Finite Element Analysis on Steel-frame Designed for Self-propelled Tea Picker

The design of a steel-pipe frame for the self-propelled tea picker was subjected to a finite element analysis to determine its engineering durability. Statics of the design, as evaluated by ANSYS, showed a maximum stress of 27 Mpa and strain of 0.2 mm could be exerted on the welding at the top-left-rear corner of the frame. And, they were within the design tolerance. The vibration analysis on the design indicated that the 1^st, 2^nd and 5^th were in a bending mode, the 3^rd and 4^th a torsional mode, and the 6^th a bending-and-torsion mode. The principle frequencies of the modes were 18.021, 25.346, 31.636, 36.209, 45.892 and 51.694 Hz for the 1^st through the 6^th mode, respectively. The analysis also showed the sources of vibrations were 38.3～41.7 Hz coming from the engine, 20 Hz from the cutter, and 3 Hz or lower from the ground-surface friction. Thus, the vibrations would not likely to resonate with the 6 modes listed above to cause a concern for the mechanical integrity of the picker frame. Consequently, the design was considered safe and functional for the engineering requirements.