Ultrasonic sensor is used for preventing automotive collision. Its directivity of the beam is required to be vertically narrow so as not to react to the curbstones, and horizontally wide so that the number of components is reduced.
In this application, an ultrasonic sensor made by piezoelectric element is analyzed.
An analysis model is shown in Fig. 1. A piezoelectric element is attached to the case. It is driven by voltage. The piezoelectric-acoustic coupled analysis is performed to analyze the directivity of the sound wave.
Fig. 2 shows piezoelectric analysis results of a symmetric quarter model. It is confirmed from the deformed shape that the desired vibration characteristics of the case are obtained.
Fig. 3 shows the acoustic analysis results of sound pressure distribution, and Fig. 4 shows the directivity.
It is confirmed that the horizontal and vertical directivities are obtained as desired.