ACCELERATION ANALYSIS OF CROP CUTTING BY HIGH-SPEED PHOTOGRAPHY

A study was made of the use of photoinstrumentation as an aid in determining the proportion of soybean seed loss attributable to stem cutting, with a view toward improving the process for more efficient crop recovery. Soybean seed loss during harvesting may exceed 10% of the crop, mostly due to losses encountered at the combine cutterbar. Laboratory cutting analyzers were built that enabled cutting to be studied under controlled conditions of speed and blade-stem interaction. Both repetitive-flash (stroboscopic) still photography and Hycam motion-picture analysis were made of the cutting and pod-shattering process. Finite differencing and the Taylor's series expansion were used in the development of a computer program for the reduction of displacement vs elapsed time (or frame number) data from motion-picture records to provide velocity and acceleration graphical printouts. Shatter loss with single-impact cutting was found to be severe but declined gradually with increasing speed of knife up to 12,000 ft/min. At high blade speeds, stems were often subject to multiple cuts before severance. Seed loss was substantially lower for the multiple-cut stems where there was less transfer of energy along the stem. The lateral vibration of the stem was measurable on film and provided quantitative information on energy transfer into the stem.