| Paddy soil is mainly composed of kinds of particles, lacuna and water, without external exc itation, they are in a mechanical equilibrium state. If given a continuous vibration, the balance of the soil will be broken, the soil will flow, so the particles can be isolated from the soil. Water chestnut harvest boat based on the princ iple of soil liquefaction is a machine that can mine, clean and pack water chestnut, overcome the shortcoming of artificial harvest which have a low efficiency and high labor intensity in China, greatly improving the effic iency of water chestnut harvest. Digger device is the key part of water chestnut harvesting boat, its key components are digging tooth, vibrating tooth, barrel, central shaft and eccentric block. Digger device can break the balance of soil through its own vibration, making the soil flow as well as isolating water chestnut from the soil to achieve the purpose of harvesting water chestnut. In order to reduce soil liquefaction time and improve the effic iency of water chestnut harvest, the working frequency of digger device must be within the range of liquefaction frequency,namely 80~150Hz to improve the soil liquefaction and shorten the time of soil liquefaction. So the vibration performance of digging machine has a direct influence on soil liquefaction and water chestnut harvest. Meanwhile, the vibration of digger device has a great impact on the boat, making it vibration, so it is very necessary to reduce the vibration, insure the harvest boat can work normally.Every component of digger device is built by Solid Works,then assembled to entity model, at last imported to ANSYS Workbench to conduct finite element analys is:First of all, the stress analys is of digging device is conducted, then the static analys is is conducted by ANSYS Workbench, the result shows that the static strength of the key components of digging device meet the requirements.Second, based on the static analys is, the modal analysis of digger device is conducted by ANSYS Workbench, obtaining its first six order natural frequenc ies and vibration mode By the modal superposition method, its harmonic response analys is is conducted, according to analytical result, within the liquefaction frequency, the working frequency of digger device is redefined, which is 90.7Hz, the eccentric block is redesigned.Third, the damping of digger device is researched, according to the new working frequency of digger device and damping theory, rubber material hardness is 76. And the static analysis of shock absorber is conducted by ANSYS Workbench, the result shows: the stiffness and strength of the rubber damper’s key components meet the requirements.At last, the finite element models of stiffness mistuning and mass mistuning of digger device are built, the mode localization phenomena caused by the stiffness and mass mistuning are analyzed. The result shows the tidy mistuning has a great influence on the modal shape of digger device, not only increas ing the maximum amplitude of digger tooth and vibration tooth and reducing their number, vibration focuses on a few teeth. In order to change the vibration characteristics of digger device, the deliberate mistuning model of digger device is built. The change of the vibration characteristic that caused by the wrong frequency disturbance is analyzed, the result shows the deliberate mistuning design does not make digger device shows the expected mode shape, but causes the mode localization. |
PDF Full Text Request