接处的纵向位移、纵向力、横向位移和转角连续条件，推导了变换体的频率方程。谐振频率的计算值与实验测试值基本吻合。各输出端的位移随电压增大基本呈线性增加，表明具有较好的线性输出特征。另外，也做了一些利用超声技术辨识金属材料真伪方面的研究工作。