Design and experimentation of sensitive element of piezoelectric crystal sensor array for grain cleaning loss
This study described the optimal design for the sensitive element of the piezoelectric crystal sensor array for grain cleaning loss. To improve the signal-to-noise and resolution of grain cleaning loss, the dynamic model for grain collision sensor array was established by using elastic thin plate theory and also the best structural parameters of sensitive element were determined to make out the grain and the stems momentum. The structural parameters of the thin plate were length of 300 mm, width of 200 mm, thickness of 1.5 mm, plate structural style and four corners fixed. Then, the experiment that grain impacted the sensitive elements with the thickness of 0.5, 1.5 and 2.5 mm was established on the test bench to verify the overall performance of the sensitive element. The results showed that the stiffness of the sensitive element designed was moderate, grain collision signal amplitude was about 1.2 V and decay time was within 1s, which was easily separated from other signals generated from the glumes and the straws. The sensitive element not only had high resolution between grain and stems, but also measured the highest frequency of grain impact, which significantly improved the overall performance of grain cleaning loss sensor.
Key words: Grain cleaning loss, sensor array, sensitive element, elastic thin plate theory, structural parameters.