Besides that, because of the width of horizontal beam and vertical beam is much smaller than the diaphragm, the force acting on them is also ignored.If the width of each square diaphragm is a, the distance between two square diaphragms is 2L, the resultant force F acting on the structure can selleck catalog be Inhibitors,Modulators,Libraries expressed as:F=��spdS=2apaej��tk sin ��sin[k(L+a)sin ��]?sin(kL sin ��)(4)and the resultant moment M can be expressed as:M=��sxpdS=2apaej(��t?��/2)k sin ��?cos[k(L+a) sin ��](L+a)?cos(kL sin ��)L?sin[k(L+a) sin ��]/(k sin ��)?sin(kL sin ��)/(k sin ��)(5)It is clear that the resultant force and resultant moment also vary harmonically with time. If L is equal to 0.
4 mm, a is equal to 1 mm, sound frequency f is equal to 1 kHz and the sound pressure amplitude pa is equal to 1 Pa, the relation curves between the amplitude of resultant force or resultant moment and the incident angle can be plot in polar coordinate system, as shown in Figure 4.Figure 4.Resultant Inhibitors,Modulators,Libraries force (a) and resultant moment (b) versus incident angle.As we can see from Inhibitors,Modulators,Libraries the figure, when Inhibitors,Modulators,Libraries the characteristic length of the structure is much smaller than the wavelength, the resultant force keep constant as the incident angle varies. There is approximately no relationship between the resultant force and incident angle. But the resultant moment expresses a directivity pattern of ���ޡ� as the incident angle varies. In order to enhance the directivity of the structure, the sensitivity to pressure gradient should be increased.3.
?FEA SimulationIt is difficult to characterize the dynamic behavior of the sensitive structure in the acoustic field through analytic method because of complicated structure vibration equation and distributed acoustic loading. For such reason, finite element analysis was performed using FEA software ANSYS.3.1. Mode AnalysisFirstly, structure modal analysis was performed to determine the vibration Dacomitinib characteristics (natural frequencies and mode shapes) of the sensitive structure. During the simulation, besides in-phase and out-of-phase vibration modes, several other vibration modes were also found within the frequency range of analysis; for example, the vibration mode in which the structure rotates around z axis and bending vi
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